A Second Earth-sized Planet in the Habitable Zone of the M Dwarf, TOI-700

Emily A. Gilbert, Andrew Vanderburg, Joseph E. Rodriguez, Benjamin J. Hord, Matthew S. Clement, Thomas Barclay, Elisa V. Quintana, Joshua E. Schlieder, Stephen R. Kane, Jon M. Jenkins, Joseph D. Twicken, Michelle Kunimoto, Roland Vanderspek, Giada N. Arney, David Charbonneau, Maximilian N. Günther, Chelsea X. Huang, Giovanni Isopi, Veselin B. Kostov, Martti H. KristiansenDavid W. Latham, Franco Mallia, Eric E. Mamajek, Ismael Mireles, Samuel N. Quinn, George R. Ricker, Jack Schulte, S. Seager, Gabrielle Suissa, Joshua N. Winn, Allison Youngblood, Aldo Zapparata

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We report the discovery of TOI-700 e, a 0.95 R planet residing in the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled by multiple years of monitoring from NASA’s Transiting Exoplanet Survey Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby (31.1 pc), inactive, M2.5 dwarf (V mag = 13.15). TOI-700 is already known to host three planets, including the small, HZ planet, TOI-700 d. The new planet has an orbital period of 27.8 days, and based on its radius (0.95 R ), it is likely rocky. TOI-700 was observed for 21 sectors over Years 1 and 3 of the TESS mission, including 10 sectors at 20 s cadence in Year 3. Using this full set of TESS data and additional follow-up observations, we identify, validate, and characterize TOI-700 e. This discovery adds another world to the short list of small, HZ planets transiting nearby and bright host stars. Such systems, where the stars are bright enough that follow-up observations are possible to constrain planet masses and atmospheres using current and future facilities, are incredibly valuable. The presence of multiple small, HZ planets makes this system even more enticing for follow-up observations.

Original languageEnglish (US)
Article numberL35
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Feb 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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