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

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.