Constraints of age, distance and progenitor of the supernova remnant RX J0852.0-4622/GRO J0852-4642

The discovery of the nearest young supernova remnant RX J0852.0-4622 / GRO J0852-4642 in the Galaxy by ROSAT and COMPTEL has been reported recently Age and distance are determined to similar to 680 years and similar to 200 pc by the Xray diameter and the gamma-ray line flux of radioactive Ti-44. Here we discuss the implications of the X-ray spectra and of the fact that 1.8 MeV gamma-ray line emission from the decay of Al-26 has been measured from the Vela region with a certain fraction possibly associated with the new SNR. We estimate an uncertainty of the age of +/- 100 yrs for a fixed yield of Ti-44. The highest values of Ti-44 yield provided by current supernova explosion models give worst case upper limits of 1100 yrs for the age and of 500 pc for the distance. Also the unknown ionization stage of Ti-44 adds to the uncertainty of age and distance which is at most another 35% on top. Both the energy balance compiled for the remnant and yield predictions for Ti-44 and Al-26 by supernova models favour a core-collapse event. Two point sources have been found in the vicinity of the explosion center, either one of these might be the neutron star left by the supernova. If there is a neutron star the X-ray count rates of the two point sources provide an upper limit of the blackbody surface temperature, which is very unlikely to exceed 3x10(5) K. The supernova might have been observed some 700 +/- 150 yrs ago, but based on the data of SN 1181, e.g., there is a realistic chance that it has been missed if the supernova was sub-luminous.