arXiv subjects

S. Vine

Publications and source records attributed to S. Vine.

3 recordsLinked to original sources

arXiv2003

Mass segregation in the young open cluster NGC 2547

We present a study of mass segregation of the young (20-35 Myr isochronal age), open cluster NGC 2547. We find good evidence that mass segregation exists in NGC 2547 down to 3 Msun, and weak evidence for mass segregation down to 1 Msun. Theoretical models of an initially unsegregated model of NGC 2547 using the NBODY2 code show weaker mass segregation, implying that at least some of the observed mass segregation has a primordial origin. We also report the discovery of three possible escaped cluster members, which share the proper motion and colours of the cluster, but lie nearly a degree from the cluster centre.

astro-ph↗

arXiv1997

Simulations of Spheroidal Systems with Substructure: Trees in Fields

We present a hybrid technique of N-body simulation to deal with collisionless stellar systems having an inhomogeneous global structure. We combine a treecode and a self-consistent field code such that each of the codes model a different component of the system being investigated. The treecode is suited to treatment of dynamically cold or clumpy systems which may undergo significant evolution within a dynamically hot system. The hot system is appropriately evolved by the self-consistent field code. This combined code is particularly suited to a number of problems in galactic dynamics. Applications of the code to these problems are briefly discussed.

astro-ph↗

arXiv1993

On the probability of major-axis precession in triaxial ellipsoidal potentials

Orbits in triaxial ellipsoidal potentials precess about either the major or minor axis of the ellipsoid. In standard perturbation theory it can be shown that a circular orbit will precess about the minor axis if its angular momentum vector lies in a region bounded by two great circles which pass through the intermediate axis and which are inclined with minimum separation $i_T$ from the minor axis. We test the accuracy of the standard formula for $i_T$ by performing orbit integrations to determine $i_S$, the simulated turnover angle corresponding to $i_T$. We reach two principal conclusions: (i) $i_S$ is usually greater than $i_T$, by as much as 12 degrees even for moderate triaxialities, $A/1.2<B<C/0.8$. This reduces the expected frequency of polar rings. (ii) $i_S$ is not a single, well-defined number but can vary by a few degrees depending upon the initial phase of the orbit. This means that there is a reasonable probability for capture of gas onto orbits which precess about both axes. Interactions can then lead to substantial loss of angular momentum and subsequent infall to the galactic centre.

astro-ph↗