J/MNRAS/489/5046 GALEX absolute calibration based on white dwarfs (Wall+, 2019)
GALEX absolute calibration and extinction coefficients based on white dwarfs.
Wall R.E., Kilic M., Bergeron P., Rolland B., Genest-Beaulieu C.,
Gianninas A.
<Mon. Not. R. Astron. Soc., 489, 5046-5052 (2019)>
=2019MNRAS.489.5046W 2019MNRAS.489.5046W (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Photometry, ultraviolet ; Milky Way
Keywords: instrumentation: detectors - telescopes - white dwarfs -
ultraviolet: general
Abstract:
We use 1837 DA white dwarfs with high signal-to-noise ratio spectra
and Gaia parallaxes to verify the absolute calibration and extinction
coefficients for the Galaxy Evolution Explorer (GALEX). We use white
dwarfs within 100pc to verify the linearity correction to the GALEX
data. We find that the linearity correction is valid for magnitudes
brighter than 15.95 and 16.95 for the far-ultraviolet (FUV) and
near-ultraviolet (NUV) bands, respectively. We also use DA white
dwarfs beyond 250pc to calculate extinction coefficients in the FUV
and NUV bands: RFUV=8.01±0.07 and RNUV=6.72±0.04. These are
consistent with the predicted extinction coefficients for Milky
Way-type dust in the FUV, but smaller than predictions in the NUV.
With well understood optical spectra and state-of-the-art model
atmosphere analysis, these white dwarfs currently provide the best
constraints on the extinction coefficients for the GALEX data.
Description:
In order to improve calibrations for the GALEX data, we select all
spectroscopically confirmed DA white dwarfs from the SDSS data
releases 7, 10, and 12 with S/N≥20 spectra (Kleinman et al.
2013ApJS..204....5K 2013ApJS..204....5K, Cat. J/ApJS/204/5; Kepler et al.
2015MNRAS.446.4078K 2015MNRAS.446.4078K, Cat. J/MNRAS/446/4078, 2016MNRAS.455.3413K 2016MNRAS.455.3413K, Cat.
J/MNRAS/455/3413).
We cross-reference our initial sample of 3733 DA white dwarfs from the
SDSS with Panoramic Survey Telescope and Rapid Response System
(Pan-STARRS), and we cross-reference our sample once more with Gaia
Data Release (DR2) (Gaia Collaboration, 2018A&A...616A...1G 2018A&A...616A...1G, Cat.
I/345), selecting all stars with parallax/error≥5. We then
cross-reference our sample with the GALEX catalogue of unique UV
sources from the AIS (GUVcat) presented in Bianchi, Shiao & Thilker
(2017ApJS..230...24B 2017ApJS..230...24B, Cat. II/335). We use a search radius of
2 arcsec and find a total of 1837 stars with GALEX photometry.
We break our initial sample of stars into two groups based on Gaia
distance: stars within 100 pc and stars further than 250 pc. There
are 339 (627) and 451 (628) stars with FUV and NUV photometry in the
100 (d>250) pc sample, respectively. We leave the examination of
stars between 100 and 250 pc for future work.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 60 341 Properties of stars within 100 pc in our sample
table4.dat 60 629 Properties of stars beyond 250 pc in our sample
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7)
(Bianchi+ 2017)
J/ApJS/204/5 : SDSS DR7 white dwarf catalog (Kleinman+, 2013)
J/MNRAS/446/4078 : New white dwarf stars in SDSS DR10 (Kepler+, 2015)
J/MNRAS/455/3413 : New white dwarf and subdwarf stars in SDSS DR12
(Kepler+, 2016)
J/ApJ/743/138 : Spectroscopic survey of bright white dwarfs
(Gianninas+, 2011)
Byte-by-byte Description of file: table1.dat table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 A20 --- Name White dwarf name (1)
22- 27 F6.3 mag FUVs Synthetic FUV magnitude (2)
29- 34 F6.3 mag NUVs Synthetic NUV magnitude (2)
36- 41 F6.3 mag FUVmag ? GALEX FUV-band magnitude
43- 47 F5.3 mag e_FUVmag ? Error on FUVmag
49- 54 F6.3 mag NUVmag GALEX NUV-band magnitude
56- 60 F5.3 mag e_NUVmag Error on NUVmag
--------------------------------------------------------------------------------
Note (1): Stars with white dwarf (WD) names are from Gianninas et al.
(2011ApJ...743..138G 2011ApJ...743..138G, Cat. J/ApJ/743/138)
Note (2): We use SDSS u and Pan-STARRS grizy photometry and Gaia parallaxes to
derive photometric temperatures and radii for all stars in our final
sample. These temperature and radius measurements are then used to
calculate a model spectrum for each white dwarf.
(See section 3 of the article for more details).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 18-Jan-2023