RX J0852.0-4622: Another nonthermal shell-type supernova remnant (G266.2-1.2)

The newly discovered supernova remnant G266.2-1.2 (RX J0852.0-4622), along the line of sight to the Vela supernova remnant (SNR), was observed with AS CA for 120 ks. We find that the X-ray spectrum is featureless and well desc ribed by a power law, extending to three of the class of shell-type SNRs do minated by nonthermal X-ray emission. Like G347.3-0.5, this low-latitude re mnant displays discrete regions of enhanced emission along the rim as well as faint nonthermal emission from the interior. We derive limits on the the rmal content of the remnant emission, although the presence of the Vela SNR compromises our ability to seriously constrain a low-temperature component . Limits placed on the amount of Sc-K emission are compared with the expect ed flux based on the reported Ti-44 emission from G266.2-1.2. We also repor t on an unresolved X-ray source surrounded by diffuse emission near the cen ter of the remnant. The properties of the source are not well determined bu t appear consistent with the interpretation that the source is a neutron st ar surrounded by a synchrotron nebula. Alternatively, the source may be ass ociated with one of two stars located within the positional error circle, b ut this appears somewhat unlikely.