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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
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). 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 59 10 Observing Log table2.dat 63 55 Field Stars table3.dat 132 37 Members of Taurus
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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)
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), see Fig.5. d = Selected from photometry in Briceno et al. (2002ApJ...580..317B).
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
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)
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 2 = Luhman & Rieke, 1998ApJ...497..354L 3 = White & Hillenbrand, 2004ApJ...616..998W 4 = this work 5 = Guieu et al., 2006, Cat. J/A+A/446/485 6 = Briceno et al., 1999AJ....118.1354B
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 02-Oct-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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