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Issue A&A Volume 373, Number 1, July I 2001 Page(s) L9 - L12 Section Letters DOI 10.1051/0004-6361:20010704

A&A 373, L9-L12 (2001)
DOI: 10.1051/0004-6361:20010704

On star formation rates in dwarf galaxies

P. M. Weilbacher and U. Fritze-v.Alvensleben

Universitäts-Sternwarte, Geismarlandstr. 11, 37083 Göttingen, Germany

(Received 7 May 2001 / Accepted 16 May 2001 )

Abstract
We present evolutionary synthesis models of starbursts on top of old stellar populations to investigate in detailed time evolution the relation between H luminosity and star formation rate (SFR). The models show that several effects have an impact on the ratio between and SFR. Metallicity different from solar abundance, a time delay between star formation and maximum H-luminosity, and a varying stellar initial mass function give rise to strong variations in the ratio of H luminosity to SFR and can cause large errors in the determination of the SFR when employing well-known calibrations. When studying star-bursting dwarf galaxies, and sub-galactic fragments at high redshift, which show SFR fluctuating on short timescales, these effects can add up to errors of two orders of magnitude compared with the calibrations. To accurately determine the true current SFR additional data in combination with models for the spectral energy distribution are needed.

Key words: galaxies: starbursts -- galaxies: dwarf -- galaxies: evolution -- galaxies: fundamental parameters

Offprint request: P. Weilbacher, weilbach@uni-sw.gwdg.de

© ESO 2001

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