Gravity-darkening Analysis of the Misaligned Hot Jupiter MASCARA-4 b

John P. Ahlers , Ethan Kruse , Knicole D. Colón , Patrick Dorval , Geert Jan Talens , Ignas Snellen , Simon Albrecht , Gilles Otten (1) , George Ricker , Roland Vanderspek , David Latham , Sara Seager , Joshua Winn , Jon M. Jenkins , Kari Haworth , Scott Cartwright , Robert Morris , Pam Rowden , Peter Tenenbaum , Eric B. Ting

1 LAM - Laboratoire d'Astrophysique de Marseille

MASCARA-4 b is a hot Jupiter in a highly misaligned orbit around a rapidly rotating A3V star that was observed for 54 days by the Transiting Exoplanet Survey Satellite (TESS). We perform two analyses of MASCARA-4 b using a stellar gravity-darkened model. First, we measure MASCARA-4 b’s misaligned orbital configuration by modeling its TESS photometric light curve. We take advantage of the asymmetry in MASCARA-4 b’s transit due to its host star’s gravity-darkened surface to measure MASCARA-4 b’s true spin-orbit angle to be 104°{}_-{13^{^\circ} }^{+{7^\circ} }. We also detect a ∼4σ secondary eclipse at 0.491 ± 0.007 orbital phase, proving that the orbit is slightly eccentric. Second, we model MASCARA-4 b’s insolation including gravity darkening and find that the planet’s received X-ray and ultraviolet flux varies by 4% throughout its orbit. MASCARA-4 b’s short-period, polar orbit suggests that the planet likely underwent dramatic orbital evolution to end up in its present-day configuration and that it receives a varying stellar irradiance that perpetually forces the planet out of thermal equilibrium. These findings make MASCARA-4 b an excellent target for follow-up characterization to better understand the orbital evolution and present-day environment of planets around high-mass stars.

Mots clés: Exoplanet systems; Exoplanet astronomy; Stellar rotation; Exoplanets; Extrasolar gas giants; Hot Jupiters; Gravity darkening; von Zeipel theorem; Planetary alignment; Inclination; 484; 486; 1629; 498; 509; 753; 680; 1781; 1243; 780; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics

Domaines: Planète et Univers [physics]

John P. Ahlers, Ethan Kruse, Knicole D. Colón, Patrick Dorval, Geert Jan Talens, et al.. Gravity-darkening Analysis of the Misaligned Hot Jupiter MASCARA-4 b. The Astrophysical Journal, 2020, 888, ⟨10.3847/1538-4357/ab59d0⟩. ⟨insu-03667143⟩