This paper continues the series presenting cataclysmic variables identified during the fourth year (2003) of the Sloan Digital Sky Survey. We describe 44 close binary systems, of which 12 are the previously known systems EN Cet, EG Cnc, V844 Her, GG Leo, Leo 7, CY UMa, DV UMa, EK UMa, EV UMa, UMa 8, EUVE J0854+390, and RX J0859.1+0537 and 32 are new cataclysmic variables. As in the previous papers, the positions, colors, and spectra of all 44 systems are shown, along with follow-up spectroscopic, photometric, and/or polarimetric observations of 15 of the new systems. The new objects include one eclipsing system, eight with prominent He ii emission (of which two are confirmed new polars), and 12 systems showing features of the underlying stars. Our spectropolarimetry also confirms EUVE J0854+390 as a polar.

We present a spectroscopic sample of 747 detached close binary systems from the Sloan Digital Sky Survey (SDSS) Fourth Data Release. The majority of these binaries consist of a white dwarf primary and a low-mass secondary (typically M dwarf ) companion. We have determined the temperature and gravity for 496 of the white dwarf primaries and the spectral type and magnetic activity properties for 661 of the low-mass secondaries. We have estimated the distances for each of the white dwarf-main-sequence star binaries and use white dwarf evolutionary grids to establish the age of each binary system from the white dwarf cooling times. With respect to a spectroscopically identified sample of $8000 isolated M dwarf stars in the SDSS, the M dwarf secondaries show enhanced activity with a higher active fraction at a given spectral type. The white dwarf temperatures and gravities are similar to the distribution of $1900 DA white dwarfs from the SDSS. The ages of the binaries in this study range from $0.5 Myr to nearly 3 Gyr (average age $0.20 Gyr).

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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...

This is the first in a series of three papers describing a project with the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure abundances of the neutral interstellar medium (ISM) in a sample of 9 nearby star-forming galaxies. The goal is to assess the (in)homogeneities of the multiphase ISM in galaxies where the bulk of metals can be hidden in the neutral phase, yet the metallicity is inferred from the ionized gas in the H ii regions. The sample, spanning a wide range in physical properties, is to date the best suited to investigate the metallicity behavior of the neutral gas at redshift z = 0. ISM absorption lines were detected against the far-ultraviolet spectra of the brightest star-forming region(s) within each galaxy. Here we report on the observations, data reduction, and analysis of these spectra. Column densities were measured by a multi-component line-profile fitting technique, and neutral-gas abundances were obtained for a wide range of elements. Several caveats were considered including line saturation, ionization corrections, and dust depletion. Ionization effects were quantified with 'ad-hoc' CLOUDY models reproducing the complex photoionization structure of the ionized and neutral gas surrounding the UV-bright sources. An 'average spectrum of a redshift z = 0 star-forming galaxy' was obtained from the average column densities of unsaturated profiles of neutral-gas species. This template can be used as a powerful tool for studies of the neutral ISM at both low and high redshift.