Search for broad absorption lines in spectra of stars in the field of supernova remnant RX J0852.0-4622 (Vela Jr.)

¹ Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany e-mail: ani@mpe.mpg.de
² Skobeltsyn Institute of Nuclear Physics, Moscow State University, Vorob'evy Gory, 119992 Moscow, Russian Federation
³ Institute of Astronomy, RAS, Pyatnitskaya 48, 119017, Moscow, Russian Federation
⁴ Stockholm University, AlbaNova University Center, Department of Astronomy, 106 91 Stockholm, Sweden

Received: 9 January 2010
Accepted: 24 May 2010

Abstract

Aims. 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.

Methods. Spectral synthesis is performed for all the stars in the wavelength range of 3740-4020 Å to extract the broad absorption lines of Ca II related to the SNR RX J0852.0-4622.

Results. We do not detect any broad absorption line and place a 3σ upper limit on the relative depths of <0.04 for the broad Ca II absorption produced by the SNR. We detect narrow low and high velocity absorption components of Ca II. High velocity ~ 100–140 km s^-1 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 1.16 MeV lead us to conclude that SNR RX J0852.0-4622 was probably produced by an energetic SN Ic explosion.