10/09/14: SO/NOAO Joint Colloquium Series: Andrej Prsa, Villanova University
Andrej Prsa, Villanova University
Unprecedented accuracy in the fundamental parameters of stars from multiple stellar systems
Eclipsing binary stars have long served as calibrators of the fundamental stellar properties across the H-R diagram. Because of the favorable geometric alignment and well understood dynamical laws that govern the motions of the components, the modeling of their light and radial velocity curves can provide us with masses, radii, temperatures and luminosities to a precision better than 1-2%. NASA's Kepler mission observed a 100-deg^2 patch of the sky in the Cygnus-Lyra region essentially uninterruptedly for 4 years, and it attained an unprecedented photometric precision of ~20ppm. The mission harvested over 2600 eclipsing binaries; of those, ~20% were found to be triples by means of eclipse timing variations. Most interestingly, there are more that 30 objects that show tertiary transits, either by another stellar companion or by a circumbinary planet. In those cases the fundamental stellar parameters can be attained a full order of magnitude more precisely than from eclipsing binaries alone, typically to 0.1% and, in two cases, even better. I will present the methodology and the first results of these studies, and stress the implications for the low-mass end of the H-R diagram.
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