J/AJ/143/67 SLoWPoKES. II. Properties of wide, low-mass binaries (Dhital+, 2012)
Refined metallicity indices for M dwarfs using the SLoWPoKES catalog of wide,
low-mass binaries.
Dhital S., West A.A., Stassun K.G., Bochanski J.J., Massey A.P.,
Bastien F.A.
<Astron. J., 143, 67 (2012)>
=2012AJ....143...67D 2012AJ....143...67D
ADC_Keywords: Stars, M-type ; Stars, double and multiple ; Radial velocities ;
Equivalent widths ; Spectral types ; Proper motions ;
Stars, distances ; Photometry, SDSS
Keywords: binaries: spectroscopic - binaries: visual - brown dwarfs -
stars: abundances - stars: kinematics and dynamics - stars: low-mass -
stars: magnetic field
Abstract:
We report the results from spectroscopic observations of 113
ultra-wide, low-mass binary systems, largely composed of M0-M3 dwarfs,
from the SLoWPoKES catalog of common proper motion pairs identified in
the Sloan Digital Sky Survey (Dhital et al., 2010, Cat. J/AJ/139/2566).
Radial velocities of each binary member were used to confirm that they
are comoving and, consequently, to further validate the high fidelity
of the SLoWPoKES catalog. Ten stars appear to be spectroscopic
binaries based on broad or split spectral features, supporting
previous findings that wide binaries are likely to be hierarchical
systems. We measured the Hα equivalent width of the stars in our
sample and found that components of 81% of the observed pairs have
similar Hα levels. The difference in Hα equivalent width
among components with similar masses was smaller than the range of
Hα variability for individual objects. We confirm that the
Lepine et al. (2007ApJ...669.1235L 2007ApJ...669.1235L) ζ-index traces
iso-metallicity loci for most of our sample of M dwarfs. However, we
find a small systematic bias in ζ, especially in the early-type M
dwarfs. We use our sample to recalibrate the definition of ζ.
While representing a small change in the definition, the new ζ is
a significantly better predictor of iso-metallicity for the
higher-mass M dwarfs.
Description:
In Paper I (Dhital et al., 2010, Cat. J/AJ/139/2566), we identified
the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars
(SLoWPoKES) catalog consisting of 1342 ultra-wide, low-mass common
proper motion (CPM) binary systems from the SDSS-DR7 (Cat. II/294) by
matching angular separations, photometric distances, and proper
motions. For this paper, the spectroscopic targets were selected from
Paper I based on their brightnesses, colors, and inferred mass ratios.
Observations were carried out with the GoldCam spectrograph on the
KPNO 2.1m telescope on two separate observing runs on 2009 January
11-16 UT and 2010 March 26-31 UT.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 171 113 Properties of observed SLoWPoKES binaries
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
J/AJ/141/97 : SDSS DR7 M dwarfs (West+, 2011)
J/AJ/139/2566 : Paper I: SLoWPoKES catalog (Dhital+, 2010)
J/AJ/140/1402 : M dwarf flares from SDSS spectra (Hilton+, 2010)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/AJ/131/1674 : Close binary systems from SDSS DR4 (Silvestri+, 2006)
J/AJ/128/426 : Subdwarfs in the SDSS (West+, 2004)
J/AJ/125/1598 : New high proper motion stars in northern sky (Lepine+, 2003)
J/AJ/123/3356 : Palomar/MSU star spectroscopic survey. III. (Gizis+, 2002)
J/A+A/331/581 : Rotation and activity in field M dwarfs (Delfosse+ 1998)
J/AJ/113/806 : M-Subdwarfs (Gizis 1997)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [SLW]
5- 11 A7 --- SLW Binary identifier in SLoWPoKES catalog, as in
SLoWPoKES.I (J/AJ/139/2566) (HHMM+DD; J2000) (1)
13- 14 I2 h RA1h Primary's Hour of Right Ascension (J2000)
16- 17 I2 min RA1m Primary's Minute of Right Ascension (J2000)
19- 23 F5.2 s RA1s Primary's Second of Right Ascension (J2000)
25 A1 --- DE1- Sign of the Primary's Declination (J2000)
26- 27 I2 deg DE1d Primary's Degree of Declination (J2000)
29- 30 I2 arcmin DE1m Primary's Arcminute of Declination (J2000)
32- 35 F4.1 arcsec DE1s Primary's Arcsecond of Declination (J2000)
37- 38 I2 h RA2h Secondary's Hour of Right Ascension (J2000)
40- 41 I2 min RA2m Secondary's Minute of Right Ascension (J2000)
43- 47 F5.2 s RA2s Secondary's Second of Right Ascension (J2000)
49 A1 --- DE2- Sign of the Secondary's Declination (J2000)
50- 51 I2 deg DE2d Secondary's Degree of Declination (J2000)
53- 54 I2 arcmin DE2m Secondary's Arcminute of Declination (J2000)
56- 59 F4.1 arcsec DE2s Secondary's Arcsecond of Declination (J2000)
61- 63 I3 pc Dist1 Primary's photometric distance (2)
65- 67 I3 pc Dist2 Secondary's photometric distance (2)
69- 72 I4 mas/yr pmRA1 Primary's proper motion in RA (2)
74- 77 I4 mas/yr pmRA2 Secondary's proper motion in RA (2)
79- 82 I4 mas/yr pmDE1 Primary's proper motion in DE (2)
84- 87 I4 mas/yr pmDE2 Secondary's proper motion in DE (2)
89- 94 F6.1 km/s RVel1 Primary's radial velocity (3)
96-101 F6.1 km/s RVel2 Secondary's radial velocity (3)
103-107 F5.2 mag rmag1 Primary's SDSS r band psf magnitude (4)
109-113 F5.2 mag rmag2 Secondary's SDSS r band psf magnitude (4)
115-118 F4.2 mag (r-z)1 [0.66/2.52] Primary's SDSS (r-z) color index
120-123 F4.2 mag (r-z)2 [0.77/3.08] Secondary's SDSS (r-z) color index
125-126 A2 --- SpT1 Primary's spectral type (K7, M0 to M4) (5)
128-129 A2 --- SpT2 Secondary's spectral type (K7, M0 to M5) (5)
131-135 F5.2 0.1nm EW1 Primary's Hα equivalent width
137-141 F5.2 0.1nm EW2 Secondary's Hα equivalent width
143-146 F4.2 --- CaH2.1 Primary's CaH2 molecular band index (6)
148-151 F4.2 --- CaH2.2 Secondary's CaH2 molecular band index (6)
153-156 F4.2 --- CaH3.1 Primary's CaH3 molecular band index (6)
158-161 F4.2 --- CaH3.2 Secondary's CaH3 molecular band index (6)
163-166 F4.2 --- TiO5.1 Primary's TiO5 molecular band index (6)
168-171 F4.2 --- TiO5.2 Secondary's TiO5 molecular band index (6)
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Note (1): The identifiers were generated using coordinates of the primary star.
Pairs are in Simbad and stars are .
Note (2): From SLoWPoKES catalog (Dhital et al., 2010, Cat. J/AJ/139/2566)
Note (3): The radial velocities of the stars were measured by cross-correlating
the program spectra with the appropriate SDSS template spectra
(Bochanski et al., 2007AJ....133..531B 2007AJ....133..531B).
Note (4): Both components were required to be brighter than r∼17 so as to obtain
the desired signal-to-noise ratio (S/N) within a reasonable
integration time.
Note (5): Even though our observed sample was limited to r∼17 and, thus, a
dearth of late-type M dwarfs was to be expected, there are nonetheless
11 pairs with at least one component later than M4 and only 2 pairs
with both components later than M4.
Note (6): Lepine et al. (2007ApJ...669.1235L 2007ApJ...669.1235L) defined the metallicity-dependent
quantity ζ using the Reid et al. (Cat. III/198) CaH2, CaH3, and
TiO5 molecular band heads.
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History:
From electronic version of the journal
References:
Dhital et al. Paper I. 2010AJ....139.2566D 2010AJ....139.2566D Cat. J/AJ/139/2566
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 29-Apr-2013