The First Habitable Zone Earth-sized Planet from TESS. I: Validation of the TOI-700 System
Creators: name: Gilbert, Emily A.
name: Barclay, Thomas
name: Schlieder, Joshua E.
name: Quintana, Elisa V.
name: Hord, Benjamin J.
name: Kostov, Veselin B.
name: Lopez, Eric D.
name: Rowe, Jason F.
name: Hoffman, Kelsey
name: Walkowicz, Lucianne M.
name: Silverstein, Michele L.
name: Rodriguez, Joseph E.
name: Vanderburg, Andrew
name: Suissa, Gabrielle
name: Airapetian, Vladimir S.
name: Clement, Matthew S.
name: Raymond, Sean N.
name: Mann, Andrew W.
name: Kruse, Ethan
name: Lissauer, Jack J.
name: Colón, Knicole D.
name: Kopparapu, Ravi kumar
name: Kreidberg, Laura
name: Zieba, Sebastian
name: Collins, Karen A.
name: Quinn, Samuel N.
name: Howell, Steve B.
name: Ziegler, Carl
name: Vrijmoet, Eliot Halley
name: Adams, Fred C.
name: Arney, Giada N.
name: Boyd, Patricia T.
name: Brande, Jonathan
name: Burke, Christopher J.
name: Cacciapuoti, Luca
name: Chance, Quadry
name: Christiansen, Jessie L.
name: Covone, Giovanni
name: Daylan, Tansu
name: Dineen, Danielle
name: Dressing, Courtney D.
name: Essack, Zahra
name: Fauchez, Thomas J.
name: Galgano, Brianna
name: Howe, Alex R.
name: Kaltenegger, Lisa
name: Kane, Stephen R.
name: Lam, Christopher
name: Lee, Eve J.
name: Lewis, Nikole K.
name: Logsdon, Sarah E.
name: Mandell, Avi M.
name: Monsue, Teresa
name: Mullally, Fergal
name: Mullally, Susan E.
name: Paudel, Rishi
name: Pidhorodetska, Daria
name: Plavchan, Peter
name: Reyes, Naylynn Tañón
name: Rinehart, Stephen A.
name: Rojas-Ayala, Bárbara
name: Smith, Jeffrey C.
name: Stassun, Keivan G.
name: Tenenbaum, Peter
name: Vega, Laura D.
name: Villanueva, Geronimo L.
name: Wolf, Eric T.
name: Youngblood, Allison
name: Ricker, George R.
name: Vanderspek, Roland K.
name: Latham, David W.
name: Seager, Sara
name: Winn, Joshua N.
name: Jenkins, Jon M.
name: Bakos, Gáspár Á.
name: Briceño, César
name: Ciardi, David R.
name: Cloutier, Ryan
name: Conti, Dennis M.
name: Couperus, Andrew
name: Di Sora, Mario
name: Eisner, Nora L.
name: Everett, Mark E.
name: Gan, Tianjun
name: Hartman, Joel D.
name: Henry, Todd
name: Isopi, Giovanni
name: Jao, Wei-Chun
name: Jensen, Eric L. N.
name: Law, Nicholas
name: Mallia, Franco
name: Matson, Rachel A.
name: Shappee, Benjamin J.
name: Wood, Mackenna Lee
name: Winters, Jennifer G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present the discovery and validation of a three-planet system orbiting the nearby (31.1 pc) M2 dwarf star TOI-700 (TIC 150428135). TOI-700 lies in the TESS continuous viewing zone in the Southern Ecliptic Hemisphere; observations spanning 11 sectors reveal three planets with radii ranging from 1 R$_\oplus$ to 2.6 R$_\oplus$ and orbital periods ranging from 9.98 to 37.43 days. Ground-based follow-up combined with diagnostic vetting and validation tests enable us to rule out common astrophysical false-positive scenarios and validate the system of planets. The outermost planet, TOI-700 d, has a radius of $1.19\pm0.11$ R$_\oplus$ and resides in the conservative habitable zone of its host star, where it receives a flux from its star that is approximately 86% of the Earth's insolation. In contrast to some other low-mass stars that host Earth-sized planets in their habitable zones, TOI-700 exhibits low levels of stellar activity, presenting a valuable opportunity to study potentially-rocky planets over a wide range of conditions affecting atmospheric escape. While atmospheric characterization of TOI-700 d with the James Webb Space Telescope (JWST) will be challenging, the larger sub-Neptune, TOI-700 c (R = 2.63 R$_\oplus$), will be an excellent target for JWST and beyond. TESS is scheduled to return to the Southern Hemisphere and observe TOI-700 for an additional 11 sectors in its extended mission, which should provide further constraints on the known planet parameters and searches for additional planets and transit timing variations in the system.
description: Accepted for publication in AJ (30 pages, 13 figures, 4 tables, 2 appendices)