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Session 106 - Herbig Ae/Be Stars.
Display session, Thursday, January 18
North Banquet Hall, Convention Center

[106.04] Diagnosing the Circumstellar Environment of HD163296

K. S. Bjorkman, M. R. Meade, B. L. Babler, C. M. Anderson, A. D. Code, G. K. Fox, J. J. Johnson, W. T. Sanders, A. J. Weitenbeck, N. E. B. Zellner, K. H. Nordsieck, S. Pozdell, J. Hanson, W. Ager, M. Putman (U. Wisconsin), O. L. Lupie (STScI), R. J. Edgar (SAO), K. A. Johansen, H. A. Kobulnicky (U. Minnesota)

We present ultraviolet and optical spectropolarimetric observations of the suspected pre-main-sequence Herbig Ae/Be star HD163296. The observations were obtained in March 1995 with the Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) aboard the Astro-2 mission, and in summer 1995 at the University of Wisconsin's Pine Bluff Observatory (PBO). HD163296 is thought to be observed at an intermediate inclination angle. Interestingly, the polarimetric data show a 90 degree position angle flip between the optical and the ultraviolet, similar to that observed in HD45677 by WUPPE on Astro-1. Since the WUPPE and PBO observations were made 10 weeks apart, there could be a question of whether the PA flip existed at the time of the WUPPE observations; however, optical broad-band (BVRI) polarimetric observations made at Mt. Lemmon Observatory one week after the WUPPE observations confirm that the optical was at the same PA as measured in the PBO data. For HD45677, which is seen equator-on, the PA flip was interpreted as evidence for a bipolar geometry of the circumstellar environment (Schulte-Ladbeck et al. 1992). We will discuss this possibility as well as other potential interpretations for HD163296, especially in light of the evidence for infall detected in our contemporaneous IUE observations (Grady et al, this session).

WUPPE is supported under NASA contract NAS5-26777 with the University of Wisconsin.

Program listing for Thursday