The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc
نویسندگان
چکیده
We present the TESS discovery of LHS 1678 (TOI-696) exoplanet system, comprised two approximately Earth-sized transiting planets and a likely astrometric brown dwarf orbiting bright ($V_J$=12.5, $K_s$=8.3) M2 at 19.9 pc. The TESS-detected are radius 0.70$\pm$0.04 $R_\oplus$ 0.98$\pm$0.06 in 0.86-day 3.69-day orbits, respectively. Both validated characterized via ground-based follow-up observations. HARPS RV monitoring yields 97.7 percentile mass upper limits 0.35 $M_\oplus$ 1.4 for b c, companion detected by CTIO/SMARTS 0.9m has an orbital period on order decades is undetected other means. Additional observations constrain to being high-mass or smaller. Each planet unique interest; inner ultra-short period, outer Venus zone. promising targets atmospheric characterization with JWST measurements extreme-precision radial velocity. A third candidate 0.9$\pm$0.1 4.97-day orbit also identified multi-Cycle data validation future work. host star associated observed gap lower main sequence Hertzsprung-Russell diagram. This tied transition from partially- fully-convective interiors M dwarfs, effect stellar astrophysics evolution currently unknown. culmination these system properties makes unique, compelling playground comparative science understanding formation small, short-period exoplanets low-mass stars.
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ژورنال
عنوان ژورنال: The Astronomical Journal
سال: 2022
ISSN: ['1538-3881', '0004-6256']
DOI: https://doi.org/10.3847/1538-3881/ac32e3