Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2010-10-13
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
Accepted for publication in MNRAS on August 18, 2010
Scientific paper
The Kepler Mission has acquired 33.5d of continuous one-minute photometry of KPD 1946+4340, a short-period binary system that consists of an sdB and a white dwarf. In the light curve, eclipses are clearly seen, with the deepest occurring when the compact white dwarf crosses the disc of the sdB (0.4%) and the more shallow ones (0.1%) when the sdB eclipses the white dwarf. As expected, the sdB is deformed by the gravitational field of the white dwarf, which produces an ellipsoidal modulation of the light curve. Spectacularly, a very strong Doppler beaming (aka Doppler boosting) effect is also clearly evident at the 0.1% level. This originates from the sdB's orbital velocity, which we measure to be 164.0\pm1.9 km/s from supporting spectroscopy. We present light curve models that account for all these effects, as well as gravitational lensing. We derive system parameters and uncertainties from the light curve using Markov Chain Monte Carlo simulations. Adopting a theoretical white dwarf mass-radius relation, the mass of the subdwarf is found to be 0.47\pm0.03 Msun and the mass of the white dwarf 0.59\pm0.02 Msun. The effective temperature of the white dwarf is 15 900\pm300K. With a spectroscopic effective temperature of Teff = 34 730\pm250K and a surface gravity of log g = 5.43\pm0.04, the sdB is in a shell He burning stage. The detection of Doppler beaming in Kepler light curves potentially allows one to measure radial velocities without the need of spectroscopic data. For the first time, a photometrically observed Doppler beaming amplitude is compared to a spectroscopically established value. The sdB's radial velocity amplitude derived from the photometry 168\pm4 km/s is in perfect agreement with the spectroscopic value. After subtracting our best model for the orbital effects, we searched the residuals for stellar oscillations but did not find any significant pulsation frequencies.
Aerts Christine
Bloemen Steven
Borucki William. J.
Brassard Pierre
Charpinet Stephane
No associations
LandOfFree
Kepler observations of the beaming binary KPD 1946+4340 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Kepler observations of the beaming binary KPD 1946+4340, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Kepler observations of the beaming binary KPD 1946+4340 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-227316