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View Full Version : A new relationship is discovered regarding star clusters....



trinitree88
2012-Aug-04, 05:26 PM
The authors report a new relationship between galactocentric distance and scale size.....SEE:http://arxiv.org/abs/1208.0340....such that there is "no need to assume accretion to explain large clusters at large galactocentric distances in galaxies like the Milky Way." pete

neilzero
2012-Aug-06, 03:31 PM
Many of the words in the sumarry have no meaning to me. Can someone translate to layman's words? Neil

StupendousMan
2012-Aug-06, 04:46 PM
The basic idea is that globular star clusters may change in size for several reasons. Tidal forces from close passes through a galaxy can strip off stars from the outer regions of the cluster, while interactions between stars in the dense core of the cluster can boost some stars into the outer regions of the cluster. The paper shows that the size of clusters we observe now -- billions of years after the clusters were formed -- may have little relationship to the original size of the cluster when it formed.

kzb
2012-Aug-06, 05:17 PM
Neilzero -what StupendousMan says, plus one of the conclusions, is that globular clusters orbiting at large enough galactocentric distance can survive more or less intact since the galaxy was first formed. What is more, their derived relationship between galactocentric distance and globular cluster size is backed up by observations. There is no need to suppose that GC's are the remaining cores of accreted smaller galaxies.

SRH
2012-Aug-06, 05:26 PM
Neilzero -what StupendousMan says, plus one of the conclusions, is that globular clusters orbiting at large enough galactocentric distance can survive more or less intact since the galaxy was first formed. What is more, their derived relationship between galactocentric distance and globular cluster size is backed up by observations. There is no need to suppose that GC's are the remaining cores of accreted smaller galaxies.

just to clarify, the cluster diameter increases with distance from the galaxy center, correct?

kzb
2012-Aug-07, 11:32 AM
just to clarify, the cluster diameter increases with distance from the galaxy center, correct?

Err.. not sure without re-reading it. I think it is more correct to say the half-light radius relative to its mass increases with distance from the galaxy centre.

trinitree88
2012-Aug-07, 01:28 PM
Many of the words in the sumarry have no meaning to me. Can someone translate to layman's words? Neil

This might help,too http://en.wikipedia.org/wiki/Globular_clusterl