Catalogs of Hot White Dwarfs in the Milky Way from GALEX's Ultraviolet Sky Surveys. Constraining Stellar Evolution - Astrophysics > Solar and Stellar AstrophysicsReportar como inadecuado




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Abstract: We present comprehensive catalogs of hot star candidates in the Milky Way,selected from GALEX far-UV FUV, 1344-1786 AA and near-UV NUV, 1771-2831 AAimaging. The FUV and NUV photometry allows us to extract the hottest stellarobjects, in particular hot white dwarfs WD, which are elusive at otherwavelengths because of their high temperatures and faint optical luminosities.We generated catalogs of UV sources from two GALEX-s surveys: AIS All-SkyImaging Survey, depth ABmag~19.9-20.8 in FUV-NUV and MIS Medium-depth ImagingSurvey, depth ~22.6-22.7mag. The two catalogs from GALEX fifth data releasecontain 65.3-12.6 million AIS-MIS unique UV sources with errorNUV<0.5mag,over 21,435-1,579 square degrees. We also constructed subcatalogs of the UVsources with matched optical photometry from SDSS 7th data release: thesecontain 0.6-0.9million AIS-MIS sources with errors <0.3mag in both FUV andNUV, excluding sources with multiple optical counterparts, over an area of7,325-1,103 square degrees. All catalogs are available online. We then selected28,319AIS-9,028MIS matched sources with FUV-NUV<-0.13; this color cutcorresponds to stellar Teff hotter than ~18,000 K. An additional color cut ofNUV-r>0.1 isolates binaries with largely differing Teff-s, and some intrudingQSOs. Available spectroscopy for a subsample indicates that hot-star candidateswith NUV-r<0.1 have negligible contamination by non-stellar objects. We discussthe distribution of sources in the catalogs, and the effects of error and colorcuts on the samples. The density of hot-star candidates increases from high tolow Galactic latitudes, but drops on the MW plane due to dust extinction. Ourhot-star counts at all latitudes are better matched by Milky Way modelscomputed with an initial-final mass relation that favours lower final masses.ABRIDGED



Autor: Luciana Bianchi, Boryana Efremova, James Herald, Leo Girardi, Alexandre Zabot, Paola Marigo, Christopher Martin

Fuente: https://arxiv.org/







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