ORCID Profile
0000-0001-9204-0779
Current Organisation
Lund University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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.
Stellar Astronomy and Planetary Systems | Astronomical and Space Sciences
Publisher: Oxford University Press (OUP)
Date: 06-05-2015
DOI: 10.1093/MNRAS/STV770
Publisher: IOP Publishing
Date: 16-07-2008
Publisher: Cambridge University Press (CUP)
Date: 2009
DOI: 10.1071/AS09008
Abstract: We present montage , a post-processing nucleosynthesis code that combines a traditional network for isotopes lighter than calcium with a rapid algorithm for calculating the s -process nucleosynthesis of the heavier isotopes. The separation of those parts of the network where only neutron-capture and beta-decay reactions are significant provides a substantial advantage in computational efficiency. We present the yields for a complete set of s -process isotopes for a 3-M ⊙ , Z = 0.02 stellar model, as a demonstration of the utility of the approach. Future work will include a large grid of models suitable for use in calculations of Galactic chemical evolution.
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: Oxford University Press (OUP)
Date: 06-06-2007
Publisher: American Astronomical Society
Date: 30-03-2012
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: Oxford University Press (OUP)
Date: 15-11-2019
Abstract: We investigate the hypothesis that ingestion of a terrestrial or super-Earth planet could cause the anomalously high metal abundances seen in a turn-off star in the open cluster M67, when compared to other turn-off stars in the same cluster. We show that the mass of the convective envelope of the star is likely only 3.45 × 10−3 M⊙, and hence 5.2 M⊕ of rock is required to obtain the observed 0.128 dex metal enhancement. Rocky planets dissolve entirely in the convective envelope if they enter it with sufficiently tangential orbits: we find that the critical condition for dissolution is that the planet’s radial velocity must be less than 40% of its total velocity at the stellar surface or, equivalently, the impact parameter must be greater than about 0.9. We model the delivery of rocky planets to the stellar surface both by planet-planet scattering in a realistic multi-planet system, and by Lidov–Kozai cycles driven by a more massive planetary or stellar companion. In both cases almost all planets that are ingested arrive at the star on grazing orbits and hence will dissolve in the surface convection zone. We conclude that super-Earth ingestion is a good explanation for the metal enhancement in M67 Y2235, and that a high-resolution spectroscopic survey of stellar abundances around the turn-off and main sequence of M67 has the potential to constrain the frequency of late-time dynamical instability in planetary systems.
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: Oxford University Press (OUP)
Date: 10-09-2014
Publisher: EDP Sciences
Date: 06-2020
DOI: 10.1051/0004-6361/202037484
Abstract: Context. Binary stellar systems form a large fraction of the Galaxy’s stars. They are useful as laboratories for studying the physical processes taking place within stars, and must be correctly taken into account when observations of stars are used to study the structure and evolution of the Galaxy. The advent of large-scale spectroscopic and photometric surveys allows us to obtain large s les of binaries that permit characterising their populations. Aims. We aim to obtain a large s le of double-lined spectroscopic binaries (SB2s) by analysis of spectra from the GALAH survey in combination with photometric and astrometric data. A combined analysis will provide stellar parameters of thousands of binary stars that can be combined to form statistical observables of a given population. We aim to produce a catalogue of well-characterised systems, which can in turn be compared to models of populations of binary stars, or to follow-up in idual systems of interest. Methods. We obtained a list of candidate SB2 systems from a t-distributed stochastic neighbour embedding (t-SNE) classification and a cross-correlation analysis of GALAH spectra. To compute parameters of the primary and secondary star, we used a Bayesian approach that includes a parallax prior from Gaia DR2, spectra from GALAH, and apparent magnitudes from APASS, Gaia DR2, 2MASS, and WISE. We used a Markov chain Monte Carlo approach to s le the posterior distributions of the following model parameters for the two stars: T eff[1,2] , log g [1,2] , [Fe/H], V r [1,2] , v mic[1,2] , v broad[1,2] , R [1,2] , and E ( B − V ). Results. We present results for 12 760 binary stars detected as SB2s. We construct the statistical observables T 1 ∕ T 2 , Δ V r , and R 1 ∕ R 2 , which demonstrate that our s le mostly consists of dwarfs, with a significant fraction of evolved stars and several dozen members of the giant branch. The majority of these binary stars is concentrated at the lower boundary of the Δ V r distribution, and the R 1 ∕ R 2 ratio is mostly close to unity. The derived metallicity of our binary stars is statistically lower than that of single dwarf stars from the same magnitude-limited s le. Conclusions. Our s le of binary stars represents a large population of well-characterised double-lined spectroscopic binaries that are appropriate for statistical studies of the binary populations. The derived stellar properties and their distributions show trends that are expected for a population of close binary stars ( a 10 AU) detected through double lines in their spectra. Our detection technique allows us to probe binary systems with mass ratios 0.5 ≤ q ≤ 1.
Publisher: American Astronomical Society
Date: 24-01-2011
Publisher: Springer Science and Business Media LLC
Date: 15-07-2028
DOI: 10.1007/S41114-022-00041-Y
Abstract: The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and space-born instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA’s first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed ultra-compact stellar-mass binaries, massive black hole binaries, and extreme or interme-diate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help making progress in the different areas. New research avenues that LISA itself, or its joint exploitation with upcoming studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe.
Publisher: EDP Sciences
Date: 24-01-2019
DOI: 10.1051/0004-6361/201833280
Abstract: A deep understanding of the Milky Way galaxy, its formation and evolution requires observations of huge numbers of stars. Stellar photometry, therefore, provides an economical method to obtain intrinsic stellar parameters. With the addition of distance information – a prospect made real for more than a billion stars with the second Gaia data release – deriving reliable ages from photometry is a possibility. We have developed a Bayesian method that generates 2D probability maps of a star’s age and metallicity from photometry and parallax using isochrones. Our synthetic tests show that including a near-UV passband enables us to break the degeneracy between a star’s age and metallicity for certain evolutionary stages. It is possible to find well-constrained ages and metallicities for turn-off and sub-giant stars with colours including a U band and a parallax with uncertainty less than ∼20%. Metallicities alone are possible for the main sequence and giant branch. We find good agreement with the literature when we apply our method to the Gaia benchmark stars, particularly for turn-off and young stars. Further tests on the old open cluster NGC 188, however, reveal significant limitations in the stellar isochrones. The ages derived for the cluster stars vary with evolutionary stage, such that turn-off ages disagree with those on the sub-giant branch, and metallicities vary significantly throughout. Furthermore, the parameters vary appreciably depending on which colour combinations are used in the derivation. We identify the causes of these mismatches and show that improvements are needed in the modelling of giant branch stars and in the creation and calibration of synthetic near-UV photometry. Our results warn against applying isochrone fitting indiscriminately. In particular, the uncertainty on the stellar models should be quantitatively taken into account. Further efforts to improve the models will result in significant advancements in our ability to study the Galaxy.
Publisher: Cambridge University Press (CUP)
Date: 08-2015
DOI: 10.1017/S1743921316004725
Abstract: The Monχey project will provide a large and homogeneous set of stellar yields for the low- and intermediate- mass stars and has applications particularly to galactic chemical evolution modelling. We describe our detailed grid of stellar evolutionary models and corresponding nucleosynthetic yields for stars of initial mass 0.8 M ⊙ up to the limit for core collapse supernova (CC-SN) ≈ 10 M ⊙ . Our study covers a broad range of metallicities, ranging from the first, primordial stars (Z = 0) to those of super-solar metallicity (Z = 0.04). The models are evolved from the zero-age main-sequence until the end of the asymptotic giant branch (AGB) and the nucleosynthesis calculations include all elements from H to Bi. A major innovation of our work is the first complete grid of heavy element nucleosynthetic predictions for primordial AGB stars as well as the inclusion of extra-mixing processes (in this case thermohaline) during the red giant branch. We provide a broad overview of our results with implications for galactic chemical evolution as well as highlight interesting results such as heavy element production in dredge-out events of super-AGB stars. We briefly introduce our forthcoming web-based database which provides the evolutionary tracks, structural properties, internal/surface nucleosynthetic compositions and stellar yields. Our web interface includes user- driven plotting capabilities with output available in a range of formats. Our nucleosynthetic results will be available for further use in post processing calculations for dust production yields.
Publisher: Cambridge University Press (CUP)
Date: 2009
DOI: 10.1071/AS08062
Abstract: An N -body code containing live stellar evolution through combination of the software packages nbody6 and stars is presented. Operational details of the two codes are outlined and the changes that have been made to combine them discussed. We have computed the evolution of clusters of 10 4 stars using the combined code and we compare the results with those obtained using nbody6 and the synthetic stellar evolution code sse . We find that, providing the physics package within stars is set up correctly to match the parameters of the models used to construct sse , the results are very similar. This provides a good indication that the new code is working well. We also demonstrate how this physics can be changed simply in the new code with convective overshooting as an ex le. Similar changes in sse would require considerable reworking of the model fits. We conclude by outlining proposed future development of the code to include more complete models of single stars and binary star systems.
Publisher: Oxford University Press (OUP)
Date: 11-07-2009
Publisher: Oxford University Press (OUP)
Date: 17-07-2014
Publisher: American Astronomical Society
Date: 06-08-2018
Start Date: 06-2022
End Date: 06-2025
Amount: $470,000.00
Funder: Australian Research Council
View Funded Activity