The relation between the most-massive star and its parental star cluster mass

By C. Weidner, Pavel Kroupa, I. B. S. A. University, P. U. C. D. Chile, A. Bonn. 2009

177 citations recorded by the source corpus.

We present a thorough literature study of the most-massive star, mmax, in several young star clusters in order to assess whether or not star clusters are populated from the stellar initial mass function (IMF) by random sampling over the mass range 0.01 6 m 6 150 M⊙ without being constrained by the cluster mass, Mecl. The data reveal a partition of the sample into lowest mass objects (Mecl 6 10 2 M⊙), moderate mass clusters (10 2 M⊙ < Mecl 6 10 3 M⊙) and rich clusters above 10 3 M⊙. Additionally, there is a plateau of a constant maximal star mass (mmax � 25 M⊙) for clusters with masses between 10 3 M⊙ and 4 · 10 3 M⊙. Statistical tests of this data set reveal that the hypothesis of random sampling from the IMF between 0.01 and 150 M⊙ is highly unlikely for star clusters more massive than 10 2 M⊙ with a probability of p � 2· 10 −7 for the objects with Mecl between 10 2 M⊙ and 10 3 M⊙ and p � 3 · 10 −9 for the more massive star clusters. Also, the spread of mmax values at a given Mecl is smaller than expected from random sampling. We suggest that the basic physical process able to explain this dependence of stellar inventory of a star cluster on its mass may be the interplay between stellar feedback and the binding energy of the cluster-forming molecular cloud core. Given these results, it would follow that an integrated galactic initial mass function (IGIMF) sampled from such clusters would automatically be steeper in comparison to the IMF within individual star clusters.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9be6b3100e45358ec03165b4566a537777599a95

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Citations in the corpus

The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 M⊙ stellar mass limit (2010, background): “They reveal that the average relation between the maximum stellar mass and cluster mass (in the 102 and 104 M interval) is recovered (Weidner et al. 2010), without the constraint that the cluster mass governs the maximum possible stellar mass (Parker & Goodwin 2007).”
The stellar and sub-stellar IMF of simple and composite populations (2011, methodology): “The semi-analytical calculation of the mmax −Mecl relation by Kroupa & Weidner (2003) and Weidner et al. (2010) is less accurate by not including the correction term mmax.”
Evidence for top-heavy stellar initial mass functions with increasing density and decreasing metallicity (2012, background): “Weidner et al. (2010) show, using a geometrical argument, that a high density will be a problem for the formation of individual stars in clusters more massive than ≈ 105M⊙.”
LIMITING ACCRETION ONTO MASSIVE STARS BY FRAGMENTATION-INDUCED STARVATION (2010, background): “…that are massive enough so that purely random sampling of the initial mass function (IMF) (Kroupa 2002; Chabrier 2003) without upper mass limit should have yielded stars above 150 M (Weidner & Kroupa 2004; Figer 2005; Oey & Clarke 2005; Weidner et al. 2010, see however, Selman & Melnick 2008).”
Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionization (2016, background): “First, we do not take into account the fact that the mass of the most massive star within a cluster is correlated with the total cluster mass (Weidner et al. 2010; Kirk & Myers 2011).”
Physical Processes in the Interstellar Medium (2014, background): “If this mass limit holds, then purely random sampling of the initial mass function (IMF) (Kroupa, 2002; Chabrier, 2003a) without an upper mass limit should have yielded stars above 150M (Weidner & Kroupa 2004; Figer 2005; Oey & Clarke 2005; Weidner et al. 2010; see however, Selman & Melnick 2008).”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, methodology): “…the cluster mass, based either on direct comparisons of stellar and cluster masses in the Milky Way (Kroupa & Weidner 2003; Weidner & Kroupa 2006; Weidner et al. 2010, 2013), or on indirect indicators such as X-ray binary populations (Dabringhausen et al. 2009, 2012) and globular cluster…”