TOI-1431b/MASCARA-5b: A Highly Irradiated Ultra-Hot Jupiter Orbiting One of the Hottest &amp; Brightest Known Exoplanet Host Stars
Creators: name: Addison, Brett Christopher
name: Knudstrup, Emil
name: Wong, Ian
name: Hebrard, Guillaume
name: Dorval, Patrick
name: Snellen, Ignas
name: Albrecht, Simon
name: Bello-Arufe, Aaron
name: Almenara, Jose-Manuel
name: Boisse, Isabelle
name: Bonfils, Xavier
name: Dalal, Shweta
name: Demangeon, Olivier
name: Hoyer, Sergio
name: Kiefer, Flavien
name: Santos, N. C.
name: Nowak, Grzegorz
name: Luque, Rafael
name: Stangret, Monika
name: Palle, Enric
name: Tronsgaard, Rene
name: Antoci, Victoria
name: Buchhave, Lars A.
name: Gunther, Maximilian N.
name: Daylan, Tansu
name: Murgas, Felipe
name: Parviainen, Hannu
name: Esparza-Borges, Emma
name: Crouzet, Nicolas
name: Narita, Norio
name: Fukui, Akihiko
name: Kawauchi, Kiyoe
name: Watanabe, Noriharu
name: Rabus, Markus
name: Johnson, Marshall C.
name: Otten, Gilles P. P. L.
name: Talens, Geert Jan
name: Cabot, Samuel H. C.
name: Fischer, Debra A.
name: Grundahl, Frank
name: Andersen, Mads Fredslund
name: Jessen-Hanse, Jens
name: Palle, Pere
name: Shporer, Avi
name: Ciardi, David R.
name: Clark, Jake T.
name: Wittenmyer, Robert A.
name: Wright, Duncan J.
name: Horner, Jonathan
name: Collins, Karen A.
name: Jensen, Eric L. N.
name: Kielkopf, John F.
name: Schwarz, Richard P.
name: Srdoc, Gregor
name: Yilmaz, Mesut
name: Senavci, Hakan Volkan
name: Diamond, Brendan
name: Harbeck, Daniel
name: Komacek, Thaddeus D.
name: Smith, Jeffrey C.
name: Wang, Songhu
name: Eastman, Jason D.
name: Stassun, Keivan G.
name: Latham, David W.
name: Vanderspek, Roland
name: Seager, Sara
name: Winn, Joshua N.
name: Jenkins, Jon M.
name: Louie, Dana R.
name: Bouma, Luke G.
name: Twicken, Joseph D.
name: Levine, Alan M.
name: McLean, Brian
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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.
description: Accepted for publication in the Astronomical Journal. 39 pages, 18 figures, and 4 tables