ORCID Profile
0000-0002-5510-8751
Current Organisation
University of Birmingham
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Publisher: Springer Science and Business Media LLC
Date: 08-2009
DOI: 10.1038/NATURE08245
Abstract: The 'hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only approximately 0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10 M(Jup)), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 10(6), as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.
Publisher: Oxford University Press (OUP)
Date: 14-03-2019
DOI: 10.1093/MNRAS/STZ742
Publisher: American Astronomical Society
Date: 24-05-2022
Abstract: The Transiting Exoplanet Survey Satellite (TESS) mission has enabled discoveries of the brightest transiting planet systems around young stars. These systems are the benchmarks for testing theories of planetary evolution. We report the discovery of a mini-Neptune transiting a bright star in the AB Doradus moving group. HIP 94235 (TOI-4399, TIC 464646604) is a V mag = 8.31 G-dwarf hosting a 3.00 − 0.28 + 0.32 R ⊕ mini-Neptune in a 7.7 day period orbit. HIP 94235 is part of the AB Doradus moving group, one of the youngest and closest associations. Due to its youth, the host star exhibits significant photometric spot modulation, lithium absorption, and X-ray emission. Three 0.06% transits were observed during Sector 27 of the TESS Extended Mission, though these transit signals are dwarfed by the 2% peak-to-peak photometric variability exhibited by the host star. Follow-up observations with the Characterising Exoplanet Satellite confirmed the transit signal and prevented the erosion of the transit ephemeris. HIP 94235 is part of a 50 au G-M binary system. We make use of diffraction limited observations spanning 11 yr, and astrometric accelerations from Hipparcos and Gaia, to constrain the orbit of HIP 94235 B. HIP 94235 is one of the tightest stellar binaries to host an inner planet. As part of a growing s le of bright, young planet systems, HIP 94235 b is ideal for follow-up transit observations, such as those that investigate the evaporative processes driven by high-energy radiation that may sculpt the valleys and deserts in the Neptune population.
Publisher: American Astronomical Society
Date: 28-06-2021
Publisher: Oxford University Press (OUP)
Date: 11-11-2014
Publisher: Oxford University Press (OUP)
Date: 30-05-2022
Abstract: We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 d, identified through photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission. The host star is located 33 pc away with a radius of R* = 0.34 ± 0.02 R⊙, a mass of $0.34\\pm 0.02 \\, \\mathrm{M}_{\\odot }$, and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 d based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multiwavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from Canada–France–Hawaii Telescope (CFHT)/SpectroPolarimètre InfraROUge (SPIRou). Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 R⊕ and a mass of 6.4 ± 2.4 M⊕. The mass and radius of TOI-2136 b are consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass-loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.
Publisher: Oxford University Press (OUP)
Date: 26-07-2019
Abstract: SuperWASP, the Northern hemisphere WASP observatory, has been observing the skies from La Palma since 2004. In that time, more than 50 planets have been discovered with data contributions from SuperWASP. In the process of validating planets, many false-positive candidates have also been identified. The TESS telescope is set to begin observations of the northern sky in 2019. Similar to the WASP survey, the TESS pixel size is relatively large (13 arcsec for WASP and 21 arcsec for TESS), making it susceptible to many blended signals and false detections caused principally by grazing and blended stellar eclipsing binary systems. In order to reduce duplication of effort on targets, we present a catalogue of 1 041 Northern hemisphere SuperWASP targets that have been rejected as planetary transits through follow-up observation.
Publisher: American Astronomical Society
Date: 22-01-2021
DOI: 10.3847/PSJ/ABD022
Abstract: We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit an N -body dynamical analysis of the seven-planet system using our complete set of times from which we refine the mass ratios of the planets to the star. We next carry out a photodynamical analysis of the Spitzer light curves to derive the density of the host star and the planet densities. We find that all seven planets’ densities may be described with a single rocky mass–radius relation which is depleted in iron relative to Earth, with Fe 21 wt% versus 32 wt% for Earth, and otherwise Earth-like in composition. Alternatively, the planets may have an Earth-like composition but enhanced in light elements, such as a surface water layer or a core-free structure with oxidized iron in the mantle. We measure planet masses to a precision of 3%–5%, equivalent to a radial-velocity (RV) precision of 2.5 cm s −1 , or two orders of magnitude more precise than current RV capabilities. We find the eccentricities of the planets are very small, the orbits are extremely coplanar, and the system is stable on 10 Myr timescales. We find evidence of infrequent timing outliers, which we cannot explain with an eighth planet we instead account for the outliers using a robust likelihood function. We forecast JWST timing observations and speculate on possible implications of the planet densities for the formation, migration, and evolution of the planet system.
Publisher: Cambridge University Press (CUP)
Date: 07-2011
DOI: 10.1017/S1743921311026822
Abstract: Two upcoming large scale surveys, the ESA Gaia and LSST projects, will bring a new era in astronomy. The number of binary systems that will be observed and detected by these projects is enormous, estimations range from millions for Gaia to several tens of millions for LSST. We review some tools that should be developed and also what can be gained from these missions on the subject of binaries and exoplanets from the astrometry, photometry, radial velocity and their alert systems.
Publisher: American Astronomical Society
Date: 11-04-2022
Abstract: Astronomers do not have a complete picture of the effects of wide-binary companions (semimajor axes greater than 100 au) on the formation and evolution of exoplanets. We investigate these effects using new data from Gaia Early Data Release 3 and the Transiting Exoplanet Survey Satellite mission to characterize wide-binary systems with transiting exoplanets. We identify a s le of 67 systems of transiting exoplanet candidates (with well-determined, edge-on orbital inclinations) that reside in wide visual binary systems. We derive limits on orbital parameters for the wide-binary systems and measure the minimum difference in orbital inclination between the binary and planet orbits. We determine that there is statistically significant difference in the inclination distribution of wide-binary systems with transiting planets compared to a control s le, with the probability that the two distributions are the same being 0.0037. This implies that there is an overabundance of planets in binary systems whose orbits are aligned with those of the binary. The overabundance of aligned systems appears to primarily have semimajor axes less than 700 au. We investigate some effects that could cause the alignment and conclude that a torque caused by a misaligned binary companion on the protoplanetary disk is the most promising explanation.
Publisher: Oxford University Press (OUP)
Date: 17-05-2019
Abstract: The TRAPPIST-1 planetary system is a favourable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 μm) with the UKIRT and the AAT, and in the NB2090 band (2.1 μm) with the VLT during the period 2015–18. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of 0.003 (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of 3 yr. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f.
Publisher: American Astronomical Society
Date: 07-07-2016
Publisher: Oxford University Press (OUP)
Date: 13-10-2020
Abstract: The chemical abundances of exoplanet atmospheres may provide valuable information about the bulk compositions, formation pathways, and evolutionary histories of planets. Exoplanets with large, relatively cloud-free atmospheres, and which orbit bright stars provide the best opportunities for accurate abundance measurements. For this reason, we measured the transmission spectrum of the bright (V ∼ 10.2), large (1.37 RJ), sub-Saturn mass (0.19 MJ) exoplanet WASP-127b across the near-UV to near-infrared wavelength range (0.3–5 μm), using the Hubble and Spitzer Space Telescopes. Our results show a feature-rich transmission spectrum, with absorption from Na, H2O, and CO2, and wavelength-dependent scattering from small-particle condensates. We ran two types of atmospheric retrieval models: one enforcing chemical equilibrium, and the other which fit the abundances freely. Our retrieved abundances at chemical equilibrium for Na, O, and C are all supersolar, with abundances relative to solar values of 9$^{+15}_{-6}$, 16$^{+7}_{-5}$, and 26$^{+12}_{-9}$, respectively. Despite giving conflicting C/O ratios, both retrievals gave supersolar CO2 volume mixing ratios, which adds to the likelihood that WASP-127b’s bulk metallicity is supersolar, since CO2 abundance is highly sensitive to atmospheric metallicity. We detect water at a significance of 13.7σ. Our detection of Na is in agreement with previous ground-based detections, though we find a much lower abundance, and we also do not find evidence for Li or K despite increased sensitivity. In the future, spectroscopy with James Webb Space Telescope will be able to constrain WASP-127b’s C/O ratio, and may reveal the formation history of this metal-enriched, highly observable exoplanet.
Publisher: American Astronomical Society
Date: 09-03-2022
Abstract: Mature super-Earths and sub-Neptunes are predicted to be ≃ Jovian radius when younger than 10 Myr. Thus, we expect to find 5–15 R ⊕ planets around young stars even if their older counterparts harbor none. We report the discovery and validation of TOI 1227b, a 0.85 ± 0.05 R J (9.5 R ⊕ ) planet transiting a very-low-mass star (0.170 ± 0.015 M ⊙ ) every 27.4 days. TOI 1227's kinematics and strong lithium absorption confirm that it is a member of a previously discovered subgroup in the Lower Centaurus Crux OB association, which we designate the Musca group. We derive an age of 11 ± 2 Myr for Musca, based on lithium, rotation, and the color–magnitude diagram of Musca members. The TESS data and ground-based follow-up show a deep (2.5%) transit. We use multiwavelength transit observations and radial velocities from the IGRINS spectrograph to validate the signal as planetary in nature, and we obtain an upper limit on the planet mass of ≃0.5 M J . Because such large planets are exceptionally rare around mature low-mass stars, we suggest that TOI 1227b is still contracting and will eventually turn into one of the more common R ⊕ planets.
Publisher: American Astronomical Society
Date: 03-11-2020
Publisher: Oxford University Press (OUP)
Date: 08-2013
Publisher: Oxford University Press (OUP)
Date: 09-02-2023
Abstract: We present the discovery of two exoplanets transiting TOI-836 (TIC 440887364) using data from TESS Sector 11 and Sector 38. TOI-836 is a bright (T = 8.5 mag), high proper motion (∼200 mas yr−1), low metallicity ([Fe/H]≈−0.28) K-dwarf with a mass of 0.68 ± 0.05 M⊙ and a radius of 0.67 ± 0.01 R⊙. We obtain photometric follow-up observations with a variety of facilities, and we use these data sets to determine that the inner planet, TOI-836 b, is a 1.70 ± 0.07 R⊕ super-Earth in a 3.82-d orbit, placing it directly within the so-called ‘radius valley’. The outer planet, TOI-836 c, is a 2.59 ± 0.09 R⊕ mini-Neptune in an 8.60-d orbit. Radial velocity measurements reveal that TOI-836 b has a mass of 4.5 ± 0.9 M⊕, while TOI-836 c has a mass of 9.6 ± 2.6 M⊕. Photometric observations show Transit Timing Variations (TTVs) on the order of 20 min for TOI-836 c, although there are no detectable TTVs for TOI-836 b. The TTVs of planet TOI-836 c may be caused by an undetected exterior planet.
Publisher: American Astronomical Society
Date: 27-07-2022
Abstract: As an all-sky survey, NASA’s Transiting Exoplanet Survey Satellite (TESS) mission is able to detect the brightest and rarest types of transiting planetary systems, including young planets that enable study of the evolutionary processes that occur within the first billion years. Here we report the discovery of a young, multiplanet system orbiting the bright K4.5V star, TOI-712 ( V = 10.838, M ⋆ = 0.733 − 0.025 + 0.026 M ⊙ , R ⋆ = 0.674 ± 0.016 R ⊙ , T eff = 4622 − 60 + 61 K). From the TESS light curve, we measure a rotation period of 12.48 days and derive an age between about 500 Myr and 1.1 Gyr. The photometric observations reveal three transiting mini-Neptunes ( R b = 2.049 − 0.080 + 0.120 R ⊕ , R c = 2.701 − 0.082 + 0.092 R ⊕ , R d = 2.474 − 0.082 + 0.090 R ⊕ ), with orbital periods of P b = 9.531 days, P c = 51.699 days, and P d = 84.839 days. After modeling the three-planet system, an additional Earth-sized candidate is identified, TOI-712.05 ( P = 4.32 days, R P = 0.81 ± 0.11 R ⊕ ). We calculate that the habitable zone falls between 0.339 and 0.844 au (82.7 and 325.3 days), placing TOI-712 d near its inner edge. Among planetary systems harboring temperate planets, TOI-712 ( T = 9.9) stands out as a relatively young star bright enough to motivate further characterization.
Publisher: EDP Sciences
Date: 06-06-2011
Publisher: American Astronomical Society
Date: 18-10-2023
Publisher: EDP Sciences
Date: 28-02-2013
Publisher: Oxford University Press (OUP)
Date: 22-11-2018
Publisher: Oxford University Press (OUP)
Date: 06-12-2021
Abstract: We present ground- and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag = 8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1) and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing c aign using eight different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with litudes of ∼10 min and a super-period of ∼3 yr, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modelling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of $M_{\\mathrm{b}}=1.48\\pm 0.18\\, M_\\oplus$, $M_{\\mathrm{c}}=6.20\\pm 0.31\\, M_\\oplus$, and $M_{\\mathrm{d}}=4.20\\pm 0.16\\, M_\\oplus$ for planets b, c, and d, respectively. We also detect small but significant eccentricities for all three planets : eb = 0.0167 ± 0.0084, ec = 0.0044 ± 0.0006, and ed = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H2O atmosphere for the outer two. TOI-270 is now one of the best constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization.
Publisher: Oxford University Press (OUP)
Date: 07-09-2021
Abstract: We present the discovery and characterization of an eclipsing binary identified by the Next Generation Transit Survey in the ∼115-Myr-old Blanco 1 open cluster. NGTS J0002−29 comprises three M dwarfs: a short-period binary and a companion in a wider orbit. This system is the first well-characterized, low-mass eclipsing binary in Blanco 1. With a low mass ratio, a tertiary companion, and binary components that straddle the fully convective boundary, it is an important benchmark system, and one of only two well-characterized, low-mass eclipsing binaries at this age. We simultaneously model light curves from NGTS, TESS, SPECULOOS, and SAAO, radial velocities from VLT/UVES and Keck/HIRES, and the system’s spectral energy distribution. We find that the binary components travel on circular orbits around their common centre of mass in Porb = 1.098 005 24 ± 0.000 000 38 d, and have masses Mpri = 0.3978 ± 0.0033 M⊙ and Msec = 0.2245 ± 0.0018 M⊙, radii Rpri = 0.4037 ± 0.0048 R⊙ and Rsec = 0.2759 ± 0.0055 R⊙, and effective temperatures $T_{\\rm pri}=\\mbox{$3372\\, ^{+44}_{-37}$}$ K and $T_{\\rm sec}=\\mbox{$3231\\, ^{+38}_{-31}$}$ K. We compare these properties to the predictions of seven stellar evolution models, which typically imply an inflated primary. The system joins a list of 19 well-characterized, low-mass, sub-Gyr, stellar-mass eclipsing binaries, which constitute some of the strongest observational tests of stellar evolution theory at low masses and young ages.
Publisher: American Astronomical Society
Date: 12-06-2023
Abstract: NASA’s Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting nearby bright stars. It has identified more than 329 transiting exoplanets, and almost 6000 candidates remain unvalidated. In this manuscript, we discuss the findings from the ongoing Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project, which aims to validate new exoplanets for further characterization. We validated 11 new exoplanets by examining the light curves of 24 candidates using the LATTE and TESS-Plot tools and computing the false-positive probabilities using the statistical validation tool TRICERATOPS . These include planets suitable for atmospheric characterization using transmission spectroscopy (TOI-2194b), emission spectroscopy (TOI-3082b and TOI-5704b) and for both transmission and emission spectroscopy (TOI-672b, TOI-1694b, and TOI-2443b). Our validated planets have one super-Earth (TOI-2194b) orbiting a bright ( V = 8.42 mag), metal-poor ([Fe/H] = −0.3720 ± 0.1) star, and one short-period Neptune-like planet (TOI-5704) in the hot-Neptune desert. In total, we validated one super-Earth, seven sub-Neptunes, one Neptune-like, and two sub-Saturn or super-Neptune-like exoplanets. Additionally, we identify five likely planet candidates (TOI-323, TOI-1180, TOI-2200, TOI-2408, and TOI-3913), which can be further studied to establish their planetary nature.
Publisher: American Astronomical Society
Date: 07-05-2020
Publisher: Oxford University Press (OUP)
Date: 20-09-2019
Abstract: We report the discovery and characterization of WASP-180Ab, a hot Jupiter confirmed by the detection of its Doppler shadow and by measuring its mass using radial velocities. We find the 0.9 ± 0.1 MJup, 1.24 ± 0.04 RJup planet to be in a misaligned, retrograde orbit around an F7 star with Teff = 6500 K and a moderate rotation speed of vsin i⋆ = 19.9 km s−1. The host star is the primary of a V = 10.7 binary, where a secondary separated by ∼5 arcsec (∼1200 au) contributes ∼ 30 per cent of the light. WASP-180Ab therefore adds to a small s le of transiting hot Jupiters known in binary systems. A 4.6-d modulation seen in the WASP data is likely to be the rotational modulation of the companion star, WASP-180B.
Publisher: American Astronomical Society
Date: 24-06-2015
Publisher: Oxford University Press (OUP)
Date: 30-09-2019
Abstract: We report on four new transiting hot Jupiters discovered by the WASP-South survey. WASP-178b transits a V = 9.9, A1V star with Teff = 9350 ± 150 K, the second-hottest transit host known. It has a highly bloated radius of 1.81 ± 0.09 RJup, in line with the known correlation between high irradiation and large size. With an estimated temperature of 2470 ± 60 K, the planet is one of the best targets for studying ultrahot Jupiters that is visible from the Southern hemisphere. The three host stars WASP-184, WASP-185, and WASP-192 are all post-main-sequence G0 stars of ages 4–8 Gyr. The larger stellar radii (1.3–1.7 M⊙) mean that the transits are relatively shallow (0.7–0.9 per cent) even though the planets have moderately inflated radii of 1.2–1.3 RJup. WASP-185b has an eccentric orbit (e = 0.24) and a relatively long orbital period of 9.4 d. A star that is 4.6 arcsec from WASP-185 and 4.4 mag fainter might be physically associated.
Publisher: EDP Sciences
Date: 08-2021
DOI: 10.1051/0004-6361/202141145
Abstract: We report the discovery of five transiting companions near the hydrogen-burning mass limit in close orbits around main sequence stars originally identified by the Transiting Exoplanet Survey Satellite (TESS) as TESS objects of interest (TOIs): TOI-148, TOI-587, TOI-681, TOI-746, and TOI-1213. Using TESS and ground-based photometry as well as radial velocities from the CORALIE, CHIRON, TRES, and FEROS spectrographs, we found the companions have orbital periods between 4.8 and 27.2 days, masses between 77 and 98 M Jup , and radii between 0.81 and 1.66 R Jup . These targets have masses near the uncertain lower limit of hydrogen core fusion (~73-96 M Jup ), which separates brown dwarfs and low-mass stars. We constrained young ages for TOI-587 (0.2 ± 0.1 Gyr) and TOI-681 (0.17 ± 0.03 Gyr) and found them to have relatively larger radii compared to other transiting companions of a similar mass. Conversely we estimated older ages for TOI-148 and TOI-746 and found them to have relatively smaller companion radii. With an effective temperature of 9800 ± 200 K, TOI-587 is the hottest known main-sequence star to host a transiting brown dwarf or very low-mass star. We found evidence of spin-orbit synchronization for TOI-148 and TOI-746 as well as tidal circularization for TOI-148. These companions add to the population of brown dwarfs and very low-mass stars with well measured parameters ideal to test formation models of these rare objects, the origin of the brown dwarf desert, and the distinction between brown dwarfs and hydrogen-burning main sequence stars.
Publisher: Oxford University Press (OUP)
Date: 08-05-2020
Abstract: SPECULOOS-South, an observatory composed of four independent 1-m robotic telescopes, located at ESO Paranal, Chile, started scientific operation in 2019 January. This Southern hemisphere facility operates as part of the Search for Habitable Planets EClipsing ULtra-cOOl Stars (SPECULOOS), an international network of 1-m-class telescopes surveying for transiting terrestrial planets around the nearest and brightest ultracool dwarfs (UCDs). To automatically and efficiently process the observations of SPECULOOS-South, and to deal with the specialized photometric requirements of UCD targets, we present our automatic pipeline. This pipeline includes an algorithm for automated differential photometry and an extensive correction technique for the effects of telluric water vapour, using ground measurements of the precipitable water vapour. Observing very red targets in the near-infrared can result in photometric systematics in the differential light curves, related to the temporally-varying, wavelength-dependent opacity of the Earth’s atmosphere. These systematics are sufficient to affect the daily quality of the light curves, the longer time-scale variability study of our targets and even mimic transit-like signals. Here we present the implementation and impact of our water vapour correction method. Using the 179 nights and 98 targets observed in the I + z′ filter by SPECULOOS-South since 2019 January, we show the impressive photometric performance of the facility (with a median precision of ∼1.5 mmag for 30-min binning of the raw, non-detrended light curves) and assess its detection potential. We compare simultaneous observations with SPECULOOS-South and TESS, to show that we readily achieve high-precision, space-level photometry for bright, UCDs, highlighting SPECULOOS-South as the first facility of its kind.
Publisher: Oxford University Press (OUP)
Date: 23-08-2019
Abstract: We present the discovery of four new giant planets from the Wide Angle Search for Planets-South (WASP-South), three hot Jupiters and one bloated sub-Saturn mass planet: WASP-169b, WASP-171b, WASP-175b, and WASP-182b. Besides the discovery photometry from WASP-South we use radial velocity measurements from CORALIE and HARPS and follow-up photometry from EulerCam, TRAPPIST-North and -South, and SPECULOOS. WASP-169b is a low-density Jupiter ($M=0.561 \\pm 0.061\\,{M_{\\rm Jup}},\\ R=1.304^{+0.150}_{-0.073}\\,{R_{\\rm Jup}}$) orbiting a V = 12.17 F8 subgiant in a 5.611 d orbit. WASP-171b is a typical hot Jupiter ($M=1.084 \\pm 0.094\\,{M_{\\rm Jup}},\\ R=0.98^{+0.07}_{-0.04}\\,{R_{\\rm Jup}}$, P = 3.82 d) around a V = 13.05 G0 star. We find a linear drift in the radial velocities of WASP-171 spanning 3.5 yr, indicating the possibility of an additional outer planet or stellar companion. WASP-175b is an inflated hot Jupiter (M = 0.99 ± 0.13 MJup, R = 1.208 ± 0.081 RJup, P = 3.07 d) around a V = 12.04 F7 star, which possibly is part of a binary system with a star 7.9 arcsec away. WASP-182b is a bloated sub-Saturn mass planet (M = 0.148 ± 0.011 MJup, R = 0.850 ± 0.030 RJup) around a metal-rich V = 11.98 G5 star ([Fe/H] = 0.27 ± 0.11). With an orbital period of P = 3.377 d, it sits right in the apex of the sub-Jovian desert, bordering the upper and lower edge of the desert in both the mass–period and radius–period plane. WASP-169b, WASP-175b, and WASP-182b are promising targets for atmospheric characterization through transmission spectroscopy, with expected transmission signals of 121, 150, and 264 ppm, respectively.
Publisher: Oxford University Press (OUP)
Date: 16-04-2021
Abstract: HIP 41378 f is a temperate 9.2 ± 0.1 R⊕ planet with period of 542.08 d and an extremely low density of 0.09 ± 0.02 g cm−3. It transits the bright star HIP 41378 (V = 8.93), making it an exciting target for atmospheric characterization including transmission spectroscopy. HIP 41378 was monitored photometrically between the dates of 2019 November 19 and 28. We detected a transit of HIP 41378 f with NGTS, just the third transit ever detected for this planet, which confirms the orbital period. This is also the first ground-based detection of a transit of HIP 41378 f. Additional ground-based photometry was also obtained and used to constrain the time of the transit. The transit was measured to occur 1.50 h earlier than predicted. We use an analytic transit timing variation (TTV) model to show the observed TTV can be explained by interactions between HIP 41378 e and HIP 41378 f. Using our TTV model, we predict the epochs of future transits of HIP 41378 f, with derived transit centres of TC, 4 = $2459\\,355.087^{+0.031}_{-0.022}$ (2021 May) and TC, 5 = $2459\\,897.078^{+0.114}_{-0.060}$ (2022 November).
Publisher: EDP Sciences
Date: 07-2010
Publisher: American Astronomical Society
Date: 06-2023
Abstract: We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite as TOI-588 b. HIP 33609 b is a large ( R b = 1.580 − 0.070 + 0.074 R J ) brown dwarf on a highly eccentric ( e = 0.560 − 0.031 + 0.029 ) orbit with a 39 days period. The host star is a bright ( V = 7.3 mag), T eff = 10,400 − 660 + 800 K star with a mass of M * = 2.383 − 0.095 + 0.10 M ⊙ and radius of R * = 1.863 − 0.082 + 0.087 R ⊙ , making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M b = 68.0 − 7.1 + 7.4 M J as well as the host star's rotation rate ( v sin i * = 55.6 ± 1.8 km s −1 ). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 ± 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.
Publisher: American Astronomical Society
Date: 14-03-2019
Publisher: Oxford University Press (OUP)
Date: 27-07-2021
Abstract: We present TOI-1259Ab, a 1.0RJup gas giant planet transiting a 0.71R⊙ K-dwarf on a 3.48 d orbit. The system also contains a bound white dwarf companion TOI-1259B with a projected distance of ∼1600 au from the planet host. Transits are observed in nine TESS sectors and are 2.7 per cent deep – among the deepest known – making TOI-1259Ab a promising target for atmospheric characterization. Our follow-up radial velocity measurements indicate a variability of semi litude $K=71\\, \\rm m\\, s^{-1}$, implying a planet mass of 0.44MJup. By fitting the spectral energy distribution of the white dwarf, we derive a total age of $4.08^{+1.21}_{-0.53}$ Gyr for the system. The K dwarf’s light curve reveals rotational variability with a period of 28 d, which implies a gyrochronology age broadly consistent with the white dwarf’s total age.
Publisher: American Astronomical Society
Date: 10-2021
Publisher: American Astronomical Society
Date: 04-03-2021
Abstract: TOI-216 hosts a pair of warm, large exoplanets discovered by the TESS mission. These planets were found to be in or near the 2:1 resonance, and both of them exhibit transit timing variations (TTVs). Precise characterization of the planets’ masses and radii, orbital properties, and resonant behavior can test theories for the origins of planets orbiting close to their stars. Previous characterization of the system using the first six sectors of TESS data suffered from a degeneracy between planet mass and orbital eccentricity. Radial-velocity measurements using HARPS, FEROS, and the Planet Finder Spectrograph break that degeneracy, and an expanded TTV baseline from TESS and an ongoing ground-based transit observing c aign increase the precision of the mass and eccentricity measurements. We determine that TOI-216c is a warm Jupiter, TOI-216b is an eccentric warm Neptune, and that they librate in 2:1 resonance with a moderate libration litude of deg, a small but significant free eccentricity of for TOI-216b, and a small but significant mutual inclination of 1.°2–3.°9 (95% confidence interval). The libration litude, free eccentricity, and mutual inclination imply a disturbance of TOI-216b before or after resonance capture, perhaps by an undetected third planet.
Publisher: Oxford University Press (OUP)
Date: 03-10-2018
Publisher: EDP Sciences
Date: 05-2019
DOI: 10.1051/0004-6361/201935356
Abstract: Context. Since 1998, a planet-search around main sequence stars within 50 pc in the southern hemisphere has been underway with the CORALIE spectrograph at La Silla Observatory. Aims. With an observing time span of more than 20 yr, the CORALIE survey is able to detect long-term trends in data with masses and separations large enough to select ideal targets for direct imaging. Detecting these giant companion candidates will allow us to start bridging the gap between radial-velocity-detected exoplanets and directly imaged planets and brown dwarfs. Methods. Long-term precise Doppler measurements with the CORALIE spectrograph reveal radial-velocity signatures of massive planetary companions and brown dwarfs on long-period orbits. Results. In this paper, we report the discovery of new companions orbiting HD 181234, HD 13724, HD 25015, HD 92987 and HD 50499. We also report updated orbital parameters for HD 50499b, HD 92788b and HD 98649b. In addition, we confirm the recent detection of HD 92788c. The newly reported companions span a period range of 15.6–40.4 yr and a mass domain of 2.93–26.77 M Jup , the latter of which straddles the nominal boundary between planets and brown dwarfs. Conclusions. We report the detection of five new companions and updated parameters of four known extrasolar planets. We identify at least some of these companions to be promising candidates for imaging and further characterisation.
Publisher: Oxford University Press (OUP)
Date: 12-09-2023
Publisher: Oxford University Press (OUP)
Date: 09-10-2018
Publisher: Oxford University Press (OUP)
Date: 10-07-2019
Abstract: We report the discovery of WASP-166b, a super-Neptune planet with a mass of 0.1 MJup (1.9 MNep) and a bloated radius of 0.63 RJup. It transits a V = 9.36, F9V star in a 5.44-d orbit that is aligned with the stellar rotation axis (sky-projected obliquity angle λ = 3 ± 5 deg). Variations in the radial-velocity measurements are likely the result of magnetic activity over a 12-d stellar rotation period. WASP-166b appears to be a rare object within the ‘Neptune desert’.
Publisher: American Astronomical Society
Date: 03-08-2021
Publisher: EDP Sciences
Date: 30-06-2023
DOI: 10.1051/0004-6361/202346406
Abstract: While the s le of confirmed exoplanets continues to grow, the population of transiting exoplanets around early-type stars is still limited. These planets allow us to investigate the planet properties and formation pathways over a wide range of stellar masses and study the impact of high irradiation on hot Jupiters orbiting such stars. We report the discovery of TOI-615b, TOI-622b, and TOI-2641b, three Saturn-mass planets transiting main sequence, F-type stars. The planets were identified by the Transiting Exoplanet Survey Satellite (TESS) and confirmed with complementary ground-based and radial velocity observations. TOI-615b is a highly irradiated (~1277 F ⊕ ) and bloated Saturn-mass planet (1.69 −0.06 +0.05 R Jup and 0.43 −0.08 +0.09 M Jup ) in a 4.66 day orbit transiting a 6850 K star. TOI-622b has a radius of 0.82 −0.03 +0.03 R Jup and a mass of 0.30 −0.08 +0.07 M Jup in a 6.40 day orbit. Despite its high insolation flux (~600 F ⊕ ), TOI-622b does not show any evidence of radius inflation. TOI-2641b is a 0.39 −0.04 +0.02 M Jup planet in a 4.88 day orbit with a grazing transit (b = 1.04 −0.06 +0.05 ) that results in a poorly constrained radius of 1.61 −0.64 +0.46 R Jup . Additionally, TOI-615b is considered attractive for atmospheric studies via transmission spectroscopy with ground-based spectrographs and JWST. Future atmospheric and spin-orbit alignment observations are essential since they can provide information on the atmospheric composition, formation, and migration of exoplanets across various stellar types.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
No related grants have been discovered for Amaury Triaud.