AAS 201st Meeting, January, 2003
Session 25. Circumstellar Material and Mass Loss
Oral, Monday, January 6, 2003, 10:00-11:30am, 602-604

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[25.03] Circumstellar Disks around Young Brown Dwarfs

M. C. Liu (IfA/Hawai`i), J. Najita (NOAO), A. T. Tokunaga (IfA/Hawai`i)

We present results from a large thermal IR (L'-band; 3.8 micron) survey for disks around young spectroscopically identified brown dwarfs and low mass stars. Our sample encompasses objects with spectral types from M6 to M9.5, corresponding to masses of ~15 to 100 MJup and ages of a few Myr based on current models. We find that ~75% of our sample show intrinsic IR excesses, indicative of circum(sub)stellar disks. The observed excesses are well-correlated with Halpha emission, consistent with a common disk accretion origin. Because the excesses are modest, conventional analyses using only IR colors would have missed most of the sources with disks. In the same star-forming regions, we find that disks around brown dwarfs and T Tauri stars are contemporaneous; assuming coevality, this demonstrates that substellar disks are at least as long-lived as stellar disks. Altogether, the frequency and properties of circumstellar disks are similar from the stellar regime down to the substellar and planetary-mass regime.

This work has been supported by the Beatrice Watson Parrent Fellowship at the University of Hawai`i.

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© 2002. The American Astronomical Soceity.