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K.J. Borkowski, S.P. Hendrick, S.P. Reynolds (NCSU)
We present observations with the Chandra X-Ray Observatory of the supernova remnant 0049-73.6 in the Small Magellanic Cloud (SMC). In addition to the outer shell of the swept-up SMC gas, a bright ejecta dominated-ring is present in the remnant's interior. X-ray spectrum of the outer shell shows normal SMC abundances, and allows us to estimate the current blast wave speed at 600 km s-1. The swept-up mass is equal to 160 M\odot, the SNR age is 16,000 yr, and the explosion energy is 8 \times 1050 ergs. The brightest parts of the inner ring are dominated by O- and Ne-rich heavy-element ejecta. 0049-73.6 is thus a remnant of a core-collapse explosion. More diffuse interior ejecta emission shows less prominent O and Ne lines. We performed 1-D hydrodynamical simulations in order to understand the spatial structure of 0049-73.6. We identify the bright inner ring with a dense shell of ejecta interior to the contact discontinuity separating the shocked SMC gas and the SN ejecta. The reverse shock itself might might have already propagated into the low-density innermost ejecta. The observed location of the bright ring allows us to set up an upper limit of about 7-8 M\odot of SN ejecta. The total mass of O within heavy-element ejecta is about 0.2--0.3 M\odot. The filling fraction of the O-rich gas is less than 1%, and its high ionization state suggests that the observed emission is dominated by the dense ejecta clumps. The progenitor mass is estimated at about 10 M\odot. It is likely that the progenitor star was a red supergiant star such as seen in a recent Type II-plateau SN 2003gd.
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.