ORCID Profile
0000-0001-7019-649X
Current Organisation
Australian National University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Astronomical and Space Sciences | Galactic Astronomy | Astronomy And Astrophysics | Cosmology and Extragalactic Astronomy | Astronomical and Space Instrumentation | Astrobiology | Stellar Astronomy and Planetary Systems | Atomic And Molecular Physics |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Physical sciences | Computer software and services not elsewhere classified | Expanding Knowledge in the Information and Computing Sciences | Higher education | Scientific instrumentation
Related Links
Publications
Gaia and Hubble Unveil the Kinematics of Stellar Populations in the Type II Globular Clusters ω Centauri and M22
Publisher: American Astronomical Society
Date: 03-08-2020
Accurate radial velocities using cross-correlation techniques and TV detector. I. The velocity dispersion of NGC 6397.
Publisher: American Astronomical Society
Date: 10-1977
DOI: 10.1086/112131
Magnesium Isotope Ratios in ω Centauri Red Giants
Publisher: American Astronomical Society
Date: 30-04-2013
S 5: Probing the Milky Way and Magellanic Clouds potentials with the 6D map of the Orphan–Chenab stream
Publisher: Oxford University Press (OUP)
Date: 20-02-2023
Abstract: We present a 6D map of the Orphan–Chenab (OC) stream by combining the data from Southern Stellar Stream Spectroscopic Survey (S5) and Gaia. We reconstruct the proper motion, radial velocity, distance, on-sky track, and stellar density along the stream with spline models. The stream has a total luminosity of MV = −8.2 and metallicity of [Fe/H] = −1.9, similar to classical Milky Way (MW) satellites like Draco. The stream shows drastic changes in its physical width varying from 200 pc to 1 kpc, but a constant line-of-sight velocity dispersion of 5 $\\mathrm{km\\, s^{-1}}$. Despite the large apparent variation in the stellar number density along the stream, the flow rate of stars along the stream is remarkably constant. We model the 6D stream track by a Lagrange-point stripping method with a flexible MW potential in the presence of a moving extended Large Magellanic Cloud (LMC). This allows us to constrain the mass profile of the MW within the distance range 15.6 & r & 55.5 kpc, with the best measured enclosed mass of $(2.85\\pm 0.1)\\times 10^{11}\\, \\mathrm{\\, M_\\odot }$ within 32.4 kpc. Our stream measurements are highly sensitive to the LMC mass profile with the most precise measurement of its enclosed mass made at 32.8 kpc, $(7.02\\pm 0.9)\\times 10^{10}\\, {\\rm M}_\\odot$. We also detect that the LMC dark matter halo extends to at least 53 kpc. The fitting of the OC stream allows us to constrain the past LMC trajectory and the degree of dynamical friction it experienced. We demonstrate that the stars in the OC stream show large energy and angular momentum spreads caused by LMC perturbation.
Metallicities for Old Stellar Systems from CA II Triplet Strengths in Member Giants
Publisher: American Astronomical Society
Date: 04-1991
DOI: 10.1086/115769
A Sr-rich Star on the Main Sequence of ω Centauri
Publisher: American Astronomical Society
Date: 05-12-2006
DOI: 10.1086/510530
A Chemical Signature from Fast-rotating Low-metallicity Massive Stars: ROA 276 in ω Centauri
Publisher: American Astronomical Society
Date: 16-03-2017
A Second Shell in the Fornax dSph Galaxy
Publisher: Cambridge University Press (CUP)
Date: 2005
DOI: 10.1071/AS04067
Abstract: In the search for tidal structure in Galactic satellite systems, we have conducted a photometric survey over a 10 deg 2 area centred on the Fornax dSph galaxy. The survey was made in two colours, and the resulting colour–magnitude data were used as a mask to select candidate Fornax RGB stars, thereby increasing the contrast of Fornax stars to background sources in the outer regions. Previously, we reported the presence of a shell (age 2 Gyr) located towards the centre of Fornax. In this contribution we reveal a second shell, significantly larger than the first, located 1.3° north-west from the centre of Fornax, outside the nominal tidal radius. Moreover, the distribution of Fornax RGB stars reveals two lobes extending to the spatial limit of our survey, and aligned with the minor axis and with the two shells. These results support the hypothesis of a merger between Fornax and a gas-rich companion approximately 2 Gyr ago.
Iron and s-elements abundance variations in NGC 5286: comparison with ‘anomalous' globular clusters and Milky Way satellites
Publisher: Oxford University Press (OUP)
Date: 04-2015
DOI: 10.1093/MNRAS/STV420
Segue 3: An Old, Extremely Low Luminosity Star Cluster in the Milky Way's Halo
Publisher: American Astronomical Society
Date: 16-08-2011
The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda VI
Publisher: American Astronomical Society
Date: 09-2002
DOI: 10.1086/341823
Commission 37: Star Clusters and Associations
Publisher: Cambridge University Press (CUP)
Date: 14-05-2010
DOI: 10.1017/S174392131000517X
Abstract: The business session for Commission 37 was held on 11 August 2009 at the IAU General Assembly in Rio de Janeiro. The meeting was attended by about a dozen members of our Comission, including President Elmegreen, VP Carraro and several committee members. We introduced ourselves and then went through a powerpoint presentation first prepared by outgoing President Hatzidimitriou and revised by incoming President Elmegreen. The contents of the powerpoint presentation are given in this summary.
A close look at the Centaurus A group of galaxies. II. Intermediate-age populations in early-type dwarfs
Publisher: EDP Sciences
Date: 11-05-2011
An investigation of C, N, and Na abundances in red giant stars of the Sculptor dwarf spheroidal galaxy
Publisher: Oxford University Press (OUP)
Date: 15-05-2019
DOI: 10.1093/MNRAS/STZ112
The star formation history of the Fornax dwarf spheroidal galaxy
Publisher: Cambridge University Press (CUP)
Date: 08-2010
DOI: 10.1017/S1743921310003200
Abstract: We present the first results of a comprehensive HST study of the star-formation history of Fornax dSph, based on WFPC2 imaging of 7 Fornax fields. Our observations reach the oldest main-sequence turnoffs, allowing us to address fundamental questions of dwarf galaxy evolution, such as the spatial variations in the stellar content, and whether the old stellar population is made up of stars formed in a very early burst or the result of a more continuous star formation.
PORTRAIT of A DARK HORSE: A PHOTOMETRIC and SPECTROSCOPIC STUDY of the ULTRA-FAINT MILKY WAY SATELLITE PEGASUS III
Publisher: American Astronomical Society
Date: 02-12-2016
Identification of Globular Cluster Stars in RAVE data II: Extended tidal debris around NGC 3201
Publisher: Oxford University Press (OUP)
Date: 06-02-2016
DOI: 10.1093/MNRAS/STW083
The Age of the Small Magellanic Cloud Globular Cluster NGC 411
Publisher: American Astronomical Society
Date: 06-1986
DOI: 10.1086/164241
The main-sequence turn off of the metal-rich globular cluster NGC 6171.
Publisher: American Astronomical Society
Date: 07-1984
DOI: 10.1086/162183
Probing the stellar halo of the milky way with the SEKBO RR Lyrae survey
Publisher: American Astronomical Society
Date: 09-08-2012
Metallicity Variations in the Type II Globular Cluster NGC 6934
Publisher: American Astronomical Society
Date: 25-05-2018
The Ca II triplet in red giant spectra: [Fe/H] determinations and the role of [Ca/Fe]
Publisher: Oxford University Press (OUP)
Date: 02-11-2016
Main-sequence photometry of the SMC globular cluster Kron 3.
Publisher: American Astronomical Society
Date: 11-1984
DOI: 10.1086/162627
The Evolution of Copper in the Globular Cluster ω Centauri
Publisher: American Astronomical Society
Date: 07-2002
DOI: 10.1086/340967
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda III
Publisher: American Astronomical Society
Date: 07-2002
DOI: 10.1086/340965
Exploring the Galaxy’s halo and very metal-weak thick disc with SkyMapper and Gaia DR2
Publisher: Oxford University Press (OUP)
Date: 04-11-2020
Abstract: In this work, we combine spectroscopic information from the SkyMapper survey for Extremely Metal-Poor stars and astrometry from Gaia DR2 to investigate the kinematics of a s le of 475 stars with a metallicity range of $-6.5 \le \rm [Fe/H] \le -2.05$ dex. Exploiting the action map, we identify 16 and 40 stars dynamically consistent with the Gaia Sausage and Gaia Sequoia accretion events, respectively. The most metal poor of these candidates have metallicities of $\rm [Fe/H]=-3.31\, \mathrm{ and }\, -3.74$, respectively, helping to define the low-metallicity tail of the progenitors involved in the accretion events. We also find, consistent with other studies, that ∼21 per cent of the s le have orbits that remain confined to within 3 kpc of the Galactic plane, that is, |Zmax| ≤ 3 kpc. Of particular interest is a subs le (∼11 per cent of the total) of low |Zmax| stars with low eccentricities and prograde motions. The lowest metallicity of these stars has [Fe/H] = –4.30 and the subs le is best interpreted as the very low-metallicity tail of the metal-weak thick disc population. The low |Zmax|, low eccentricity stars with retrograde orbits are likely accreted, while the low |Zmax|, high eccentricity pro- and retrograde stars are plausibly associated with the Gaia Sausage system. We find that a small fraction of our s le (∼4 per cent of the total) is likely escaping from the Galaxy, and postulate that these stars have gained energy from gravitational interactions that occur when infalling dwarf galaxies are tidally disrupted.
The radial velocity, velocity dispersion, and mass-to-light ratio of the Sculptor dwarf galaxy.
Publisher: American Astronomical Society
Date: 10-1986
DOI: 10.1086/114211
Hydrogen-helium inhomogeneities and the solar neutrino problem.
Publisher: Oxford University Press (OUP)
Date: 03-1975
Structured star formation in the Magellanic inter-Cloud region
Publisher: Oxford University Press (OUP)
Date: 12-08-2017
Stellar Substructures Around the Hercules Dwarf Spheroidal Galaxy
Publisher: American Astronomical Society
Date: 12-05-2015
Neutral hydrogen in early-type dwarf galaxies of the Sculptor Group
Publisher: Cambridge University Press (CUP)
Date: 03-2005
Globular clusters in the Sculptor group galaxy NGC 55.
Publisher: American Astronomical Society
Date: 10-1982
DOI: 10.1086/160319
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda II
Publisher: American Astronomical Society
Date: 02-2000
DOI: 10.1086/301223
The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda II
Publisher: American Astronomical Society
Date: 2004
DOI: 10.1086/380613
The GALAH survey: accreted stars also inhabit the Spite plateau
Publisher: Oxford University Press (OUP)
Date: 15-07-2021
Abstract: The European Space Agency (ESA) Gaia mission has enabled the remarkable discovery that a large fraction of the stars near the solar neighbourhood are debris from a single in-falling system, the so-called Gaia-Sausage-Enceladus (GSE). This discovery provides astronomers for the first time with a large cohort of easily observable, unevolved stars that formed in a single extragalactic environment. Here we use these stars to investigate the ‘Spite plateau’ – the near-constant lithium abundance observed in unevolved metal-poor stars across a wide range of metallicities (−3 & [Fe/H] & −1). Our aim is to test whether in idual galaxies could have different Spite plateaus – e.g. the interstellar medium could be more depleted in lithium in a lower galactic mass system due to it having a smaller reservoir of gas. We identified 93 GSE dwarf stars observed and analysed by the GALactic Archaeology with HERMES (GALAH) survey as part of its Data Release 3 (DR3). Orbital actions were used to select s les of GSE stars, and comparison s les of halo and disc stars. We find that the GSE stars show the same lithium abundance as other likely accreted stars and in situ Milky Way stars. Formation environment leaves no imprint on lithium abundances. This result fits within the growing consensus that the Spite plateau, and more generally the ‘cosmological lithium problem’ – the observed discrepancy between the amount of lithium in warm, metal-poor dwarf stars in our Galaxy, and the amount of lithium predicted to have been produced by big bang nucleosynthesis – is the result of lithium depletion processes within stars.
The GALAH survey: co-orbiting stars and chemical tagging
Publisher: Oxford University Press (OUP)
Date: 10-11-2018
FORS2/VLT survey of Milky Way globular clusters. II. Fe and Mg abundances of 51 Milky Way globular clusters on a homogeneous scale
Publisher: EDP Sciences
Date: 28-04-2016
Hubble Space Telescope Photometry of the Metal-rich Globular Clusters NGC 6624 and NGC 6637
Publisher: American Astronomical Society
Date: 08-2000
DOI: 10.1086/301461
The Magellanic Edges Survey – IV. Complex tidal debris in the SMC outskirts
Publisher: Oxford University Press (OUP)
Date: 18-10-2022
Abstract: We use data from the Magellanic Edges Survey (MagES) in combination with Gaia EDR3 to study the extreme southern outskirts of the Small Magellanic Cloud (SMC), focussing on a field at the eastern end of a long arm-like structure which wraps around the southern periphery of the Large Magellanic Cloud (LMC). Unlike the remainder of this structure, which is thought to be comprised of perturbed LMC disc material, the aggregate properties of the field indicate a clear connection with the SMC. We find evidence for two stellar populations in the field: one having properties consistent with the outskirts of the main SMC body, and the other significantly perturbed. The perturbed population is on average ∼0.2 dex more metal-rich, and is located ∼7 kpc in front of the dominant population with a total space velocity relative to the SMC centre of ∼230 km s−1 broadly in the direction of the LMC. We speculate on possible origins for this perturbed population, the most plausible of which is that it comprises debris from the inner SMC that has been recently tidally stripped by interactions with the LMC.
The closest extremely low-mass white dwarf to the Sun
Publisher: Oxford University Press (OUP)
Date: 24-04-2020
Abstract: We present the orbit and properties of 2MASS J050051.85−093054.9, establishing it as the closest (d ≈ 71 pc) extremely low-mass white dwarf to the Sun. We find that this star is hydrogen rich with $T_\\textrm {eff}\\approx 10\\, 500$ K, log g ≈ 5.9, and, following evolutionary models, has a mass of ≈0.17 M⊙. Independent analysis of radial velocity and Transiting Exoplanet Survey Satellite(TESS) photometric time series reveals an orbital period of ≈9.5 h. Its high velocity litude ($K\\approx 144~\\textrm {km}\\, \\textrm {s}^{-1}$) produces a measurable Doppler beaming effect in the TESSlight curve with an litude of 1 mmag. The unseen companion is most likely a faint white dwarf. J0500−0930 belongs to a class of post-common envelope systems that will most likely merge through unstable mass transfer and in specific circumstances lead to Type Ia supernova explosions.
The SkyMapper DR1.1 search for extremely metal-poor stars
Publisher: Oxford University Press (OUP)
Date: 12-09-2019
Abstract: We present and discuss the results of a search for extremely metal-poor stars based on photometry from data release DR1.1 of the SkyMapper imaging survey of the southern sky. In particular, we outline our photometric selection procedures and describe the low-resolution (R ≈ 3000) spectroscopic follow-up observations that are used to provide estimates of effective temperature, surface gravity, and metallicity ([Fe/H]) for the candidates. The selection process is very efficient: of the 2618 candidates with low-resolution spectra that have photometric metallicity estimates less than or equal to −2.0, 41 per cent have [Fe/H] ≤ −2.75 and only approximately seven per cent have [Fe/H] −2.0 dex. The most metal-poor candidate in the s le has [Fe/H] −4.75 and is notably carbon rich. Except at the lowest metallicities ([Fe/H] −4), the stars observed spectroscopically are dominated by a ‘carbon-normal’ population with [C/Fe]1D, LTE ≤ +1 dex. Consideration of the A(C)1D, LTE versus [Fe/H]1D, LTE diagram suggests that the current selection process is strongly biased against stars with A(C)1D, LTE 7.3 (predominantly CEMP-s) while any bias against stars with A(C)1D, LTE 7.3 and [C/Fe]1D,LTE +1 (predominantly CEMP-no) is not readily quantifiable given the uncertainty in the SkyMapper v-band DR1.1 photometry. We find that the metallicity distribution function of the observed s le has a power-law slope of Δ(Log N)/Δ[Fe/H] = 1.5 ± 0.1 dex per dex for −4.0 ≤ [Fe/H] ≤ −2.75, but appears to drop abruptly at [Fe/H] ≈ −4.2, in line with previous studies.
Ancient Stars Beyond the Local Group: RR Lyrae Variables and Blue Horizontal Branch Stars in Sculptor Group Dwarf Galaxies
Publisher: American Astronomical Society
Date: 22-12-2010
Deriving metallicities from calcium triplet spectroscopy in combination with near-infrared photometry
Publisher: EDP Sciences
Date: 03-2014
High-resolution spectroscopic follow-up of the most metal-poor candidates from SkyMapper DR1.1
Publisher: Oxford University Press (OUP)
Date: 15-07-2021
Abstract: We present chemical abundances for 21 elements (from Li to Eu) in 150 metal-poor Galactic stars spanning −4.1 & [Fe/H] & −2.1. The targets were selected from the SkyMapper survey and include 90 objects with [Fe/H] ≤ −3 of which some 15 have [Fe/H] ≤ −3.5. When combining the s le with our previous studies, we find that the metallicity distribution function has a power-law slope of Δ(log N)/Δ[Fe/H] = 1.51 ± 0.01 dex per dex over the range −4 ≤ [Fe/H] ≤ −3. With only seven carbon-enhanced metal-poor stars in the s le, we again find that the selection of metal-poor stars based on SkyMapper filters is biased against highly carbon-rich stars for [Fe/H] & −3.5. Of the 20 objects for which we could measure nitrogen, 11 are nitrogen-enhanced metal-poor (NEMP) stars. Within our s le, the high NEMP fraction (55 per cent ± 21 per cent) is compatible with the upper range of predicted values (between 12 per cent and 35 per cent). The chemical abundance ratios [X/Fe] versus [Fe/H] exhibit similar trends to previous studies of metal-poor stars and Galactic chemical evolution models. We report the discovery of nine new r-I stars, four new r-II stars, one of which is the most metal-poor known, nine low-α stars with [α/Fe] ≤ 0.15 as well as one unusual star with [Zn/Fe] = +1.4 and [Sr/Fe] = +1.2 but with normal [Ba/Fe]. Finally, we combine our s le with literature data to provide the most extensive view of the early chemical enrichment of the Milky Way Galaxy.
The Giant Branch of omega Centauri. IV. Abundance Patterns Based on Echelle Spectra of 40 Red Giants
Publisher: American Astronomical Society
Date: 07-1995
DOI: 10.1086/175909
The Age of the Large Magellanic Cloud Globular Cluster NGC 2173
Publisher: American Astronomical Society
Date: 10-1986
DOI: 10.1086/164575
Abundances and Kinematics of the Globular Cluster Systems of the Galaxy and of the Sagittarius Dwarf
Publisher: American Astronomical Society
Date: 06-1995
DOI: 10.1086/117469
The intermediate age SMC globular cluster Lindsay 113.
Publisher: American Astronomical Society
Date: 05-1984
DOI: 10.1086/162031
The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge
Publisher: Oxford University Press (OUP)
Date: 05-11-2014
The EMBLA survey – metal-poor stars in the Galactic bulge
Publisher: Oxford University Press (OUP)
Date: 29-04-2016
Commission 37: Star Clusters and Associations
Publisher: Cambridge University Press (CUP)
Date: 12-2007
DOI: 10.1017/S1743921308024009
Abstract: The Commission business meeting was held on 17 August 2006. Approximately 20 people attended, including the Commission vice-president, Rainer Spurzem. The sole member of the Commission Organizing Committee that was present was Gary Da Costa, who, along with Patricia Whitelock, the outgoing president of Division VII and Commission 33, served as chairs of the meeting.
Commission 37: Star Clusters
Publisher: Cambridge University Press (CUP)
Date: 12-2007
DOI: 10.1017/S1743921306004698
Abstract: During the period 2004 to 2005, the following symposia and colloquia were related to the activities of the commission: The A-Star Puzzle (IAUS224), Massive Star Birth: A Crossroads of Astrophysics (IAUS227), and From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution (IAUS228).
The Dynamics of the Outer Parts of ω Centauri
Publisher: American Astronomical Society
Date: 27-04-2012
The Host Galaxy of Quasar IRAS 00275-2859: an Interacting System
Publisher: American Astronomical Society
Date: 10-1987
DOI: 10.1086/114518
Discovery of a Faint Outer Halo Milky Way Star Cluster in the Southern Sky
Publisher: American Astronomical Society
Date: 16-04-2015
The Southern Stellar Stream Spectroscopic Survey (S5): Chemical Abundances of Seven Stellar Streams
Publisher: American Astronomical Society
Date: 24-09-2020
Dynamics in the outskirts of four Milky Way globular clusters: it’s the tides that dominate
Publisher: Oxford University Press (OUP)
Date: 08-12-2022
Abstract: We present the results of a spectroscopic survey of the outskirts of four globular – 1261, NGC 4590, NGC 1904, and NGC 1851 – covering targets within 1° from the cluster centres, with 2dF/AAOmega on the Anglo-Australian Telescope (AAT) and FLAMES on the very large telescope (VLT). We extracted chemo-dynamical information for in idual stars, from which we estimated the velocity dispersion profile and the rotation of each cluster. The observations are compared to direct N-body simulations and appropriate limepy/spes models for each cluster to interpret the results. In NGC 1851, the detected internal rotation agrees with existing literature, and NGC 1261 shows some rotation signal beyond the truncation radius, likely coming from the escaped stars. We find that the dispersion profiles for both the observations and the simulations for NGC 1261, NGC 1851, and NGC 1904 do not decrease as the limepy/spes models predict beyond the truncation radius, where the N-body simulations show that escaped stars dominate the dispersion profile of NGC 4590 follows the predictions of the limepy/spes models, though the data do not effectively extend beyond the truncation radius. The increasing/flat dispersion profiles in the outskirts of NGC 1261, NGC 1851, and NGC 1904, are reproduced by the simulations. Hence, the increasing/flat dispersion profiles of the clusters in question can be explained by the tidal interaction with the galaxy without introducing dark matter.
The Age of the Large Magellanic Cloud Cluster NGC 2193
Publisher: American Astronomical Society
Date: 10-1987
DOI: 10.1086/165666
Clarification of the Nature of the Galaxy [CFC97] Cen 05
Publisher: IOP Publishing
Date: 11-2004
DOI: 10.1086/426123
Nucleosynthesis in a Primordial Supernova: Carbon and Oxygen Abundances in SMSS J031300.36-670839.3
Publisher: American Astronomical Society
Date: 08-06-2015
Discovery of a nearby 1700 km s−1 star ejected from the Milky Way by Sgr A*
Publisher: Oxford University Press (OUP)
Date: 04-11-2019
Abstract: We present the serendipitous discovery of the fastest main-sequence hyper-velocity star (HVS) by the Southern Stellar Stream Spectroscopic Survey (S5). The star S5-HVS1 is a ∼2.35 M⊙ A-type star located at a distance of ∼9 kpc from the Sun and has a heliocentric radial velocity of 1017 ± 2.7 $\\mathrm{\\, km\\, s^{-1}}$ without any signature of velocity variability. The current 3D velocity of the star in the Galactic frame is 1755 ± 50 $\\mathrm{\\, km\\, s^{-1}}$. When integrated backwards in time, the orbit of the star points unambiguously to the Galactic Centre, implying that S5-HVS1 was kicked away from Sgr A* with a velocity of ∼1800 $\\mathrm{\\, km\\, s^{-1}}$ and travelled for 4.8 Myr to its current location. This is so far the only HVS confidently associated with the Galactic Centre. S5-HVS1 is also the first hyper-velocity star to provide constraints on the geometry and kinematics of the Galaxy, such as the Solar motion Vy,⊙ = 246.1 ± 5.3 $\\mathrm{\\, km\\, s^{-1}}$ or position R0 = 8.12 ± 0.23 kpc. The ejection trajectory and transit time of S5-HVS1 coincide with the orbital plane and age of the annular disc of young stars at the Galactic Centre, and thus may be linked to its formation. With the S5-HVS1 ejection velocity being almost twice the velocity of other hyper-velocity stars previously associated with the Galactic Centre, we question whether they have been generated by the same mechanism or whether the ejection velocity distribution has been constant over time.
Stellar overdensities in the halo: the extent of the Virgo overdensity
Publisher: Oxford University Press (OUP)
Date: 04-2009
An HST study of the supernovae accompanying GRB 040924 and GRB 041006
Publisher: American Astronomical Society
Date: 2006
DOI: 10.1086/498009
Dwarf Elliptical Galaxies in the M81 Group: The Structure and Stellar Populations of BK5N and F8D1
Publisher: American Astronomical Society
Date: 02-1998
DOI: 10.1086/300233
The lowest detected stellar Fe abundance: the halo star SMSS J160540.18-144323.1
Publisher: Oxford University Press (OUP)
Date: 17-07-2019
Abstract: We report the discovery of SMSS J160540.18−144323.1, a new ultra metal-poor halo star discovered with the SkyMapper telescope. We measure $\\left[\\rm {Fe}/\\rm {H}\\right]= -6.2 \\pm 0.2$ (1D LTE), the lowest ever detected abundance of iron in a star. The star is strongly carbon-enhanced, $\\left[\\rm {C}/\\rm {Fe}\\right] = 3.9 \\pm 0.2$, while other abundances are compatible with an α-enhanced solar-like pattern with $\\left[\\rm {Ca}/\\rm {Fe}\\right] = 0.4 \\pm 0.2$, $\\left[\\rm {Mg}/\\rm {Fe}\\right] = 0.6 \\pm 0.2$, $\\left[\\rm {Ti}/\\rm {Fe}\\right] = 0.8 \\pm 0.2$, and no significant s- or r-process enrichment, $\\left[\\rm {Sr}/\\rm {Fe}\\right] \\lt 0.2$ and $\\left[\\rm {Ba}/\\rm {Fe}\\right] \\lt 1.0$ (3σ limits). Population III stars exploding as fallback supernovae may explain both the strong carbon enhancement and the apparent lack of enhancement of odd-Z and neutron-capture element abundances. Grids of supernova models computed for metal-free progenitor stars yield good matches for stars of about $10\\, \\rm M_\\odot$ imparting a low kinetic energy on the supernova ejecta, while models for stars more massive than roughly $20\\, \\rm M_\\odot$ are incompatible with the observed abundance pattern.
The Age-Metallicity Relation of the SMC
Publisher: Springer Berlin Heidelberg
Date: 2009
Loophole-free Bell inequality violation with superconducting circuits
Publisher: Springer Science and Business Media LLC
Date: 10-05-2023
DOI: 10.1038/S41586-023-05885-0
Abstract: Superposition, entanglement and non-locality constitute fundamental features of quantum physics. The fact that quantum physics does not follow the principle of local causality 1–3 can be experimentally demonstrated in Bell tests 4 performed on pairs of spatially separated, entangled quantum systems. Although Bell tests, which are widely regarded as a litmus test of quantum physics, have been explored using a broad range of quantum systems over the past 50 years, only relatively recently have experiments free of so-called loopholes 5 succeeded. Such experiments have been performed with spins in nitrogen–vacancy centres 6 , optical photons 7–9 and neutral atoms 10 . Here we demonstrate a loophole-free violation of Bell’s inequality with superconducting circuits, which are a prime contender for realizing quantum computing technology 11 . To evaluate a Clauser–Horne–Shimony–Holt-type Bell inequality 4 , we deterministically entangle a pair of qubits 12 and perform fast and high-fidelity measurements 13 along randomly chosen bases on the qubits connected through a cryogenic link 14 spanning a distance of 30 metres. Evaluating more than 1 million experimental trials, we find an average S value of 2.0747 ± 0.0033, violating Bell’s inequality with a P value smaller than 10 −108 . Our work demonstrates that non-locality is a viable new resource in quantum information technology realized with superconducting circuits with potential applications in quantum communication, quantum computing and fundamental physics 15 .
Abundances on the Main Sequence of ω Centauri
Publisher: American Astronomical Society
Date: 10-2007
DOI: 10.1086/520794
A high-resolution spectroscopic search for multiple populations in the 2 Gyr old cluster NGC 1846
Publisher: Oxford University Press (OUP)
Date: 05-12-2023
Abstract: We present detailed C, O, Na, Mg, Si, Ca, Ti, V, Fe, Zr, Ba, and Eu abundance measurements for 20 red giant branch (RGB) stars in the Large Magellanic Cloud (LMC) star cluster NGC 1846 ([Fe/H] = −0.59). This cluster is 1.95 Gyr old and lies just below the supposed lower age limit (2 Gyr) for the presence of multiple populations in massive star clusters. Our measurements are based on high- and low-resolution VLT/FLAMES spectra combined with photometric data from Hubble Space Telescope (HST). Corrections for non-local thermodynamic equilibrium effects are also included for O, Na, Mg, Si, Ca, Fe, and Ba. Our results show that there is no evidence for multiple populations in this cluster based on the lack of any intrinsic star-to-star spread in the abundances of Na and O: We place 95 per cent confidence limits on the intrinsic dispersion for these elements of ≤0.07 and ≤0.09 dex, respectively. However, we do detect a significant spread in the carbon abundances, indicating varying evolutionary mixing occurring on the RGB that increases with luminosity. Overall, the general abundance patterns for NGC 1846 are similar to those seen in previous studies of intermediate-age LMC star clusters and field stars.
The structure and stellar content of globular clusters. I. Surface-brightness profiles for four southern clusters.
Publisher: American Astronomical Society
Date: 04-1979
DOI: 10.1086/112443
Commission 37: Star Clusters and Associations
Publisher: Cambridge University Press (CUP)
Date: 12-2012
A VLT/FLAMES Study of the Peculiar Intermediate-age Large Magellanic Cloud Star Cluster NGC 1846. I. Kinematics
Publisher: American Astronomical Society
Date: 14-12-2013
The anticorrelation of cyanogen and CH on the giant branch of 47 Tucanae.
Publisher: American Astronomical Society
Date: 02-1984
DOI: 10.1086/161732
Young Clusters in the Magellanic Clouds. II.
Publisher: American Astronomical Society
Date: 02-2001
DOI: 10.1086/318741
r-Process elements from magnetorotational hypernovae
Publisher: Springer Science and Business Media LLC
Date: 07-07-2021
DOI: 10.1038/S41586-021-03611-2
Abstract: Neutron-star mergers were recently confirmed as sites of rapid-neutron-capture (r-process) nucleosynthesis
Multiple stellar populations in Magellanic Cloud clusters - IV. The double main sequence of the young cluster NGC 1755
Publisher: Oxford University Press (OUP)
Date: 15-03-2016
DOI: 10.1093/MNRAS/STW608
Detection of Neutral Hydrogen in Early-Type Dwarf Galaxies of the Sculptor Group
Publisher: American Astronomical Society
Date: 11-2005
DOI: 10.1086/496977
Derivation and validation of a clinical prediction model for risk-stratification of children hospitalized with severe pneumonia in Bangladesh
Publisher: Public Library of Science (PLoS)
Date: 08-2023
DOI: 10.1371/JOURNAL.PGPH.0002216
Abstract: Children with severe pneumonia in low- and middle-income countries (LMICs) suffer from high rates of treatment failure despite appropriate World Health Organization (WHO)-directed antibiotic treatment. Developing a clinical prediction rule for treatment failure may allow early identification of high-risk patients and timely intervention to decrease mortality. We used data from two separate studies conducted at the Dhaka Hospital of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b) to derive and externally validate a clinical prediction rule for treatment failure of children hospitalized with severe pneumonia. The derivation dataset was from a randomized clinical trial conducted from 2018 to 2019, studying children aged 2 to 59 months hospitalized with severe pneumonia as defined by WHO. Treatment failure was defined by the persistence of danger signs at the end of 48 hours of antibiotic treatment or the appearance of any new danger signs within 24 hours of enrollment. We built a random forest model to identify the top predictors. The top six predictors were the presence of grunting, room air saturation, temperature, the presence of lower chest wall indrawing, the presence of respiratory distress, and central cyanosis. Using these six predictors, we created a parsimonious model with a discriminatory performance of 0.691, as measured by area under the receiving operating curve (AUC). We performed external validation using a temporally distinct dataset from a cohort study of 191 similarly aged children with severe acute malnutrition and pneumonia. In external validation, discriminatory performance was maintained with an improved AUC of 0.718. In conclusion, we developed and externally validated a parsimonious six-predictor model using random forest methods to predict treatment failure in young children with severe pneumonia in Bangladesh. These findings can be used to further develop and validate parsimonious and pragmatic prognostic clinical prediction rules for pediatric pneumonia, particularly in LMICs.
NGC 6366: The Most Metal-Rich Halo Globular Cluster?
Publisher: American Astronomical Society
Date: 02-1989
DOI: 10.1086/114990
The abundance spread in the giants of NGC 6752.
Publisher: American Astronomical Society
Date: 02-1981
DOI: 10.1086/158698
Standard Globular Cluster Giant Branches in the (M(I), (V - I)o) Plane
Publisher: American Astronomical Society
Date: 07-1990
DOI: 10.1086/115500
A 10 kpc stellar substructure at the edge of the Large Magellanic Cloud: perturbed outer disc or evidence for tidal stripping?
Publisher: Oxford University Press (OUP)
Date: 14-03-2016
DOI: 10.1093/MNRAS/STW497
The halo+cluster system of the Galactic globular cluster NGC 1851★
Publisher: Oxford University Press (OUP)
Date: 28-06-2014
Gemini/GMOS photometry of intermediate-age star clusters in the Large Magellanic Cloud
Publisher: Oxford University Press (OUP)
Date: 28-08-2014
SMC in space and time: a project to study the evolution of the prototype interacting late-type dwarf galaxy
Publisher: Cambridge University Press (CUP)
Date: 06-2008
DOI: 10.1017/S1743921308025118
Abstract: We introduce the SMC in space and time , a large coordinated space and ground-based program to study star formation processes and history, as well as variable stars, structure, kinematics and chemical evolution of the whole SMC. Here, we present the Colour-Magnitude Diagrams (CMDs) resulting from HST/ACS photometry, aimed at deriving the star formation history (SFH) in six fields of the SMC. The fields are located in the central regions, in the stellar halo, and in the wing toward the LMC. The CMDs are very deep, well beyond the oldest Main Sequence Turn-Off, and will allow us to derive the SFH over the entire Hubble time.
[CLC]Ca[/CLC] [CSC]ii[/CSC] Triplet Spectroscopy of Giants in Small Magellanic Cloud Star Clusters: Abundances, Velocities, and the Age-Metallicity Relation
Publisher: American Astronomical Society
Date: 05-1998
DOI: 10.1086/300340
Upper GI bleeding in rural Australia: general surgery still alive and well!
Publisher: Wiley
Date: 12-04-2023
DOI: 10.1111/ANS.18454
Abstract: The complex and critically unwell upper gastrointestinal bleeding (UGIB) patient is a common emergency presentation in Australia. Managed medically and endoscopically by rural general surgeons in rural and remote Australian hospitals which lack a gastroenterology service, this can be ameliorated by clear evidence‐based guidelines. A single‐centre retrospective review of adult patients who underwent emergency gastroscopy for UGIB at the Mackay Base Hospital, January 2019 to January 2022. Detailed patient data from the assessment, resuscitation, time to endoscopy, endoscopic intervention, and outcomes were compared against key international gastroenterology society safety and quality standards for UGIB. Two hundred patients had a comprehensive initial assessment and resuscitation with PRBC (39%), anticoagulation reversal (18%), pantoprazole infusion (81%), tranexamic acid (10.50%) and octreotide (16.50%). Risk scores were calculated retrospectively as none were documented. Time‐to‐endoscopy targets were achieved in over 70% of variceal or non‐variceal UGIB patients. Bleeding was found in 59.50% of patients but 63% of patients did not require a manoeuvre to stop the bleeding. Post‐operative complications were scarce. This study reflects on the need for a local multidisciplinary protocol to help expedite the current high‐quality healthcare delivered by rural general surgeons in managing patients with UGIB. Implementing risk assessment scores would shorten the time to endoscopy in the initial assessment Guidelines would optimize resuscitation ensuring appropriate replacement, medication administration, anticoagulation reversal, and preventing unnecessary therapy. Despite these nuisances, the time to endoscopy, endoscopic intervention, and patient outcomes were largely in line with international quality assurance and safety targets.
Kinematics of Antlia 2 and Crater 2 from the Southern Stellar Stream Spectroscopic Survey (S 5)
Publisher: American Astronomical Society
Date: 28-10-2021
Hunting the Parent of the Orphan Stream. II. The First High-resolution Spectroscopic Study
Publisher: American Astronomical Society
Date: 27-02-2014
Evidence of globular cluster abundance anomalies in the SMC intermediate-age cluster Kron 3
Publisher: Oxford University Press (OUP)
Date: 21-06-2022
Abstract: Using spectra obtained with the VLT/FORS2 and Gemini-S/GMOS-S instruments, we have investigated carbon, nitrogen, and sodium abundances in a s le of red giant members of the Small Magellanic Cloud star cluster Kron 3. The metallicity and luminosity of the cluster are comparable to those of Galactic globular clusters but it is notably younger (age ≈ 6.5 Gyr). We have measured the strengths of the CN and CH molecular bands, finding a bimodal CN band-strength distribution and a CH/CN anticorrelation. Application of spectrum synthesis techniques reveals that the difference in the mean [N/Fe] and [C/Fe] values for the CN-strong and CN-weak stars are Δ & [N/Fe]& = 0.63 ± 0.16 dex and Δ & [C/Fe]& = −0.01 ± 0.07 dex after applying corrections for evolutionary mixing. We have also measured sodium abundances from the Na D lines finding an observed range in [Na/Fe] of ∼0.6 dex that correlates positively with the [N/Fe] values and a Δ & [Na/Fe]& = 0.12 ± 0.12 dex. While the statistical significance of the sodium abundance difference is not high, the observed correlation between the Na and N abundances supports its existence. The outcome represents the first star-by-star demonstration of correlated abundance variations involving sodium in an intermediate-age star cluster. The results add to existing photometric and spectroscopic indications of the presence of multiple populations in intermediate-age clusters with masses in excess of ∼105 M⊙. It confirms that the mechanism(s) responsible for the multiple populations in ancient globular clusters cannot solely be an early cosmological effect applying only in old clusters.
FORS2/VLT survey of Milky Way globular clusters. I. Description of the method for derivation of metal abundances in the optical and application to NGC 6528, NGC 6553, M 71, NGC 6558, NGC 6426, and Terzan 8
Publisher: EDP Sciences
Date: 10-12-2015
The outer envelopes of globular clusters. II. NGC 1851, NGC 5824 and NGC 1261*
Publisher: Oxford University Press (OUP)
Date: 12-09-2018
Substructures and Tidal Distortions in the Magellanic Stellar Periphery
Publisher: American Astronomical Society
Date: 11-05-2018
The GALAH+ survey: Third data release
Publisher: Oxford University Press (OUP)
Date: 06-05-2021
Abstract: The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678 423 spectra for 588 571 mostly nearby stars (81.2 per cent of stars are within & kpc), observed with the HERMES spectrograph at the Anglo-Australian Telescope. This release (hereafter GALAH+ DR3) includes all observations from GALAH Phase 1 (bright, main, and faint survey, 70 per cent), K2-HERMES (17 per cent), TESS-HERMES (5 per cent), and a subset of ancillary observations (8 per cent) including the bulge and & stellar clusters. We derive stellar parameters Teff, log g, [Fe/H], vmic, vbroad, and vrad using our modified version of the spectrum synthesis code Spectroscopy Made Easy (sme) and 1D marcs model atmospheres. We break spectroscopic degeneracies in our spectrum analysis with astrometry from Gaia DR2 and photometry from 2MASS. We report abundance ratios [X/Fe] for 30 different elements (11 of which are based on non-LTE computations) covering five nucleosynthetic pathways. We describe validations for accuracy and precision, flagging of peculiar stars/measurements and recommendations for using our results. Our catalogue comprises 65 per cent dwarfs, 34 per cent giants, and 1 per cent other/unclassified stars. Based on unflagged chemical composition and age, we find 62 per cent young low-$\\alpha$, 9 per cent young high-$\\alpha$, 27 per cent old high-$\\alpha$, and 2 per cent stars with [Fe/H] ≤ −1. Based on kinematics, 4 per cent are halo stars. Several Value-Added-Catalogues, including stellar ages and dynamics, updated after Gaia eDR3, accompany this release and allow chrono-chemodynamic analyses, as we showcase.
The Age of the Large Magellanic Cloud Cluster NGC 1953
Publisher: American Astronomical Society
Date: 10-1993
DOI: 10.1086/173260
The Chemistry of the Trailing Arm of the Sagittarius Dwarf Galaxy
Publisher: American Astronomical Society
Date: 13-08-2010
The M31 Dwarf Spheroidal Companion Andromeda V: g', r', and i' Imaging with the Gemini Multi-Object Spectrograph on Gemini North
Publisher: American Astronomical Society
Date: 08-2002
DOI: 10.1086/341645
Keck HIRES spectroscopy of SkyMapper commissioning survey candidate extremely metal-poor stars
Publisher: Oxford University Press (OUP)
Date: 07-03-2019
DOI: 10.1093/MNRAS/STZ645
Abstract: We present results from the analysis of high-resolution spectra obtained with the Keck HIRES spectrograph for a s le of 17 candidate extremely metal-poor (EMP) stars originally selected from commissioning data obtained with the SkyMapper telescope. Fourteen of the stars have not been observed previously at high dispersion. Three have [Fe/H] ≤ −3.0, while the remainder, with two more metal-rich exceptions, have −3.0 ≤ [Fe/H] ≤ −2.0 dex. Apart from Fe, we also derive abundances for the elements C, N, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, and Zn, and for n-capture elements Sr, Ba, and Eu. None of the current s le of stars is found to be carbon-rich. In general, our chemical abundances follow previous trends found in the literature, although we note that two of the most metal-poor stars show very low [Ba/Fe] (∼−1.7) coupled with low [Sr/Ba] (∼−0.3). Such stars are relatively rare in the Galactic halo. One further star, and possibly two others, meet the criteria for classification as a r-I star. This study, together with that of Jacobson et al. (2015), completes the outcomes of the SkyMapper commissioning data survey for EMP stars.
Shell Structure in the Fornax Dwarf Spheroidal Galaxy
Publisher: American Astronomical Society
Date: 02-2004
DOI: 10.1086/381298
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda I
Publisher: American Astronomical Society
Date: 12-1996
DOI: 10.1086/118204
Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way
Publisher: Springer Science and Business Media LLC
Date: 11-2015
DOI: 10.1038/NATURE15747
Abstract: The first stars are predicted to have formed within 200 million years after the Big Bang, initiating the cosmic dawn. A true first star has not yet been discovered, although stars with tiny amounts of elements heavier than helium ('metals') have been found in the outer regions ('halo') of the Milky Way. The first stars and their immediate successors should, however, preferentially be found today in the central regions ('bulges') of galaxies, because they formed in the largest over-densities that grew gravitationally with time. The Milky Way bulge underwent a rapid chemical enrichment during the first 1-2 billion years, leading to a dearth of early, metal-poor stars. Here we report observations of extremely metal-poor stars in the Milky Way bulge, including one star with an iron abundance about 10,000 times lower than the solar value without noticeable carbon enhancement. We confirm that most of the metal-poor bulge stars are on tight orbits around the Galactic Centre, rather than being halo stars passing through the bulge, as expected for stars formed at redshifts greater than 15. Their chemical compositions are in general similar to typical halo stars of the same metallicity although intriguing differences exist, including lower abundances of carbon.
M22: An [Fe/H] Abundance Range Revealed
Publisher: American Astronomical Society
Date: 21-10-2009
THE GLOBULAR CLUSTER SYSTEM OF THE MILKY WAY: ACCRETION IN A COSMOLOGICAL CONTEXT
Publisher: American Astronomical Society
Date: 13-12-2011
Multiple populations in globular clusters and their parent galaxies
Publisher: Oxford University Press (OUP)
Date: 26-10-2020
Abstract: The ‘chromosome map’ diagram (ChM) proved a successful tool to identify and characterize multiple populations (MPs) in 59 Galactic globular clusters (GCs). Here, we construct ChMs for 11 GCs of both Magellanic Clouds (MCs) and with different ages to compare MPs in Galactic and extragalactic environments, and explore whether this phenomenon is universal through ‘place’ and ‘time’. MPs are detected in five clusters. The fractions of 1G stars, ranging from ∼50 per cent to & per cent, are significantly higher than those observed in Galactic GCs with similar present-day masses. By considering both Galactic and MC clusters, the fraction of 1G stars exhibits: (i) a strong anticorrelation with the present-day mass, and (ii) with the present-day mass of 2G stars (iii) a mild anticorrelation with 1G present-day mass. All Galactic clusters without MPs have initial masses smaller than ∼1.5 · 105 M⊙ but a mass threshold governing the occurrence of MPs seems challenged by massive simple-population MC GCs (iv) Milky Way clusters with large perigalactic distances typically host larger fractions of 1G stars, but the difference disappears when we use initial cluster masses. These facts are consistent with a scenario where the stars lost by GCs mostly belong to the 1G. By exploiting recent work based on Gaia, half of the known Type II GCs appear clustered in a distinct region of the integral of motions space, thus suggesting a common progenitor galaxy. Except for these Type II GCs, we do not find any significant difference in the MPs between clusters associated with different progenitors.
Structural Parameters of Seven Small Magellanic Cloud Intermediate-Age and Old Star Clusters
Publisher: American Astronomical Society
Date: 10-2009
The Blue Stragglers of Omega Centauri
Publisher: American Astronomical Society
Date: 09-1986
DOI: 10.1086/164547
Efficacy of a Green Banana–Mixed Diet in the Management of Persistent Diarrhea: Protocol for an Open-Labeled, Randomized Controlled Trial
Publisher: No publisher found
Date: 2020
DOI: 10.2196/15759
The scientific potential for astronomy from the Antarctic Plateau
Publisher: Cambridge University Press (CUP)
Date: 08-1994
DOI: 10.1017/S1323358000019809
Abstract: Our knowledge of the universe comes from recording the photon and particle fluxes incident on the Earth from space. We thus require sensitive measurement across the entire energy spectrum, using large telescopes with efficient instrumentation located on superb sites. Technological advances and engineering constraints are nearing the point where we are recording as many photons arriving at a site as is possible. Major advances in the future will come from improving the quality of the site. The ultimate site is, of course, beyond the Earth’s atmosphere, such as on the Moon, but economic limitations prevent our exploiting this avenue to the degree that the scientific community desires. Here we describe an alternative, which offers many of the advantages of space for a fraction of the cost: the Antarctic Plateau.
The extragalactic distance scale without Cepheids. IV.
Publisher: American Astronomical Society
Date: 06-05-2011
Hunting the Parent of the Orphan Stream: Identifying Stream Members from Low-resolution Spectroscopy
Publisher: American Astronomical Society
Date: 23-01-2013
Structural analysis of the Sextans dwarf spheroidal galaxy
Publisher: Oxford University Press (OUP)
Date: 22-04-2016
DOI: 10.1093/MNRAS/STW949
SkyMapper Early Data Release
Publisher: No publisher found
Date: 2016
The radial velocity and metal abundance of the Sextans dwarf spheroidal galaxy.
Publisher: Oxford University Press (OUP)
Date: 04-1991
Finding RR lyrae stars with skymapper: An observational test
Publisher: Cambridge University Press (CUP)
Date: 2013
DOI: 10.1017/PASA.2013.28
Abstract: One of the major science goals of the SkyMapper survey of the Southern Hemisphere sky is the determination of the shape and extent of the halo of the Galaxy. In this paper, we quantify the likely efficiency and completeness of the survey as regards the detection of RR Lyrae variable stars, which are excellent tracers of the halo stellar population. We have accomplished this via observations of the RR Lyrae-rich globular cluster NGC 3201. We find that for single-epoch uvgri observations followed by two further epochs of g , r imaging, as per the intended three-epoch survey strategy, we recover known RR Lyraes with a completeness exceeding 90%. We also investigate boundaries in the gravity-sensitive single-epoch two-colour diagram that yield high completeness and high efficiency (i.e., minimal contamination by non-RR Lyraes) and the general usefulness of this diagram in separating populations.
A New Red Giant-based Distance Modulus of 13.3 Mpc to the Antennae Galaxies and Its Consequences
Publisher: American Astronomical Society
Date: 05-2008
DOI: 10.1086/533408
Spectroscopy and Photometry of the Least Massive Type II Globular Clusters: NGC 1261 and NGC 6934*
Publisher: American Astronomical Society
Date: 12-2021
Abstract: Recent work has revealed two classes of globular clusters (GCs), dubbed Type I and Type II. Type II GCs are characterized by both a blue and a red red giant branch composed of stars with different metallicities, often coupled with distinct abundances in the slow neutron-capture elements (s-elements). Here we continue the chemical tagging of Type II GCs by adding the two least massive clusters of this class, NGC 1261 and NGC 6934. Based on both spectroscopy and photometry, we find red stars in NGC 1261 to be slightly enhanced in [Fe/H] by ∼0.1 dex and confirm that red stars of NGC 6934 are enhanced in iron by ∼0.2 dex. Neither NGC 1261 nor NGC 6934 show internal variations in the s-elements, which suggests a GC mass threshold for the occurrence of s -process enrichment. We found a significant correlation between the additional Fe locked in the red stars of Type II GCs and the present-day mass of the cluster. Nevertheless, most Type II GCs retained a small fraction of Fe produced by SNe II, lower than the 2% NGC 6273, M54, and ω Centauri are remarkable exceptions. In the Appendix, we infer for the first time chemical abundances of lanthanum, assumed as representative of the s-elements, in M54, the GC located in the nucleus of the Sagittarius dwarf galaxy. Red-sequence stars are marginally enhanced in [La/Fe] by 0.10 ± 0.06 dex, in contrast with the large [La/Fe] spread of most Type II GCs. We suggest that different processes are responsible for the enrichment in iron and s -elements in Type II GCs.
The outer envelopes of globular clusters - I. NGC 7089 (M2)
Publisher: Oxford University Press (OUP)
Date: 07-2016
The Dwarf Spheroidal Companions to M31: A Color-Magnitude Diagram for and III
Publisher: American Astronomical Society
Date: 09-1993
DOI: 10.1086/116698
Stellar populations in local group dwarf elliptical galaxies. I. NGC 147.
Publisher: American Astronomical Society
Date: 07-1983
DOI: 10.1086/161141
The giant branch of the globular cluster NGC 3201.
Publisher: American Astronomical Society
Date: 09-1981
DOI: 10.1086/159187
Spectroscopy and Photometry of Multiple Populations along the Asymptotic Giant Branch of NGC 2808 and NGC 6121 (M4)
Publisher: American Astronomical Society
Date: 05-07-2017
Present-day Mass Function of Six Small Magellanic Cloud Intermediate-age and Old Star Clusters
Publisher: American Astronomical Society
Date: 24-06-2011
The Magellanic Edges Survey – III. Kinematics of the disturbed LMC outskirts
Publisher: Oxford University Press (OUP)
Date: 22-03-2022
Abstract: We explore the structural and kinematic properties of the outskirts of the Large Magellanic Cloud (LMC) using data from the Magellanic Edges Survey (MagES) and Gaia EDR3. Even at large galactocentric radii (8° & R & 11°), we find the north-eastern LMC disc is relatively unperturbed: its kinematics are consistent with a disc of inclination ∼36.5° and line-of-nodes position angle ∼145° east of north. In contrast, fields at similar radii in the southern and western disc are significantly perturbed from equilibrium, with non-zero radial and vertical velocities, and distances significantly in front of the disc plane implied by our north-eastern fields. We compare our observations to simple dynamical models of the Magellanic or Milky Way system which describe the LMC as a collection of tracer particles within a rigid potential, and the Small Magellanic Cloud (SMC) as a rigid Hernquist potential. A possible SMC crossing of the LMC disc plane ∼400 Myr ago, in combination with the LMC’s infall to the Milky Way potential, can qualitatively explain many of the perturbations in the outer disc. Additionally, we find the claw-like and arm-like structures south of the LMC have similar metallicities to the outer LMC disc ([Fe/H] ∼ −1), and are likely comprised of perturbed LMC disc material. The claw-like substructure is particularly disturbed, with out-of-plane velocities & km s−1 and apparent counter-rotation relative to the LMC’s disc motion. More detailed N-body models are necessary to elucidate the origin of these southern features, potentially requiring repeated interactions with the SMC prior to ∼1 Gyr ago.
Stellar populations in Local Group dwarf elliptical galaxies.II. NGC 205.
Publisher: American Astronomical Society
Date: 03-1984
DOI: 10.1086/161824
Equivalent Widths for 54 Red Giants in 47 Tucanae, omega Centauri, NGC 6397, M22, and NGC 6752
Publisher: American Astronomical Society
Date: 08-1995
DOI: 10.1086/192200
A VIC Color-Magnitude Diagram of the Globular Cluster NGC 6352 From Hubble Space Telescope Planetary Camera Observations
Publisher: American Astronomical Society
Date: 08-1995
DOI: 10.1086/117552
S 5: The Orbital and Chemical Properties of One Dozen Stellar Streams
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We report the kinematic, orbital, and chemical properties of 12 stellar streams with no evident progenitors using line-of-sight velocities and metallicities from the Southern Stellar Stream Spectroscopic Survey ( S 5 ), proper motions from Gaia EDR3, and distances derived from distance tracers or the literature. This data set provides the largest homogeneously analyzed set of streams with full 6D kinematics and metallicities. All streams have heliocentric distances between ∼10 and 50 kpc. The velocity and metallicity dispersions show that half of the stream progenitors were disrupted dwarf galaxies (DGs), while the other half originated from disrupted globular clusters (GCs), hereafter referred to as DG and GC streams. Based on the mean metallicities of the streams and the mass–metallicity relation, the luminosities of the progenitors of the DG streams range between those of Carina and Ursa Major I (−9.5 ≲ M V ≲ −5.5). Four of the six GC streams have mean metallicities of [Fe/H] −2, more metal poor than typical Milky Way (MW) GCs at similar distances. Interestingly, the 300S and Jet GC streams are the only streams on retrograde orbits in our dozen-stream s le. Finally, we compare the orbital properties of the streams with known DGs and GCs in the MW, finding several possible associations. Some streams appear to have been accreted with the recently discovered Gaia–Enceladus–Sausage system, and others suggest that GCs were formed in and accreted together with the progenitors of DG streams whose stellar masses are similar to those of Draco to Carina (∼10 5 –10 6 M ⊙ ).
Homogeneous metallicities and radial velocities for Galactic globular clusters. First CaT metallicities for twenty clusters
Publisher: EDP Sciences
Date: 20-03-2012
Main-Sequence Star Populations in the Virgo Overdensity Region
Publisher: American Astronomical Society
Date: 30-04-2013
The southern stellar stream spectroscopic survey (S5): Overview, target selection, data reduction, validation, and early science
Publisher: Oxford University Press (OUP)
Date: 03-10-2019
Abstract: We introduce the southern stellar stream spectroscopy survey (S5), an on-going program to map the kinematics and chemistry of stellar streams in the southern hemisphere. The initial focus of S5 has been spectroscopic observations of recently identified streams within the footprint of the dark energy survey (DES), with the eventual goal of surveying streams across the entire southern sky. Stellar streams are composed of material that has been tidally striped from dwarf galaxies and globular clusters and hence are excellent dynamical probes of the gravitational potential of the Milky Way, as well as providing a detailed snapshot of its accretion history. Observing with the 3.9 m Anglo-Australian Telescope’s 2-degree-Field fibre positioner and AAOmega spectrograph, and combining the precise photometry of DES DR1 with the superb proper motions from Gaia DR2, allows us to conduct an efficient spectroscopic survey to map these stellar streams. So far S5 has mapped nine DES streams and three streams outside of DES the former are the first spectroscopic observations of these recently discovered streams. In addition to the stream survey, we use spare fibres to undertake a Milky Way halo survey and a low-redshift galaxy survey. This paper presents an overview of the S5 program, describing the scientific motivation for the survey, target selection, observation strategy, data reduction, and survey validation. Finally, we describe early science results on stellar streams and Milky Way halo stars drawn from the survey. Updates on S5, including future public data releases, can be found at s5collab.github.io.
The Globular Clusters of the Dwarf Elliptical Galaxies NGC 147, NGC 185, and NGC 205. I. Abundances
Publisher: American Astronomical Society
Date: 11-1988
DOI: 10.1086/166826
A Spectroscopic Survey for ω Centauri Members at and beyond the Cluster Tidal Radius
Publisher: American Astronomical Society
Date: 13-06-2008
A search for stellar structures around nine outer halo globular clusters in the Milky Way
Publisher: Oxford University Press (OUP)
Date: 21-03-2022
Abstract: We use deep imaging from the Dark Energy Camera to explore the peripheral regions of nine globular clusters in the outer halo of the Milky Way. Apart from Whiting 1 and NGC 7492, which are projected against the Sagittarius stream, we see no evidence for adjacent stellar populations to indicate any of these clusters is associated with coherent tidal debris from a destroyed host dwarf. We also find no evidence for tidal tails around any of the clusters in our s le however, both NGC 1904 and 6981 appear to possess outer envelopes. Motivated by a slew of recent Gaia-based discoveries, we compile a s le of clusters with robust detections of extra-tidal structure, and search for correlations with orbital properties. While we observe that clusters with tidal tails are typically on moderately or very eccentric orbits that are highly inclined to the Galactic plane and often retrograde, these are neither necessary nor sufficient conditions for the formation of extra-tidal structure. That many objects with tidal tails appear to be accreted leads us to speculate that this lack of consistency may stem from the inhomogeneous dynamical history of the Milky Way globular cluster system. Finally, we note that clusters with prominent stellar envelopes detected in ground-based imaging (such as NGC 1851 and 7089) are now all known from Gaia to possess long tidal tails – experimental confirmation that the presence of an extended envelope is indicative of tidal erosion.
The age of the LMC globular cluster NGC 2213.
Publisher: American Astronomical Society
Date: 10-1985
DOI: 10.1086/163554
Near IR imaging of Centaurus group dwarf elliptical galaxies
Publisher: Cambridge University Press (CUP)
Date: 03-2005
The SkyMapper search for extremely metal-poor stars in the Large Magellanic Cloud
Publisher: Oxford University Press (OUP)
Date: 30-06-2023
Abstract: We present results of a search for extremely metal-poor stars in the Large Magellanic Cloud (LMC), which can provide crucial information about the properties of the first stars as well as on the formation conditions prevalent during the earliest stages of star formation in dwarf galaxies. Our search utilized SkyMapper photometry, together with parallax and proper motion cuts (from Gaia), colour–magnitude cuts (by selecting the red giant branch region), and finally a metallicity-sensitive cut. Low-resolution spectra of a s le of photometric candidates were taken using the ANU 2.3m telescope/WiFeS spectrograph, from which seven stars with $\\rm [Fe/H] \\le -2.75$ were identified, two of which have $\\rm [Fe/H] \\le -3$. Radial velocities, derived from the Ca ii triplet lines, closely match the outer rotation curve of the LMC for the majority of the candidates in our s le. Therefore, our targets are robustly members of the LMC based on their 6D phase-space information (coordinates, spectrophotometric distance, proper motions, and radial velocities), and they constitute the most metal-poor stars so far discovered in this galaxy.
The structure and stellar content of globular clusters. II. Star counts and main-sequence luminosity functions for 47 Tuc, NGC 6397, and NGC 6752.
Publisher: American Astronomical Society
Date: 07-1982
DOI: 10.1086/113182
The Aquarius comoving group is not a disrupted classical globular cluster★
Publisher: Oxford University Press (OUP)
Date: 16-07-2014
The s-Process Enrichment of the Globular Clusters M4 and M22
Publisher: American Astronomical Society
Date: 09-10-2014
A black hole detected in the young massive LMC cluster NGC 1850
Publisher: Oxford University Press (OUP)
Date: 11-11-2021
Abstract: We report on the detection of a black hole (NGC 1850 BH1) in the ∼100-Myr-old massive cluster NGC 1850 in the Large Magellanic Cloud. It is in a binary system with a main-sequence turn-off star (4.9 ± 0.4 M⊙), which is starting to fill its Roche lobe and is becoming distorted. Using 17 epochs of Very Large Telescope/Multi-Unit Spectroscopic Explorer observations, we detected radial velocity variations exceeding 300 km s−1 associated with the target star, linked to the ellipsoidal variations measured by the fourth phase of the Optical Gravitational Lensing Experiment in the optical bands. Under the assumption of a semidetached system, the simultaneous modelling of radial velocity and light curves constrains the orbital inclination of the binary to 38° ± 2°, resulting in a true mass of the unseen companion of $11.1_{-2.4}^{+2.1}\\,{\\rm M}_{\\odot }$. This represents the first direct dynamical detection of a black hole in a young massive cluster, opening up the possibility of studying the initial mass function and the early dynamical evolution of such compact objects in high-density environments.
Spectroscopic follow-up of statistically selected extremely metal-poor star candidates from GALAH DR3
Publisher: Oxford University Press (OUP)
Date: 17-01-2023
Abstract: The advent of large-scale stellar spectroscopic surveys naturally leads to the implementation of machine learning techniques to isolate, for ex le, small sub-s les of potentially interesting stars from the full data set. A recent ex le is the application of the t-SNE statistical method to ∼600 000 stellar spectra from the GALAH survey in order to identify a s le of candidate extremely metal-poor (EMP [Fe/H] ≤ –3) stars. We report the outcome of low-resolution spectroscopic follow-up of 83 GALAH EMP candidates that lack any previous metallicity estimates. Overall, the statistical selection is found to be efficient (∼one-third of the candidates have [Fe/H] ≤ –2.75) with low contamination (& per cent have [Fe/H] & –2), and with a metallicity distribution function that is consistent with previous work. Five stars are found to have [Fe/H] ≤ –3.0, one of which is a main sequence turnoff star. Two other stars are revealed as likely carbon-enhanced metal-poor (CEMP) stars of type CEMP-s, and a known carbon star is re-identified. The results indicate that the statistical selection approach employed was successful, and therefore it can be applied to forthcoming even larger stellar spectroscopic surveys with the expectation of similar positive outcomes.
The Sodium/Aluminum--Oxygen Anticorrelation in omega Centauri and Other Clusters
Publisher: American Astronomical Society
Date: 03-1995
DOI: 10.1086/187795
Extended stellar substructure surrounding the Boötes I dwarf spheroidal galaxy
Publisher: Oxford University Press (OUP)
Date: 04-07-2016
Nitrogen variations on the main sequence of 47 Tucanae - Implications from stellar structure theory.
Publisher: American Astronomical Society
Date: 08-1982
DOI: 10.1086/160159
The Magellanic Edges Survey I: Description and first results
Publisher: Oxford University Press (OUP)
Date: 14-07-2020
Abstract: We present an overview of, and first science results from, the Magellanic Edges Survey (MagES), an ongoing spectroscopic survey mapping the kinematics of red clump and red giant branch stars in the highly substructured periphery of the Magellanic Clouds. In conjunction with Gaia astrometry, MagES yields a s le of ~7000 stars with in idual 3D velocities that probes larger galactocentric radii than most previous studies. We outline our target selection, observation strategy, data reduction, and analysis procedures, and present results for two fields in the northern outskirts (& ° on-sky from the centre) of the Large Magellanic Cloud (LMC). One field, located in the vicinity of an arm-like overdensity, displays apparent signatures of perturbation away from an equilibrium disc model. This includes a large radial velocity dispersion in the LMC disc plane, and an asymmetric line-of-sight velocity distribution indicative of motions vertically out of the disc plane for some stars. The second field reveals 3D kinematics consistent with an equilibrium disc, and yields Vcirc = 87.7 ± 8.0 km s−1 at a radial distance of ~10.5 kpc from the LMC centre. This leads to an enclosed mass estimate for the LMC at this radius of (1.8 ± 0.3) × 1010 M⊙.
The Environmental Influence on the Evolution of Local Galaxies
Publisher: American Astronomical Society
Date: 13-01-2009
Different Stellar Rotations in the Two Main Sequences of the Young Globular Cluster NGC 1818: The First Direct Spectroscopic Evidence
Publisher: American Astronomical Society
Date: 22-08-2018
The Gut-Brain-Axis on the Manifestation of Depressive Symptoms in Epilepsy: An Evidence-Driven Hypothesis
Publisher: Frontiers Media SA
Date: 08-04-2020
Kinematics and Chemistry of Halo Substructures: The Vicinity of the Virgo Overdensity
Publisher: American Astronomical Society
Date: 14-03-2012
The dynamics of the globular cluster NGC 3201 out to the Jacobi radius
Publisher: Oxford University Press (OUP)
Date: 04-02-2021
Abstract: As part of a chemodynamical survey of five nearby globular clusters with 2dF/AAOmega on the Anglo-Australian Telescope (AAT), we have obtained kinematic information for the globular cluster NGC 3201. Our new observations confirm the presence of a significant velocity gradient across the cluster which can almost entirely be explained by the high proper motion of the cluster (${\\sim}9\\, \\mathrm{mas\\, yr^{-1}}$). After subtracting the contribution of this perspective rotation, we found a remaining rotation signal with an litude of ${\\sim}1\\, \\mathrm{km\\, s^{-1}}$ around a different axis to what we expect from the tidal tails and the potential escapers, suggesting that this rotation is internal and can be a remnant of its formation process. At the outer part, we found a rotational signal that is likely a result from potential escapers. The proper motion dispersion at large radii reported by Bianchini et al. ($3.5\\pm 0.9\\, \\mathrm{km\\, s^{-1}}$) has previously been attributed to dark matter. Here, we show that the LOS dispersion between 0.5 and 1 Jacobi radius is lower ($2.01\\pm 0.18\\, \\mathrm{km\\, s^{-1}}$), yet above the predictions from an N-body model of NGC 3201 that we ran for this study ($1.48\\pm 0.14\\, \\mathrm{km\\, s^{-1}}$). Based on the simulation, we find that potential escapers cannot fully explain the observed velocity dispersion. We also estimate the effect on the velocity dispersion of different amounts of stellar-mass black holes and unbound stars from the tidal tails with varying escape rates and find that these effects cannot explain the difference between the LOS dispersion and the N-body model. Given the recent discovery of tidal tail stars at large distances from the cluster, a dark matter halo is an unlikely explanation. We show that the effect of binary stars, which is not included in the N-body model, is important and can explain part of the difference in dispersion. We speculate that the remaining difference must be the result of effects not included in the N-body model, such as initial cluster rotation, velocity anisotropy, and Galactic substructure.
Population gradients and photometric metallicities in early- and transition-type dwarf galaxies: Clues from the Sculptor group
Publisher: EDP Sciences
Date: 17-01-2013
Factors associated with severe sepsis in diarrheal adults and their outcome at an urban hospital, Bangladesh: A retrospective analysis
Publisher: Public Library of Science (PLoS)
Date: 20-09-2021
DOI: 10.1371/JOURNAL.PONE.0257596
Abstract: To describe factors associated with severe sepsis in diarrheal adults and their outcomes and offender in blood and stool to understand their interplay as clinical features of sepsis and severe diarrhea often overlap. We used this retrospective chart analysis employing an unmatched case-control design to study critically ill diarrheal adults aged ≥18 years treated in ICU of Dhaka hospital, icddr,b between January 2011 to December 2015. Of 8,863 in-patient diarrheal adults, 350 having severe sepsis were cases and an equal number of randomly selected non-septic patients were the controls. Cases died significantly more (14.9% vs 4.6%, p = .001) than controls. 69% of the cases progressed to septic shock. In logistic regression analysis, steroid intake, ileus, acute kidney injury (AKI), metabolic acidosis, and hypocalcemia were significantly associated with severe sepsis in diarrheal adults (all, p .05). 12% of cases (40/335) had bacteremia. Streptococcus pneumoniae [9 (22.5%)] was the single most common pathogen and gram-negatives [27 (67.5%)] were prevailing as a group. Diarrheal adults who had ileus, AKI, metabolic acidosis, hypocalcemia, and also took steroids were found to have an association with severe sepsis. Strikingly, gram-negative were the predominant bacteria among the diarrheal adults having severe sepsis.
Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by S 5
Publisher: American Astronomical Society
Date: 12-2021
Abstract: Stellar streams are excellent probes of the underlying gravitational potential in which they evolve. In this work, we fit dynamical models to five streams in the Southern Galactic hemisphere, combining observations from the Southern Stellar Stream Spectroscopic Survey ( S 5 ), Gaia EDR3, and the Dark Energy Survey, to measure the mass of the Large Magellanic Cloud (LMC). With an ensemble of streams, we find a mass of the LMC ranging from ∼14–19 × 10 10 M ⊙ , probed over a range of closest approach times and distances. With the most constraining stream (Orphan–Chenab), we measure an LMC mass of 18.8 − 4.0 + 3.5 × 10 10 M ⊙ , probed at a closest approach time of 310 Myr and a closest approach distance of 25.4 kpc. This mass is compatible with previous measurements, showing that a consistent picture is emerging of the LMC’s influence on structures in the Milky Way. Using this s le of streams, we find that the LMC’s effect depends on the relative orientation of the stream and LMC at their point of closest approach. To better understand this, we present a simple model based on the impulse approximation and we show that the LMC’s effect depends both on the magnitude of the velocity kick imparted to the stream and the direction of this kick.
Age Determination of Six Intermediate-Age Small Magellanic Cloud Star Clusters with HST/ACS
Publisher: American Astronomical Society
Date: 12-09-2008
Is NGC 1851-UV5 a binary star in a globular cluster ?
Publisher: IOP Publishing
Date: 10-1982
DOI: 10.1086/131063
HIGH-RESOLUTION SPECTROSCOPIC STUDY of EXTREMELY METAL-POOR STAR CANDIDATES from the SKYMAPPER SURVEY
Publisher: American Astronomical Society
Date: 09-07-2015
Interstellar Medium Disruption in the Centaurus A Group
Publisher: American Astronomical Society
Date: 12-12-2007
DOI: 10.1086/509132
Commission 37: Star Clusters and Associations
Publisher: Cambridge University Press (CUP)
Date: 12-2009
DOI: 10.1017/S1743921308025684
Abstract: Star clusters are valuable tools for theoretical and observational astronomy across a wide range of disciplines from cosmology to stellar spectroscopy. For ex le, properties of globular clusters are used to constrain stellar evolutionary models, nucleosynthesis and chemical evolution, as well as the star formation and assembly histories of galaxies and the distribution of dark matter in present-day galaxies. Open clusters are widely used as stellar laboratories for the study of specific stellar phenomena (e.g., various emission-line stars, pulsating pre-MS stars, magnetic massive stars, binarity, stellar rotation, etc.). They also provide observational constraints on models of massive star evolution and of Galactic disk formation and chemical evolution.
The Age and Metallicity Relation of ω Centauri
Publisher: American Astronomical Society
Date: 20-08-2006
DOI: 10.1086/505571
The GALAH Survey: A New Sample of Extremely Metal-poor Stars Using a Machine-learning Classification Algorithm
Publisher: American Astronomical Society
Date: 05-2022
Abstract: Extremely metal-poor (EMP) stars provide a valuable probe of early chemical enrichment in the Milky Way. Here we leverage a large s le of ∼600,000 high-resolution stellar spectra from the GALAH survey plus a machine-learning algorithm to find 54 candidates with estimated [Fe/H] ≤−3.0, six of which have [Fe/H] ≤−3.5. Our s le includes ∼20% main-sequence EMP candidates, unusually high for EMP star surveys. We find the magnitude-limited metallicity distribution function of our s le is consistent with previous work that used more complex selection criteria. The method we present has significant potential for application to the next generation of massive stellar spectroscopic surveys, which will expand the available spectroscopic data well into the millions of stars.
The Extended Main-sequence Turnoff Clusters of the Large Magellanic Cloud—Missing Links in Globular Cluster Evolution
Publisher: American Astronomical Society
Date: 18-03-2011
Green Banana mixed Diet is Beneficial in the Management of Childhood Persistent Diarrhea: an Open, Randomized-Controlled Trial (Preprint)
Publisher: JMIR Publications Inc.
Date: 26-08-2021
Abstract: ersistent diarrhea (PD), diarrhea for ≥14 days, accounts for 36%-56% of all diarrhea-related death. Studies demonstrated that green banana helps in the resolution of diarrhea. e assessed whether a lactose-free diet rice suji (RS) or rice suji containing green banana (GB-RS), improves outcome compared with 3/4th strength rice suji (3/4th RS) in 6 to 35 months old children having PD in the icddr,b Dhaka hospital. n this open-labeled, randomized, controlled trial, children with PD not improving with milk suji (the initial diet) received any of the three study diets: GB-RS, RS, 3/4th RS. The primary outcome was the percentage of children who recovered from diarrhea by day 5 with an intention to treat analysis. rom 1st December 2017 to 31st August 2019, we randomly allocated 45 children to each group. By day 5, 66 children recovered from PD, of whom 26 (58%), 14 (31%), 26 (58%) received GB-RS, RS, and 3/4th RS respectively. Significantly more resolution of PD occurred in GB-RS and 3/4th RS groups compared to RS group [relative risk (RR) 1⸱71, 95% CI 1⸱19-2⸱60 p=0⸱019]. Two (10%) children died, one each in RS group and GB-RS group. TaqMan array card (TAC) identified EAEC, rotavirus, norovirus, EPEC, astrovirus, and C ylobacter as the major pathogens associated with PD. B-RS and 3/4th RS are efficacious in the management of PD in young children. We also demonstrated a wide range of entero-pathogen associated with PD by TAC which needs further study to find a causal link. linicalTrials.gov, ID: NCT03366740 Registered on 8th December 2017 R2-10.2196/15759
Metallicities for the Outer-Halo Globular Cluster PAL 3,4 and 14
Publisher: American Astronomical Society
Date: 07-1992
DOI: 10.1086/116228
The Metal Abundance and Age of the Globular Cluster Ruprecht 106
Publisher: American Astronomical Society
Date: 07-1992
DOI: 10.1086/116227
Abundances of C, N, Sr, and Ba on the Red Giant Branch of ω Centauri
Publisher: American Astronomical Society
Date: 15-04-2010
Correlated cyanogen and sodium anomalies in the globular clusters 47 TUC and NGC 6752.
Publisher: American Astronomical Society
Date: 04-1981
DOI: 10.1086/183527
NGC 5824: a luminous outer halo globular cluster with an intrinsic abundance spread
Publisher: Oxford University Press (OUP)
Date: 28-01-2014
The Absence of Extratidal Structure in the Sculptor Dwarf Spheroidal Galaxy
Publisher: American Astronomical Society
Date: 09-2005
DOI: 10.1086/432662
S 5: The Destruction of a Bright Dwarf Galaxy as Revealed by the Chemistry of the Indus Stellar Stream
Publisher: American Astronomical Society
Date: 07-2021
COVID-19 and Seasonal Flu Vaccination Hesitancy: Links to Personality and General Intelligence in a Large, UK Cohort
Publisher: Center for Open Science
Date: 21-10-2021
Abstract: Vaccines are a powerful and relatively safe tool to protect against a range of serious diseases. Nonetheless, a sizeable minority of people express ‘vaccination hesitancy’. Accordingly, understanding the bases of this hesitancy represents a significant public health challenge. In the present study we sought to examine the role of Big Five personality traits and general intelligence as predictors of vaccination hesitancy, across two vaccination types, in a large (N= 9667) s le of UK adults drawn from the Understanding Society longitudinal household study. We found that lower general intelligence was associated with COVID-19 and seasonal flu vaccination hesitancy, and lower neuroticism was associated with COVID-19 vaccination hesitancy. Although the self-reported reasons for being vaccine hesitant indicated a range of factors were important to people, lower general intelligence was associated with virtually all of these reasons. In contrast, Big 5 personality traits showed more nuanced patterns of association. These findings provide important insights into vaccination hesitancy and help to reconcile some of the inconsistencies found in previous literature.
A panoramic view of the Local Group dwarf galaxy NGC 6822
Publisher: Oxford University Press (OUP)
Date: 15-09-2021
Abstract: We present a panoramic survey of the isolated Local Group dwarf irregular galaxy NGC 6822. Our photometry reaches ∼2–3 mag deeper than most previous studies and spans the widest area around the dwarf compared to any prior work. We observe no stellar overdensities in the outskirts of NGC 6822 to V ∼ 30 mag arcsec−2 and a projected radius of 16.5 kpc. This indicates that NGC 6822 has not experienced any recent interaction with a companion galaxy, despite previous suggestions to the contrary. Similarly, we find no evidence for any dwarf satellites of NGC 6822 to a limiting luminosity MV ≈ −5. NGC 6822 contains a disc of H i gas and young stars, oriented at ∼60○ to an extended spheroid composed of old stellar populations. We observe no correlation between the distribution of young stars and spheroid members. Our imaging allows us to trace the spheroid to nearly 11 kpc along its major axis, commensurate with the extent of the NGC 6822 globular cluster system. We find that the spheroid becomes increasingly flattened at larger radii, and its position angle twists by up to 40○. We use Gaia EDR3 astrometry to measure a proper motion for NGC 6822, and then s le its orbital parameter space. While this galaxy has spent the majority of its life in isolation, we find that it likely passed within the virial radius of the Milky Way ∼3–4 Gyr ago. This may explain the apparent flattening and twisting observed in the outskirts of its spheroid.
Nucleosynthesis in the Stellar Systems ω Centauri and M22
Publisher: Cambridge University Press (CUP)
Date: 2011
DOI: 10.1071/AS10027
Abstract: The stellar system ω Centauri (ω Cen) is well known for the large range in elemental abundances among its member stars. Recent work has indicated that the globular cluster M22 (NGC 6656) also possesses an internal abundance range, albeit substantially smallerthan that in ω Cen. Here we compare, as a function of [Fe/H], element-to-iron ratios in the two systems for a number of different elements using data from abundance analyses of red giant branch stars. It appears that the nucleosynthetic enrichment processes were very similar in these two systems despite the substantial difference in total mass.
Dwarf Galaxies Beyond Our Doorstep: the Centaurus Group
Publisher: EDP Sciences
Date: 2011
DOI: 10.1051/EAS/1148008
Abundances on the main sequence of the globular cluster ω Centauri
Publisher: Cambridge University Press (CUP)
Date: 05-2005
Tidal Tails around the Outer Halo Globular Clusters Eridanus and Palomar 15
Publisher: American Astronomical Society
Date: 11-05-2037
A Hero’s Dark Horse: Discovery of an Ultra-faint Milky Way Satellite in Pegasus
Publisher: American Astronomical Society
Date: 12-05-2015
A Wide-Field Survey of the Fornax Dwarf Spheroidal Galaxy
Publisher: American Astronomical Society
Date: 03-2005
DOI: 10.1086/427966
QSOs behind the nearest Milky Way satellite galaxies
Publisher: Oxford University Press (OUP)
Date: 11-02-1997
Explaining the Mysterious Age Gap of Globular Clusters in the Large Magellanic Cloud
Publisher: American Astronomical Society
Date: 02-07-2004
DOI: 10.1086/423372
PAL 14: an intermediate metal abundance globular cluster inthe outer galactic halo.
Publisher: American Astronomical Society
Date: 06-1982
DOI: 10.1086/160019
Confirming the intrinsic abundance spread in the globular cluster NGC 6273 (M19) with calcium triplet spectroscopy
Publisher: Oxford University Press (OUP)
Date: 09-05-2016
The structure and mass function of the globular cluster M3.
Publisher: American Astronomical Society
Date: 05-1976
DOI: 10.1086/154363
Discovery of the first carbon star in NGC 6822.
Publisher: American Astronomical Society
Date: 02-1984
DOI: 10.1086/184190
The Galah Survey: Classification and Diagnostics with t-SNE Reduction of Spectral Information
Publisher: American Astronomical Society
Date: 23-02-2017
The GALAH survey: The data reduction pipeline
Publisher: Oxford University Press (OUP)
Date: 17-08-2017
Wide Field Planetary Camera 2 Imaging of Young Clusters in the Magellanic Clouds
Publisher: American Astronomical Society
Date: 04-2000
DOI: 10.1086/301282
The GALAH Survey: Chemically tagging the Fimbulthul stream to the globular cluster ω Centauri
Publisher: Oxford University Press (OUP)
Date: 05-11-2020
Abstract: Using kinematics from Gaia and the large elemental abundance space of the second data release of the GALAH survey, we identify two new members of the Fimbulthul stellar stream, and chemically tag them to massive, multimetallic globular cluster ω Centauri. Recent analysis of the second data release of Gaia had revealed the Fimbulthul stellar stream in the halo of the Milky Way. It had been proposed that the stream is associated with the ω Cen, but this proposition relied exclusively upon the kinematics and metallicities of the stars to make the association. In this work, we find our two new members of the stream to be metal-poor stars that are enhanced in sodium and aluminium, typical of second population globular cluster stars, but not otherwise seen in field stars. Furthermore, the stars share the s-process abundance pattern seen in ω Cen, which is rare in field stars. Apart from one star within 1.5 deg of ω Cen, we find no other stars observed by GALAH spatially near ω Cen or the Fimbulthul stream that could be kinematically and chemically linked to the cluster. Chemically tagging stars in the Fimbulthul stream to ω Cen confirms the earlier work, and further links this tidal feature in the Milky Way halo to ω Cen.
Milky Way Tomography with the SkyMapper Southern Survey. II. Photometric Recalibration of SMSS DR2
Publisher: American Astronomical Society
Date: 29-01-2021
The WAGGS project-III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity
Publisher: Oxford University Press (OUP)
Date: 20-01-2020
Abstract: Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population models provide the stellar masses that underpin most of extragalactic astronomy, near and far. We have derived radial velocities for 1622 stars located in the centres of 59 Milky Way GCs – 12 of which have no previous kinematic information – using integral-field unit data from the WAGGS project. Using N-body models, we determine dynamical masses and M/LV for the studied clusters. Our s le includes NGC 6528 and NGC 6553, which extend the metallicity range of GCs with measured M/L up to [Fe/H] ∼ −0.1 dex. We find that metal-rich clusters have M/LV more than two times lower than what is predicted by simple stellar population models. This confirms that the discrepant M/L–[Fe/H] relation remains a serious concern. We explore how our findings relate to previous observations, and the potential causes for the ergence, which we conclude is most likely due to dynamical effects.
The Age of the Small Magellanic Cloud Cluster Lindsay 11
Publisher: American Astronomical Society
Date: 10-1992
DOI: 10.1086/191726
How stellar rotation shapes the colour−magnitude diagram of the massive intermediate-age star cluster NGC 1846
Publisher: Oxford University Press (OUP)
Date: 23-12-2019
Abstract: We present a detailed study of stellar rotation in the massive 1.5 Gyr old cluster NGC 1846 in the Large Magellanic Cloud. Similar to other clusters at this age, NGC 1846 shows an extended main-sequence turn-off (eMSTO), and previous photometric studies have suggested it could be bimodal. In this study, we use MUSE integral-field spectroscopy to measure the projected rotational velocities (vsin i) of around $1400$ stars across the eMSTO and along the upper main sequence of NGC 1846. We measure vsin i values up to $\\sim 250\\, {\\rm km\\, s^{-1}}$ and find a clear relation between the vsin i of a star and its location across the eMSTO. Closer inspection of the distribution of rotation rates reveals evidence for a bimodal distribution, with the fast rotators centred around $v\\sin i=140\\, {\\rm km\\, s^{-1}}$ and the slow rotators centred around $v\\sin i=60\\, {\\rm km\\, s^{-1}}$. We further observe a lack of fast rotating stars along the photometric binary sequence of NGC 1846, confirming results from the field that suggest that tidal interactions in binary systems can spin-down stars. However, we do not detect a significant difference in the binary fractions of the fast and slowly rotating sub-populations. Finally, we report on the serendipitous discovery of a planetary nebula associated with NGC 1846.
Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo
Publisher: American Astronomical Society
Date: 16-07-2018
The stellar populations of dSph galaxies in nearby groups
Publisher: Cambridge University Press (CUP)
Date: 03-2005
Intermediate-Age Core Helium-burning Stars and the Distance to the Magellanic Clouds
Publisher: American Astronomical Society
Date: 02-1987
DOI: 10.1086/164961
Discovery of RR Lyrae Stars in the Sculptor Group Dwarf Galaxies
Publisher: EDP Sciences
Date: 2011
DOI: 10.1051/EAS/1148010
Scl-dE1 GC1: An Extended Globular Cluster in a Low-Luminosity Dwarf Elliptical Galaxy
Publisher: American Astronomical Society
Date: 06-04-2009
The main-sequence turnoff of the old SMC globular cluster NGC121
Publisher: American Astronomical Society
Date: 11-1985
DOI: 10.1086/163639
The Magellanic Edges Survey – II. Formation of the LMC’s northern arm
Publisher: Oxford University Press (OUP)
Date: 25-11-2021
Abstract: The highly-substructured outskirts of the Magellanic Clouds provide ideal locations for studying the complex interaction history between both Clouds and the Milky Way (MW). In this paper, we investigate the origin of a & ° long arm-like feature in the northern outskirts of the Large Magellanic Cloud (LMC) using data from the Magellanic Edges Survey (MagES) and Gaia EDR3. We find that the arm has a similar geometry and metallicity to the nearby outer LMC disc, indicating that it is comprised of perturbed disc material. Whilst the azimuthal velocity and velocity dispersions along the arm are consistent with those in the outer LMC, the in-plane radial velocity and out-of-plane vertical velocity are significantly perturbed from equilibrium disc kinematics. We compare these observations to a new suite of dynamical models of the Magellanic/MW system, which describe the LMC as a collection of tracer particles within a rigid potential, and the SMC as a rigid Hernquist potential. Our models indicate the tidal force of the MW during the LMC’s infall is likely responsible for the observed increasing out-of-plane velocity along the arm. Our models also suggest close LMC/SMC interactions within the past Gyr, particularly the SMC’s pericentric passage ∼150 Myr ago and a possible SMC crossing of the LMC disc plane ∼400 Myr ago, likely do not perturb stars that today comprise the arm. Historical interactions with the SMC prior to ∼1 Gyr ago may be required to explain some of the observed kinematic properties of the arm, in particular its strongly negative in-plane radial velocity.
HI Observations of the Tucana Dwarf Elliptical Galaxy
Publisher: American Astronomical Society
Date: 11-1996
DOI: 10.1086/118155
The GALAH survey: chemical tagging of star clusters and new members in the Pleiades
Publisher: Oxford University Press (OUP)
Date: 17-10-2017
Palomar 5 and its tidal tails: a search for new members in the tidal stream
Publisher: Oxford University Press (OUP)
Date: 08-12-2015
A Search for Binaries in the Globular Cluster NGC 3201
Publisher: American Astronomical Society
Date: 1994
DOI: 10.1086/191858
C 0422-213 (Eridanus) : a second intermediate metal abundance globular cluster in the outer galactic halo.
Publisher: American Astronomical Society
Date: 04-1985
DOI: 10.1086/163061
Scl-1013644: a CEMP-s star in the Sculptor dwarf spheroidal galaxy
Publisher: Oxford University Press (OUP)
Date: 11-08-2016
The GALAH survey: observational overview andGaiaDR1 companion
Publisher: Oxford University Press (OUP)
Date: 03-11-2016
Exploring the Sagittarius Stream With SEKBO Survey RR Lyrae Stars
Publisher: American Astronomical Society
Date: 10-2009
Signature of a Massive Rotating Metal-poor Star Imprinted in the Phoenix Stellar Stream*
Publisher: American Astronomical Society
Date: 11-2021
Distant Ring Galaxies as Evidence for a Steeply Increasing Galaxy Interaction Rate with Redshift
Publisher: American Astronomical Society
Date: 10-08-1996
DOI: 10.1086/310194
The Age of the Large Magellanic Cloud Globular Cluster NGC 1651
Publisher: American Astronomical Society
Date: 05-1986
DOI: 10.1086/164160
A spectroscopy-based Age-Metallicity Relation of the SMC
Publisher: Cambridge University Press (CUP)
Date: 12-2007
Chemical abundances in bright giants of the globular cluster M62 (NGC 6266)★
Publisher: Oxford University Press (OUP)
Date: 15-02-2014
DOI: 10.1093/MNRAS/STU118
The Age of the Large Magellanic Cloud Cluster NGC 2031
Publisher: American Astronomical Society
Date: 05-1993
DOI: 10.1086/172573
The Stellar Populations of dE Galaxies in Nearby Groups
Publisher: Cambridge University Press (CUP)
Date: 2004
DOI: 10.1071/AS04044
Abstract: In this contribution Gemini-North NIRI J , K -observations are used to investigate the upper-Asymptotic Giant Branch (AGB) intermediate-age population in the M81 Group dwarf elliptical (dE) F8D1. Hubble Space Telescope ( HST ) ‘snapshot’ V , I -observations are also analysed to investigate the upper-AGB populations in two other M81 Group dEs, DDO 71 and kk077. In all three dEs, significant intermediate-age populations are found. Further, there are sizeable dE-to-dE differences in these populations: F8D1 contains relatively more, and relatively more luminous, upper-AGB stars. These results are compared with existing information for Local Group and Sculptor group dwarfs. It is suggested that ‘environmental harrassment’ plays an important role in governing dwarf galaxy evolution.
Design and construction of a single phase claw pole permanent magnet motor using composite magnetic material
Publisher: Elsevier BV
Date: 2001
Factors Associated withKlebsiellaBacteremia and Its Outcome in Under-Five Children Admitted with Diarrhea
Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/4760610
Abstract: Although Klebsiella bacteremia in children is perceived to be associated with fatal consequences, data are scarce on those children presenting with diarrhea. We evaluated the factors associated with Klebsiella bacteremia in such children. In this retrospective chart analysis, data of all diarrheal children was retrieved from electronic medical record system (named as SHEBA) of Dhaka Hospital of International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), from January 1, 2010, to December 31, 2012, who had their blood culture done. This was a study having a case-control design where comparison of clinical and laboratory characteristics was done among children with Klebsiella bacteremia (cases = 30) and those without any bacteraemia (controls = 90). Controls were selected randomly. The cases more often had fatal outcome ( p 0.001 ). In logistic regression analysis, after adjusting for potential confounders such as young age, severe dehydration, severe wasting, abnormal mentation, hypotension, and fast breathing, the cases were independently associated with hospital-acquired infection and positive stool growth (for all, p 0.05 ). The study highlights the importance of obtaining blood cultures in hospitalized children under five years old with diarrheal illness in the presence of either hospital-acquired infection or positive stool culture to have better outcome.
Broken into Pieces: ATLAS and Aliqa Uma as One Single Stream
Publisher: American Astronomical Society
Date: 04-2021
Abstract: We present the first spectroscopic measurements of the ATLAS and Aliqa Uma streams from the Southern Stellar Stream Spectroscopic Survey ( S 5 ), in combination with the photometric data from the Dark Energy Survey and astrometric data from Gaia. From the coherence of spectroscopic members in radial velocity and proper motion, we find that these two systems are extremely likely to be one stream with discontinuity in morphology and density on the sky (the “kink” feature). We refer to this entire stream as the ATLAS-Aliqa Uma stream, or the AAU stream. We perform a comprehensive exploration of the effect of baryonic substructures and find that only an encounter with the Sagittarius dwarf ∼0.5 Gyr ago can create a feature similar to the observed “kink.” In addition, we also identify two gaps in the ATLAS component associated with the broadening in the stream width (the “broadening” feature). These gaps have likely been created by small mass perturbers, such as dark matter halos, as the AAU stream is the most distant cold stream known with severe variations in both the stream surface density and the stream track on the sky. With the stream track, stream distance, and kinematic information, we determine the orbit of the AAU stream and find that it has been affected by the Large Magellanic Cloud, resulting in a misalignment between the proper motion and stream track. Together with the Orphan-Chenab Stream, AAU is the second stream pair that has been found to be a single stream separated into two segments by external perturbation.
Extending the Virgo Stellar Stream with SEKBO Survey RR Lyrae Stars
Publisher: American Astronomical Society
Date: 09-01-2009
STAR FORMATION HISTORY OF THE SMALL MAGELLANIC CLOUD: SIXHUBBLE SPACE TELESCOPE/ADVANCED CAMERA FOR SURVEY FIELDS
Publisher: American Astronomical Society
Date: 09-2009
Are the globular clusters with significant internal [Fe/H] spreads all former dwarf galaxy nuclei?
Publisher: Cambridge University Press (CUP)
Date: 08-2016
DOI: 10.1017/S174392131500678X
Abstract: In this contribution the hypothesis that the Galactic globular clusters with substantial internal [Fe/H] abundance ranges are the former nuclei of disrupted dwarf galaxies is discussed. Evidence considered includes the form of the metallicity distribution function, the occurrence of large diffuse outer envelopes in cluster density profiles, and the presence of ([ s -process/Fe], [Fe/H]) correlations. The hypothesis is shown to be plausible but with the caveat that if significantly more than the current nine clusters known to have [Fe/H] spreads are found, then re-evaluation will be required.
The age (s?) of the Sculptor dwarf galaxy.
Publisher: American Astronomical Society
Date: 10-1984
DOI: 10.1086/162523
Dwarf elliptical galaxies in Centaurus A group: stellar populations in AM 1339-445 and AM 1343-452
Publisher: EDP Sciences
Date: 03-2006
The luminosity function on the subgiant branch of 47 Tucanae : a comparison of observation and theory.
Publisher: American Astronomical Society
Date: 12-1985
DOI: 10.1086/163733
Evidence for a Central Massive Object in the X-Ray Cluster M15
Publisher: American Astronomical Society
Date: 09-1976
DOI: 10.1086/182232
Advanced skills for general surgeons and carving out a niche: Endoscopic retrograde cholangiopancreatography in regional Australia
Publisher: Wiley
Date: 07-05-2023
DOI: 10.1111/ANS.18506
Abstract: The provision of high‐quality healthcare in rural Australian hospitals has necessitated general surgeons to take up the challenge and expand their expertise to advanced endoscopy techniques including endoscopic retrograde cholangiopancreatography (ERCP). This study examines the utility of ERCP in a regional setting especially in decreasing patient transfers and associated costs while achieving exceptional safety by measuring key indicators of safety and efficacy. A single‐centre retrospective cross‐sectional cohort review in a rural Queensland hospital of patients who underwent ERCP (emergent and elective) from January 2019 until July 2022. Standardized international ERCP performance indicators were collected and compared to benchmark literature values including the rate of cannulation, stone extraction, successful stent placement, and post‐ERCP pancreatitis. The majority of the ERCP performance indicator benchmarks were met. 100% of patients had an appropriate indication for the procedure and consent. 98.95% successful CBD cannulation with only 14.14% requiring multiple attempts. 92.22% successful stone retrieval with 100% stent placement, well above guideline targets. The post‐procedural complication rate was 6.81% (2.09% pancreatitis 1.05% pancreatitis 1.05% duodenal perforation). Antibiotic prophylaxis adherence was identified to require improvement (12.57%). High‐quality ERCP procedures can be performed in a regional hospital by general surgeons in a safe and cost‐effective manner, significantly decreasing the costs associated with patient transfer. This study reflects strong evidence for consistently achieving international ERCP performance benchmarks and the provision of high‐quality healthcare by a regional hospital and provides a strong argument for increasing access to ERCP in rural and remote hospitals.
Carbon and nitrogen abundances on the first giant branche of NGC 6752.
Publisher: American Astronomical Society
Date: 03-1980
DOI: 10.1086/183203
Extended Star Formation in the Intermediate-age Large Magellanic Cloud Star Cluster NGC 2209
Publisher: American Astronomical Society
Date: 15-11-2012
Iron and neutron-capture element abundance variations in the globular cluster M2 (NGC 7089)★
Publisher: Oxford University Press (OUP)
Date: 31-05-2014
DOI: 10.1093/MNRAS/STU806
Asymptotic giant branch stars in the Phoenix dwarf galaxy
Publisher: Oxford University Press (OUP)
Date: 04-2008
The Nature of the Density Clump in the Fornax Dwarf Spheroidal Galaxy
Publisher: American Astronomical Society
Date: 02-2006
DOI: 10.1086/498895
The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda I and Andromeda III
Publisher: American Astronomical Society
Date: 05-2005
DOI: 10.1086/428372
A single low-energy, iron-poor supernova as the source of metals in the star SMSS J031300.36-670839.3
Publisher: Springer Science and Business Media LLC
Date: 02-2014
DOI: 10.1038/NATURE12990
Abstract: The element abundance ratios of four low-mass stars with extremely low metallicities (abundances of elements heavier than helium) indicate that the gas out of which the stars formed was enriched in each case by at most a few--and potentially only one--low-energy supernova. Such supernovae yield large quantities of light elements such as carbon but very little iron. The dominance of low-energy supernovae seems surprising, because it had been expected that the first stars were extremely massive, and that they disintegrated in pair-instability explosions that would rapidly enrich galaxies in iron. What has remained unclear is the yield of iron from the first supernovae, because hitherto no star has been unambiguously interpreted as encapsulating the yield of a single supernova. Here we report the optical spectrum of SMSS J031300.36-670839.3, which shows no evidence of iron (with an upper limit of 10(-7.1) times solar abundance). Based on a comparison of its abundance pattern with those of models, we conclude that the star was seeded with material from a single supernova with an original mass about 60 times that of the Sun (and that the supernova left behind a black hole). Taken together with the four previously mentioned low-metallicity stars, we conclude that low-energy supernovae were common in the early Universe, and that such supernovae yielded light-element enrichment with insignificant iron. Reduced stellar feedback both chemically and mechanically from low-energy supernovae would have enabled first-generation stars to form over an extended period. We speculate that such stars may perhaps have had an important role in the epoch of cosmic reionization and the chemical evolution of early galaxies.
The Spectroscopic Age of 47 Tucanae
Publisher: American Astronomical Society
Date: 09-1999
DOI: 10.1086/301013
KIM 3: An Ultra-faint Star Cluster in the Constellation of Centaurus
Publisher: American Astronomical Society
Date: 29-03-2016
The two metallicity groups of the globular cluster M 22: a chemical perspective
Publisher: EDP Sciences
Date: 12-07-2011
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