Hubble and Spitzer Observations of an Edge-on Circumstellar Disk around a Brown Dwarf
Luhman, K. L.; McLeod, Kim K.; Hartmann, Lee; Calvet, Nuria; Watson, Dan M.; Sargent, B.; D'Alessio, Paola; Forrest, William J.; Adame, Lucía; Bohac, C. J.
United States, Mexico
Abstract
We present observations of a circumstellar disk that is inclined close to edge-on around a young brown dwarf in the Taurus star-forming region. Using data obtained with SpeX at the NASA Infrared Telescope Facility, we find that the slope of the 0.8-2.5 μm spectrum of the brown dwarf 2MASS J04381486+2611399 cannot be reproduced with a photosphere reddened by normal extinction. Instead, the slope is consistent with scattered light, indicating that circumstellar material is occulting the brown dwarf. By combining the SpeX data with mid-infrared photometry and spectroscopy from the Spitzer Space Telescope and previously published millimeter data from Scholz and coworkers, we construct the spectral energy distribution (SED) for 2MASS J04381486+2611399 and model it in terms of a young brown dwarf surrounded by an irradiated accretion disk. The presence of both silicate absorption at 10 μm and silicate emission at 11 μm constrains the inclination of the disk to be ~70°, i.e., ~20° from edge-on. Additional evidence of the high inclination of this disk is provided by our detection of asymmetric bipolar extended emission surrounding 2MASS J04381486+2611399 in high-resolution optical images obtained with the Hubble Space Telescope. According to our modeling for the SED and images of this system, the disk contains a large inner hole that is indicative of a transition disk (Rin~58R*~0.275 AU) and is somewhat larger than expected from embryo ejection models (Rout=20-40 AU vs. Rout<10-20 AU).
Based on observations made with the NASA/ESA Hubble Space Telescope and the Spitzer Space Telescope. The HST observations are associated with proposal ID 10511 and were obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Spitzer is operated by the Jet Propulsion Laboratory at the California Institute of Technology under NASA contract 1407.