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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We have identified a ring-shaped emission-line nebula and a possible bipolaroutflow centered on the B1.5 supergiant Sher #25 in the Galactic giant HIIregion NGC 3603 (distance 6 kpc). The clumpy ring around Sher #25 appears to betilted by 64 deg against the plane of the sky. Its semi-major axis (positionangle approx. 165 deg) is 6.9" long, which corresponds to a ring diameter of0.4 pc. The bipolar outflow filaments, presumably located above and below thering plane on either side of Sher #25, show a separation of approx. 0.5 pc fromthe central star.  High-resolution spectra show that the ring has a systemic velocity of V_LSR =+19 km/s and a de-projected expansion velocity of 20 km/s, and that one of thebipolar filaments has an outflow speed of approx. 83 km/s. The spectra alsoshow high [NII]/Halpha ratio, suggestive of strong N enrichment. Sher #25 mustbe an evolved blue supergiant (BSG) past the red supergiant (RSG) stage. Wefind that the ratio of equatorial to polar mass-loss rate during the redsupergiant phase was approx 16. We discuss the results in the framework ofRSG-BSG wind evolutionary models.  We compare Sher #25 to the progenitor of SN 1987A, which it resembles in manyaspects.

Ring Nebula and Bipolar Outflows Associated with the B1.5 Supergiant Sher 25 in NGC 3603