J/MNRAS/445/1331 White-dwarf + main-sequence binaries in SDSS DR9 (Li+, 2014)
White-dwarf + main-sequence binaries identified from the ninth data release of
the Sloan Digital Sky Survey.
Li L., Zhang F., Han Q., Kong X., Gong X.
<Mon. Not. R. Astron. Soc., 445, 1331-1338 (2014)>
=2014MNRAS.445.1331L 2014MNRAS.445.1331L
ADC_Keywords: Stars, double and multiple ; Stars, white dwarf ; Stars, dwarfs ;
Photometry, SDSS ; Photometry, infrared
Keywords: Sun: fundamental parameters - stars: AGB and post-AGB -
binaries: close - binaries: spectroscopic - stars: evolution
Abstract:
We have identified 227 new spectroscopic white-dwarf + main-sequence
(WDMS) binaries from the ninth data release (DR9) of the Sloan Digital
Sky Survey (SDSS). The SDSS spectra of the newly found WDMS binaries
with a DA white dwarf and an M-dwarf are analysed based on a spectral
decomposition/fitting method. We obtain the effective temperatures,
surface gravities and masses of the white dwarf, together with the
spectral types and metallicities of the secondary star. Two
independent distance estimates are derived from the flux-scaling
factors between the WDMS SDSS spectra and the white dwarf and M-dwarf
model spectra. We find that about 25 per cent of the newly found WDMS
binaries show a significant discrepancy between the two distance
estimates. This might be caused by the effects of M-dwarf stellar
activity or irradiation of the M-dwarf companions by the white dwarf.
The stellar parameter distributions are used to investigate the global
properties of the newly found WDMS binaries. We find that the WDMS
binaries with a low signal-to-noise ratio (S/N≤4.0) usually have a
massive DA white dwarf component with a higher surface gravity, and
the metallicity is usually significantly different from solar. This
suggests that the observational selection effects and the spectral S/N
of the WDMS binaries have a significant influence on the
determinations of these physical parameters of WDMS binaries.
Description:
In 2012, we developed theoretical colour-selection criteria for
searching the WDMS binaries from the SDSS, based on SDSS photometry
(Liu et al., 2012, Cat. J/MNRAS/424/1841). We found that the number of
WDMS binaries identified by us based on our colour-selection criteria
is lower than the number identified by other investigators, such as
Rebassa-Mansergas et al. (2012MNRAS.419..806R 2012MNRAS.419..806R). Therefore, we enlarged
the region of our colour-selection criteria based on distributions of
our theoretical models because the previous colour-selection criteria
did not completely cover some theoretical tracks in Liu et al. (2012,
Cat. J/MNRAS/424/1841).
Based on the enlarged colour-selection criteria mentioned above, we
identified 1323 WDMS binaries from the SDSS DR9, and 1096 of these
WDMS binaries have been identified by previous investigators
(Silvestri et al., 2007, Cat. J/AJ/134/741; Heller et al., 2009, Cat.
J/A+A/496/191; Liu et al., 2012, Cat. J/MNRAS/424/1841; Wei et al.,
2013MNRAS.431.1800W 2013MNRAS.431.1800W; Rebassa-Mansergas et al., 2013, Cat.
J/MNRAS/433/3398). Therefore, 227 new WDMS binaries have been
identified from the SDSS DR9, and most of these (177) are WDMS
binaries with a DA WD and an M-dwarf.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 123 227 Object name, coordinates, and SDSS ugriz, UKIDSS YJHK,
2MASS JHK and WISE W1W2 magnitudes of the 227 WDMS
binaries newly identified from SDSS DR9
table2.dat 124 227 Stellar parameters for 227 WDMS binaries newly
identified from SDSS DR9
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See also:
J/A+A/496/191 : Spectral analysis of 636 SDSS WD-M binaries (Heller+, 2009)
J/MNRAS/424/1841 : SDSS-UKIDSS white dwarf-main sequence binaries (Liu+, 2012)
J/MNRAS/424/1841 : SDSS-UKIDSS white dwarf-main sequence binaries (Liu+, 2012)
J/MNRAS/433/3398 : White dwarf main-sequence binaries (Rebassa-Mansergas+ 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS SDSS designation (HHMMSS.ss+DDMMSS.s)
20- 28 F9.5 deg RAdeg Right ascension (J2000)
30- 37 F8.5 deg DEdeg Declination (J2000)
39- 43 F5.2 mag umag SDSS u magnitude
45- 49 F5.2 mag gmag SDSS g magnitude
51- 55 F5.2 mag rmag SDSS r magnitude
57- 61 F5.2 mag imag SDSS i magnitude
63- 67 F5.2 mag zmag SDSS z magnitude
69- 73 F5.2 mag Ymag ?=- UKIDSS Y magnitude
75- 79 F5.2 mag Jmag ?=- UKIDSS J magnitude
81- 85 F5.2 mag Hmag ?=- UKIDSS H magnitude
87- 91 F5.2 mag Kmag ?=- UKIDSS Ks magnitude
93- 97 F5.2 mag J2mag ?=- 2MASS J magnitude
99-103 F5.2 mag H2mag ?=- 2MASS H magnitude
105-109 F5.2 mag K2mag ?=- 2MASS Ks magnitude
111-115 F5.2 mag W1mag ?=- WISE W1 magnitude (3.4µm)
117 A1 --- r_W1mag [1] 1 = D'Angelo et al. 2006AJ....132..650D 2006AJ....132..650D
119-123 F5.2 mag W2mag ?=- WISE W2 magnitude (4.6µm)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS SDSS designation (HHMMSS.ss+DDMMSS.s)
20- 25 A6 --- Type Binary spectral type
27- 30 I4 --- Plate SDSS plate number
32- 36 I5 --- MJD SDSS plate number
38- 40 I3 --- Fiber SDSS fiber number
42- 45 F4.1 kK Teff1 [6/60]?=- White dwarf effective temperature
47- 50 F4.2 [cm/s2] logg1 [6.5/9]?=- White dwarf surface gravity
52- 56 F5.2 [Sun] [Fe/H] [-2/0.4]?=- Metallicity
57- 62 F6.1 K Teff2 [2281/3843]?=- Secondary effective temperature
64- 66 F3.1 [cm/s2] logg2 [3.5/5.5]?=- Secondary surface gravity
68- 75 F8.3 pc d1 [44/2840]?=- White dwarf distance
77- 80 F4.2 Msun M1 [0.18/1.22]?=- White dwarf mass
82- 86 F5.3 Rsun R1 [0.006/0.041]?=- White dwarf radius
88- 95 F8.3 pc d2 [89/2179]?=- Secondary distance
97-100 F4.2 Msun M2 [0.12/0.47]?=- Secondary mass
102-106 F5.3 Rsun R2 [0.11/0.49]?=- Secondary radius
107-112 F6.3 --- C [-1.1/1.1]?=- C parameter used to describe the
difference between d1 and d2 (1)
114-118 F5.3 [yr] logA [5.2/9.8]?=- Age
120-124 F5.2 --- chi2r [0.1/56]?=- Reduced χ2 value
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Note (1): C parameter proposed by Heller et al. (2009A&A...496..191H 2009A&A...496..191H):
C = sqrt(2)*(d1-d2)/(d1+d2).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-May-2015