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

Galactic supernova remnants (SNRs) with angular dimensions greater than a fewdegrees are relatively rare, as are remnants located more than ten degrees offthe Galactic plane. Here we report a UV and optical investigation of twopreviously suspected SNRs more than ten degrees in both angular diameter andGalactic latitude. One is a proposed remnant discovered in 2008 through 1420MHz polarization maps near Galactic coordinates $l$ = 353, $b$ = $-$34. GALEXfar UV (FUV) and H$\alpha$ emission mosaics show the object's radio emissioncoincident with a 11 x 14 degree shell of UV filaments surrounding a diffuseH$\alpha$ emission ring. Another proposed high latitude SNR is the 20 x 26degree Antlia nebula (G275.5+18.4) discovered in 2002 through low-resolutionall-sky H$\alpha$ and ROSAT soft X-ray emissions. GALEX UV and H$\alpha$mosaics along with optical spectra indicate the presence of shocks throughoutthe Antlia nebula with estimated shock velocities of 70 to over 100 kms$^{-1}$. We also present evidence that it has collided with the northeast rimof the Gum Nebula. We find both of these nebulae are bona fide SNRs with agesless than 10$^{5}$ yr despite their unusually large angular dimensions. We alsopresent FUV and optical images along with optical spectra of a newhigh-latitude SNR (G249.7+24.7) some 4.5 degrees in diameter which has alsobeen independently discovered in X-rays and radio (Becker at al. 2021). We findthis remnant's distance to be $\leq$400 pc based on the detection of red andblue shifted Na I absorption features in the spectra of two background stars.

Far UV and Optical Emissions from Three Very Large Supernova Remnants Located at Unusually High Galactic Latitudes