Post common envelope binaries from SDSS

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 HJD mid = 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 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 , while the mass of the white dwarf is most likely M wd = 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 R wd = 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.

Post common envelope binaries from SDSS

“…Fifteen orbital periods have already been published by Pyrzas et al (2011);Schreiber et al (2008); Rebassa-Mansergas et al (2008);Nebot Gómez-Morán et al (2009), andPyrzas et al (2009). Here we report period determinations for 58 additional systems, four of which were measured from follow-up photometry, the rest from follow-up spectroscopy.…”

“…For additional details on the reduction and calibration of the data, see Schreiber et al (2008); Rebassa-Mansergas et al (2008) and Nebot Gómez-Morán et al (2009).…”

“…We have initiated an intensive follow-up study of the SDSS WDMS binaries, with the ultimate aim to substantially improve our understanding of compact binary evolution. First results on individual systems and small subsets of this sample have been published Rebassa-Mansergas et al 2008;Nebot Gómez-Morán et al 2009;Pyrzas et al 2009;Schwope et al 2009), as well as several studies that analyse the total sample in the context of close binary evolution Zorotovic et al 2010;Rebassa-Mansergas et al 2011b). Here we present one of the fundamental results of this project: the orbital period distribution of 79 SDSS WDMS binaries, which we discuss in the context of current theories of compact binary evolution.…”

The SDSS spectroscopic catalogue of white dwarf-main-sequence binaries: new identifications from DR 9–12

“…These include for example: constraining current theories of close compact binary evolution (Davis, Kolb & Willems 2010;Zorotovic et al 2010Zorotovic et al , 2011aRebassa-Mansergas et al 2012b); demonstrating in a robust way that the majority of low-mass white dwarfs are formed in binaries (Rebassa-Mansergas et al 2011); constraining the pairing properties of main-sequence stars (Ferrario 2012); providing robust observational evidence for disrupted magnetic braking ; constraining the rotationage-activity relation of low-mass main-sequence stars (RebassaMansergas, Schreiber & Gänsicke 2013a); studying the statistical properties of the PCEB population using Monte Carlo techniques (Toonen & Nelemans 2013;Camacho et al 2014;Zorotovic et al 2014); analysing why the average mass of white dwarfs in cataclysmic variables is significantly larger than the average mass of single white dwarfs (Zorotovic, Schreiber & Gänsicke 2011b;Nelemans et al 2016;Schreiber, Zorotovic & Wijnen 2016); testing hierarchical probabilistic models used to infer properties of unseen companions to low-mass white dwarfs (Andrews, Price-Whelan & Agüeros 2014); detecting new gravitational wave verification sources (Kilic et al 2014); analysing the interior structural effects of common envelope evolution on low-mass pulsating white dwarfs (Hermes et al 2015). In addition, many eclipsing SDSS PCEBs have been identified (Nebot Gómez-Morán et al 2009;Pyrzas et al 2009Pyrzas et al , 2012Parsons et al 2013Parsons et al , 2015 which are being used to test theoretical mass-radius relations of both white dwarfs and lowmass main-sequence stars (Parsons et al 2012b,a), as well as the existence of circumbinary planets (Zorotovic & Schreiber 2013;Marsh et al 2014;Parsons et al 2014).…”

Post common envelope binaries from SDSS

“…Important in this respect, SDSS has not only provided a deep sample of CVs, but also the first-ever large homogeneous population of detached white-dwarf/main-sequence (WDMS) binaries (e.g., Silvestri et al 2007;Rebassa-Mansergas et al 2010) of which a considerable fraction, ∼30%, are PCEBs (Rebassa-Mansergas et al 2007, 2010Schreiber et al 2008;Nebot Gómez-Morán et al 2009Pyrzas et al 2009;Schwope et al 2009). Those PCEBs that will evolve into semidetached binaries undergoing stable mass transfer on timescales shorter than the age of the Galaxy are representative of the progenitors of the current-day CV population.…”