Browse
this table...

SDSSWDSD - Sloan Digital Sky Survey DR4 White Dwarf & Hot Subdwarf Catalog

HEASARC
Archive

Overview

This is the Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4) Catalog of White Dwarfs (WDs) and Hot Subdwarf (SD) stars. It contains 9316 spectroscopically confirmed white dwarfs which have been selected through photometric cuts and spectroscopic modeling, backed up by a set of visual inspections. About 6000 of the WD stars are new discoveries, roughly doubling the number of spectroscopically confirmed WD stars. The authors have analyzed the stars by performing temperature and surface gravity fits to grids of pure hydrogen and helium atmospheres. Among the rare outliers are a set of presumed helium-core DA WDs with estimated masses below 0.3 solar masses, including two candidates that may be the lowest-mass WDs yet found. This catalog also contains a list of 928 hot SD stars.

The SDSS DR4 (Adelman-McCarthy et al. 2006, ApJS, 162, 38; see also http://www.sdss.org/dr4/ ) contains 800,000 spectra from 4783 square degrees. The authors have used automated techniques supplemented by visual classification to select 13,000 candidates. An extensive analysis of these objects has yielded 9316 white dwarfs, including 8000 DA, 713 DB, 41 DO or PG1159, 289 DC, 104 DQ, and 133 DZ types, as well as 928 hot subdwarf stars. As well as the 10,244 primary spectra, the authors have also presented 774 duplicate spectra of WD stars and 60 duplicate spectra of SD stars. Thus, the present table has 11,078 (=10,244 + 774 + 60) entries.

Much more information on the SDSS is available at the project's web site at http://www.sdss.org/.


Catalog Bibcode

2006ApJS..167...40E

References

A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan
Digital Sky Survey Data Release 4
      Eisenstein D.J., Liebert J., Harris H.C., Kleinman S.J., Nitta A.,
      Silvestri N., Anderson S.A., Barentine J.C., Brewington H.J.,
      Brinkmann J., Harvanek M., Krzesinski J., Neilsen E.H., Long D.,
      Schneider D.P., Snedden S.A.
     <Astrophys. J. Suppl., 167, 40-58 (2006)>
     =2006ApJS..167...40E

Provenance

This table was created by the HEASARC in February 2007 based on the merger of Table 1B and 1C obtained from the electronic ApJS website.

HEASARC Implementation

The HEASARC has created an extra parameter called broad_class to differentiate entries from the two original tables which were merged to create this Browse table: white dwarfs from the original Table 1B have been given a broad_class value of 'WD', while the hot subdwarfs listed in Table 1C have been assigned a broad_class of 'SD'.

Parameters

Spect_Type
The spectral classification of the white dwarf or subdwarf, mostly using the usual spectral typing scheme. Automatic classifications (limited to the typing DA, DB, SD or other) for which a human has not confirmed the classification are indicated by the addition of "auto" to the spectral type. See Section 4 and Tables 2, 3 and 4 in the published paper for more details on the classification procedure and the breakdown of the catalog by WD and SD spectral types

Wd_Name
The name of the object in the McCook & Sion (1999, ApJS, 121, 1) White Dwarf Catalog (as of 2005 August).

Ref_Spect_Type
The provenance of the SDSS classification. Notice that this is merely to track the provenance of the quoted spectral classification; it does not indicate discovery or literature classifications, which can be tracked through the McCook & Sion (1999) catalog. 'Kle04' stands for Kleinman et al. (2004, ApJ, 607, 426), 'Sil05' for Silvestri et al. (2006, AJ, 131, 1674), and 'DR4' for spectral types from this paper itself.

Primary_Flag
This parameter flags whether the entry refers to a primary spectrum (set to 1), or to a duplicate spectrum (set to 0).

Name
The SDSS IAU-style name for the object, using the 'SDSS J' prefix and the J2000 coordinates (HHMMSS.ssdDDMMSS.s). This is the name from the SDSS DR4. Because of tiny astrometry shifts, it is possible that this name may differ from the name in previous SDSS releases. This breaks the IAU convention that published names never change. The authors strongly recommend that associations be performed on the astrometric coordinates rather than on the name.

RA
The Right Ascension of the object in the selected equinox (given in J2000 decimal degree coordinates and to a precision of 10-6 degrees in the original table). The epoch of the coordinates is given by the time of the SDSS imaging observation as specified in the value of the imaging_date parameter.

Dec
The Declination of the object in the selected equinox (given in J2000 decimal degree coordinates and to a precision of 10-6 degrees in the original table). The epoch of the coordinates is given by the time of the SDSS imaging observation as specified in the value of the imaging_date parameter.

LII
The Galactic Longitude of the object.

BII
The Galactic Latitude of the object.

PM_Tot
The total proper motion of the object, in mas/yr. This was converted from the units of arcseconds per century used in the original reference.

PM_PA
The proper-motion position angle, in degrees, where 0 means North, 90 degrees means East, etc.

PM_RA
The proper motion of the object in Right Ascension, in mas/yr. This was converted from the units of arcseconds per century used in the original reference.

PM_Dec
The proper motion of the object in Declination, in mas/yr. This was converted from the units of arcseconds per century used in the original reference.

Imaging_Date
The date and time of the imaging observation for the object. This was given in Modified Julian Date (MJD) and to a precision of 0.01 days (~14 minutes) in the original table.

SDSS_Run_Number
The SDSS run number.

SDSS_Rerun_Number
The SDSS rerun number.

SDSS_Camera_Column
The SDSS camera column.

SDSS_Field_Number
The SDSS field number.

SDSS_Id_Number
The SDSS identification (ID) number within the field. This is not the objID parameter referred to in the SDSS Catalog Archive Server.

Umag
The point-spread function PSF, as observed, SDSS u-band magnitude.

Gmag
The point-spread function PSF, as observed, SDSS g-band magnitude.

Rmag
The point-spread function PSF, as observed, SDSS r-band magnitude.

Imag
The point-spread function PSF, as observed, SDSS i-band magnitude.

Zmag
The point-spread function PSF, as observed, SDSS z-band magnitude.

Umag_Error
The error in the u magnitude.

Gmag_Error
The error in the g magnitude.

Rmag_Error
The error in the r magnitude.

Imag_Error
The error in the i magnitude.

Zmag_Error
The error in the z magnitude.

Umag_Flag
The photometry flag for the u magnitude, where 1 means bad and 0 means good.

Gmag_Flag
The photometry flag for the g magnitude, where 1 means bad and 0 means good.

Rmag_Flag
The photometry flag for the r magnitude, where 1 means bad and 0 means good.

Imag_Flag
The photometry flag for the i magnitude, where 1 means bad and 0 means good.

Zmag_Flag
The photometry flag for the z magnitude, where 1 means bad and 0 means good.

Gmag_Extinction
The extinction in the g band, A_g, in magnitudes. The canonical SDSS extinction curve implies relative extinctions in the u, g, r, i and z bands of 1.36, 1.00, 0.73, 0.55, and 0.39 times A_g.

Plate_Number
The plate number of the spectroscopic observation.

Fiber_Number
The fiber number of the object for the spectroscopic observation.

Spectrum_Date
The date and time of the spectroscopic observation for the object. This was given in Modified Julian Date (MJD) and to a precision of 1 day in the original table.

Spectrum_Gmag_SNR
The signal-to-noise ratio (SNR) of the spectrum in the g band, per spectroscopic pixel.

Deblend_Flag
This flag indicates whether or not the object was deblended: 1 means that the object was isolated, 0 that it had to be deblended. Most of the relevant target selection catagories require that the object be sufficiently isolated on the sky that it was not blended with any other object. Blended stars have much lower completeness; see Section 5.6 of the published paper for more details.

Dec_Prim_Target_Flag
The decimal PrimTarget flag. This flag is one of the flags which records the decisions from the various spectroscopic targeting algorithms. See Stoughton et al. (2002, AJ, 123, 485) and Adelman-McCarthy et al. (2006, ApJS, 162, 38) or the SDSS online documentation for more details. The southern survey bit (0x80000000) has been suppressed in the secTarget flag for brevity but retained in the primTarget flag (Adelman-McCarthy et al. 2006).

Hex_Prim_Target_Flag
The hexadecimal PrimTarget flag. This flag is one of the flags which records the decisions from the various spectroscopic targeting algorithms. See Stoughton et al. (2002, AJ, 123, 485) and Adelman-McCarthy et al. (2006, ApJS, 162, 38) or the SDSS online documentation for more details. The southern survey bit (0x80000000) has been suppressed in the secTarget flag for brevity but retained in the primTarget flag (Adelman-McCarthy et al. 2006).

Dec_Sec_Target_Flag
The decimal SecTarget flag. This flag is one of the flags which records the decisions from the various spectroscopic targeting algorithms. See Stoughton et al. (2002, AJ, 123, 485) and Adelman-McCarthy et al. (2006, ApJS, 162, 38) or the SDSS online documentation for more details. The southern survey bit (0x80000000) has been suppressed in the secTarget flag for brevity but retained in the primTarget flag (Adelman-McCarthy et al. 2006).

Hex_Sec_Target_Flag
The hexadecimal SecTarget flag. This flag is one of the flags which records the decisions from the various spectroscopic targeting algorithms. See Stoughton et al. (2002, AJ, 123, 485) and Adelman-McCarthy et al. (2006, ApJS, 162, 38) or the SDSS online documentation for more details. The southern survey bit (0x80000000) has been suppressed in the secTarget flag for brevity but retained in the primTarget flag (Adelman-McCarthy et al. 2006).

Autofit_Quality_Flag
The autofit quality flag, where 1 means good and 0 means do not use the autofit numbers for anything but diagnostic searching. Autofit is the name of the method used to fit the spectra and the photometry of the candidate objects relative to a model astmosphere grid by a chi-squared miniminzation procedure, thereby yielding a temperature and surface gravity estimate, as well as a classification of helium or hydrogen atmosphere. This enabled the authors to separate the white dwarfs from lower gravity objects. Autofit is described in full by Kleinman et al. (2004, ApJ, 607, 426).

Autofit_Element_Flag
The autofit atmosphere element flag, being 1 for hydrogen, 2 for helium atmospheres.

Autofit_Eff_Temp
The autofit effective temperature estimate, in K.

Autofit_Eff_Temp_Error
The error in the autofit effective temperature, in K.

Autofit_Log_G
The autofit logarithmic surface gravity, log g, in units of dex(cm/s2)

Autofit_Log_G_Error
The error in log g, in dex(cm/s2).

Autofit_Red_Chisquared
The autofit chi-squared value per degrees of freedom, i.e., the reduced chi-squared, of the fit to the object.

Broad_Class
The broad classification of the object: 'WD' means white dwarf, while 'SD' means hot subdwarf. The HEASARC created this parameter to differentiate entries from the two original tables which were merged to create this Browse table: white dwarfs from the original Table 1B have been given a broad_class value of 'WD', while the hot subdwarfs listed in Table 1C have been assigned a broad_class of 'SD'.

Class
The HEASARC Browse object classification, based on the value of the spect_type parameter.


Contact Person

Questions regarding the SDSSWDSD database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 27-Apr-2009