Star cluster ecology-IV. Dissection of an open star cluster: photometry

By S. P. Portegies Zwart, S. McMillan, P. Hut, J. Makino. 2000

306 citations recorded by the source corpus.

The evolution of star clusters is studied using N-body simulations in which the evolution of single stars and binaries is taken self-consistently into account. Initial conditions are chosen to represent relatively young Galactic open clusters, such as the Pleiades, Praesepe and the Hyades. The calculations include a realistic mass function, primordial binaries and the external potential of the parent Galaxy. Our model clusters are generally significantly flattened by the Galactic tidal field, and dissolve before deep core collapse occurs. The binary fraction decreases initially because of the destruction of soft binaries, but increases later because lower mass single stars escape more easily than the more massive binaries. At late times, the cluster core is quite rich in giants and white dwarfs. There is no evidence for preferential evaporation of old white dwarfs. On the contrary, the white dwarfs formed are likely to remain in the cluster. Stars tend to escape from the cluster through the first and second Lagrange points, in the direction of and away from the Galactic Centre. Mass segregation manifests itself in our models well within an initial relaxation time. As expected, giants and white dwarfs are much more strongly affected by mass segregation than main-sequence stars. Open clusters are dynamically rather inactive. However, the combined effects of stellar mass-loss and evaporation of stars from the cluster potential drive the dissolution of a cluster on a much shorter time-scale than if these effects are neglected. The often-used argument that a star cluster is barely older than its relaxation time and therefore cannot be dynamically evolved is clearly in error for the majority of star clusters. An observation of a blue straggler in an eccentric orbit around an unevolved star or a blue straggler of more than twice the turn-off mass might indicate past dynamical activity. We find two distinct populations of blue stragglers: those formed above the main-sequence turn-off, and those which appear as blue stragglers as the cluster's turn-off drops below the mass of the rejuvenated star.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8d8b5e52f33861eb289be6a56a293116881a4b9a

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Citations in the corpus

Gravitational N-Body Simulations (2003, methodology): “The former process is characterized by a fully consistent treatment of stellar structure [cf. Mardling & Aarseth, 2001] and may be preceded by a stage of chaotic evolution, whereas the latter involves a step-wise adjustment of the orbital parameters [Portegies Zwart et al., 1997].”
The Runaway Growth of Intermediate-Mass Black Holes in Dense Star Clusters (2002, methodology): “Portegies Zwart et al. (2001a) found that their model clusters dissolved within about 30% of the two-body relaxation time at the tidal radius (defined by substituting the tidal radius instead of the virial radius in eq.”
Formation and dynamical evolution of multiple stellar generations in globular clusters (2008, methodology): “All simulations were carried out using the Starlab package (Portegies Zwart et al. 2001, http://www.manybody.org/) accelerated by GRAPE-6 special-purpose hardware (Makino et al. 2003).”
Massive black hole binaries from runaway collisions: the impact of metallicity (2016, methodology): “…the corresponding evolutionary stage (e.g. τSG for a sub-giant star), while t(m1) indicates the time the star of mass m1 has already spent on its current evolutionary stage (e.g. the time spent in the sub-giant branch), instead of the total stellar age (see Portegies Zwart et al. 2001 for details).”
The mass spectrum of compact remnants from the parsec stellar evolution tracks (2015, methodology): “4.4 (default SEBA stellar evolution module, hereafter simply STARLAB ; Portegies Zwart et al. 2001), STARLABMM (Mapelli et al. 2013) and SSE .”
Stellar collisions during binary–binary and binary–single star interactions (2004, methodology): “STARLAB is a collection of modular software tools designed to simulate the evolution of dense stellar systems and analyse the resulting data (see Portegies Zwart et al. 2001, for a detailed description).”
Dynamics of stellar black holes in young star clusters with different metallicities – II. Black hole–black hole binaries (2014, methodology): “STARLAB; see Portegies Zwart et al. 2001).”
Young Massive Star Clusters (2010, methodology): “13, which presents the results of an isolated N = 128k body simulation, run on a GRAPE-4 (Makino & Taiji 1998) using the starlab software environment (Portegies Zwart et al. 2001).”
The evolution of runaway stellar collision products (2009, methodology): “The merger sequences used in this work were extracted from N-body simulations of young star clusters using the kira integrator of the starlab software environment (Portegies Zwart et al. 2001).”
Clusters and mirages: cataloguing stellar aggregates in the Milky Way (2019, background): “Since the total mass of clusters decreases as they age (because of escaping stars and stellar evolution) and the stars with the highest velocities are ejected first, their velocity dispersion also decreases (Portegies Zwart et al. 2001).”
On the mass function of star clusters (2002, background): “As an example, Portegies Zwart et al. (2001) infer the initial mass of the Pleiades (about 100 Myr old), Hyades (about 600 Myr) and Praesepe (400-900 Myr) to have been about the same (1600M⊙), but such classical estimates do not account for the gas-expulsion (ǫ < 0.5) and associated loss of stars.”
A complete N-body model of the old open cluster M67 (2005, methodology): “Pac., San Francisco, p. 290 Pooley D. et al., 2003, ApJ, 591, L131 Portegies Zwart S. F., McMillan S. L.W., Hut P., Makino J., 2001, MNRAS, 321, 199 Portegies Zwart S. F., Hut P., McMillan S. L. W., Makino J., 2004, MNRAS, 351, 473 Press W. H., Teukolsky S. A., 1977, ApJ, 213, 183 Preston G. W., Sne”
Disruption time scales of star clusters in different galaxies (2004, methodology): “All simulations were performed with NBODY4 (Aarseth 1999; BM03) and the Starlab (Portegies Zwart et al. 2001a)1 software environment with both codes running on the GRAPE family of special purpose computers (Makino 2003).”
The gravitational million-body problem (2001, methodology): “The present day mass function of the globular cluster NGC 6712 can be understood if it has lost about 99% of its original mass (Takahashi & Portegies Zwart 2000), and since its current mass is estimated to be of order 105M⊙ (Pryor & Meylan 1993), its likely original particle number puts it far beyon”
DYNAMICAL MASS SEGREGATION ON A VERY SHORT TIMESCALE (2009, unknown): “(Portegies Zwart et al. 2001).”
The effects of fly‐bys on planetary systems (2010, methodology): “We have calculated numerically the capture cross-section for substellar mass intruders (mI = 3, 10 and 30 mJ) in an encounter with a planetary system consisting of a Jupiter-mass planet orbiting a solar-mass star at 30 au using the N-body code STARLAB (Portegies Zwart et al. 2001).”