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M.D. Perrin, J.R. Graham, P. Kalas (UC Berkeley)
The combination of LGS AO polarimetry at Lick and LGS AO imaging spectroscopy at Keck provides a unique and powerful view of the dusty circumstellar environments of young stars. We describe our imaging polarimetric survey of Herbig Ae/Be stars, conducted with the Lick Observatory AO system in both natural and laser guide star modes. Laser guide star AO is needed to observe the complete population of HAEBEs: even though these young, massive stars are intrinsically bright, many (particularly the youngest) are very embedded and thus faint. The laser guide star system at Lick allows us to observe essentially all northern hemisphere HAEBEs at the high resolution afforded by adaptive optics, while differential polarimetry provides high sensitivity to light scattered by circumstellar dust. Using the Lick LGS system, we have resolved circumstellar dust around eight HAEBEs (LkHa 198, LkHa 233, V376 Cas, VY Mon, LkHa 225, Parsamian 21, Parsamian 22, & V645 Cyg), plus a similar number of objects in NGS mode. The revealed dust structures variously include face-on and edge-on disks, extended circumstellar envelopes, bipolar outflow cavities, and tidal streamers between binary stars. In addition, we have recently observed several of these targets using Keck LGS AO and OSIRIS, the new integral field spectrograph, to search for outflows traced by near-IR [FeII] emission lines. These observations will enable us to test proposed models for jet launching and collimation around HAEBEs. Parsamian 21 and LkHa 233 both display [FeII] emission on subarcsecond scales, in the case of LkHa 233 taking the form of a narrowly collimated jet which can be traced to within 0.1 arcsec of the central source.
This work has been supported by the NSF Center for Adaptive Optics and the NASA Michelson Fellowship Program.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.