J/MNRAS/411/2770 Hot white dwarfs in GALEX-DR5 (Bianchi+, 2011)
Catalogues of hot white dwarfs in the Milky way from GALEX's ultraviolet sky
surveys: constraining stellar evolution.
Bianchi L., Efremova B., Herald J., Girardi L., Zabot A., Marigo P.,
Martin C.
<Mon. Not. R. Astron. Soc., 411, 2770-2791 (2011)>
=2011MNRAS.411.2770B 2011MNRAS.411.2770B
ADC_Keywords: Stars, blue ; Ultraviolet ; Stars, white dwarf
Keywords: catalogues ; surveys ; stars: evolution ; white dwarfs ;
Galaxy: stellar content ; ultraviolet: stars
Abstract:
We present comprehensive catalogues of hot star candidates in the
Milky Way (MW), selected from Galaxy Evolution Explorer (GALEX) far-UV
(FUV; 1344-1786Å) and near-UV (NUV; 1771-2831Å) imaging. The FUV
and NUV photometry allows us to extract the hottest stellar objects,
in particular hot white dwarfs (WD), which are elusive at other
wavelengths because of their high temperatures and faint optical
luminosities. We generated catalogues of UV sources from two GALEX's
surveys: All-Sky Imaging Survey (AIS; depth AB magnitude ∼19.9/20.8 in
FUV/NUV) and Medium-depth Imaging Survey (MIS; depth ∼22.6/22.7mag).
The two catalogues (from GALEX fifth data release) contain 65.3/12.6
million (AIS/MIS) unique UV sources with errorNUV≤ 0.5 mag, over 21
435/1579deg2. We also constructed subcatalogues of the UV sources
with matched optical photometry from Sloan Digital Sky Survey (SDSS;
seventh data release): these contain 0.6/0.9 million (AIS/MIS) sources
with errors ≤0.3mag in both FUV and NUV, excluding sources with
multiple optical counterparts, over an area of 7325/1103 deg2. All
catalogues are available online. We then selected 28 319 (AIS)/9028
(MIS) matched sources with FUV-NUV←0.13; this colour cut corresponds
to stellar Teff hotter than ∼18 000K (the exact value varying with
gravity). An additional colour cut of NUV-r>0.1 isolates binaries with
largely differing Teffs, and some intruding quasi-stellar objects
(QSOs; more numerous at faint magnitudes). Available spectroscopy for
a subsample indicates that hot-star candidates with NUV-r<0.1 (mostly
'single' hot stars) have negligible contamination by non-stellar
objects. We discuss the distribution of sources in the catalogues, and
the effects of error and colour cuts on the samples. The density of
hot-star candidates increases from high to low Galactic latitudes, but
drops on the MW plane due to dust extinction. Our hot-star counts at
all latitudes are better matched by MW models computed with an
initial-final mass relation (IFMR) that favours lower final masses.
The model analysis indicates that the brightest sample is likely
composed of WDs located in the thin disc, at typical distances between
0.15 and 1kpc, while the fainter sample comprises also a fraction of
thick disc and halo stars. Proper motion distributions, available only
for the bright sample (NUV<18mag), are consistent with the kinematics
of a thin-disc population.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gr5-ais.dat 228 28333 *Catalog of hot star candidates, from
All-Sky Imaging Survey, GALEX-AIS-SDSS (FUV≤20)
gr5-mis.dat 228 9032 *Catalog of hot star candidates, from
Medium-depth Imaging Survey, GALEX-MIS-SDSS
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Note on gr5-ais.dat, gr5-mis.dat: only sources with "rank=0" included,
i.e. UV sources with one SDSS counterpart (within the match radius of 3"),
see paper for more details.
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See also:
ftp://archive.stsci.edu/pub/hlsp/bianchi_gr5xdr7 : GALEX-GR5 Home Page
Byte-by-byte Description of file: gr5-ais.dat gr5-mis.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- IAU GALEX ID following the IAU convention,
JHHMMSS.ss+DDMMSS.s
21- 39 A19 --- GALEX GALEX ID
41- 51 F11.6 deg RAdeg Right ascension (J2000)
53- 63 F11.6 deg DEdeg Declination (J2000)
65- 75 F11.6 deg GLON Galactic longitude
77- 87 F11.6 deg GLAT Galactic latitude
89-107 A19 --- SDSS SDSS designation
109-111 F3.1 arcsec Dist Distance between the GALEX and SDSS source
113-117 F5.2 mag FUV GALEX FUV magnitude (AB mag)
119-123 F5.2 mag e_FUV GALEX FUV magnitude error
125-129 F5.2 mag NUV GALEX NUV magnitude (AB mag)
131-135 F5.2 mag e_NUV GALEX NUV magnitude error
137-141 F5.2 mag umag SDSS u magnitude (AB mag)
143-147 F5.2 mag e_umag ?=89 SDSS u magnitude error (1)
149-153 F5.2 mag gmag SDSS g magnitude (AB mag)
155-159 F5.2 mag e_gmag ?=89 SDSS g magnitude error (1)
161-165 F5.2 mag rmag SDSS r magnitude (AB mag)
167-171 F5.2 mag e_rmag ?=89 SDSS r magnitude error (1)
173-177 F5.2 mag imag SDSS i magnitude (AB mag)
179-183 F5.2 mag e_imag ?=89 SDSS i magnitude error (1)
185-189 F5.2 mag zmag SDSS z magnitude (AB mag)
191-195 F5.2 mag e_zmag ?=89 SDSS z magnitude error (1)
197-201 F5.2 mag E(B-V) E(B-V) from Schlegel maps at the
source position
203-205 I3 --- f_NUV NUV artifact flag from GALEX pipeline
207 I1 --- n_IAU [0/1] Flag set to 1 for sources with
(NUV-r)<0.1 (single star candidates)
209-228 A20 --- SpecId SDSS Spectrum ID
(0 if no SDSS spectrum exists)
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Note (1): Sources saturated in an SDSS band have their errors set to 89,
those not detected in an SDSS band have their errors set to 99.
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History:
Copied at ftp://archive.stsci.edu/pub/hlsp/bianchi_gr5xdr7
(End) Patricia Vannier [CDS] 30-Mar-2011