SPIN-ORBIT ALIGNMENT FOR THE CIRCUMBINARY PLANET HOST KEPLER-16 A
- Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
- Department of Astrophysics, California Institute of Technology, MC249-17, Pasadena, CA 91125 (United States)
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
- McDonald Observatory, University of Texas, Austin, TX 78712 (United States)
- Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
- Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
- Carl Sagan Center for the Study of Life in the Universe, SETI Institute, Mountain View, CA 94043 (United States)
- Astronomy Department, San Diego State University, San Diego, CA 92182 (United States)
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
- Las Cumbres Observatory Global Telescope Network, Santa Barbara, CA 93117 (United States)
- National Optical Astronomy Observatory, Tucson, AZ 85726 (United States)
- Department of Astronomy and Astrophysics, Villanova University, Villanova, PA 19085 (United States)
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.{sup 0}6 {+-} 2.{sup 0}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%.
- OSTI ID:
- 21565359
- Journal Information:
- Astrophysical Journal Letters, Vol. 741, Issue 1; Other Information: DOI: 10.1088/2041-8205/741/1/L1; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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