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Paper: New Light Curves and Spectra of the Close PG1159 Binary System SDSS J212531.92−010745.9
Volume: 391, Hydrogen-Deficient Stars
Page: 133
Authors: Schuh, S.; Nagel, T.; Traulsen, I.; Beeck, B.
Abstract: Methods to measure masses of PG1159 stars in order to test evolutionary scenarios are currently based on spectroscopic masses or asteroseismological mass determinations. SDSS J212531.92−010745.9, a recently discovered PG1159 star in a close binary system, may finally allow the first dynamical mass determination, and has so far been analysed on the basis of one SDSS spectrum and photometric monitoring. In order to be able to phase radial velocity measurements of the system SDSS J212531.92−010745.9, we have followed up the photometric monitoring of this system. New white light time series of the brightness variation of SDSS J212531.92−010745.9 with the Tübingen 80 cm and Göttingen 50 cm telescopes extend the monitoring into a second season (2006). We give the improved ephemeris for the orbital motion of the system, based on a sine fit which now results in a period of 6.95573(5) h. In 2007, we have obtained a series of phase-resolved medium-resolution spectra with the TWIN spectrograph at the 3.5m telescope at Calar Alto, which will allow us to derive the radial velocity curves for both components of the system, and to perform spectral analyses of the irradiating and irradiated components at different phases. We briefly describe the newly obtained spectra. The light curve and radial velocities combined will allow us to carry out a mass determination.
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