J/AJ/133/971 Wide companions of low-mass stars and brown dwarfs (Allen+, 2007)
A new brown dwarf desert? A scarcity of wide ultracool binaries.
Allen P.R., Koerner D.W., McElwain M.W., Cruz K.L., Reid I.N.
<Astron. J., 133, 971-978 (2007)>
=2007AJ....133..971A 2007AJ....133..971A
ADC_Keywords: Stars, double and multiple ; Stars, dwarfs
Keywords: binaries: general - stars: low-mass, brown dwarfs
Abstract:
We present the results of a deep-imaging search for wide companions to
low-mass stars and brown dwarfs using NSFCam on the Infrared Telescope
Facility. We searched a sample of 132 M7-L8 dwarfs to magnitude
limits of J∼20.5 and K∼18.5, corresponding to secondary-to-primary
mass ratios of ∼0.5. No companions were found with separations between
2" and 31" (∼40 to ∼1000AU). This null result implies a wide
companion frequency below 2.3% at the 95% confidence level within the
sensitivity limits of the survey. Preliminary modeling efforts
indicate that we could have detected 85% of companions more massive
than 0.05M☉ and 50% above 0.03M☉.
Description:
We observed all 132 targets using NSFCam on NASA's Infrared Telescope
Facility (IRTF). The initial observations were obtained over four
epochs, 2000 August, 2001 May, 2001 October, and 2002 February.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 132 IRTF and WIYN Observations
table2.dat 72 36 Color-Selected Candidate Companions
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See also:
J/ApJ/476/311 : 2MASS M-dwarf discoveries (Kirkpatrick+ 1997)
J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Object name
11- 15 F5.2 mag Jmag The IRTF J band magnitude
17- 20 F4.2 mag e_Jmag Uncertainty in Jmag
22- 26 F5.2 mag Ksmag The IRTF Ks band magnitude
28- 31 F4.2 mag e_Ksmag Uncertainty in Kmag
33- 36 A4 --- SpType Spectral type
38- 41 F4.1 pc Dist Distance
43 A1 --- f_Dist Flag on Dist (1)
45- 49 F5.2 mag Jlim The J band limit
51- 55 F5.2 mag Klim The K band limit
57- 84 A28 --- Obs The IRTF observation date(s)
86- 87 I2 --- Ref Reference(s) (2)
89 A1 --- Note [*] Individual note (3)
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Note (1): Derived from trigonometric parallaxes in Dahn et al.
(2002AJ....124.1170D 2002AJ....124.1170D).
Note (2): References as follows:
1 = Gizis et al. (2000AJ....120.1085G 2000AJ....120.1085G)
2 = Kirkpatrick et al. (1999ApJ...519..802K 1999ApJ...519..802K)
3 = Kirkpatrick et al. (2000AJ....120..447K 2000AJ....120..447K)
4 = Cruz et al. (2003, Cat. J/AJ/126/2421)
5 = Kirkpatrick et al. (1997, Cat. J/ApJ/476/311)
6 = Dahn et al. (2002AJ....124.1170D 2002AJ....124.1170D)
7 = Delfosse et al. (1999A&AS..135...41D 1999A&AS..135...41D)
8 = Martin et al. (1999AJ....118.2466M 1999AJ....118.2466M)
9 = Fan et al. (2000AJ....119..928F 2000AJ....119..928F)
10 = Hawley et al. (2002, Cat. J/AJ/123/3409)
Note (3): For 2M2054+15, Ksmag=15.58 was corrected into Ksmag=14.82 as in
Kirkpatrick et al., 2000AJ....120..447K 2000AJ....120..447K
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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- 9 A9 --- Name Object name
12- 15 A4 --- SpType Primary spectral type
17- 20 F4.1 mag JMAG Secondary absolute magnitude
22- 25 F4.1 mag J-K Secondary J-K colour index
27- 30 F4.1 pc Dist Distance
32- 36 F5.1 arcsec DRA Offset in RA from the primary
38- 42 F5.1 arcsec DDE Offset in DE from the primary
44- 72 A29 --- Notes Notes (1)
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Note (1): Notes as follows:
SDSS = Object is in SDSS DR5 field.
WIYNa = Field observed with WIYN in 2002 August.
WIYNf = Field observed with WIYN in 2003 February.
All objects detected in either SDSS or with WIYN imaging have
colors that are too blue to be consistent with an ultracool dwarf.
* = Candidates that still require follow-up observations to
determine their nature.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 09-Jan-2009