Publication details

TOI-1408: Discovery and Photodynamical Modeling of a Small Inner Companion to a Hot Jupiter Revealed by Transit Timing Variations

Authors	KORTH Judith CHATURVEDI Priyanka PARVIAINEN Hannu CARLEO Ilaria ENDL Michael GUENTHER Eike W NOWAK Grzegorz PERSSON Carina M MACQUEEN Phillip J MUSTILL Alexander J CABRERA Juan COCHRAN William D LILLO-BOX Jorge HOBBS David MURGAS Felipe GREKLEK-MCKEON Michael KELLERMANN Hanna HEBRARD Guillaume FUKUI Akihiko PALLE Enric JENKINS Jon M TWICKEN Joseph D COLLINS Karen A QUINN Samuel N SUBJAK Jan BECK Paul G GANDOLFI Davide MATHUR Savita DEEG Hans J LATHAM David W ALBRECHT Simon BARRADO David BOISSE Isabelle BOUY Herve DELFOSSE Xavier DEMANGEON Olivier GARCIA Rafael A HATZES Artie P HEIDARI Neda IKUTA Kai KABATH Petr KNUTSON Heather A LIVINGSTON John MARTIOLI Eder MORALES-CALDERON Maria MORELLO Giuseppe NARITA Norio ORELL-MIQUEL Jaume OSBORNE Hanna L M PALAKKATHARAPPIL Dinil B PINTER Viktoria REDFIELD Seth RELLES Howard M SCHWARZ Richard P SEAGER Sara SHPORER Avi SKARKA Marek SRDOC Gregor STANGRET Monika THOMAS Luis VINCENT Van Eylen WATANABE Noriharu WINN Joshua N
Year of publication	2024
Type	Article in Periodical
Magazine / Source	Astrophysical Journal Letters
MU Faculty or unit	Faculty of Science
Citation
web	https://iopscience.iop.org/article/10.3847/2041-8213/ad65fd
Doi	http://dx.doi.org/10.3847/2041-8213/ad65fd
Keywords	Exoplanet dynamics; Hot Jupiters; Hot Neptunes; Transit timing variation method; Transit photometry; Radial velocity
Description	We report the discovery and characterization of a small planet, TOI-1408 c, on a 2.2 day orbit located interior to a previously known hot Jupiter, TOI-1408 b (P = 4.42 days, M = 1.86 ± 0.02 MJup, R = 2.4 ± 0.5 RJup) that exhibits grazing transits. The two planets are near 2:1 period commensurability, resulting in significant transit timing variations (TTVs) for both planets and transit duration variations for the inner planet. The TTV amplitude for TOI-1408 c is 15% of the planet's orbital period, marking the largest TTV amplitude relative to the orbital period measured to date. Photodynamical modeling of ground-based radial velocity (RV) observations and transit light curves obtained with the Transiting Exoplanet Survey Satellite and ground-based facilities leads to an inner planet radius of 2.22 ± 0.06 R? and mass of 7.6 ± 0.2 M? that locates the planet into the sub-Neptune regime. The proximity to the 2:1 period commensurability leads to the libration of the resonant argument of the inner planet. The RV measurements support the existence of a third body with an orbital period of several thousand days. This discovery places the system among the rare systems featuring a hot Jupiter accompanied by an inner low-mass planet.