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  • On the Metallicity Dependen...
    Relaño, M; Lisenfeld, U; Pérez-González, P. G; Vílchez, J. M; Battaner, E

    Astrophysical journal/˜The œAstrophysical journal, 10/2007, Letnik: 667, Številka: 2
    Journal Article

    We investigate the use of the rest-frame 24 mu m luminosity as an indicator of the star formation rate (SFR) in galaxies with different metallicities by comparing it to the (extinction-corrected) H alpha luminosity. We carry out this analysis in two steps: First, we compare the emission from H II regions in different galaxies with metallicities between 12 + log(O/H) = 8.1 and 8.9. We find that the 24 mu m and the extinction-corrected H alpha luminosities from individual H II regions follow the same correlation for all galaxies, independent of their metallicity. Second, the role of metallicity is explored further for the integrated luminosity in a sample of galaxies with metallicities in the range of 12 + log (O/H) = 7.2-9.1. For this sample we compare the 24 mu m and H alpha luminosities integrated over the entire galaxies and find a lack of the 24 mu m emission for a given H alpha luminosity for low-metallicity objects, likely reflecting a low dust content. These results suggest that the 24 mu m luminosity is a good metallicity-independent tracer for the SFR in individual H II regions. On the other hand, metallicity has to be taken into account when using the 24 mu m luminosity as a tracer for the SFR of entire galaxies.