Test computations on the dynamical evolution of star clusters

Impact of metallicity on the evolution of young star clusters

“…It has long been debated whether mass-loss by stellar winds and/or supernovae (SNe) is efficient in affecting core collapse (e.g. Angeletti & Giannone 1977, 1980Applegate 1986;Chernoff & Shapiro 1987;Chernoff & Weinberg 1990;Hurley et al 2004;Schulman et al 2012;Downing 2012;Sippel et al 2012). In fact, stellar winds and SNe eject mass from a SC, making the central potential well shallower and quenching the onset of gravothermal instability.…”

Star clusters under stress: why small systems cannot dynamically relax

“…It has long been appreciated that the mass loss associated with stellar evolution can have a dramatic effect on the early life of a cluster (Angeletti & Giannone 1977;Applegate 1986;Terlevich 1987;Bastian et al 2008). As its largest stars die out, the cluster's total mass can decrease significantly.…”

Gravity, Particles, and Astrophysics

“…Star clusters in general, though, have been used to gain information on G-variability by comparing computer simulations of the dynamics of stars in a cluster affected by a decreasing G with those of stars in a cluster with constant G. Angeletti and Giannone (1978) have carried out such a comparison, taking into account various non-cosmological effects that are significant for cluster evolution such as mass loss by the stars in the cluster due to astrophysical processes. These workers note that if one adopts a rate of change of G of about the size found by Van Flandern, and assumes that GIG = constant in time, then G ex e-t and the dynamical evolution of a cluster of stars is seriously affected by such a variation because its influence is cumulative over the long history of such a system.…”

“…Some astrophysical systems do have td < t 0 and in the reasonable case where td < < t 0 and there is virial equilibrium, Marchant and Mansfield have shown that the qualitative evolution of Newtonian N-body systems will not reveal a variation of G. This does not, however, mean that such studies are a waste of time, as there are two cases in which simulation of N-body systems might yield information on G-variability, namely those in which two-body relaxation is important (this may apply to the work of Angeletti and Giannone, 1978) and those in which the condition td < < t 0 does not hold. Some astrophysical systems do have td < t 0 and in the reasonable case where td < < t 0 and there is virial equilibrium, Marchant and Mansfield have shown that the qualitative evolution of Newtonian N-body systems will not reveal a variation of G. This does not, however, mean that such studies are a waste of time, as there are two cases in which simulation of N-body systems might yield information on G-variability, namely those in which two-body relaxation is important (this may apply to the work of Angeletti and Giannone, 1978) and those in which the condition td < < t 0 does not hold.…”