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Session 43 - Variable Stars.
Display session, Thursday, January 08
We present plans for an atlas of spectropolarimetric observations of 61 bright northern Be stars obtained from 1989-94 using the halfwave polarimeter (HPOL) at the 0.9m telescope of the U. Wisconsin Pine Bluff Observatory (PBO). The data cover the wavelength range from \sim 3400-7600Åwith a spectral resolution of \sim 25ÅThis atlas will contain all data (297 observations total) obtained as part of a survey program with HPOL when the detector in use was a dual Reticon array; the survey observations with HPOL continue, using a new CCD detector which extends the spectral coverage out to 1.05\mum and improves the spectral resolution to \sim 12ÅThe CCD observations will be presented later in a second volume of the atlas.
This poster summarizes the findings of the survey from the first 5 years of the project. The general wavelength dependence of polarization for classical Be stars is discussed on the basis of these observations, and results on polarimetric variability are also presented. We find that 56% (20 of 36) of the Be stars observed \ge3 times from 1989-94 show significantly variable polarization at the level of 0.1% changes (inclusion of preliminary results from the continuing CCD survey indicates that the percentage may be even higher). The timescales for these changes range from as short as night-to-night to as long as several months. Several of the stars showed evidence for polarimetric ``outbursts'' during the time period covered by the observations. Part of the purpose of this poster is also to discuss options for presenting this data in a way that will be useful for the astronomical community, and feedback or suggestions are welcomed and encouraged.
This work has been supported under NASA contract NAS5-26777 with the University of Wisconsin, and by NASA grant NAG5-3248 to the University of Toledo.
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Program listing for Thursday