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 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 2008ApJ...672L..49S).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 117 596 Spitzer photometry for 371 probable members of
σ Ori
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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
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Bytes Format Units Label Explanations
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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
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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 1999ApJ...521..671B, 2001ApJ...556..830B 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.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Jan-2011