J/ApJ/586/1356 White dwarfs with cool companions (Wachter+, 2003)
Cool companions to white dwarfs from the
Two Micron All-Sky Survey Second Incremental Data Release.
Wachter S., Hoard D.W., Hansen K.H., Wilcox R.E., Taylor H.M.,
Finkelstein S.L.
<Astrophys. J. 586, 1356 (2003)>
=2003ApJ...586.1356W 2003ApJ...586.1356W
ADC_Keywords: Stars, double and multiple ; Infrared sources ;
Photometry, infrared
Keywords: binaries: general - infrared: stars - stars: fundamental parameters -
surveys - white dwarfs
Abstract:
We present near-infrared (IR) magnitudes for all white dwarfs
(selected from the catalog of McCook & Sion, 1999, See Cat. III/235)
contained in the Two Micron All-Sky Survey second incremental data
release (2MASS 2IDR, Cat. II/241). We show that the near-IR
color-color diagram is an effective means of identifying candidate
binary stars containing a WD and a low-mass, main-sequence star. The
loci of single WDs and WD+red dwarf binaries occupy distinct regions
of the near-IR color-color diagram. We recovered all known unresolved
WD+red dwarf binaries located in the 2IDR sky coverage and also
identified as many new candidate binaries (47 new candidates out of 95
total). Using observational near-IR data for WDs and M-L dwarfs, we
have compared a sample of simulated WD+red dwarf binaries with our
2MASS data. The colors of the simulated binaries are dominated by the
low-mass companion through the late M to early L spectral types. As
the spectral type of the companion becomes progressively later,
however, the colors of unresolved binaries become progressively bluer.
Binaries containing the lowest mass companions will be difficult to
distinguish from single WDs solely on the basis of their near-IR
colors.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 95 White dwarf+low-mass, main-sequence star
binary candidates
table2.dat 68 15 Tentative WD+low-mass, main-sequence star
binary candidates
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See also:
II/241 : 2MASS Catalog Intermediate Data Release (IPAC/UMass, 2000)
III/235 : Spectroscopically Identified White Dwarfs (McCook+, 2003)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- WD WD designation (based on 1950 positions)
12- 20 A9 --- Ref Reference for binarity (1)
22 A1 --- n_Ref [a-j] Note on Ref (2)
24- 29 F6.3 mag Jmag J magnitude
32- 36 F5.3 mag e_Jmag rms uncertainty on Jmag
40- 45 F6.3 mag Hmag H magnitude
48- 52 F5.3 mag e_Hmag rms uncertainty on Hmag
56- 61 F6.3 mag Ksmag Ks magnitude
64- 68 F5.3 mag e_Ksmag rms uncertainty on Ksmag
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Note (1): References as follows:
1 = Schultz, Zuckerman, & Becklin, 1996ApJ...460..402S 1996ApJ...460..402S
2 = Greenstein, 1986AJ.....92..867G 1986AJ.....92..867G
3 = Schultz et al., 1993BAAS...25..824S 1993BAAS...25..824S
4 = Gizis & Reid, 1997PASP..109..849G 1997PASP..109..849G, Cat. J/PASP/109/849
5 = Fulbright & Liebert 1993
6 = Orosz et al., 1999AJ....117.1598O 1999AJ....117.1598O
7 = Koester et al., 2001A&A...378..556K 2001A&A...378..556K, Cat. J/A+AS/378/556
8 = Stepanian et al., 2001AJ....122.3361S 2001AJ....122.3361S
9 = Zuckerman & Becklin, 1992ApJ...386..260Z 1992ApJ...386..260Z
10 = Finley, Koester & Basri 1997
11 = Reid et al., 1988AJ.....96..275R 1988AJ.....96..275R
12 = Marsh & Duck, 1996MNRAS.278..565M 1996MNRAS.278..565M
MS99 = McCook & Sion, 1999ApJS..121....1M 1999ApJS..121....1M, See Cat. III/235
Note (2): Individual notes as follows:
a = WD 0023+388 is a known triple system composed of a close WD+red
dwarf pair with a wide red dwarf companion (Reid, 1988AJ.....96..275R 1988AJ.....96..275R)
b = WD 0034-211 is classified as a close double-degenerate binary in
MS99 (See Cat. III/235). Bragaglia et al.
(1990ApJ...365L..13B 1990ApJ...365L..13B) reclassified it as a WD+red dwarf binary,
which is supported by its 2MASS colors.
c = WD 0102+210.2 is classified as one component of a wide
double-degenerate binary (Sion et al., 1991AJ....101.1476S 1991AJ....101.1476S), but
our 2MASS colors suggest that it may be a close WD+red dwarf
binary also.
d = WD 0205+133 may be an sdOB+red dwarf binary instead of a WD+red
dwarf binary (Allard et al., 1994AJ....107.1565A 1994AJ....107.1565A).
e = This object is classified as the WD component of a wide
(resolved) WD+red dwarf binary, but our 2MASS colors suggest
that the WD may also be a close WD+red dwarf binary.
f = The binary separation of WD 0628-020 (4) is near the 2MASS
resolution limit. There is only one entry in the 2IDR point
source catalog, but these magnitudes may be for the red dwarf
component only.
g = The companion of WD 1517+502 is a dwarf carbon star
(Liebert et al., 1994ApJ...421..733L 1994ApJ...421..733L).
h = WD 1610+383 is barely resolved on the DSS images as a common
proper motion pair with red and blue components at a separation
of 4. Blinking of the DSS and 2MASS images suggests that only
the red component is detected by 2MASS. Its near-IR colors are
consistent with an early M spectral type.
i = This object is classified as the WD component of a wide
(resolved) binary, but our 2MASS colors suggest that the WD may
also be a close WD+red dwarf binary.
j = MS99 (See Cat. III/235) note that WD 1247+550 is
"possibly the coolest known degenerate star."
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History:
From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 22-May-2003