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 bipolar outflow centered on the B1.5 supergiant Sher 25 in the Galactic giant H II region NGC 3603 (distance 6 kpc). The clumpy ring around Sher 25 appears to be tilted by 64 degrees against the plane of the sky. Its semimajor axis (position angle approximate to 165 degrees) is 6.9'' long, which corresponds to a ring diameter of 0.4 pc. The bipolar outflow filaments, presumably located above and below the ring plane on either side of Sher 25, show a separation of approximate to 0.5 pc from the central star. High-resolution spectra show that the ring has a systemic velocity of V-LSR = +19 km s(-1) and a deprojected expansion velocity of 20 km s(-1), and that one of the bipolar filaments has an outflow speed of similar to 83 km s(-1). The spectra also show a high [N II]/H alpha ratio, suggestive of strong N enrichment. Sher 25 must be an evolved blue supergiant (BSG) past the red supergiant (RSG) stage. We find that the ratio of equatorial to polar mass-loss rate during the RSG phase was approximate to 16. We discuss the results in the framework of RSG-BSG wind evolutionary models. We compare Sher 25 to the progenitor of SN 1987A, which it resembles in many aspects.