December
2021
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2021AJ....162..292A
Authors
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Addison, Brett C.
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Knudstrup, Emil
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Wong, Ian
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Hébrard, Guillaume
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Dorval, Patrick
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Snellen, Ignas
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Albrecht, Simon
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Bello-Arufe, Aaron
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Almenara, Jose-Manuel
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Boisse, Isabelle
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Bonfils, Xavier
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Dalal, Shweta
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Demangeon, Olivier D. S.
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Hoyer, Sergio
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Kiefer, Flavien
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Santos, N. C.
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Nowak, Grzegorz
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Luque, Rafael
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Stangret, Monika
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Palle, Enric
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Tronsgaard, René
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Antoci, Victoria
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Buchhave, Lars A.
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Günther, Maximilian N.
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Daylan, Tansu
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Murgas, Felipe
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Parviainen, Hannu
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Esparza-Borges, Emma
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Crouzet, Nicolas
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Narita, Norio
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Fukui, Akihiko
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Kawauchi, Kiyoe
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Watanabe, Noriharu
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Rabus, Markus
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Johnson, Marshall C.
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Otten, Gilles P. P. L.
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Jan Talens, Geert
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Cabot, Samuel H. C.
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Fischer, Debra A.
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Grundahl, Frank
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Fredslund Andersen, Mads
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Jessen-Hansen, Jens
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Pallé, Pere
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Shporer, Avi
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Ciardi, David R.
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Clark, Jake T.
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Wittenmyer, Robert A.
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Wright, Duncan J.
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Horner, Jonathan
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Collins, Karen A.
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Jensen, Eric L. N.
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Kielkopf, John F.
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Schwarz, Richard P.
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Srdoc, Gregor
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Yilmaz, Mesut
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Senavci, Hakan Volkan
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Diamond, Brendan
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Harbeck, Daniel
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Komacek, Thaddeus D.
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Smith, Jeffrey C.
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Wang, Songhu
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Eastman, Jason D.
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Stassun, Keivan G.
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Latham, David W.
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Vanderspek, Roland
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Seager, Sara
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Winn, Joshua N.
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Jenkins, Jon M.
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Louie, Dana R.
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Bouma, Luke G.
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Twicken, Joseph D.
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Levine, Alan M.
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McLean, Brian
Abstract
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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.
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