TY - JOUR
T1 - ORBITAL CIRCULARIZATION of HOT and COOL KEPLER ECLIPSING BINARIES
AU - Eylen, Vincent Van
AU - Winn, Joshua N.
AU - Albrecht, Simon
N1 - Funding Information:
The research is supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (grant agreement No. 267864). We acknowledge ASK for covering travels in relation to this publication. Part of this work was supported by the Danish Council for Independent Research, through a DFF Sapere Aude Starting grant No. 4181-00487B.
Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved.
PY - 2016/6/10
Y1 - 2016/6/10
N2 - The rate of tidal circularization is predicted to be faster for relatively cool stars with convective outer layers, compared to hotter stars with radiative outer layers. Observing this effect is challenging because it requires large and well-characterized samples that include both hot and cool stars. Here we seek evidence of the predicted dependence of circularization upon stellar type, using a sample of 945 eclipsing binaries observed by Kepler. This sample complements earlier studies of this effect, which employed smaller samples of better-characterized stars. For each Kepler binary we measure e cos ω based on the relative timing of the primary and secondary eclipses. We examine the distribution of e cos ω as a function of period for binaries composed of hot stars, cool stars, and mixtures of the two types. At the shortest periods, hot-hot binaries are most likely to be eccentric; for periods shorter than four days, significant eccentricities occur frequently for hot-hot binaries, but not for hot-cool or cool-cool binaries. This is in qualitative agreement with theoretical expectations based on the slower dissipation rates of hot stars. However, the interpretation of our results is complicated by the largely unknown ages and evolutionary states of the stars in our sample.
AB - The rate of tidal circularization is predicted to be faster for relatively cool stars with convective outer layers, compared to hotter stars with radiative outer layers. Observing this effect is challenging because it requires large and well-characterized samples that include both hot and cool stars. Here we seek evidence of the predicted dependence of circularization upon stellar type, using a sample of 945 eclipsing binaries observed by Kepler. This sample complements earlier studies of this effect, which employed smaller samples of better-characterized stars. For each Kepler binary we measure e cos ω based on the relative timing of the primary and secondary eclipses. We examine the distribution of e cos ω as a function of period for binaries composed of hot stars, cool stars, and mixtures of the two types. At the shortest periods, hot-hot binaries are most likely to be eccentric; for periods shorter than four days, significant eccentricities occur frequently for hot-hot binaries, but not for hot-cool or cool-cool binaries. This is in qualitative agreement with theoretical expectations based on the slower dissipation rates of hot stars. However, the interpretation of our results is complicated by the largely unknown ages and evolutionary states of the stars in our sample.
KW - binaries: eclipsing
KW - planets and satellites: dynamical evolution and stability
KW - stars: evolution
KW - stars: fundamental parameters
UR - http://www.scopus.com/inward/record.url?scp=84976449005&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84976449005&partnerID=8YFLogxK
U2 - 10.3847/0004-637X/824/1/15
DO - 10.3847/0004-637X/824/1/15
M3 - Article
AN - SCOPUS:84976449005
SN - 0004-637X
VL - 824
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 15
ER -