J/MNRAS/486/4574 62 new variable white dwarfs from GALEX (Rowan+, 2019)
Detections and constraints on white dwarf variability from time-series GALEX
observations.
Rowan D.M., Tucker M.A., Shappee B.J., Hermes J.J.
<Mon. Not. R. Astron. Soc., 486, 4574-4589 (2019)>
=2019MNRAS.486.4574R 2019MNRAS.486.4574R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Stars, variable ; Photometry, ultraviolet ;
Optical
Keywords: stars: oscillations - white dwarfs
Abstract:
We search for photometric variability in more than 23000 known and
candidate white dwarfs (WDs), the largest ultraviolet survey compiled
for a single study of WDs. We use GPHOTON, a publicly available
calibration/reduction pipeline, to generate time-series photometry of
WDs observed by GALEX. By implementing a system of weighted metrics,
we select sources with variability due to pulsations and eclipses.
Although GALEX observations have short baselines (=<30min), we
identify intrinsic variability in sources as faint as Gaia G=20mag.
With our ranking algorithm, we identify 48 new variable WDs in
archival GALEX observations. We detect 40 new pulsators: 36 have
hydrogen-dominated atmospheres (DAVs), including one possible massive
DAV, and four are helium-dominated pulsators (DBVs). We also detect
eight new eclipsing systems; five are new discoveries, and three were
previously known spectroscopic binaries. We perform synthetic
injections of the light curve of WD 1145+017, a system with known
transiting debris, to test our ability to recover similar systems. We
find that the 3σ maximum occurrence rate of WD 1145+017-like
transiting objects is =<0.5 per cent.
Description:
Photometric observations for WDs in our survey were taken with the
GALEX space telescope (Morrissey et al. 2005ApJ...619L...7M 2005ApJ...619L...7M; Martin et
al. 2016ApJ...833..292M 2016ApJ...833..292M). GALEX observed ∼77 per cent of the sky in
two UV bands: the near-ultraviolet (NUV, 1771-2831Å) and
far-ultraviolet (FUV, 1344-1786Å). GALEX observations were taken
during the night side of each orbit, known as an 'eclipse', with each
observation lasting up to 30min. Most of our WD sources have been
observed by GALEX multiple times. We henceforth refer to a single
exposure lasting up to 30 minutes as an observation.
Our sample of 23676 WDs comes from four separate catalogues -
Spectroscopically confirmed and high-probability candidate WDs from
the SDSS White Dwarf Catalog (DR8, 10, and 12, 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,
J/MNRAS/455/3413) (any subdwarfs are excluded); WDs with probability
PWD≥0.5 from the VLT Survey Telescope ATLAS (Gentile Fusillo et al.
2017MNRAS.469..621G 2017MNRAS.469..621G, Cat. J/MNRAS/469/621); Sources from Montreal
White Dwarf Database (MWDD, Dufour et al. 2017ASPC..509....3D 2017ASPC..509....3D);
Sources in Gaia DR2 (Gaia Collaboration et al. 2018A&A...616A...1G 2018A&A...616A...1G,
Cat. I/345) following the criteria: G+5log(plx/100)>4(GBP-GRP),
1.0+0.015(GBP-GRP)<EBP/RP, 1.3+0.06(GBP-GRP)2>EBP/RP,
where EBP/RP is the excess factor measured with respect to the Gaia
G band.
Out of the total 23676 WDs, we detect 40 new pulsators, 13 known
pulsators, 8 new eclipsing WDs, and 1 known eclipsing WD. Their
properties are presented in Table 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 97 62 Information on all detected variable WDs
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
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/MNRAS/469/621 : VST ATLAS white dwarf candidates cat.
(Gentile Fusillo+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Source name
27- 28 I2 --- ID Internal object identifier
30- 38 F9.5 deg RAdeg Right ascension (J2000)
40- 48 F9.5 deg DEdeg Declination (J2000)
50- 54 F5.2 mag Gmag Gaia DR2 G-band magnitude
56- 69 A14 --- Class White dwarf classification
71- 75 A5 --- SpType Spectral type (1)
77- 80 I4 s Period ? Variability period (2)
82- 83 I2 s e_Period ? Error on Perdiod (2)
85- 86 I2 --- NUVamp ? NUV amplitude (per cent) (2)
88- 89 I2 --- e_NUVamp ? Error on NUVamp (2)
91- 92 I2 --- FUVamp ? FUV amplitude (per cent) (2)
94- 95 I2 --- e_FUVamp ? Error on FUVamp (2)
97 A1 --- ref References for known WD pulsators and binaries
detected (3)
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Note (1): Estimates of spectral type based on Gaia CMD position for sources
without known classification
Note (2): Variability period, NUV amplitude, and FUV amplitude are estimated by
fitting sinusoids to the light curves
Note (3): References as follows:
a = Castanheira et al. (2007A&A...462..989C 2007A&A...462..989C)
b = Eisenstein et al. (2006ApJS..167...40E 2006ApJS..167...40E, Cat. J/ApJS/167/40)
c = Fontaine et al. (2001ApJ...557..792F 2001ApJ...557..792F)
d = Kepler et al. (2015MNRAS.446.4078K 2015MNRAS.446.4078K, Cat. J/MNRAS/446/4078)
f = Kotak et al. (2003A&A...397.1043K 2003A&A...397.1043K)
g = Mukadam et al. (2004ApJ...607..982M 2004ApJ...607..982M)
h = Mullally et al. (2005ASPC..334..581M 2005ASPC..334..581M)
i = Silvestri et al. (2006AJ....131.1674S 2006AJ....131.1674S, Cat. J/AJ/131/1674)
j = Stobie et al. (1995MNRAS.272L..21S 1995MNRAS.272L..21S)
k = Tucker et al. (2018MNRAS.475.4768T 2018MNRAS.475.4768T)
l = Voss et al. (2006A&A...450.1061V 2006A&A...450.1061V)
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History:
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(End) Ana Fiallos [CDS] 26-Oct-2022