Hubble and Spitzer Observations of an Edge-on Circumstellar Disk around a Brown Dwarf - AstrophysicsReport as inadecuate

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Abstract: We present observations of a circumstellar disk that is inclined close toedge-on around a young brown dwarf in the Taurus star-forming region. Usingdata obtained with SpeX at the NASA Infrared Telescope Facility, we find thatthe slope of the 0.8-2.5 um spectrum of the brown dwarf 2MASS J04381486+2611399cannot be reproduced with a photosphere reddened by normal extinction. Instead,the slope is consistent with scattered light, indicating that circumstellarmaterial is occulting the brown dwarf. By combining the SpeX data with mid-IRphotometry and spectroscopy from the Spitzer Space Telescope and previouslypublished millimeter data from Scholz and coworkers, we construct the spectralenergy distribution for 2MASS J04381486+2611399 and model it in terms of ayoung brown dwarf surrounded by an irradiated accretion disk. The presence ofboth silicate absorption at 10 um and silicate emission at 11 um constrains theinclination of the disk to be ~70 deg, i.e. ~20 deg from edge-on. Additionalevidence of the high inclination of this disk is provided by our detection ofasymmetric bipolar extended emission surrounding 2MASS J04381486+2611399 inhigh-resolution optical images obtained with the Hubble Space Telescope.According to our modeling for the SED and images of this system, the diskcontains a large inner hole that is indicative of a transition disk R in~58R star~0.275 AU and is somewhat larger than expected from embryo ejectionmodels R out=20-40 AU vs. R out<10-20 AU.

Author: K. L. Luhman, Lucia Adame, Paola D'Alessio, Nuria Calvet, Kim K. McLeod, C. J. Bohac, William J. Forrest, Lee Hartmann, B. S


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