TOI-1431b/MASCARA-5b: A Highly Irradiated Ultra-Hot Jupiter Orbiting One of the Hottest & Brightest Known Exoplanet Host Stars

Brett Addison , Emil Knudstrup , Ian Wong , Guillaume Hébrard (1) , Patrick Dorval , Ignas Snellen (2) , Simon Albrecht , Aaron Bello-Arufe (3) , Jose-Manuel Almenara (4) , Isabelle Boisse (5) , Xavier Bonfils (4) , Shweta Dalal , Olivier Demangeon , Sergio Hoyer , Flavien Kiefer , N. C. Santos , Grzegorz Nowak , Rafael Luque , Monika Stangret , Enric Palle , René Tronsgaard , Victoria Antoci , Lars Buchhave , Maximilian Günther , Tansu Daylan , Felipe Murgas , Hannu Parviainen , Emma Esparza-Borges , Nicolas Crouzet , Norio Narita , Akihiko Fukui , Kiyoe Kawauchi , Noriharu Watanabe , Markus Rabus , Marshall Johnson , Gilles Otten , Geert Jan Talens , Samuel Cabot , Debra Fischer , Frank Grundahl , Mads Fredslund Andersen , Jens Jessen-Hansen , Pere Pallé , Avi Shporer , David Ciardi , Jake Clark , Robert Wittenmyer , Duncan Wright , Jonathan Horner , Karen Collins , Eric Jensen , John Kielkopf , Richard Schwarz , Gregor Srdoc , Mesut Yilmaz , Hakan Volkan Senavci , Brendan Diamond , Daniel Harbeck , Thaddeus Komacek , Jeffrey Smith , Songhu Wang , Jason Eastman , Keivan Stassun , David Latham , Roland Vanderspek , Sara Seager , Joshua Winn , Jon Jenkins , Dana Louie , Luke Bouma , Joseph Twicken , Alan Levine , Brian Mclean

1 IAP - Institut d'Astrophysique de Paris
2 Leiden Observatory [Leiden]
3 DTU Space - National Space Institute [Lyngby]
4 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
5 IAP - Institut d'Astrophysique de Paris

We present the discovery of a highly irradiated and moderately inflated ultra-hot Jupiter, TOI-1431b/MASCARA-5b (HD 201033b), first detected by NASA's Transiting Exoplanet Survey Satellite mission (TESS) and the Multi-site All-Sky CAmeRA (MASCARA). The signal was established to be of planetary origin through radial velocity measurements obtained using SONG, SOPHIE, FIES, NRES, and EXPRES, which show a reflex motion of $K=294.1\pm1.1$ m s$^{-1}$. A joint analysis of the TESS and ground-based photometry and radial velocity measurements reveals that TOI-1431b has a mass of $M_{p}=3.12\pm0.18$ $\rm{M_J}$ ($990\pm60$ M$_{\oplus}$), an inflated radius of $R_{p}=1.49\pm0.05$ $\rm{R_J}$ ($16.7\pm0.6$ R$_{\oplus}$), and an orbital period of $P=2.650237\pm0.000003$ d. Analysis of the spectral energy distribution of the host star reveals that the planet orbits a bright ($\mathrm{V}=8.049$ mag) and young ($0.29^{+0.32}_{-0.19}$ Gyr) Am type star with $T_{\rm eff}=7690^{+400}_{-250}$ $\rm{K}$, resulting in a highly irradiated planet with an incident flux of $\langle F \rangle=7.24^{+0.68}_{-0.64}\times$10$^9$ erg s$^{-1}$ cm$^{-2}$ ($5300^{+500}_{-470}\mathrm{S_{\oplus}}$) and an equilibrium temperature of $T_{eq}=2370\pm70$ K. TESS photometry also reveals a secondary eclipse with a depth of $127^{+4}_{-5}$ppm as well as the full phase curve of the planet's thermal emission in the red-optical. This has allowed us to measure the dayside and nightside temperature of its atmosphere as $T_\mathrm{day}=3004\pm64$ K and $T_\mathrm{night}=2583\pm63$ K, the second hottest measured nightside temperature. The planet's low day/night temperature contrast ($\sim$420 K) suggests very efficient heat transport between the dayside and nightside hemispheres.

Domains: Astrophysics [astro-ph]

Brett Addison, Emil Knudstrup, Ian Wong, Guillaume Hébrard, Patrick Dorval, et al.. TOI-1431b/MASCARA-5b: A Highly Irradiated Ultra-Hot Jupiter Orbiting One of the Hottest & Brightest Known Exoplanet Host Stars. The Astronomical Journal, 2021, 162 (6), pp.292. ⟨10.3847/1538-3881/ac224e⟩. ⟨insu-03458424⟩