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arXiv · 2001.05790

Unveiling Vela -- Variability of Interstellar Lines in the Direction of the Vela Supernova Remnant III. Na D and Ca II K

N. Kameswara Rao·David L. Lambert·Arumalla B. S Reddy·Ranjan Gupta·S. Muneer·Baba Varghese·Harinder P. Singh
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Abstract

High-resolution optical spectra were obtained in 2017-2019 with The Southern African Large Telescope of fifteen stars in the direction of the Vela supernova remnant. Interstellar Ca ii H and 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 & 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) 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 timescale may be 20-50 years. 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.

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N. Kameswara Rao, David L. Lambert, Arumalla B. S Reddy, Ranjan Gupta, S. Muneer, Baba Varghese, Harinder P. Singh. 2020-01-16. Unveiling Vela -- Variability of Interstellar Lines in the Direction of the Vela Supernova Remnant III. Na D and Ca II K. https://doi.org/10.1093/mnras%2Fstaa231

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