Unveiling Vela - variability of interstellar lines in the direction of the Vela supernova remnant - III. Na D and Ca II K
Abstract
High-resolution optical spectra were obtained in 2017-2019 with The Southern African Large Telescope of 15 stars in the direction of the Vela supernova remnant. Interstellar Ca II H & K and Na I D lines are discussed in this paper. In particular, the line profiles are compared with profiles at a comparable spectral resolution obtained in 1993-1996 by Cha and Sembach. Ten of the lines of sight show changes to one or more of the components in that line of sight. Changes include small changes (1-2 km s-1) in radial velocity and/or increases/decreases in equivalent width over the two decades between the periods of observation. Changes are more obvious in the Ca K line than in the Na D lines. These changes are attributed to gas disturbed by interactions between the supernova ejecta and the surrounding interstellar medium. A representative time-scale may be 20-50 yr. Small-scale variations in line profiles across the face of the remnant suggest, as previously remarked, that a linear scale for interactions is a small fraction of the 40 pc size of the present remnant.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2020
- DOI:
- 10.1093/mnras/staa231
- arXiv:
- arXiv:2001.05790
- Bibcode:
- 2020MNRAS.493..497K
- Keywords:
-
- ISM: lines and bands;
- ISM: supernova remnants;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 24 pages, 18 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal