J/MNRAS/469/2102 White dwarf population from the SDSS DR12 (Anguiano+, 2017)
The kinematics of the white dwarf population from the SDSS DR12.
Anguiano B., Rebassa-Mansergas A., Garcia-Berro E., Torres S.,
Freeman K.C., Zwitter T.
<Mon. Not. R. Astron. Soc., 469, 2102-2120 (2017)>
=2017MNRAS.469.2102A 2017MNRAS.469.2102A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Stars, masses ; Stars, distances ;
Stars, ages ; Radial velocities ; Proper motions
Keywords: white dwarfs - Galaxy: evolution - Galaxy: general -
Galaxy: kinematics and dynamics - solar neighbourhood -
Galaxy: stellar content
Abstract:
We use the Sloan Digital Sky Survey Data Release 12, which is the
largest available white dwarf catalogue to date, to study the
evolution of the kinematical properties of the population of white
dwarfs in the Galactic disc. We derive masses, ages, photometric
distances and radial velocities for all white dwarfs with
hydrogen-rich atmospheres. For those stars for which proper motions
from the USNO-B1 catalogue are available, the true three-dimensional
components of the stellar space velocity are obtained. This subset of
the original sample comprises 20 247 objects, making it the largest
sample of white dwarfs with measured three-dimensional velocities.
Furthermore, the volume probed by our sample is large, allowing us to
obtain relevant kinematical information. In particular, our sample
extends from a Galactocentric radial distance RG=7.8 to 9.3kpc,
and vertical distances from the Galactic plane ranging from Z=-0.5
to 0.5kpc. We examine the mean components of the stellar
three-dimensional velocities, as well as their dispersions with
respect to the Galactocentric and vertical distances. We confirm the
existence of a mean Galactocentric radial velocity gradient,
∂<VR>/∂RG=-3±5km/s/. We also confirm north-south
differences in <Vz> . Specifically, we find that white dwarfs with
Z>0 (in the North Galactic hemisphere) have <Vz><0, while the
reverse is true for white dwarfs with Z<0. The age-velocity
dispersion relation derived from the present sample indicates that the
Galactic population of white dwarfs may have experienced an additional
source of heating, which adds to the secular evolution of the Galactic
disc.
Description:
The SDSS has produced the largest spectroscopic sample of white
dwarfs, and its latest release, the DR 12, contains more than 30000
stars (Kepler et al. 2016, Cat. J/MNRAS/455/3413). Because of its
considerably larger size as compared to other available white dwarf
catalogues, we adopt the SDSS catalogue as the sample of study in this
work. From this sample, we select only white dwarfs with
hydrogen-dominated atmospheres, that is of the DA spectral type. For
these white dwarfs, RVs and the relevant stellar parameters can be
derived using the technique described below.
20247 DA white dwarfs selected in this way are presented in table 1,
that lists the stellar parameters, proper motions and RVs of these
stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 288 20262 Data for the 20247 SDSS hydrogen-rich white
dwarfs used in this work
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See also:
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- SDSS SDSS name (SDSSJHHMMSS.ss+DDMMSS.s)
24 A1 --- --- [_]
25- 39 A15 --- MPJ SDSS MJD-Plate-Fiber identifier
40 A1 --- n_SDSS [*] * means same WDs observed in
different plates
42- 49 F8.4 deg RAdeg Right ascension (J2000)
51- 58 F8.4 deg DEdeg Declination (J2000)
60- 64 I5 K Teff Effective temperature
66- 70 I5 K e_Teff rms uncertainty on Teff
72- 77 F6.4 Msun Mass Mass
79- 88 F10.4 Msun e_Mass ?=99999 rms uncertainty on Mass
90- 95 F6.4 [cm/s2] logg Surface gravity
97-106 F10.4 [cm/s2] e_logg ?=99999 rms uncertainty on logg
108-119 F12.4 pc Dist Distance
121-132 F12.4 pc e_Dist rms uncertainty on Dist
134-144 F11.4 mas/yr pmRA* ?=99999 Proper motion along RA, pmRA*cosDE
146-154 F9.4 mas/yr e_pmRA* ?=9999 rms uncertainty on pmRA*
156-166 F11.4 mas/yr pmDE ?=99999 Proper motion along DE
168-176 F9.4 mas/yr e_pmDE ?=9999 rms uncertainty on pmDE
178-186 F9.4 km/s RVfit Radial velocity
188-196 F9.4 km/s e_RVfit rms uncertainty on FVfit
198-208 F11.4 km/s Vgrav Gravitational redshift
210-219 F10.4 --- S/N Spectral signal-to-noise ratio
221-226 F6.4 Gyr Age1 Age (using initial-to-final mass relations of
Catalan et al., 2008MNRAS.387.1693C 2008MNRAS.387.1693C)
228-235 F8.4 Gyr e_Age1 Error on Age1 (lower value)
237-242 F6.4 Gyr E_Age1 Error on Age1 (upper value)
244-249 F6.4 Gyr Age2 Age (using initial-to-final mass relations of
Gesicki et al., 2014A&A...566A..48G 2014A&A...566A..48G)
251-258 F8.4 Gyr e_Age2 Error on Age2 (lower value)
260-265 F6.4 Gyr E_Age2 Error on Age2 (upper value)
267-272 F6.4 Gyr Age3 Age (using initial-to-final mass relations of
Ferrario et al., 2005MNRAS.361.1131F 2005MNRAS.361.1131F)
274-281 F8.4 Gyr e_Age3 Error on Age3 (lower value)
283-288 F6.4 Gyr E_Age3 Error on Age3 (upper value)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Apr-2020