Disks around Brown Dwarfs in the Sigma Orionis Cluster

Details Disks around Brown Dwarfs in the Sigma Orionis Cluster Disks around Brown Dwarfs in the Sigma Orionis Cluster

2008-08-04

arxiv.org/abs/0808.0471v1

Astrophys.J.688:362-376,2008

Astronomy and Astrophysics

Astrophysics

Astrophysical Journal, in press

Scientific paper

10.1086/592264

We have performed a census of disks around brown dwarfs in the Sigma Ori cluster using all available images from IRAC onboard 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 5 promising candidates, which may consist of 2 brown dwarfs, 2 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 Sigma 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. These results are similar to previous estimates of disk fractions in IC 348 and Cha I, which have roughly the same median ages as Sigma Ori (3 Myr). Finally, we note that our photometric measurements and the sources that we identify as having disks differ significantly from those of other recent studies that analyzed the same Spitzer images. For instance, previous work has suggested that the T dwarf S Ori 70 is redder than typical field dwarfs, which has been cited as possible evidence of youth and cluster membership. However, we find that this object is only slightly redder than the reddest field dwarfs in [3.6]-[4.5] (1.56+/-0.07 vs. 0.93-1.46). We measure a larger excess in [3.6]-[5.8] (1.75+/-0.21 vs. 0.87-1.19), but the flux at 5.8um may be overestimated because of the low signal-to-noise ratio of the detection. Thus, the Spitzer data do not offer strong evidence of youth and membership for this object, which is the faintest and coolest candidate member of Sigma Ori that has been identified to date.

Affiliated with

Also associated with

No associations

Rating

Disks around Brown Dwarfs in the Sigma Orionis Cluster does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Disks around Brown Dwarfs in the Sigma Orionis Cluster, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disks around Brown Dwarfs in the Sigma Orionis Cluster will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-384975