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