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Session 79 - CVs and Novae.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[79.11] Spectropolarimetry of AG Draconis and Eight Other Symbiotic Stars

P. M. Garnavich (CfA), S. R. Trammell (U. Chicago)

We report spectropolarimetric observations of nine symbiotic stars. Symbiotics are a diverse group of binary stars that generally consist of a hot component accreting material from a cool giant. The binary geometry combined with dust scattering, electron scattering and even Raman scattering can result in a complex polarized spectrum. Observations were made in October 1994 using the McDonald 2.7m telescope and spectropolarimeter.

Strong emission at around 6830Åbelieved to be due to Raman scattering, is observed in five of the symbiotics. The polarization of this feature is a unique probe of the binary interaction geometry and we compare our results with earlier observations by Schmid amp;\ Schild and Garnavich. In particular, the peak polarization in the V1329 Cyg Raman emission varied from 25% to less than 1% over a photometric cycle while the position angle remained constant. This confirms the period of \sim960^d and implies that the orbit is seen nearly edge-on.

Three of the systems, HM Sge, MWC 560 and S32, show no intrinsic polarization, although S32 has a strong Raman scattered emission feature.

AG Dra was observed approximately two months after the onset of an outburst and its polarized spectrum is particularly complex. The polarization of the continuum is about 0.4%\ and the position angle rotates by 20^\circ from the blue to the red. The He I lines at 5876, 6678 and 7065 Å\ show a much higher polarization than the red continuum but at the same position angle. In contrast, the polarization of the He II and H\beta lines matches that in seen the blue continuum. Observations before outburst revealed no strong polarization of the He I lines.

PU Vul was observed within days of the hot source emerging from eclipse. Its continuum shows no significant intrinsic polarization, however the strongest emission lines do appear polarized at the \sim2% level.

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