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

April 2019 • 2019ApJ...875L...7D

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

Abstract • 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 {2.61}-0.16+0.17 R , and combined archival and follow-up precision radial velocity data put the mass of the planet at {22.7}-1.9+2.2 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 ({R}p={0.892}-0.058+0.064{R}\oplus ) planet from TESS. The HD 21749 system is a prime target for comparative studies of planetary composition and architecture in multi-planet systems.

This Letter includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.


IPAC Authors


David Ciardi

Senior Scientist


Benjamin Fulton

Assistant Scientist