J/ApJ/645/676 Spatial distribution of brown dwarfs in Taurus (Luhman+, 2006)
The spatial distribution of brown dwarfs in Taurus.
Luhman K.L.
<Astrophys. J., 645, 676-687 (2006)>
=2006ApJ...645..676L 2006ApJ...645..676L
ADC_Keywords: Stars, pre-main sequence ; Photometry, infrared
Keywords: infrared: stars - stars: evolution - stars: formation -
stars: low-mass, brown dwarfs -
stars: luminosity function, mass function - stars: pre-main-sequence
Abstract:
By combining photometry from the 2MASS Point Source Catalog and the
USNO-B1.0 catalog with optical and infrared spectroscopy, I have
performed a search for young brown dwarfs in an area of 225deg2
encompassing all of the Taurus star-forming region (tau∼1Myr). From
this work, I have discovered 22 new members of Taurus, 5 of which were
independently found by Guieu and coworkers (2006, Cat.
J/A+A/446/485). Sixteen of these new members have spectral types
later than M6 and thus are likely to be brown dwarfs according to the
theoretical evolutionary models of Chabrier and Baraffe
(2000ApJ...542..464C 2000ApJ...542..464C). After adding these new members to the
previously known members of Taurus, I have compared the spatial
distributions of stars and brown dwarfs across the entire region. I
find no statistically significant difference between these two
distributions. Taurus does not contain the large, extended population
of brown dwarfs that has been predicted by some embryo ejection models
for the formation of brown dwarfs. However, these results are
consistent with other ejection models, as well as models in which
stars and brown dwarfs share a common formation mechanism.
Description:
Spectroscopy was performed on the 77 candidate Taurus members and the
15 known members.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 10 Observing Log
table2.dat 63 55 Field Stars
table3.dat 132 37 Members of Taurus
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Night Night number
4- 13 A10 "YYYY/MM/DD" Date Date of observation
15- 32 A18 --- Tel Telescope + Instrument
34- 44 A11 --- Disp Dispersive instrument
46- 49 F4.2 um lambda1 Wavelength interval
50 A1 --- --- [-]
51- 54 F4.2 um lambda2 Wavelength interval
56- 59 I4 --- Resol lambda/Deltaλ resolution
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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- 17 A17 --- 2MASS 2MASS PSC designation (JHHMMSSss+DDMMSSs)
18 A1 --- n_2MASS [bcd] Note on 2MASS (1)
20- 40 A21 --- SpType Spectral Type
43- 46 F4.2 mag J-H 2MASS PSC J-H colour index
48- 51 F4.2 mag H-Ks 2MASS PSC H-Ks colour index
53- 57 F5.2 mag Ksmag 2MASS PSC Ks magnitude
59- 63 A5 --- Nights Night numbers (defined in table1)
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Note (1): Notes as follows:
b = Spectral features suggest a surface gravity intermediate between
those of Taurus members and field dwarfs (Figs. 10 and 11).
c = Selected from photometry in Luhman (2000ApJ...544.1044L 2000ApJ...544.1044L), see Fig.5.
d = Selected from photometry in Briceno et al. (2002ApJ...580..317B 2002ApJ...580..317B).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- f_2MASS [PN] Previously known or New Member
3- 19 A17 --- 2MASS 2MASS PSC name (JHHMMSSss+DDMMSSs)
20 A1 --- n_2MASS [d] d: Also discovered by C. Slesnick et al.
(2006), in preparation.
22- 45 A24 --- Onames Other Names
47- 83 A37 --- SpTypes Spectral Types (1)
85- 91 A7 --- r_SpTypes Reference for SpTypes (3)
93-111 A19 --- Memb Membership Evidence (2)
113-116 F4.2 mag J-H 2MASS PSC J-H colour index
118-121 F4.2 mag H-Ks 2MASS PSC H-Ks colour index
123-127 F5.2 mag Ksmag 2MASS PSC Ks magnitude
129-132 A4 --- Nights Night numbers (defined in table1)
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Note (1): Uncertainties are ±0.25 and ±0.5 subclass for the optical
and IR types from this work, respectively, unless noted otherwise.
Note (2): Membership in Taurus from tje following features:
AV = AV≳1 and a position above the main sequence for the distance
of Taurus
e = strong emission lines
NaK = Na I and K I strengths intermediate between those of dwarfs and giants
Li = strong Li absorption
ex = IR excess emission
H2O = the shape of the gravity-sensitive steam bands
Note (3): References as follows:
1 = Kenyon et al., 1998AJ....115.2491K 1998AJ....115.2491K
2 = Luhman & Rieke, 1998ApJ...497..354L 1998ApJ...497..354L
3 = White & Hillenbrand, 2004ApJ...616..998W 2004ApJ...616..998W
4 = this work
5 = Guieu et al., 2006, Cat. J/A+A/446/485
6 = Briceno et al., 1999AJ....118.1354B 1999AJ....118.1354B
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 02-Oct-2007