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CATALOGS OF HOT STAR CANDIDATES

From the matched GALEX-SDSS source catalogs described above, Bianchi et al. 2011, MNRAS, 411, 2770 selected hot star candidates, by extracting the sources with GALEX UV color FUV-NUV < -0.13mag. This color cut corresponds to Effective Temperature approximately hotter than 18,000K, the exact value depending on gravity (see Sections 3 and 4 of the cited paper). While the FUV-NUV color allows one to detect the presence of a hot star, the combination of UV measurements with an additional optical band provides an approximate separation between "single" hot stars, and hot stars with a cooler companion (see Fig.1 of Bianchi 2009, ApSS, 320, 11). Bianchi et al. (2011, MNRAS, 411, 2770) adopted a color cut of NUV-r >0.1mag to separate candidate binaries among this sample. Note that the binaries locus is contaminated by some QSOs with non-canonical UV colors (Bianchi et al. 2009, AJ, 137, 3761), the relative number of extragalactic sources increases towards fainter magnitudes (Bianchi et al. 2011, ApSS, DOI: 10.1007/s10509-010-0581-x). The hot-star candidates with NUV-r <0.1mag are mostly single stars, although some types of binaries are also included in this color locus ; most importantly, serendipitous spectroscopic follow-up of a subsample indicates the QSO contamination to be negligible in this selection. Therefore, the purity of the "single hot-star" sample is much higher than for hot stars in the binary locus , and the latter are flagged in the catalogs.
The catalog header includes a byte-by-byte description of the columns. Most fields are described in the general catalog documentation, given above.
The source paper Bianchi et al. (2011, MNRAS, 411, 2770) includes an analysis of these hot-star candidates catalogs with Milky way models, which provides some constraints on the Initial-Final mass relation (IFMR).
Note that:

  1. only "rank0" sources are included in these files (see paper). These are GALEX sources with only one SDSS match. There are more GALEX sources in this color range, with multiple SDSS matches; these are included in the general catalogs (above) but not in these extracted catalogs.
  2. sources with NUV-r >0.1 are flagged: these are candidate stellar binaries with a hot star and a cool star, but some QSOs may intrude the sample (see Bianchi et al. 2009, AJ, 137, 3761).
  3. Only sources with 1-sigma error less than 0.3mag in both FUV and NUV are included.
  4. The large majority of sources are hot white dwarfs, however no gravity selection has been applied, to make the catalogs more inclusive and more generally useful.

The catalogs may be used by citing the source Bianchi et al. (2011, MNRAS, 411, 2770) (open source).
GALEX-MIS---SDSS hot star candidate catalog (9032 sources)

GALEX-AIS---SDSS hot star candidate catalog (28333 sources)