期刊
ASTRONOMY & ASTROPHYSICS
卷 495, 期 2, 页码 561-569出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361:200811244
关键词
binaries: close; binaries: eclipsing; novae, cataclysmic variables
资金
- Deutsches Zentrum fur Luft-und Raumfahrt (DLR) GmbH [FKZ 50 OR 0404]
- FONDECYT [1061199]
- DIPUV
- Center of Astrophysics at the Universidad de Valparaiso
- DFG [Schw536/23-1]
- Alfred P. Sloan Foundation
- National Science Foundation
- U. S. Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- STFC [PP/F000057/1, PP/D000955/1, ST/G002355/1, ST/F002599/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/F002599/1, PP/F000057/1, PP/D000955/1, ST/G002355/1] Funding Source: researchfish
From optical photometry we show that SDSS J121258.25-012310.1 is a new eclipsing, post common-envelope binary with an orbital period of 8.06 h and an eclipse length of 23 min. We observed the object over 11 nights in different bands and determined the ephemeris of the eclipse to HJD(mid) = 2 454 104.7086(2) + 0.3358706(5) x E, where numbers in parenthesis indicate the uncertainties in the last digit. The depth of the eclipse is 2.85 +/- 0.17 mag in the V band, 1.82 +/- 0.08 mag in the R band and 0.52 +/- 0.02 mag in the I band. From spectroscopic observations we measured the semi-amplitude of the radial velocity K-2 = 181 +/- 3 km s(-1) for the secondary star. The stellar and binary parameters of the system were constrained from a) fitting the SDSS composite spectrum of the binary, b) using a K-band luminosty-mass relation for the secondary star, and c) from detailed analyses of the eclipse light curve. The white dwarf has an effective temperature of 17 700 +/- 300 K, and its surface gravity is log g = 7.53 +/- 0.2. We estimate that the spectral type of the red dwarf is M4 +/- 1 and the distance to the system is 230 +/- 20 parsec. The mass of the secondary star is estimated to be in the range M-sec = 0.26-0.29 M-circle dot, while the mass of the white dwarf is most likely M-wd = 0.46-0.48 M-circle dot. From an empirical mass-radius relation we estimate the radius of the red dwarf to be in the range 0.28-0.31 R-circle dot, whereas we get R-wd = 0.016-0.018 R-circle dot from a theoretical mass-radius realation. Finally we discuss the spectral energy distribution and the likely evolutionary state of SDSS1212-0123.
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