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| Paper: |
The Galaxy-wide IMF - from Star Clusters to Galaxies |
| Volume: |
440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function? |
| Page: |
19 |
| Authors: |
Weidner, C.; Pflamm-Altenburg, J.; Kroupa, P. |
| Abstract: |
Over the past years observations of young and populous star clusters
have shown that the stellar initial mass function (IMF) can be
conveniently described by a two-part power-law with an exponent
α2 = 2.3 for stars more massive than about 0.5 M☉ and
an exponent of α1 = 1.3 for less massive stars. A
consensus has also emerged that most, if not all, stars form in
stellar groups and
star clusters, and that the mass function of these can
be described as a power-law (the embedded cluster mass function, ECMF)
with an exponent β ≈ 2. These two results imply that the
integrated galactic IMF (IGIMF) for early-type stars cannot be a
Salpeter power-law, but that they must have a steeper exponent. An
application to star-burst galaxies shows that the IGIMF
can become top-heavy. This has important consequences for the
distribution of stellar remnants and for the chemo-dynamical and
photometric evolution of galaxies. In this contribution the IGIMF
theory is described, and the accompanying contribution by
Pflamm-Altenburg, Weidner & Kroupa (this volume) documents the
applications of the IGIMF theory to galactic astrophysics. |
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