2010A&A...519A..86I

Supernova remnant (SNR) RX J0852.0-4622 is one of the youngest and is most likely the closest among known Galactic SNRs. It was detected in X-rays, the ⁴⁴Ti γ-line, and radio. We obtain and analyze medium-resolution spectra of 14 stars in the direction towards the SNR RX J0852.0-4622 in an attempt to detect broad absorption lines of unshocked ejecta against background stars. Spectral synthesis is performed for all the stars in the wavelength range of 3740-4020Å to extract the broad absorption lines of CaII related to the SNR RX J0852.0-4622. We do not detect any broad absorption line and place a 3σ upper limit on the relative depths of <0.04 for the broad CaII absorption produced by the SNR. We detect narrow low and high velocity absorption components of CaII. High velocity |V_LSR|∼100-140km/s components are attributed to radiative shocks in clouds engulfed by the old Vela SNR. The upper limit to the absorption line strength combined with the width and flux of the ⁴⁴Ti γ-ray line 1.16MeV lead us to conclude that SNR RX J0852.0-4622 was probably produced by an energetic SN Ic explosion.