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Session 44 - New Light on Supernova Remnants.
Display session, Wednesday, June 11
South Main Hall,
We present spectra of 31 supernova remnant (SNR) candidates in M31, obtained from the KPNO 4m and RC spectrograph, and covering a wavelength range of 3600--7600 ÅThe candidates were identified from our digital emission-line survey of the entire galaxy (Williams amp; Winkler, in preparation) and include objects with a wide variety of diameters and galactocentric distances. Twenty candidates can be unambiguously identified as supernova remnants on the basis of their high [S\thinspace \footnotesize II]/H\alpha\ ratio and the strength of lines from other low-excitation ions, including [O\thinspace \footnotesize I], [O\thinspace \footnotesize II], and [N\thinspace \footnotesize II]\@. Most of the remaining objects are probably SNRs whose spectra are contaminated by H\thinspace \footnotesize II regions which are nearly coincident on the spectrograph slit. We have estimated the energy content of the SNRs in our sample by using the density-sensitive [S\thinspace \footnotesize II] \lambda\lambda\ 6716, 6731 ratio to obtain the pressure, and our images to give the sizes of the remnants. We find a mean energy of 4 \times 10^50\ ergs, essentially independent of remnant diameter up to diameters of 50 pc\@. Elemental abundances, derived through comparison of our observed spectra with a detailed grid of shock models, will also be discussed.
This work has been supported by the NSF through grant AST-9315967 and by the W.M. Keck Foundation through the Keck Northeast Astronomy Consortium.
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