Material Traces of War Barker, Stacey; Cooke, Krista; McCullough, Molly
2020, 2021-11-02
eBook
This book uses largely unknown material culture to tell the stories of Canadian women during the world wars. Thematic vignettes present the women who worked as civilians, served in the military, ...volunteered their time, and grieved lost loved ones.
The interaction between the expanding supernova (SN) ejecta with the circumstellar material (CSM) that was expelled from the progenitor prior to explosion is a long-sought phenomenon, yet ...observational evidence is scarce. Here we confirm a new example: SN 2004dk, originally a hydrogen-poor, helium-rich Type Ib SN that reappeared as a strong -emitting point source on narrowband images. We present follow-up optical spectroscopy that reveals the presence of a broad component with full width at half maximum of ∼ 290 in addition to the narrow +N ii emission features from the host galaxy. Such a broad component is a clear sign of an ejecta-CSM interaction. We also present observations with the XMM-Newton Observatory, the Swift satellite, and the Chandra X-ray Observatory that span 10 days to 15 years after discovery. The detection of strong radio, X-ray, and emission years after explosion allows various constraints to be put on pre-SN mass-loss processes. We present a wind-bubble model in which the CSM is "pre-prepared" by a fast wind interacting with a slow wind. Much of the outer density profile into which the SN explodes corresponds to no steady-state mass-loss process. We estimate that the shell of compressed slow wind material was ejected ∼1400 yr prior to explosion, perhaps during carbon burning, and that the SN shock had swept up about 0.04 of material. The region emitting the has a density of order .
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