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The survival of stellar clusters

Arvidsson, Tobias LU (2014) In Lund Observatory Examenasarbeten ASTK01 20141
Department of Astronomy and Theoretical Physics - Has been reorganised
Lund Observatory - Has been reorganised
Abstract
In this project I have studied the effect of gas expulsion on the evolution of stellar clusters.
What effect the rate of gas removal and the quantity of gas removed has on the evolution
on the cluster will be studied through computer simulations with the NBody6 code and
compared to analytical predictions. The rate at which gas is removed has a very significant
impact on how the cluster evolves and it is particular relevant to look at rates compared to
the crossing time-scale of the cluster. Having small timescales of gas removal on the order
(τg << τc) can disrupt a cluster, while if the timescale is large (τg >> τc) the cluster can
recover equilibrium internally.

How much initial gas is needed in order for the cluster to... (More)
In this project I have studied the effect of gas expulsion on the evolution of stellar clusters.
What effect the rate of gas removal and the quantity of gas removed has on the evolution
on the cluster will be studied through computer simulations with the NBody6 code and
compared to analytical predictions. The rate at which gas is removed has a very significant
impact on how the cluster evolves and it is particular relevant to look at rates compared to
the crossing time-scale of the cluster. Having small timescales of gas removal on the order
(τg << τc) can disrupt a cluster, while if the timescale is large (τg >> τc) the cluster can
recover equilibrium internally.

How much initial gas is needed in order for the cluster to completely unbind after a
very rapid period of gas removal is another question investigated. If the mass of the gas
exceeds around 7 times the mass of the stars the clusters seem to completely fall apart.
The events of a SN is a possible source of rapid gas removal very shortly after a cluster
is formed. From many of the simulations less dense clusters seem to emerge from the
remnants. The fraction of mass left in the cluster with rapid removal depends a lot on the
initial amount of gas mass. For medium amount of gas (Mg ∼ (1−5)Ms) the mass fraction
of the remnant can be to some extent approximated by a Mrem/Mini ∼ Mg^(−1/2) function.
The primordial binary rate could have an effect on the evolution, but the simulations suggest
that it is not a dominant one. (Less)
Please use this url to cite or link to this publication:
author
Arvidsson, Tobias LU
supervisor
organization
course
ASTK01 20141
year
type
M2 - Bachelor Degree
subject
publication/series
Lund Observatory Examenasarbeten
report number
2014-EXA83
language
English
id
4465624
date added to LUP
2014-06-30 12:10:55
date last changed
2014-06-30 12:10:55
@misc{4465624,
  abstract     = {{In this project I have studied the effect of gas expulsion on the evolution of stellar clusters. 
What effect the rate of gas removal and the quantity of gas removed has on the evolution 
on the cluster will be studied through computer simulations with the NBody6 code and 
compared to analytical predictions. The rate at which gas is removed has a very significant 
impact on how the cluster evolves and it is particular relevant to look at rates compared to 
the crossing time-scale of the cluster. Having small timescales of gas removal on the order 
(τg << τc) can disrupt a cluster, while if the timescale is large (τg >> τc) the cluster can 
recover equilibrium internally.

How much initial gas is needed in order for the cluster to completely unbind after a
very rapid period of gas removal is another question investigated. If the mass of the gas
exceeds around 7 times the mass of the stars the clusters seem to completely fall apart.
The events of a SN is a possible source of rapid gas removal very shortly after a cluster
is formed. From many of the simulations less dense clusters seem to emerge from the
remnants. The fraction of mass left in the cluster with rapid removal depends a lot on the
initial amount of gas mass. For medium amount of gas (Mg ∼ (1−5)Ms) the mass fraction
of the remnant can be to some extent approximated by a Mrem/Mini ∼ Mg^(−1/2) function. 
The primordial binary rate could have an effect on the evolution, but the simulations suggest 
that it is not a dominant one.}},
  author       = {{Arvidsson, Tobias}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Lund Observatory Examenasarbeten}},
  title        = {{The survival of stellar clusters}},
  year         = {{2014}},
}