Description
We have obtained deep multiobject optical spectra of 49 HII regions in the outer disk of the spiral galaxy M83 (=NGC 5236) with the FORS2 spectrograph at the Very Large Telescope. The targets span the range in galactocentric distance between 0.64 and 2.64 times the R_25_ isophotal radius (5.4-22.3kpc), and 31 of them are located at R>R_25_, thus belonging to the extreme outer disk of the galaxy, populated by UV complexes revealed recently by the Galaxy Evolution Explorer satellite. In order to derive the nebular chemical abundances, we apply several diagnostics of the oxygen abundance, including R_23_, [NII]/[OII], and the [OIII]{lambda}4363 auroral line, which was detected in four HII regions.
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