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J/ApJ/688/362   Disks around brown dwarfs in σ Ori cluster (Luhman+, 2008)

Disks around brown dwarfs in the σ Orionis cluster. Luhman K.L., Hernandez J., Downes J.J., Hartmann L., Briceno C. <Astrophys. J., 688, 362-376 (2008)> =2008ApJ...688..362L
ADC_Keywords: Stars, pre-main sequence ; Photometry, infrared Keywords: accretion, accretion disks - planetary systems: protoplanetary disks - stars: formation - stars: low-mass, brown dwarfs - stars: pre-main sequence Abstract: We have performed a census of circumstellar disks around brown dwarfs in the σ Ori cluster using all available images from the Infrared Array Camera on board the Spitzer Space Telescope. To search for new low-mass cluster members with disks, we have measured photometry for all sources in the Spitzer images and have identified the ones that have red colors that are indicative of disks. We present five promising candidates, which may consist of two brown dwarfs, two stars with edge-on disks, and a low-mass protostar if they are bona fide members. Spectroscopy is needed to verify the nature of these sources. We have also used the Spitzer data to determine which of the previously known probable members of σ Ori are likely to have disks. By doing so, we measure disk fractions of ∼40% and ∼60% for low-mass stars and brown dwarfs, respectively. Description: For our study of disks around brown dwarfs in the σ Ori cluster, we use images at 3.6, 4.5, 5.8, and 8.0um obtained with Spitzer's Infrared Array Camera (IRAC). The shallow IRAC images were collected on 2004 October 9 as a part of G. Fazio's IRAC Guaranteed Time Observations in Spitzer program 37 (Hernandez et al. 2007, Cat. J/ApJ/662/1067). The deep IRAC imaging was executed on 2006 September 28, 2007 March 30-31, and 2007 April 3-4 through Spitzer program 30395 (Scholz & Jayawardhana, 2008ApJ...672L..49S). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 117 596 Spitzer photometry for 371 probable members of σ Ori
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/AJ/128/2316 : BVRIJHKs photometry in sigma Ori cluster (Sherry+, 2004) J/AN/325/705 : RIJHKs of low-mass stars in sigma Ori (Bejar+, 2004) J/A+A/446/501 : XMM observations of sigma Ori cluster (Franciosini+, 2006) J/ApJ/662/1067 : Sptizer observations of sigma Orionis (Hernandez+, 2007) J/A+A/493/931 : MAD observations of σ Ori (Bouy+, 2009) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 A5 --- S [2MASS IRAC] catalog source (1) 7- 23 A17 --- ID Source name (JHHMMSSss+DDMMSSs) (1) 25- 54 A30 --- OName Other designations (2) 56- 60 F5.2 mag [3.6] ? Spitzer/IRAC 3.6 micron band magnitude 62- 65 F4.2 mag e_[3.6] ? Uncertainty in [3.6] 67 A1 --- f_[3.6] why [3.6] is missing (3) 69- 73 F5.2 mag [4.5] ? Spitzer/IRAC 4.5 micron band magnitude 75- 78 F4.2 mag e_[4.5] ? Uncertainty in [4.5] 80 A1 --- f_[4.5] why [4.5] is missing (3) 82- 86 F5.2 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude 88- 91 F4.2 mag e_[5.8] ? Uncertainty in [5.8] 93 A1 --- f_[5.8] why [5.8] is missing (3) 95- 99 F5.2 mag [8.0] ? Spitzer/IRAC 8.0 micron band magnitude 101-104 F4.2 mag e_[8.0] ? Uncertainty in [8.0] 106 A1 --- f_[8.0] why [8.0] is missing (3) 108-117 A10 "YYYY/MM/DD" Date Date(s) of observations
Note (1): 2MASS identifications are from the 2MASS Point Source Catalog (Cat. II/246). IRAC identifications are based on J2000 coordinates measured with IRAC. Note (2): "SO" identifications are from Hernandez et al. (2007, Cat. J/ApJ/662/1067 ; <[HHM2007] NNNN> in Simbad). "S Ori" identifications are from Bejar et al. (1999ApJ...521..671B, 2001ApJ...556..830B); <[BZR99] S Ori NN> or <[BMZ2001] S Ori JHHMMSS.s+DDMMSS> in Simbad. Note (3): Measurement is absent because of the following: n = non-detection; o = position outside the field of view of the filter; s = saturated; b = contaminated by cosmic rays.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Jan-2011
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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