The HST probes the winds and feedback of metal poor OB stars in the tidally stripped Magellanic Bridge

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Metallicity is one of the most fundamental parameters governing both stellar and galactic evolution. However, the impact of metallicity on the physics of massive stars and their feedback is empirically not well constrained at low metallicities. The Magellanic Bridge, which is our nearest tidally interacting environment with significantly low mean metallicity Z<~0.1Zsol, offers a unique laboratory for this study. Recently three O-type and few early B-type stars in the Bridge were identified via optical spectroscopy. This newly discovered sample will allow to characterize the winds of metal-poor massive stars and to empirically establish the scaling of mass-loss with metallicity, which cannot be done by using optical data alone. We selected 6 UV brightest OB stars as targets to obtain COS FUV spectra. The spectra will be analyzed using advanced non-LTE stellar atmosphere models, thereby determining the stellar, wind parameters, and Fe abundances of individual massive stars in the Bridge. The empirical mass-loss rates at low metallicity will be used to constrain stellar evolution models. Two B stars in our sample showing high UV excess are suspected to be binaries and might hide a hot companion. The far UV spectra are crucial to identify and characterize the stripped He companions of B stars which are not found yet at low metallicity. The UV + optical spectral analysis is essential to quantify ionizing fluxes as well as mechanical energy provided by OB stars at low metallicity. Together with physics and abundances of diffuse gas from ISM lines, our study will shed light on stellar feedback and star formation, as well as constrain the formation history of the Bridge.

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