DYNAMICAL MASS SEGREGATION ON A VERY SHORT TIMESCALE

By R. Allison, S. Goodwin, R. Parker, R. de Grijs, S. P. Portegies Zwart, M. B. N. Kouwenhoven. 2009

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We discuss the observations and theory of star cluster formation to argue that clusters form dynamically cool (subvirial) and with substructure. We then perform an ensemble of simulations of cool, clumpy (fractal) clusters and show that they often dynamically mass segregate on timescales far shorter than expected from simple models. The mass segregation comes about through the production of a short-lived, but very dense core. This shows that in clusters like the Orion Nebula Cluster the stars ⩾ 4 M☉ can dynamically mass segregate within the current age of the cluster. Therefore, the observed mass segregation in apparently dynamically young clusters need not be primordial, but could be the result of rapid and violent early dynamical evolution.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/df6eaefc12b949712c30416ff822273e6cb82f57

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Citations in the corpus

A Universal Stellar Initial Mass Function? A critical look at variations in extreme environments (2010, methodology): “Both of these effects suggest that stars in clusters may have inhabited smaller, denser environments in the past, with corre- spondingly shorter relaxation timescales and faster dynamically evolution into a mass segregated state (McMillan et al. 2007; Allison et al. 2009; Moeckel & Bonnell 2009).”
Young Massive Star Clusters (2010, background): “…for initial mass segregation can be found in some young clusters (e.g. Hillenbrand & Hartmann 1998, Sabbi et al. 2008), simulations of star formation (e.g. Klessen 2001, Bonnell & Bate 2006), and dynamical evolution during phase 1 (McMillan, Vesperini & Portegies Zwart 2007; Allison et al. 2009).”
Evidence for top-heavy stellar initial mass functions with increasing density and decreasing metallicity (2012, background): “If a cluster is masssegregated at birth, as indicated by theory (Marks et al. 2008; Baumgardt et al. 2008; Allison et al. 2009) and observations (Littlefair et al. 2003; McCrady et al. 2005; Chen et al. 2007), the cluster will preferentially loose its lowmass stars.”
The dynamical state of stellar structure in star‐forming regions (2011, methodology): “…formation process itself (see the review by McKee & Ostriker 2007) to the fundamental properties of young star clusters (e.g. McMillan et al. 2007; Allison et al. 2009a; Moeckel & Bonnell 2009), or possibly even the global stellar mass assembly of galaxies (see e.g. Pflamm-Altenburg et al. 2007;…”
The Birth Environment of the Solar System (2010, background): “On the other hand, mass segregation can be sped up through a combination of subvirial starting velocities and sufficiently clumpy initial density distributions (Allison et al. 2009, Moeckel & Bonnell 2009).”