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

Using a combination of ground-based and HST imaging, we have constructed acatalog of 179 supernova remnants (SNRs) and SNR candidates in the nearbyspiral galaxy M51. Follow-up spectroscopy of 66 of the candidates confirms 61of these as SNRs, and suggests that the vast majority of the unobserved objectsare SNRs as well. A total of 55 of the candidates are coincident with (mostlysoft) X-ray sources identified in deep Chandra observations of M51; searchingthe positions of other soft X-ray sources resulted in several additionalpossible optical candidates. There are 16 objects in the catalog coincidentwith known radio sources. None of the sources with spectra shows the highvelocities (>500 km/s) characteristic of young, ejecta-dominated SNRs like CasA; instead, most if not all appear to be middle-aged SNRs. The generalproperties of the SNRs, size distribution and spectral characteristics,resemble those in other nearby spiral galaxies, notably M33, M83, and NGC6946,where similar samples exist. However, the spectroscopically observed [NII]:H{\alpha} ratios appear to be significantly higher than in any of theseother galaxies. Although we have explored various ideas to explain the highratios in M51, none of the explanations appears to be satisfactory.

Optical Identification and Spectroscopy of Supernova Remnants in the Galaxy M51