Exoplanets & Exomoons

The L 98-59 System: Three Transiting, Terrestrial-Sized Planets Orbiting a Nearby M-dwarf

By Keith Cowing
Press Release
March 19, 2019
Filed under
The L 98-59 System: Three Transiting, Terrestrial-Sized Planets Orbiting a Nearby M-dwarf
The pixel mask (pink squares) we used to create a lightcurve of L 98-59. The mask was created using the threshold method in the lightkurve extract aperture photometry tool.

We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-sized planets transiting L 98-59 (TOI-175, TIC 307210830) — a bright M dwarf at a distance of 10.6 pc.

Using the Gaia-measured distance and broad-band photometry we find that the host star is an M3 dwarf. Combined with the TESS transits from one sector, the corresponding stellar parameters yield planet radii ranging from 0.7 REarth to 1.3 REarth. All three planets have short orbital periods, ranging from 2.25 to 7.45 days with the outer pair just wide of a 2:1 period resonance. Diagnostic tests produced by the TESS Data Validation and the vetting package DAVE rule out common false positive sources. These analyses, along with dedicated follow-up and the multiplicity of the system, lend confidence that the observed signals are caused by planets transiting L 98-59 and are not associated with other sources in the field.

The L 98-59 system is interesting for a number of reasons: the host star is bright (V = 11.7 mag, K = 7.1 mag) and the planets are prime targets for further follow-up observations including precision radial-velocity mass measurements and future transit spectroscopy with the James Webb Space Telescope; the near resonant configuration makes the system a laboratory to study planetary system dynamical evolution; and three planets of relatively similar size in the same system present an opportunity to study terrestrial planets where other variables (age, metallicity, etc.) can be held constant. L 98-59 will be observed in 6 more TESS sectors, which will provide a wealth of information on the three currently known planets and have the potential to reveal additional planets in the system.

Veselin B. Kostov, Joshua E. Schlieder, Thomas Barclay, Elisa V. Quintana, Knicole D. Colon, Jonathan Brande, Karen A. Collins, Samuel Hadden, Stephen R. Kane, Laura Kreidberg, Ethan Kruse, Christopher Lam, Elisabeth Matthews, Benjamin T. Montet, Francisco J. Pozuelos, Keivan G. Stassun, Jennifer G. Winters, George Ricker, Roland Vanderspek, David Latham, Sara Seager, Joshua Winn, Jon M. Jenkins, Dennis Afanasev, James J. D. Armstrong, Patricia Boyd, Geert Barentsen, Khalid Barkaoui, Natalie E. Batalha, Daniel Bayliss, Artem Burdanov, Luca Cacciapuoti, Andrew Carson, David Charbonneau, Kevin I. Collins, Dennis M. Conti, Giovanni Covone, Mark Clampin, Laetitia Delrez, Courtney Dressing, Elsa Ducrot, Zahra Essack, Mark E. Everett, Daniel Foreman-Mackey, Tianjun Gan, Emily Gilbert, Michael Gillon, Aaron Hamann, Christina Hedges, Elliott P. Horch, Hannah Hocutt, Keith Horne, Shane Hynes, Michael Ireland, Jonathan M. Irwin, Giovanni Isopi, Eric L. N. Jensen, Emmanuel Jehin, John F. Kielkopf, Jack J. Lissauer, Andrew W. Mann, Franco Mallia, Rachel A. Matson, Tsevi Mazeh, Vickie Moran, Brett Morris, Philip Muirhead, Koji Mukai, Catriona Murray, Norio Narita, Enric Palle, David Quinn, Howard Relles, Stephen Rinehart, Matthew Ritsko, Joseph E. Rodriguez, Pamela Rowden, Daniel Sebastian, Ramotholo Sefako, Sahar Shahaf, Avi Shporer, Peter Tenenbaum, Eric B. Ting, Joseph D. Twicken, Gerard T. van Belle, Laura Vega, Jeffrey Volosin, Allison Youngblood
(Submitted on 19 Mar 2019)

Comments: 42 pages, 22 figures, submitted to AAS, comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1903.08017 [astro-ph.EP] (or arXiv:1903.08017v1 [astro-ph.EP] for this version)
Submission history
From: Veselin Kostov B
[v1] Tue, 19 Mar 2019 14:26:05 UTC (6,637 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻