2015/01/22 by Bieryla, Allyson, Collins, Karen, Beatty, Thomas G. +31 · 2 citations
#Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences
paper · doi:10.48550/arxiv.1501.05565
We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of 1.28 ± 0.18 MJ, radius of 1.53-0.047+0.046 RJ, and an orbital period of 2.7347749 ± 0.0000039 days. The bright host star (HD33643; KELT-7) is an F-star with V=8.54, Teff =6789-49+50 K, [Fe/H] =0.139-0.081+0.075, and logg=4.149 ± 0.019. It has a mass of 1.535-0.054+0.066 Msun, a radius of 1.732-0.045+0.043 Rsun, and is the fifth most massive, fifth hottest, and the ninth brightest star known to host a transiting planet. It is also the brightest star around which KELT has discovered a transiting planet. Thus, KELT-7b is an ideal target for detailed characterization given its relatively low surface gravity, high equilibrium temperature, and bright host star. The rapid rotation of the star (73 ± 0.5 km/s) results in a Rossiter-McLaughlin effect with an unusually large amplitude of several hundred m/s. We find that the orbit normal of the planet is likely to be well-aligned with the stellar spin axis, with a projected spin-orbit alignment of λ=9.7 ± 5.2 degrees. This is currently the second most rapidly rotating star to have a reflex signal (and thus mass determination) due to a planetary companion measured.