2011/09/22 by Joshua N. Winn, Simon Albrecht, John Asher Johnson +42 · 1 citation
Engineering · Physics and Astronomy · #Aerospace engineering #Astrobiology #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Biology #Circumbinary planet #Engineering #Host (biology) #Kepler #Orbit (dynamics) #Physics #Planet #Spin (aerodynamics) #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1088/2041-8205/741/1/l1
ApJ Letters, in press [7 pages]
arxiv created 2011/09/22 · openalex publication_date 2011/10/05 · arxiv updated 2015/05/29 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Kepler-16 is an eccentric low-mass eclipsing binary with a circumbinary transiting planet. Here, we investigate the angular momentum of the primary star, based on Kepler photometry and Keck spectroscopy. The primary star's rotation period is 35.1 ± 1.0 days, and its projected obliquity with respect to the stellar binary orbit is 1 6 ± 2 4. Therefore, the three largest sources of angular momentum—the stellar orbit, the planetary orbit, and the primary's rotation—are all closely aligned. This finding supports a formation scenario involving accretion from a single disk. Alternatively, tides may have realigned the stars despite their relatively wide separation (0.2 AU), a hypothesis that is supported by the agreement between the measured rotation period and the "pseudosynchronous" period of tidal evolution theory. The rotation period, chromospheric activity level, and fractional light variations suggest a main-sequence age of 2–4 Gyr. Evolutionary models of low-mass stars can match the observed masses and radii of the primary and secondary stars to within about 3%.