2012/06/30 by Thomas G. Beatty, Joshua Pepper, Robert J. Siverd +36 · 4 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Exoplanet #Gas giant #Hot Jupiter #Jupiter (rocket family) #Physics #Planet #Planetary system #Primary (astronomy) #RADIUS #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1088/2041-8205/756/2/l39
published as Astrophysical Journal Letters 756, L39 (2012) · 9 pages, 2 tables, 4 figures. A short video describing this paper is available at http://www.youtube.com/watch?v=wVS8lnkXXlE. Revised to reflect the ApJL version. Note that figure 4 is not in the ApJL version
openalex publication_date 2012/08/24 · arxiv created 2012/08/29 · arxiv updated 2012/08/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the discovery of KELT-2Ab, a hot Jupiter transiting the bright ( V = 8.77) primary star of the HD 42176 binary system. The host is a slightly evolved late F-star likely in the very short-lived "blue-hook" stage of evolution, with T eff = 6148 ± 48 K, log g = 4.030 +0.015 − 0.026 and [Fe/H] = 0.034 ± 0.78. The inferred stellar mass is M * = 1.314 +0.063 − 0.060 M ☉ and the star has a relatively large radius of R * = 1.836 +0.066 − 0.046 R ☉ . The planet is a typical hot Jupiter with period 4.1137913 ± 0.00001 days and a mass of M P = 1.524 ± 0.088 M J and radius of R P = 1.290 +0.064 − 0.050 R J . This is mildly inflated as compared to models of irradiated giant planets at the ∼4 Gyr age of the system. KELT-2A is the third brightest star with a transiting planet identified by ground-based transit surveys, and the ninth brightest star overall with a transiting planet. KELT-2Ab's mass and radius are unique among the subset of planets with V < 9 host stars, and therefore increases the diversity of bright benchmark systems. We also measure the relative motion of KELT-2A and -2B over a baseline of 38 years, robustly demonstrating for the first time that the stars are bound. This allows us to infer that KELT-2B is an early K dwarf. We hypothesize that through the eccentric Kozai mechanism KELT-2B may have emplaced KELT-2Ab in its current orbit. This scenario is potentially testable with Rossiter-McLaughlin measurements, which should have an amplitude of ∼44 m s −1 .