English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In a survey conducted between 2011-12 of interstellar Na I D line profiles inthe direction of the Vela supernova remnant, a few lines of sight showeddramatic changes in low velocity absorption components with respect to profilesfrom 1993-1994 reported by Cha & Sembach. Three stars - HD 63578, HD 68217 andHD 76161 showed large decrease in strength over the 1993-2012 interval. HD68217 and HD 76161 are associated with the Vela SNR whereas HD 63578 isassociated with $\gamma^2$ Velorum wind bubble. Here, we present high spectralresolution observations of Ca II K lines obtained with the Southern AfricanLarge Telescope (SALT) towards these three stars along with simultaneousobservations of Na I D lines. These new spectra confirm that the Na Dinterstellar absorption weakened drastically between 1993-1994 and 2011-2012but show for the first time that the Ca II K line is unchanged between1993-1994 and 2015. This remarkable contrast between the behaviour of Na D andCa II K line absorption lines is a puzzle concerning gas presumably affected bythe outflow from the SNR and the wind from $\gamma^2$ Velorum.

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