KELT-8b: A Highly Inflated Transiting Hot Jupiter and a New Technique for Extracting High-precision Radial Velocities from Noisy Spectra

摘要: We announce the discovery of a highly inflated transiting hot Jupiter by KELT-North survey. A global analysis including constraints from isochrones indicates that V = 10.8 host star (HD 343246) is mildly evolved, G dwarf with T_(eff)= 5754^(+54)_(-55)K, log g 4.078^(0.049)_(0.054), [Fe/H] 0.272 ± 0.038, an inferred mass M_* 1.211_(0.066)^(+0.078)M_☉, and radius R_*=1.67 _(-0.12)^(+0.14) R_☉. The planetary companion has Mp 0.867 _(-0.061)^+(0.065) MJ, R_p 1.86_(-0.16)^(+0.18) R_J, surface gravity g_p 2.793_(-0.075)^(+0.072), density 0.167_(-0.038)^(+0.047) cm^(−3). planet on roughly circular orbit with semimajor axis ɑ 0.04571_(0.00084)^(+0.00096) AU eccentricity e 0.035_(-0.025)^(+0.050). best-fit linear ephemeris T_0 2456883.4803 0.0007 BJD_(TDB) P 3.24406 0.00016 days. This one most all known exoplanets, making it few members class extremely low density, irradiated gas giants. stellar large implied are supported follow-up light curves, as well evolutionary space motion analysis. also develop new technique to extract high-precision radial velocities noisy spectra reduces observing time needed confirm candidates. boasts deep transits bright star, atmospheric scale height, high equilibrium temperature T_(eq) 1675_(-55)^(+61)K, assuming zero albedo perfect heat redistribution, best targets for future characterization studies.