Post common envelope binaries from SDSS. IV. SDSS J121258.25-012310.1, a new eclipsing system

Nebot Gómez-Morán, A.; Schwope, A. D.; Schreiber, M. R.; Gänsicke, B. T.; Pyrzas, S.; Schwarz, R.; Southworth, J.; Kohnert, J.; Vogel, J.; Krumpe, M.; Rodríguez-Gil, P.
Referencia bibliográfica

Astronomy and Astrophysics, Volume 495, Issue 2, 2009, pp.561-569

Fecha de publicación:
2
2009
Número de autores
11
Número de autores del IAC
1
Número de citas
37
Número de citas referidas
32
Descripción
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 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_&sun; , while the mass of the white dwarf is most likely M_wd= 0.46-0.48 M_&sun;. From an empirical mass-radius relation we estimate the radius of the red dwarf to be in the range 0.28-0.31 R_&sun; , whereas we get R_wd= 0.016-0.018 R_&sun; from a theoretical mass-radius realation. Finally we discuss the spectral energy distribution and the likely evolutionary state of SDSS1212-0123. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.
Proyectos relacionados
Representación de la variable cataclísmica SS Cygni (Chris Moran)
Estrellas Binarias
El estudio de las estrellas binarias es una parte esencial de la astrofísica estelar. Una gran parte de las estrellas de nuestra Galaxia y de otras galaxias se ha formado en sistemas binarios o múltiples, por lo que entender la estructura y evolución de estos sistemas es importante desde el punto de vista estelar y galáctico. Un aspecto en el que
Pablo
Rodríguez Gil