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

Kavli Affiliate: Christopher Burke

| First 5 Authors: Veselin B. Kostov, Joshua E. Schlieder, Thomas Barclay, Elisa V. Quintana, Knicole D. Colon

| Summary:

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 three sectors, the corresponding stellar parameters
yield planet radii ranging from 0.8REarth to 1.6REarth. 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 Report 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 4 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.

| Search Query: ArXiv Query: search_query=au:”Christopher Burke”&id_list=&start=0&max_results=10

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