Cataclysmic Variables from Sloan Digital Sky Survey. V. The Fifth Year (2004)

Abstract

This paper identifies the cataclysmic variables that appear in spectra obtained in 2004 as part of the Sloan Digital Sky Survey. Spectra of 41 objects, including seven systems that were previously known (CC Cnc, DW Cnc, PQ Gem, AR UMa, AN UMa, RX J1131.3+4322, and UMa 6) and 34 new cataclysmic variables are presented. The positions and ugriz photometry of all 41 systems are given, as well as additional follow-up spectroscopic, photometric, and/or polarimetric observations of eight of the new systems. The new objects include three eclipsing systems, six with prominent He ii emission, and six systems that show the underlying white dwarf. Key words: binaries: eclipsing -binaries: spectroscopic -novae, cataclysmic variables -stars: dwarf novae INTRODUCTIONAt the present time, the Sloan Digital Sky Survey (SDSS; York et al. 2000) has completed Data Release 4, which includes photometry of 180 million objects over 6670 deg 2 and spectroscopy of over 600,000 objects (Adelman-McCarthy et al. 2006). Information on previous releases is available from Stoughton et al. (2002) and Abazajian et al. (2003Abazajian et al. ( , 2004Abazajian et al. ( , 2005. 15 These data sets represent a multitude of objects and scientific programs. While the initial goals of SDSS were related to galaxies and quasars, the large database of stellar spectra and photometry has enabled a vast amount of stellar science as well. Among the latter is the identification of the true population of close binary stars with mass transfer from a late main-sequence star to a white dwarf (cataclysmic variables [CVs]). The SDSS results from the previous releases have revealed a large population of CVs with short orbital periods and mass transfer rates so low that they are sometimes only accreting by winds, and with disks so faint that the underlying stars are revealed (Szkody et al. 2002(Szkody et al. , 2003a(Szkody et al. , 2003b(Szkody et al. , 2004a(Szkody et al. , 2005Schmidt et al. 2005). A comprehensive review of CVs and all their different subtypes can be found in Warner (1995), while Wickramasinghe & Ferrario (2000) present a summary of CVs containing magnetic white dwarfs.The main differences between the SDSS and past surveys lie in its ability to go faint and cover a large amount of sky. While the SDSS is not complete in obtaining spectra of all objects, the large variety of color space sampled by quasars, serendipity, and hot white dwarf categories enables the discovery of a large number of CVs of different types and mass transfer rates. Even though the SDSS spectra themselves provide clues as to the identification of the type of close binary, e.g., strong He ii points to a magnetic white dwarf ( Polar) or a very high mass transfer rate (SW Sex system), follow-up observations are required to obtain the orbital period and other characteristics that pin down the type of object. The compendium of sources by the end of the survey will provide a good test of stellar evolution models ( Howell et al. 2001), and the wide variety of peculiar systems re...

The accretion disk in the post period-minimum cataclysmic variable SDSS J080434.20 + 510349.2

“…Aviles et al (2010) included SDSS J123813.73-033933.0 (hereafter SDSS1238) in the list of bounce-back CVs using a direct IR broad band photometry of the secondary and modeling the spectral energy distribution of the system. The subject of this paper is SDSS J080434.20+510349.2 (hereafter SDSS0804), which has a very peculiar light curve (Szkody et al 2006). A similar light curve has only been observed in one other system of SDSS1238.…”

“…1. Before the March 2006 superoutburst the brightness of the system was V ∼ 17.9 and the object displayed SDSS1238-like long-term variability (Szkody et al 2006;Zharikov et al 2006Zharikov et al , 2008. On March 4, 2006, a superoutburst commenced, exhibiting all attributes of WZ Sge-type: a large amplitude >6 mag, superhumps, and 11 echoes (Pavlenko et al 2006).…”

“…Its superoutburst in September 2010 (Pavlenko et al 2012), which was only about four years after the previous superoutburst, was unexpected. A general description of the characteristics and observational features of SDSS0804 can be found in Szkody et al (2006), Pavlenko et al (2007), Zharikov et al (2008), Kato et al (2009), andPavlenko et al (2012). A&A 549, A77 (2013) In this paper we report the results of monitoring SDSS0804 in 2008-2009 and 2012, during periods when the object almost retuned to its pre-superoutburst, quiescent level.…”

Orbital periods of cataclysmic variables identified by the SDSS

“…We observed SDSS J0743 (Szkody et al 2006) on the night of 2009/01/23, for 2 h then another 1 h after a gap of 2 h. The light curve shows nothing out of the ordinary. One outburst has been seen for this CV in 2006 October, by the CSS (Drake et al 2009), where it increased in brightness by at least 5 mag.…”

1000 cataclysmic variables from the Catalina Real-time Transient Survey

“…Szkody et al (2002Szkody et al ( , 2003Szkody et al ( , 2004Szkody et al ( , 2005Szkody et al ( , 2006Szkody et al ( , 2007Szkody et al ( , 2009Szkody et al ( , 2011) produced a catalogue of 285 CVs identified in this way. The Quasar Survey is estimated to be 95 per cent complete down to i < 19.1 (Vanden Berk et al 2005;Richards et al 2006).…”