The Large Scale IMF-from local studies to large scale Star-formation

Weidner, Carsten
Referencia bibliográfica

PROBING STELLAR POPULATIONS OUT TO THE DISTANT UNIVERSE: CEFALU 2008, Proceedings of the International Conference. AIP Conference Proceedings, Volume 1111, pp. 129-136 (2009).

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Over the past years observations of young and populous star clusters have shown that the stellar IMF appears to be an invariant featureless Salpeter power-law with an exponent α = 2.35 for stars more massive than a few Msolar. A consensus has also emerged that most, if not all, stars form in stellar groups and star clusters, and that the mass function of young star clusters in the solar-neighbourhood and in interacting galaxies can be described, over the mass range of a few 10Msolar to 107Msolar, as a power-law with an exponent β~2. Under the assumption of a relation between the most-massive star in a cluster and the cluster mass these two results imply that integrated galactic-field IMFs for early-type stars cannot be a Salpeter power-law, but that they must have a steeper exponent [1]. Furthermore, the empirical correlation between galactic star-formation rate (SFR) and the mass of the most massive cluster that forms in a galaxy [2] implies that dwarf galaxies that have low average star-formation rates will have substantially different integrated IMFs than massive galaxies such as our Milky Way [3]. This has important consequences for the distribution of stellar remnants and for the chemo-dynamical and photometric evolution of galaxies. These results suggest that dwarf galaxies ought to show large variations in their integrated field-star IMFs and consequently in their chemical enrichment, while massive galaxies tend to have the same integrated field IMFs with a corresponding smaller inter-galactic scatter in chemical abundances.