TESS Hunt for Young and Maturing Exoplanets (THYME). IV. Three Small Planets Orbiting a 120 Myr Old Star in the Pisces–Eridanus Stream*

Abstract

Young exoplanets can offer insight into the evolution of planetary atmospheres, compositions, and architectures. We present the discovery of the young planetary system TOI 451 (TIC 257605131, Gaia DR2 4844691297067063424). TOI 451 is a member of the 120-Myr-old Pisces-Eridanus stream (Psc-Eri). We confirm membership in the stream with its kinematics, its lithium abundance, and the rotation and UV excesses of both TOI 451 and its wide binary companion, TOI 451 B (itself likely an M dwarf binary). We identified three candidate planets transiting in the TESS data and followed up the signals with photometry from Spitzer and ground-based telescopes. The system comprises three validated planets at periods of 1.9, 9.2 and 16 days, with radii of 1.9, 3.1, and 4.1 R ⊕ , respectively. The host star is near-solar mass with V = 11.0 and H = 9.3 and displays an infrared excess indicative of a debris disk. The planets offer excellent prospects for transmission spectroscopy with HST and JWST, providing the opportunity to study planetary atmospheres that may still be in the process of evolving.

Gaia search for stellar companions of TESS Objects of Interest II

“…In the meantime, several of these (C)TOIs, which were revealed as members of multiple star systems in the course of our survey, could already be confirmed by follow‐up observations to be exoplanet host stars, e.g. TOI 451, 1098, 1259, and 1333 (Martin et al 2021; Newton et al 2021; Rodriguez et al 2021; Tofflemire et al 2021).…”

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

“…The TESS mission (Ricker et al 2015) provides a new opportunity for targeted searches of young exoplanets from precise time-series photometry for millions of targets across most of the sky. For example, the THYME survey has identified several planets in known young associations spanning a diversity of Galactic environments, such as the Tucana-Horologium and Ursa Major moving groups (Newton et al 2019;Mann et al 2020), the Scorpius-Centaurus OB association (Rizzuto et al 2020), the Pisces-Eridanus stream (Newton et al 2021), and even a previously unknown association (Tofflemire et al 2021). Other searches of TESS data have revealed planets orbiting young stars in the IC 2602 cluster (Bouma et al 2020) and in the field (Zhou et al 2021).…”

TESS Hunt for Young and Maturing Exoplanets (THYME) VI: an 11 Myr giant planet transiting a very low-mass star in Lower Centaurus Crux

“…The number of known young transiting planets has grown significantly in recent years (e.g., Obermeier et al 2016;David et al 2018;Benatti et al 2019;Newton et al 2021). This growth was primarily driven by a combination of the K2 and TESS missions surveying nearby young clusters and star-forming regions (Ricker et al 2014;Van Cleve et al 2016), improvements in filtering variability in young stars (e.g., Aigrain et al 2016;Rizzuto et al 2017), and more complete identification of young stellar associations from Gaia kinematics (e.g., Cantat-Gaudin et al 2018;Kerr et al 2021).…”

“…As part of the TESS Hunt for Young and Maturing Exoplanets survey (THYME; Newton et al 2019), our team searches TESS data using a specialized pipeline in order to identify young planets missed by standard searches (e.g., Rizzuto et al 2020), and checks previously-identified planet candidates for signs of membership in a young association (e.g., Newton et al 2021;Mann et al 2020). We identified TOI 1227 (2MASS J12270432-7227064, TIC 360156606) as a member of a young association, with a planet candidate (TOI1227.01) identified by the TESS mission, and astrometry consistent with membership in the Lower Centaurus Crux (LCC) region of the Scorpius-Centaurus (Sco-Cen) OB association (Goldman et al 2018;Damiani et al 2019).…”