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M. C. Liu (Univ. of Hawaii, Inst. for Astronomy)
Brown dwarfs and extrasolar planets are now being found with regularity. Most of the known objects are old, with characteristic ages of many billions of years. However, studying these objects in their infancy can provide unique avenues for detection, characterization, and, ultimately, understanding. I will discuss our current knowledge (and ignorance) of young (<100 Myr) substellar objects, both as free-floating objects and as companions to stars.
Nearby star-forming regions are fertile grounds for studying the mass distribution and physical properties of the free-floating substellar population. At ages of only a few million years, we can also search for residual signatures from the birth process, as highlighted by the recent discovery that most young brown dwarfs possess accretion disks. These ``circum(sub)stellar" disks may teach us both about the formation of brown dwarfs and the physical processes endemic to disks.
Massive brown dwarfs have been found as companions to old stars from direct imaging. However, since substellar objects are more luminous when young, even massive planets are predicted to be infrared-bright in their youth. The recent discoveries of many young stars in the solar neighborhood, combined with the advent of high-contrast adaptive optics systems on 8-10m telescopes, now open the door to direct imaging of substellar companions, well into the planetary-mass regime. Direct imaging probes larger orbital separations than current radial velocity surveys. Hence, the combination of the two approaches can lead us to a more complete picture of substellar companion formation.
The author(s) of this abstract have provided an email address for comments about the abstract: mliu@ifa.hawaii.edu
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.