TESS Delivers Its First Earth-sized Planet and a Warm Sub-Neptune

Diana Dragomir, Johanna Teske, Maximilian N. Günther, Damien Ségransan, Jennifer A. Burt, Chelsea X. Huang, Andrew Vanderburg, Elisabeth Matthews, Xavier Dumusque, Keivan G. Stassun, Joshua Pepper, George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Thomas Beatty, François Bouchy, Timothy M. BrownR. Paul Butler, David R. Ciardi, Jeffrey D. Crane, Jason D. Eastman, Luca Fossati, Jim Francis, Benjamin J. Fulton, B. Scott Gaudi, Robert F. Goeke, David James, Todd C. Klaus, Rudolf B. Kuhn, Christophe Lovis, Michael B. Lund, Scott McDermott, Martin Paegert, Francesco Pepe, Joseph E. Rodriguez, Lizhou Sha, Stephen A. Shectman, Avi Shporer, Robert J. Siverd, Aylin Garcia Soto, Daniel J. Stevens, Joseph D. Twicken, Stéphane Udry, Steven Villanueva, Sharon X. Wang, Bill Wohler, Xinyu Yao, Zhuchang Zhan

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


The future of exoplanet science is bright, as Transiting Exoplanet Survey Satellite (TESS) once again demonstrates with the discovery of its longest-period confirmed planet to date. We hereby present HD 21749b (TOI 186.01), a sub-Neptune in a 36 day orbit around a bright (V = 8.1) nearby (16 pc) K4.5 dwarf. TESS measures HD 21749b to be R , and combined archival and follow-up precision radial velocity data put the mass of the planet at M . HD 21749b contributes to the TESS Level 1 Science Requirement of providing 50 transiting planets smaller than 4 R with measured masses. Furthermore, we report the discovery of HD 21749c (TOI 186.02), the first Earth-sized () planet from TESS. The HD 21749 system is a prime target for comparative studies of planetary composition and architecture in multi-planet systems.

Original languageEnglish (US)
Article numberL7
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Apr 20 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • planetary systems
  • planets and satellites: detection
  • stars: individual (HD 21749, TIC 279741379)


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