We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of 1.28 ± 0.18MJ, radius of 1.533 0.047 0.046RJ, and an orbital period of 2.7347749 ± 0.0000039 days. The bright host star (HD 33643; KELT-7) is an F-star with V = 8.54, Teff= 6789 49 50 K, [Fe/H] 0.139 0.081 = -0.075, and log g = 4.149 ± 0.019. It has a mass of 1.535 0.054 0.066 Me, a radius of 1.732 0.045 0.043 Re, 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 Kilodegree Extremely Little Telescope (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-1) results in a RossiterMcLaughlin effect with an unusually large amplitude of several hundred m s-1. 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 = 9.7 ± 5. 2. This is currently the second most rapidly rotating star to have a reflex signal (and thus mass determination) due to a planetary companion measured.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science