J/AJ/150/57 SLoWPoKES-II catalog (Dhital+, 2015)
SLoWPoKES-II: 100,000 wide binaries identified in SDSS without proper motions.
Dhital S., West A.A., Stassun K.G., Schluns K.J., Massey A.P.
<Astron. J., 150, 57 (2015)>
=2015AJ....150...57D 2015AJ....150...57D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, M-type ; Stars, dwarfs ;
Photometry, SDSS ; Spectral types
Keywords: binaries: visual - brown dwarfs - stars: late-type - stars: low-mass -
subdwarfs - white dwarfs
Abstract:
We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent
Stars (SLoWPoKES)-II catalog of low-mass visual binaries identified
from the Sloan Digital Sky Survey (SDSS) by matching photometric
distances. The candidate pairs are vetted by comparing the stellar
information. The candidate pairs are vetted by comparing the stellar
density at their respective Galactic positions to Monte Carlo
realizations of a simulated Milky Way. In this way, we are able to
identify large numbers of bona fide wide binaries without the need for
proper motions. Here, 105537 visual binaries with angular separations
of ∼1-20" were identified, each with a probability of chance alignment
of ≤5%. This is the largest catalog of bona fide wide binaries to
date, and it contains a diversity of systems--in mass, mass ratios,
binary separations, metallicity, and evolutionary states--that should
facilitate follow-up studies to characterize the properties of M
dwarfs and white dwarfs. There is a subtle but definitive suggestion
of multiple populations in the physical separation distribution,
supporting earlier findings. We suggest that wide binaries are
composed of multiple populations, most likely representing different
formation modes. There are 141 M7 or later wide binary candidates,
representing a seven-fold increase over the number currently known.
These binaries are too wide to have been formed via the ejection
mechanism. Finally, we found that 6% of spectroscopically confirmed M
dwarfs are not included in the SDSS STAR catalog; they are
misclassified as extended sources due to the presence of a nearby or
partially resolved companion. The SLoWPoKES-II catalog is publicly
available to the entire community on the World Wide Web via the
Filtergraph data visualization portal.
Description:
We have identified the Sloan Low-mass Wide Pairs of Kinematically
Equivalent Systems (SLoWPoKES)-II catalog of 105537 wide, low-mass
binaries without using proper motions. We extend the SLoWPoKES catalog
(Paper I; Dhital et al. 2010, cat. J/AJ/139/2566) by identifying
binary systems with angular separations of 1-20'' based entirely on
SDSS photometry and astrometry. As in Paper I, we used the Catalog
Archive Server query tool (CasJobs6;
http://skyserver.sdss3.org/CasJobs/) to select the sample of low-mass
stars from the SDSS-DR8 star table as having r-i≥0.3 and i-z≥0.2,
consistent with spectral types of K5 or later.
Following Paper I (Dhital et al. 2010, cat. J/AJ/139/2566) we
classified candidate pairs with a probability of chance alignment
Pf≤0.05 as real binaries. We note that this limit does not have
any physical motivation but was chosen to minimize the number of
spurious pairs. This cut results in 105537 M dwarf (dM)+MS (see
Table3), 78 white dwarf (WD)+dM (see Table5), and 184 sdM+sdM (see
Table6) binary systems with separations of 1-20''. Of the dM+MS
binaries, 44 are very low-mass (VLM) binary candidates (see Table4),
with colors redder than the median M7 dwarf for both components. This
represents a significant increase over the SLoWPoKES catalog of 1342
common proper motion (CPM) binaries that we presented in Paper I
(Dhital et al. 2010, cat. J/AJ/139/2566).
The SLoWPoKES and SLoWPoKES-II catalogs are available on the
Filtergraph portal (http://slowpokes.vanderbilt.edu/).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 177 105537 Properties of SLoWPoKES-II pairs (dM+MS)
table4.dat 177 44 Very Low-Mass (VLM) binary candidates in
SLoWPoKES-II
table5.dat 177 78 Candidate White Dwarf+M dwarf systems (WD+dM)
table6.dat 177 184 Candidate M subdwarf systems (sdM+sdM)
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/143/67 : SLoWPoKES. II. Properties of wide, low-mass binaries
(Dhital+, 2012)
J/ApJS/204/5 : SDSS DR7 white dwarf catalog (Kleinman+, 2013)
J/AJ/141/97 : SDSS DR7 M dwarfs (West+, 2011)
J/AJ/139/2566 : SLoWPoKES catalog (Dhital+, 2010)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/ApJS/167/40 : SDSS4 confirmed white dwarfs catalog (Eisenstein+, 2006)
J/AJ/128/426 : Subdwarfs in the SDSS (West+, 2004)
J/A+A/356/529 : Catalog of wide binaries (Allen+ 2000)
http://slowpokes.vanderbilt.edu/ : Online SLoWPoKES and SLoWPoKES-II catalogs
Byte-by-byte Description of file: table[3456].dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- SLW SLoWPoKES identifier (HHMM+DDMM, J2000) (1)
11- 20 F10.6 deg RAdeg [0/360] Primary Right Ascension in decimal
degrees (J2000)
22- 31 F10.6 deg DEdeg [-25/85] Primary Declination in decimal degrees
(J2000)
33- 42 F10.6 deg RA2deg [0/360] Secondary Right Ascension in decimal
degrees (J2000)
44- 53 F10.6 deg DE2deg [-25/85] Secondary Declination in decimal
degrees (J2000)
55- 58 I4 pc Dist1 [25/2499] Primary photometric distance
60- 63 I4 pc Dist2 [25/2598] Secondary photometric distance
65- 69 F5.2 arcsec Sep [1/20] Angular separation of the CPM pair θ
71- 74 I4 deg PA [-179/179] Position Angle of the binary
76- 80 F5.2 mag gmag1 [14.6/25.6] Primary SDSS psfmag in g-band (2)
82- 86 F5.2 mag e_gmag1 [0.01/41.2] Error in gmag1
88- 92 F5.2 mag rmag1 [13.6/24] Primary SDSS psfmag in r-band (2)
94- 97 F4.2 mag e_rmag1 [0/0.9] Error in rmag1
99-103 F5.2 mag imag1 [13.1/21.4] Primary SDSS psfmag in i-band (2)
105-108 F4.2 mag e_imag1 [0/0.1] Error in imag1
110-114 F5.2 mag zmag1 [12.5/20.6] Primary SDSS psfmag in z-band (2)
116-119 F4.2 mag e_zmag1 [0.01/0.1] Error in zmag1
121-125 F5.2 mag gmag2 [13.6/26.5] Secondary SDSS psfmag in g-band (2)
127-131 F5.2 mag e_gmag2 [0.01/52.1] Error in gmag2
133-137 F5.2 mag rmag2 [13.3/24.5] Secondary SDSS psfmag in r-band (2)
139-142 F4.2 mag e_rmag2 [0/1.5] Error in rmag2
144-148 F5.2 mag imag2 [13.2/21.9] Secondary SDSS psfmag in i-band (2)
150-153 F4.2 mag e_imag2 [0/0.1] Error in imag2
155-159 F5.2 mag zmag2 [12.8/20.7] Secondary SDSS psfmag in z-band (2)
161-164 F4.2 mag e_zmag2 [0.01/0.1] Error in zmag2
166-167 A2 --- SpT1 Primary photometric spectral type (ND=No Data)
169-170 A2 --- SpT2 Secondary photometric spectral type (ND=No Data)
172-177 F6.4 % Prob [0/0.05] Probability of chance alignment Pf (3)
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Note (1): The identifiers were generated using the standard Jhhmm±ddmm format
using coordinates of the primary star and are prefaced with the string 'SLW'.
Note (2): All magnitudes are psfmag and have not been corrected for extinction.
Note that we use extinction-corrected magnitudes in our analysis.
Note (3): While false positives are inherent in all statistical samples, we have
required a relatively stringent probability of chance alignment, Pf, as
calculated by our Galactic model to be ≤5% for each of our binaries. Most
binaries have a much smaller probability of chance alignment. The entire
sample is expected to have 2464 (2.3%) chance alignments.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 24-Nov-2015