OBSERVATIONS OF DOPPLER BOOSTING IN KEPLER LIGHT CURVES

Journal Article · Thu May 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/715/1/51· OSTI ID:21448781

Van Kerkwijk, Marten H; Breton, Rene P; Justham, Stephen ^[1]; Rappaport, Saul A ^[2]; Podsiadlowski, Philipp ^[3]; Han, Zhanwen ^[4]

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1. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing (China)
2. 37-602B, MIT Department of Physics and Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States)
3. Sub-department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)
4. National Astronomical Observatories/Yunnan Observatory and Key Laboratory of the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011 (China)

Among the initial results from Kepler were two striking light curves, for KOI 74 and KOI 81, in which the relative depths of the primary and secondary eclipses showed that the more compact, less luminous object was hotter than its stellar host. That result became particularly intriguing because a substellar mass had been derived for the secondary in KOI 74, which would make the high temperature challenging to explain; in KOI 81, the mass range for the companion was also reported to be consistent with a substellar object. We re-analyze the Kepler data and demonstrate that both companions are likely to be white dwarfs. We also find that the photometric data for KOI 74 show a modulation in brightness as the more luminous star orbits, due to Doppler boosting. The magnitude of the effect is sufficiently large that we can use it to infer a radial velocity amplitude accurate to 1 km s{sup -1}. As far as we are aware, this is the first time a radial-velocity curve has been measured photometrically. Combining our velocity amplitude with the inclination and primary mass derived from the eclipses and primary spectral type, we infer a secondary mass of 0.22 {+-} 0.03 M{sub sun}. We use our estimates to consider the likely evolutionary paths and mass-transfer episodes of these binary systems.

• OSTI ID: 21448781
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 715; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DWARF STARS
ECLIPSE
EVOLUTION
INCLINATION
MASS
MASS TRANSFER
RADIAL VELOCITY
STAR EVOLUTION
STARS
VELOCITY
WHITE DWARF STARS