J/AJ/147/129 White dwarfs within 25pc of the Sun (Sion+, 2014)
The white dwarfs within 25 pc of the Sun: kinematics and spectroscopic subtypes.
Sion E.M., Holberg J.B., Oswalt T.D., McCook G.P., Wasatonic R., Myszka J.
<Astron. J., 147, 129 (2014)>
=2014AJ....147..129S 2014AJ....147..129S
ADC_Keywords: Stars, nearby ; Stars, white dwarf ; Space velocities ;
Proper motions ; Spectral types ; Stars, distances
Keywords: stars: evolution - stars: kinematics and dynamics -
stars: statistics - techniques: photometric -
techniques: spectroscopic - white dwarfs
Abstract:
We present the fractional distribution of spectroscopic subtypes,
range and distribution of surface temperatures, and kinematical
properties of the white dwarfs (WDs) within 25pc of the Sun. There is
no convincing evidence of halo WDs in the total 25pc sample of 224
WDs. There is also little to suggest the presence of genuine thick
disk subcomponent members within 25pc. It appears that the entire 25pc
sample likely belongs to the thin disk. We also find no significant
kinematic differences with respect to spectroscopic subtypes. The
total DA to non-DA ratio of the 25pc sample is 1.8, a manifestation of
deepening envelope convection, which transforms DA stars with
sufficiently thin H surface layers into non-DAs. We compare this ratio
with the results of other studies. We find that at least 11% of the
WDs within 25pc of the Sun (the DAZ and DZ stars) have photospheric
metals that likely originate from accretion of circumstellar material
(debris disks) around them. If this interpretation is correct, then it
suggests the possibility that a similar percentage have planets,
asteroid-like bodies, or debris disks orbiting them. Our
volume-limited sample reveals a pileup of DC WDs at the well-known
cutoff in DQ WDs at Teff∼6000K. Mindful of small number statistics,
we speculate on its possible evolutionary significance. We find that
the incidence of magnetic WDs in the 25pc sample is at least 8% in our
volume-limited sample, dominated by cool WDs. We derive approximate
formation rates of DB and DQ degenerates and present a preliminary
test of the evolutionary scenario that all cooling DB stars become DQ
WDs via helium convective dredge-up with the diffusion tail of carbon
extending upward from their cores.
Description:
A substantial fraction of our sample was taken from the detailed
survey of the local white dwarfs (WDs) out to 20pc by Holberg et al.
(2008, cat. J/AJ/135/1225) and Sion et al. (2009, cat. J/AJ/138/1681).
To this sample of 129 WDs, we have added 95 WDs out to a volume of
25pc radius, giving a total sample of 224 WDs including double
degenerates known out to 25pc.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 223 Observational data used in space motions
table3.dat 51 216 Space motions of white dwarfs within 25pc
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See also:
B/wd : Spectroscopically Identified White Dwarfs (McCook+, 2008)
III/235 : Spectroscopically Identified White Dwarfs (McCook+, 2008)
I/297 : NOMAD Catalog (Zacharias+ 2005)
V/70 : Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
V/32 : Stars within 25 pc of the Sun (Woolley+ 1970)
J/AJ/145/136 : Astrometry & photometry of nearby white dwarfs (Limoges+, 2013)
J/ApJ/743/138 : Spectroscopic survey of bright white dwarfs (Gianninas+, 2011)
J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011)
J/ApJS/190/77 : Detailed analysis of cool WDs in the SDSS (Kilic+, 2010)
J/AJ/138/1681 : WD within 20pc of the Sun (Sion+, 2009)
J/AJ/135/1239 : Spectral distances to DA white dwarfs (Holberg+, 2008)
J/AJ/135/1225 : Parameters of the local white dwarfs (Holberg+, 2008)
J/AJ/132/1221 : VJHK and SDSS photometry of DA white dwarfs (Holberg+, 2006)
J/A+A/447/173 : 3D-kinematics of WDs from SPY project. II. (Pauli+, 2006)
J/A+A/400/877 : White dwarfs 3D kinematics from SPY project (Pauli+, 2003)
J/AJ/124/1118 : Radial velocities of high-velocity WDs (Silvestri+, 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of the white dwarf (HHMM+DDd.N; B1950)
12- 21 A10 --- SpT Spectroscopic subtype
23- 27 I5 K Teff ? Effective temperature
29- 35 F7.3 deg RAdeg ? Right Ascension in decimal degrees (J2000)
37- 43 F7.3 deg DEdeg ? Declination in decimal degrees (J2000)
45- 49 F5.2 pc Dist [2.6/26]? Distance (1)
51- 56 F6.4 arcsec/yr pm ? Proper motion (2)
58- 65 F8.4 deg pmPA ? Position angle of proper motion vector
67- 68 A2 --- n_Dist [p s] Method of distance determination (3)
70- 76 A7 --- Ref Reference (4)
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Note (1): As in Holberg et al. (2008, cat. J/AJ/135/1225) and Sion et al. (2009,
cat. J/AJ/138/1681), the photometric distances were computed based on
spectroscopic and photometric measurements following the methods described
in Holberg et al. (2008, cat. J/AJ/135/1239).
Note (2): Taken from the McCook and Sion Catalog (2008, cat. III/235), or where
available, were determined from NOMAD (Zacharias et al., 2005, cat. I/297).
Note (3): p=trigonometric parallax; s=spectrophotometric distance.
Note (4): Reference codes are defined as follows:
L20 = Holberg et al. (2008, cat. J/AJ/135/1225);
SL = Sion et al. (2009, cat. J/AJ/138/1681);
GBD = Giammichele et al. (2012ApJS..199...29G 2012ApJS..199...29G);
G11 = Gianninas et al. (2011, cat. J/ApJ/743/138);
Lim = Limoges et al. (2013, cat. J/AJ/145/136);
Say = Sayres et al. (2012AJ....143..103S 2012AJ....143..103S);
Pi = Trigonometric parallax;
DR7 = J. Holberg et al. (2014, in preparation);
Sub08 = Subasavage et al. (2008AJ....136..899S 2008AJ....136..899S);
Sub07 = Subasavage et al. (2007, cat. J/AJ/134/252);
Ber11 = Bergeron et al. (2011ApJ...737...28B 2011ApJ...737...28B);
GJ = Gliese & Jarheise (1991, cat. V/70);
Kilic10 = Kilic et al. (2010, cat. J/ApJS/190/77);
Koe11 = Koester et al. (2011A&A...530A.114K 2011A&A...530A.114K);
Trem11 = Tremblay et al. (2011, cat. J/ApJ/730/128).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of the white dwarf (HHMM+DDd.N; B1950)
12- 18 A7 --- SpT Spectroscopic subtype
20- 27 F8.3 km/s Uvel U vector component of the space motion (1)
29- 36 F8.3 km/s Vvel V vector component of the space motion (2)
38- 43 F6.1 km/s Wvel W vector component of the space motion (3)
45- 51 F7.3 km/s VTotal Total space motion
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Note (1): Positive in the direction of the galactic anti-center (Wooley et al.,
1970, cat. V/32).
Note (2): Positive in the direction of the galactic rotation (Wooley et al.,
1970, cat. V/32).
Note (3): Positive in the direction of the north Galactic pole (Wooley et al.,
1970, cat. V/32).
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History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 22-Sep-2014