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

December 2021 • 2021AJ....162..292A

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

Abstract • We present the discovery of a highly irradiated and moderately inflated ultrahot Jupiter, TOI-1431b/MASCARA-5 b (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 ± 1.1 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 ± 0.18 M J (990 ± 60 M ), an inflated radius of R p = 1.49 ± 0.05 R J (16.7 ± 0.6 R ), and an orbital period of P = 2.650237 ± 0.000003 days. Analysis of the spectral energy distribution of the host star reveals that the planet orbits a bright (V = 8.049 mag) and young ( ${0.29}_{-0.19}^{+0.32}$ Gyr) Am type star with ${T}_{\mathrm{eff}}={7690}_{-250}^{+400}$ K, resulting in a highly irradiated planet with an incident flux of $\langle F\rangle ={7.24}_{-0.64}^{+0.68}\times $ 109 erg s-1 cm-2 ( ${5300}_{-470}^{+500}\,{S}_{\oplus }$ ) and an equilibrium temperature of T eq = 2370 ± 70 K. TESS photometry also reveals a secondary eclipse with a depth of ${127}_{-5}^{+4}$ 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 day = 3004 ± 64 K and T night = 2583 ± 63 K, the second hottest measured nightside temperature. The planet's low day/night temperature contrast (~420 K) suggests very efficient heat transport between the dayside and nightside hemispheres. Given the host star brightness and estimated secondary eclipse depth of ~1000 ppm in the K band, the secondary eclipse is potentially detectable at near-IR wavelengths with ground-based facilities, and the planet is ideal for intensive atmospheric characterization through transmission and emission spectroscopy from space missions such as the James Webb Space Telescope and the Atmospheric Remote-sensing Infrared Exoplanet Large-survey.


IPAC Authors


David Ciardi

Senior Scientist