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Stellar Populations in Dwarf Irregular Galaxies of the Local Group

Published online by Cambridge University Press:  07 August 2017

M. Tosi ,
L. Greggio ,
P. Focardi  and
G. Marconi
M. Tosi
Affiliation:
Osservatorio Astronomico, Via Zamboni 33, Bologna, Italy
L. Greggio
Affiliation:
Astronomy Dept., Bologna University, Via Zamboni 33, Bologna, Italy
P. Focardi
Affiliation:
Astronomy Dept., Bologna University, Via Zamboni 33, Bologna, Italy
G. Marconi
Affiliation:
Astronomy Dept., Bologna University, Via Zamboni 33, Bologna, Italy

Extract

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Given the uncertainties in the derivation of the current and past SFR in galaxies of any kind, the SF regime in irregulars is subject of wide debate. Since the most direct information on the stellar populations and relative histories in any system can be derived from their CMD, we have undertaken a project for accurately studying the CMDs and luminosity functions (LF) of nearby, well resolved, irregulars. The method proceeds on two tracks: a) we have developed a numerical code for Montecarlo simulations of CMDs and b) we have taken deep and accurate CCD photometry of several galaxies and derived the corresponding CMDs and LFs. The comparison of the observational data with the corresponding theoretical expectations provides several constraints on the SF history and on the IMF of the analysed objects. We do not pretend to reach unique conclusions on the evolution of irregular galaxies, but we can sensibly reduce the range of possible interpretations.

All the irregulars in our sample were selected from the DDO Catalogue and were supposed to belong to the Local Group. Detailed descriptions of the data acquisition and reduction and of the simulation code can be found in Tosi et al. (1991). In the following we briefly summarize the results relative to Sextans B, NGC 3109 and DDO 210.

Type
II. The Stellar Populations of Nearby Resolved Galaxies
Information
Symposium - International Astronomical Union , Volume 149: The Stellar populations of Galaxies , 1992 , pp. 207 - 210
Copyright
Copyright © Kluwer 

References

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