griv at bgu.ac.il
Sun Jan 8 16:06:35 IST 2017
PLACE: Seminar Room 207, Building 54
Science with Orbital Phase Curves in the Space Age
Dr. Avi Shporer, California Institute of Technology
We are living in the golden age of time series photometry, when high-quality data is delivered by space-based surveys for a large number of stars in visible light. This enables a detailed study of the minute variability following the orbital motion of stellar binaries and star-planet systems, at a precision which is beyond reach from the ground. These orbital modulations are induced by a combination of gravitational and atmospheric processes, hence the phase curve shape contains information about the companionâs mass and atmospheric characteristics. I will present the science I am doing with phase curves. This includes using phase curve variability to detect non-eclipsing systems, which can transform photometric surveys like Kepler to the equivalent of a radial velocity survey. Another important application is the mass measurement of hot Jupiters orbiting hot early-type stars, where the mass cannot be measured using radial velocities. In addition, using phase curves of tran
siting hot Jupiters I showed that the atmospheres of most such exoplanets have their optical brightest region shifted Westward of the substellar point, indicating an inhomogeneous cloud coverage. Finally, I will present a Keck/HIRES project focused on high-eccentricity binary stars identified in Kepler phase curves (aka heartbeat stars). As a whole, the above shows the high scientific potential of the study of space-based phase curves, which we have only begun to explore in recent years and will continue using data from current and future space-based surveys including K2, TESS, and PLATO.
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