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Session 78 - Supernova Remnants.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center
The Schweizer-Middleditch star is an sdOB star seen in projection behind the young galactic supernova remnant SN 1006, providing a unique opportunity to probe the cold interior of the remnant by searching for absorption due to the ejecta. SN 1006 is thought to have been a type Ia supernova, and the line of sight to the SM star passes only 2\arcmin\ from the center of the 30\arcmin\ remnant. Since one of the major components of the ejecta is predicted to be Fe, it would be an important confirmation of current SNIa theory to find hard evidence for the presence of this material.
Broad (8000 km/s FWHM) Fe\ II absorption lines have been detected in the spectrum of the SM star (Wu et al. 1993, ApJ, 416, 247), but the inferred amount of Fe is only 1/20th of that expected from the best--fitting model (Hamilton amp; Fesen 1988, ApJ, 327, 178). Hence, it is of great interest to constrain the presence of more highly ionized Fe along this line of sight.
We have used the Hopkins Ultraviolet Telescope during the Astro--2 space shuttle mission in 1995 March to observe the SM star in order to search for the strongest expected ground--state--connected Fe\ III line near 1123 Åa wavelength too short for observation with Hubble Space Telescope or IUE. Our 3100 s integration on the SM star shows no clear evidence for Fe\ III absorption in the SM star, with an upper limit of \sim2 Åalthough this exact value is dependent on knowledge of the star's intrinsic continuum level. If the model of Hamilton amp; Fesen was correct, we would have seen a broad absorption with equivalent width 8--12 Å\ (depending on atomic parameters). We will present stellar model fits to the SM star and a comparison star, derive hard limits on the presence of Fe\ III and other possible lines in the spectra, and discuss the ramifications of this measurement for models of SN 1006.
This research is supported by NASA contract NAS 5-27000 to the Johns Hopkins University.
