Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra Association

Details Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra Association Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra Association

2008-02-12

arxiv.org/abs/0802.1732v1

Astronomy and Astrophysics

Astrophysics

accepted for publication in Astrophysical Journal Letters

Scientific paper

Using SpeX at the NASA Infrared Telescope Facility and the Spitzer Infrared Spectrograph, we have obtained infrared spectra from 0.7 to 30um for three young brown dwarfs in the TW Hydra Association (~10 Myr), 2M J1207-3932, 2M J1139-3159, and SS J1102-3431. The spectral energy distribution for 2M J1139-3159 is consistent with a stellar photosphere for the entire wavelength range of our data while the other two objects exhibit significant excess emission at >5um. We are able to reproduce the excess emission from each brown dwarf using our models of irradiated accretion disks. According to our model fits, both disks have experienced a high degree of dust settling. We also find that silicate emission at 10 and 20um is absent from the spectra of these disks, indicating that grains in the upper disk layers have grown to sizes larger than ~5um. Both of these characteristics are consistent with previous observations of decreasing silicate emission with lower stellar masses and older ages. These trends suggest that either 1) the growth of dust grains, and perhaps planetesimal formation, occurs faster in disks around brown dwarfs than in disks around stars, or 2) the radii of the mid-IR-emitting regions of disks are smaller for brown dwarfs than for stars, and grains grow faster at smaller disk radii. Finally, we note the possible detection of an unexplained emission feature near 14um in the spectra of both of the disk-bearing brown dwarfs.

Affiliated with

Also associated with

No associations

Rating

Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra Association 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 Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra Association, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spitzer IRS Observations of Disks around Brown Dwarfs in the TW Hydra Association will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-676146