HEAO 1 A-2 low-energy detector X-ray spectra of the lupus loop and SN 1006

The Lupus Loop and SN 1006 were observed by the A-2 low-energy detector (LED) proportional counters on the HEAO 1 satellite as part of the all-sky survey. As a result of a major advance in understanding of detector reponse and background (by R. Fink), accurate analysis of the data has become possible. Soft X-ray spectra for both supernova remnants were constructed from the PHA data taken during the scanning observations. Single-temperature and two-temperature Raymond-Smith models were fitted to the observed spectra. In addition, power-law and power-law plus one-temperature models were fitted to the spectrum of SN 1006. Only two-component models provide an adequate description for both Lupus Loop and SN 1006 spectra. The temperatures, column densities, and emission measures are significantly more accurate than previous results. For the Lupus Loop, good fits were obtained with detailed nonequilibrium ionization (NEI) spectral model with reduced heavy element abundances. The best-fit model has an explosion energy of 10⁵¹ ergs, a distance of 1.2 kpc, an age of 49,000 years, and yields a preshock density of 0.023 cm^-3, in agreement with estimates based on a Sedov model. The spectrum of SN 1006 is interpreted in terms of the Hamilton et al. reverseshocked ejecta model.