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Stellar spectroscopy far beyond the Local Group

Fabio Bresolin·Rolf-Peter Kudritzki·Roberto H. Mendez·Norbert Przybilla
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Abstract

Multi-object spectroscopic observations of blue supergiants in NGC 3621, a spiral galaxy at a distance of 6.7 Mpc, carried out with the ESO VLT and FORS are presented. We demonstrate the feasibility of quantitative stellar spectroscopy at distances approaching a ten-fold increase over previous investigations by determining chemical composition, stellar parameters, reddening, extinction and wind properties of one of our targets, a supergiant of spectral type A1 Ia located in the outskirts of NGC 3621. The metallicity (determined from iron group elements) is reduced by a factor of two relative to the sun in qualitative agreement with results from previous abundance studies based on H II region oxygen emission lines. Reddening and extinction are E(B-V) = 0.12 and Av = 0.37, respectively, mostly caused by the galactic foreground. Comparing stellar wind momentum and absolute V magnitude with galactic and M31 counterparts we confirm the potential of the wind momentum-luminosity relationship as an alternative tool to estimate extragalactic distances.

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Fabio Bresolin, Rolf-Peter Kudritzki, Roberto H. Mendez, Norbert Przybilla. 2000-12-17. Stellar spectroscopy far beyond the Local Group. https://doi.org/10.1086/319118

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