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Session 28 - Stellar Evolution: Beyond the Main Sequence.
Oral session, Monday, June 10
Humanities 3650,
X-ray observations of supernova remnants have revealed a distinct class of objects whose X-ray morphology is in complete contrast with that expected from standard evolutionary scenarios. While the radio emission exhibits the expected limb-brightened emission profiles, the X-ray emission is centrally peaked with little or no evidence of a shell. Unlike the Crab-like remnants, however, the X-ray emission from these remnants is thermal in nature, thus ruling our a central plerion driven by a pulsar as the explanation for the central brightness. Here we present a joint spatial and spectral study of several remnants from this class, including W28 and MSH 11-61A, using data from the ROSAT and ASCA observatories. We compare the observed properties with models for evolution in a cloudy ISM as well as for characteristics of remnants which have entered the radiative phase of evolution.
