ORCID Profile
0000-0001-8105-0373
Current Organisation
Geneva University
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Publisher: American Astronomical Society
Date: 28-06-2021
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: American Astronomical Society
Date: 14-08-2020
Publisher: American Astronomical Society
Date: 07-2020
Abstract: We report the discovery of NGTS-11 b (=TOI-1847b), a transiting Saturn in a 35.46 day orbit around a mid K-type star ( = 5050 ± 80 K). We initially identified the system from a single-transit event in a TESS full-frame image light curve. Following 79 nights of photometric monitoring with an NGTS telescope, we observed a second full transit of NGTS-11 b approximately one year after the TESS single-transit event. The NGTS transit confirmed the parameters of the transit signal and restricted the orbital period to a set of 13 discrete periods. We combined our transit detections with precise radial-velocity measurements to determine the true orbital period and measure the mass of the planet. We find NGTS-11 b has a radius of , a mass of , and an equilibrium temperature of just K, making it one of the coolest known transiting gas giants. NGTS-11 b is the first exoplanet to be discovered after being initially identified as a TESS single-transit event, and its discovery highlights the power of intense photometric monitoring in recovering longer-period transiting exoplanets from single-transit events.
Publisher: American Astronomical Society
Date: 25-03-2021
Abstract: We present the discovery and characterization of five hot and warm Jupiters—TOI-628 b (TIC 281408474 HD 288842), TOI-640 b (TIC 147977348), TOI-1333 b (TIC 395171208, BD+47 3521A), TOI-1478 b (TIC 409794137), and TOI-1601 b (TIC 139375960)—based on data from NASA’s Transiting Exoplanet Survey Satellite (TESS). The five planets were identified from the full-frame images and were confirmed through a series of photometric and spectroscopic follow-up observations by the TESS Follow-up Observing Program Working Group. The planets are all Jovian size ( R P = 1.01–1.77 R J ) and have masses that range from 0.85 to 6.33 M J . The host stars of these systems have F and G spectral types (5595 ≤ T eff ≤ 6460 K) and are all relatively bright (9.5 V 10.8, 8.2 K 9.3), making them well suited for future detailed characterization efforts. Three of the systems in our s le (TOI-640 b, TOI-1333 b, and TOI-1601 b) orbit subgiant host stars ( g 4.1). TOI-640 b is one of only three known hot Jupiters to have a highly inflated radius ( R P 1.7 R J , possibly a result of its host star’s evolution) and resides on an orbit with a period longer than 5 days. TOI-628 b is the most massive, hot Jupiter discovered to date by TESS with a measured mass of M J and a statistically significant, nonzero orbital eccentricity of e = . This planet would not have had enough time to circularize through tidal forces from our analysis, suggesting that it might be remnant eccentricity from its migration. The longest-period planet in this s le, TOI-1478 b ( P = 10.18 days), is a warm Jupiter in a circular orbit around a near-solar analog. NASA’s TESS mission is continuing to increase the s le of well-characterized hot and warm Jupiters, complementing its primary mission goals.
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.
Publisher: American Astronomical Society
Date: 26-08-2020
No related grants have been discovered for Nolan Grieves.