Gravothermal oscillations in two-component models of star clusters
  In this paper, gravothermal oscillations are investigated in two-component
clusters with a range of different stellar mass ratios and total component mass
ratios. The critical number of stars at which gravothermal oscillations first
appeared is found using a gas code. The nature of the oscillations is
investigated and it is shown that the oscillations can be understood by
focusing on the behaviour of the heavier component, because of mass
segregation. It is argued that, during each oscillation, the re-collapse of the
cluster begins at larger radii while the core is still expanding. This
re-collapse can halt and reverse a gravothermally driven expansion. This
material outside the core contracts because it is losing energy both to the
cool expanding core and to the material at larger radii. The core collapse
times for each model are also found and discussed. For an appropriately chosen
case, direct N -body runs were carried out, in order to check the results
obtained from the gas model, including evidence of the gravothermal nature of
the oscillations and the temperature inversion that drives the expansion.
