Details

Autor(en) / Beteiligte

• Alves, Douglas R
• Jenkins, James S
• Vines, Jose I
• Nielsen, Louise D
• Gill, Samuel
• Acton, Jack S
• Anderson, D R
• Bayliss, Daniel
• Bouchy, François
• Breytenbach, Hannes
• Bryant, Edward M
• Burleigh, Matthew R
• Casewell, Sarah L
• Eigmüller, Philipp
• Gillen, Edward
• Goad, Michael R
• Günther, Maximilian N
• Henderson, Beth A
• Kendall, Alicia
• Lendl, Monika
• Moyano, Maximiliano
• Sefako, Ramotholo R
• Smith, Alexis M S
• Costes, Jean C
• Tilbrook, Rosanne H
• Thomas, Jessymol K
• Udry, Stéphane
• Watson, Christopher A
• West, Richard G
• Wheatley, Peter J
• Worters, Hannah L
• Osborn, Ares

Titel

NGTS-21b: an inflated Super-Jupiter orbiting a metal-poor K dwarf

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2022-11, Vol.517 (3), p.4447-4457

Ort / Verlag

Oxford University Press (OUP): Policy P - Oxford Open Option A

Erscheinungsjahr

2022

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• ABSTRACT We report the discovery of NGTS-21b , a massive hot Jupiter orbiting a low-mass star as part of the Next Generation Transit Survey (NGTS). The planet has a mass and radius of 2.36 ± 0.21 MJ and 1.33 ± 0.03 RJ, and an orbital period of 1.543 d. The host is a K3V (Teff = 4660 ± 41 K) metal-poor ([Fe/H] = −0.26 ± 0.07 dex) dwarf star with a mass and radius of 0.72 ± 0.04 M⊙ and 0.86 ± 0.04R⊙. Its age and rotation period of $10.02^{+3.29}_{-7.30}$ Gyr and 17.88 ± 0.08 d, respectively, are in accordance with the observed moderately low-stellar activity level. When comparing NGTS-21b with currently known transiting hot Jupiters with similar equilibrium temperatures, it is found to have one of the largest measured radii despite its large mass. Inflation-free planetary structure models suggest the planet’s atmosphere is inflated by $\sim \! 21{{\ \rm per\ cent}}$, while inflationary models predict a radius consistent with observations, thus pointing to stellar irradiation as the probable origin of NGTS-21b’s radius inflation. Additionally, NGTS-21b’s bulk density (1.25 ± 0.15 g cm–3) is also amongst the largest within the population of metal-poor giant hosts ([Fe/H] < 0.0), helping to reveal a falling upper boundary in metallicity–planet density parameter space that is in concordance with core accretion formation models. The discovery of rare planetary systems such as NGTS-21 greatly contributes towards better constraints being placed on the formation and evolution mechanisms of massive planets orbiting low-mass stars.