Gomez-Moran, A. Nebot, Schwope, A. D. (Axel D.), Schreiber, Matthias R., Gaensicke, B. T. (Boris T.), Pyrzas, S., Schwarz, R. (Robert), Southworth, J. (John), Kohnert, J., Vogel, J., Krumpe, M. and Rodriguez-Gil, P. (2009) Post common envelope binaries from SDSS. IV, SDSS J121258.25–012310.1, a new eclipsing system. Astronomy & Astrophysics, Vol.495 (No.2). pp. 561-569. doi:10.1051/0004-6361:200811244 ISSN 0004-6361.

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Abstract

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 HJDmid = 2 454 104.7086(2) + 0.3358706(5) × 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 K2 = 181±3 kms−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 Msec = 0.26−0.29 M , while the mass of the white dwarf is most likely Mwd = 0.46−0.48 M. From an empirical mass-radius relation we estimate the radius of the red dwarf to be in the range 0.28−0.31 R , whereas we get Rwd = 0.016−0.018 R from a theoretical
mass-radius realation. Finally we discuss the spectral energy distribution and the likely evolutionary state of SDSS1212–0123.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science, Engineering and Medicine > Science > Physics
Library of Congress Subject Headings (LCSH):	Eclipsing binaries, Double stars -- Masses, Double stars -- Motion in line of sight, Stars -- Temperature, Spectral energy distribution
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
ISSN:	0004-6361
Official Date:	February 2009
Dates:	Date Event February 2009 Published
Volume:	Vol.495
Number:	No.2
Page Range:	pp. 561-569
DOI:	10.1051/0004-6361:200811244
Status:	Peer Reviewed
Access rights to Published version:	Open Access (Creative Commons)
Funder:	Fondo Nacional de Desarrollo Científico y Tecnológico (Chile) (FONDECYT), Deutsche Forschungsanstalt für Luft- und Raumfahrt (DLR), Universidad de Valparaíso. Dirección de investigación y desarrollo (DIPUV), Universidad de Valparaíso. Centro de Astrofísica, Deutsche Forschungsgemeinschaft (DFG), Alfred P. Sloan Foundation, National Science Foundation (U.S.) (NSF), United States. Dept. of Energy, United States. National Aeronautics and Space Administration (NASA), Japan. Monbushō, Max-Planck-Gesellschaft zur Förderung der Wissenschaften [Max Planck Society for the Advancement of Science], Higher Education Funding Council for England (HEFCE), American Museum of Natural History, Astrophysical Institute Potsdam, Universität Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermi National Accelerator Laboratory (Fermilab), Institute for Advanced Study (Princeton, N.J.), Johns Hopkins University, Joint Institute for Nuclear Astrophysics, Kavli Institute for Particle Astrophysics and Cosmology, Korean Scientist Group, Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), Los Alamos National Laboratory (LANL), Max-Planck-Institut für Astronomie, Max-Planck-Institut für Astrophysik, New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, United States Naval Observatory, University of Washington
Grant number:	FKZ 50 OR 0404 (DLR), 1061199 (FONDECYT), project 35 (DIPUV), Schw536/23-1 (DFG)

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