J/AJ/132/891 Binaries among nearby L dwarfs (Reid+, 2006)
A search for binary systems among the nearest L dwarfs.
Reid I.N., Lewitus E., Allen P.R., Cruz K.L., Burgasser A.J.
<Astron. J., 132, 891-901 (2006)>
=2006AJ....132..891R 2006AJ....132..891R
ADC_Keywords: Stars, double and multiple ; Stars, nearby ; Photometry, infrared
Keywords: Stars: binaries: visual ; stars: low-mass, brown dwarfs
Abstract:
We have used the Near-Infrared Camera and Multi-Object Spectrometer
NIC1 camera on the Hubble Space Telescope to obtain high angular
resolution images of 52 ultracool dwarfs in the immediate solar
neighborhood. Nine systems are resolved as binary, with component
separations from 1.5 to 15AU. Based on current theoretical models and
empirical bolometric corrections, all systems have components with
similar luminosities and, consequently, high mass ratios, q>0.8.
Limiting analysis to L dwarfs within 20pc, the observed binary
fraction is 12%(9-19%). Applying Bayesian analysis to our data set, we
derive a mass-ratio distribution that peaks strongly at unity.
Modeling the semimajor axis distribution as a logarithmic Gaussian,
the best fit is centered at log(a0)=0.8AU (a0∼6.3AU), with a
(logarithmic) width of ±0.3. The current data are consistent with an
overall binary frequency of ∼24%.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 43 Unresolved ultracool dwarfs
table23.dat 130 27 Observational data for candidate binaries
and inferred properties of binary components
table4.dat 80 12 Additional L dwarf binaries within 20pc
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See also:
J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
J/A+A/435/363 : Southern Infrared Proper Motion Survey (Deacon+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [2MASS]
7- 24 A18 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSss)
25 A1 --- n_2MASS [*] Individual note (1)
27- 30 A4 --- SpType MK spectral type
32- 36 F5.2 mag Jmag J magnitude
38- 42 F5.2 mag Hmag H magnitude
44- 48 F5.2 mag Ksmag Ks magnitude
50- 54 F5.2 mag m110 NIC-F110W magnitude (0.8-1.4um)
56- 60 F5.2 mag m170 NIC-F170M magnitude (1.6-1.8um)
62- 66 F5.2 pc Dist Distance
68- 71 F4.2 pc e_Dist rms uncertainty on Dist
73- 75 A3 --- r_Dist Distance reference (2)
77- 83 A7 --- Notes Discovery paper (3)
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Note (1): Individual notes:
* 2M1048+01: Kendall et al. (2004A&A...416L..17K 2004A&A...416L..17K) cite a spectral type
of M7, based on IR spectra; our optical spectrum indicates a type of
L1, in agreement with Hawley et al. (2002, Cat. J/AJ/123/3409).
* 2M1705-05 has Hα emission and may have weak Li absorption
(see Schmidt & Cruz, 2006, in prep. for further details).
Note (2): Reference as follows:
D02 = Trigonometric parallax from Dahn et al. (2002AJ....124.1170D 2002AJ....124.1170D)
V04 = Trigonometric parallax from Vrba et al. (2004AJ....127.2948V 2004AJ....127.2948V)
All other distances are based on spectroscopic parallaxes, using the
Cruz et al. (2003, Cat. J/AJ/126/2421) (MJ, sp. type)
calibration; the cited distance uncertainties correspond to an
uncertainty of ∼0.5 in spectral class.
Note (3): Discovery papers are numbered as follows:
1 = Reid et al., 2001AJ....121..489R 2001AJ....121..489R
2 = Wilson et al., 2003IAUS..211..197W 2003IAUS..211..197W
3 = Geballe et al., 2002ApJ...564..466G 2002ApJ...564..466G
4 = Reid et al., in prep.
5 = Cruz et al., 2003, Cat. J/AJ/126/2421
6 = Kirkpatrick et al., 2000AJ....120..447K 2000AJ....120..447K
7 = Deacon, Hambly & Cooke, 2005, Cat. J/A+A/435/363
8 = Gizis, 2002ApJ...575..484G 2002ApJ...575..484G
9 = Hawley et al., 2002, Cat. J/AJ/123/3409
10 = Kendall et al., 2004A&A...416L..17K 2004A&A...416L..17K
11 = Menard et al., 2002A&A...396L..35M 2002A&A...396L..35M
12 = Cruz et al., 2006, AJ, submitted
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Byte-by-byte Description of file: table23.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
24 A1 --- m_2MASS [AB] Multiplicity index on 2MASS
26- 30 A5 --- SpType MK spectral type
32- 36 F5.2 mag Jmag J magnitude (1)
38- 42 F5.2 mag Hmag H magnitude (1)
44- 48 F5.2 mag Ksmag Ks magnitude (1)
49 A1 --- u_Ksmag Uncertainty flag on Ksmag
51- 55 F5.2 mag m110 ? NIC-F110W magnitude (0.8-1.4um)
57- 61 F5.2 mag m170 ? NIC-F170M magnitude (1.6-1.8um)
63- 66 F4.1 pc Dist ? Distance (2)
68- 70 F3.1 pc e_Dist ? rms uncertainty on Dist
72- 75 F4.2 arcsec delta ? Separation
77- 82 F6.1 deg theta ? Position angle
84- 90 A7 --- Notes Notes
92- 95 A4 --- Refs References (3)
97-101 F5.2 mag JMAG ? Absolute J magnitude for components
103-107 F5.2 mag Mbol ? Absolute bolometric magnitude for
components (4)
109-113 F5.3 solMass M1 ? Mass for an age of 1Gyr for components
114 A1 --- n_M1 [*] Note on M1 (5)
116-120 F5.3 solMass M3 ? Mass for an age of 3Gyr for components
122-125 F4.2 --- q1 ? Mass ratio for 1Gyr for components
127-130 F4.2 --- q3 ? Mass ratio for 3Gyr for components
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Note (1): Most J & H magnitudes for the individual components based on
deconvolving the 2MASS data using the HST flux ratios, with the
KS-band data based on the average colors for the spectral type.
The exception is LHS 102 (2MASS J00043484-4044058), where the data
are from Golimowski et al (2004AJ....128.1733G 2004AJ....128.1733G).
Note (2): Distances estimates are computed from the (MJ, spectral type)
relation (Cruz et al, 2003, Cat. J/AJ/126/2421), using data for the
primary, except for LHS 102 (parallax estimate by Golimowski et al.,
2004AJ....128.1733G 2004AJ....128.1733G) and 2MASS J07003664+3157266 (trigonometric
parallax by Tinney et al., 2003AJ....126..975T 2003AJ....126..975T). We adopt
uncertainties of ±20% for the spectroscopic parallaxes.
Note (3): References as follows:
1 = Golimowski et al, 2004AJ....128.1733G 2004AJ....128.1733G
2 = Cruz et al., 2006, AJ, submitted
3 = Reid et al., in prep.
4 = Cruz et al., 2003, Cat. J/AJ/126/2421
5 = Siegler et al., 2005ApJ...621.1023S 2005ApJ...621.1023S
6 = Thorstensen et al., 2003PASP..115.1207T 2003PASP..115.1207T
7 = Reid et al., 2006ApJ...639.1114R 2006ApJ...639.1114R
Note (4): Bolometric corrections are based on data from Golimowski et al.
(2004AJ....127.3516G 2004AJ....127.3516G), and masses are from the Burrows et al.
(1997ApJ...491..856B 1997ApJ...491..856B) set of theoretical models.
Note (5): *: The presence of strong lithium absorption in 2MASS
J00250365+4759191 implies that the age is less than 1Gyr, and the
masses and mass ratio listed are for an age of 0.5Gyrs.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs) (4)
24 A1 --- m_2MASS [AB] Multiplicity index on 2MASS
26- 32 A7 --- SpType MK spectral type
34- 38 F5.2 pc Dist ? Distance
40 A1 --- l_delta Limit flag on delta
41- 44 F4.2 arcsec delta ? Separation
46- 50 F5.2 mag JMAG ? Absolute J magnitude for components
52- 56 F5.2 mag Mbol ? Absolute bolometric magnitude for
components (1)
58- 62 F5.3 solMass M1 ? Mass for an age of 1Gyr for components
63 A1 --- n_M1 [*] Note on M1 (2)
64- 68 F5.3 solMass M3 ? Mass for an age of 3Gyr for components
70- 73 F4.2 --- q1 ? Mass ratio for 1Gyr for components
75- 78 F4.2 --- q3 ? Mass ratio for 3Gyr for components
80 I1 --- Notes ? Notes (3)
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Note (1): Bolometric corrections are based on data from Golimowski et al.
(2004AJ....127.3516G 2004AJ....127.3516G) BCK-spectral type relation.
Note (2): * indicate that masses are from mass-luminosity relations in
Burrows et al. (1997ApJ...491..856B 1997ApJ...491..856B), except Kelu 1, where the masses
are from Liu & Leggett (2005ApJ...634..616L 2005ApJ...634..616L) with tau=300Myr.
Note (3): Notes as follows:
1 = DENIS-P J0205.4-1159; see Koerner et al. (1999ApJ...526L..25K 1999ApJ...526L..25K)
2 = SDSS J042348.57-041403.5,
see Burgasser et al. (2005ApJ...634L.177B 2005ApJ...634L.177B)
3 = See Reid et al. (2001AJ....121..489R 2001AJ....121..489R)
4 = Kelu 1; see Liu & Leggett (2005ApJ...634..616L 2005ApJ...634..616L)
Note (4): JJ1305401-254106 was corrected into J13054019-2541059
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Dec-2007