The First Habitable-zone Earth-sized Planet from TESS. I. Validation of the TOI-700 System

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

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


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 ⊕ to 2.6 R ⊕ and orbital periods ranging from 9.98 to 37.43 days. Ground-based follow-up combined with diagnostic vetting and validation tests enables 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 ± 0.11 R ⊕ and resides within a conservative estimate of the host star's habitable zone, where it receives a flux from its star that is approximately 86% of 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 ⊕), will be an excellent target for JWST and future space-based observatories. TESS is scheduled to once again observe the Southern Hemisphere, and it will monitor TOI-700 for an additional 11 sectors in its extended mission. These observations should allow further constraints on the known planet parameters and searches for additional planets and transit timing variations in the system.

Original languageEnglish (US)
Article numberaba4b2
JournalAstronomical Journal
Issue number3
StatePublished - Sep 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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