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Fraser
2005-Mar-22, 05:24 PM
SUMMARY: The Milky Way has several star clusters; collections of stars pulling each other into a tight group. But now astronomers have located a super star cluster, containing hundreds of thousands of stars in a region only 6 light-years across. It's called Westerlund 1, and nobody discovered it before now because it's hidden behind thick clouds of dust. Astronomers used several of European Southern Observatory's infrared telescopes to peer through the dust and see the super cluster's true size.

View full article (http://www.universetoday.com/am/publish/super_star_cluster.html)

What do you think about this story? Post your comments below.

antoniseb
2005-Mar-22, 05:29 PM
It's interesting that the article before this one talked about the mystery of how IMBHs form, and this article talks about how clusters like this one may well be how IMBHs for.

This cluster will have to be one of the early targets for the James Webb Space Telescope once it is operational. This is a very interesting object.

Guest
2005-Mar-22, 06:28 PM
amazing how a cluster like this could be hidden in space

dave_f
2005-Mar-22, 06:47 PM
Originally posted by Guest@Mar 22 2005, 01:28 PM
amazing how a cluster like this could be hidden in space
The article mentioned that the reason no one's found it is because it was hidden behind a giant dust cloud.

lswinford
2005-Mar-22, 08:13 PM
And do they think its tight configuration is gravitational from its mutual mass interactions, a black hole(s), or perhaps compacting from the contemporary fad--dark matter/energy?

I think it would be interesting if it was an ancient remnant of a small galaxy that long ago collided and was captured by ours, with its extremity stars spun out and absorbed by the sweep of our galactic arms. Just musing, for what its worth.

dave_f
2005-Mar-23, 12:46 AM
Originally posted by lswinford@Mar 22 2005, 03:13 PM
I think it would be interesting if it was an ancient remnant of a small galaxy that long ago collided and was captured by ours, with its extremity stars spun out and absorbed by the sweep of our galactic arms. Just musing, for what its worth.
That would be interesting: The evidence of primordial galaxies existing in our very own. Somehow I don't believe these things are totally destroyed when absorbed in the Milky Way. I'm not surprised to learn that these "little galaxies" exist in some form or another in our own, considering the Milky Way's penchant for absorbing other star clusters and the like.

lloydd
2005-Mar-23, 02:52 AM
100,000 stars in a volume of a sphere 6 light years accross.

With these numbers it would almost seem that a person could stretch out their arms and touch 2 stars at one time.

Some quick math actually shows that the average distance between 2 stars would still be about 300,000,000,000 miles.

Whats seems crouded to us is still virtually empty for the universe.

Size and distance in space is truly tough to visualize.

dave_f
2005-Mar-23, 06:55 AM
Originally posted by lloydd@Mar 22 2005, 09:52 PM
100,000 stars in a volume of a sphere 6 light years accross. With these numbers it would almost seem that a person could stretch out their arms and touch 2 stars at one time. Some quick math actually shows that the average distance between 2 stars would still be about 300,000,000,000 miles. Whats seems crouded to us is still virtually empty for the universe. Size and distance in space is truly tough to visualize.
Yes it is.

But, this proves how weak a force Gravity is, even according to the Grand Unified Theory. Large masses tend to congregate, not collapse.

wstevenbrown
2005-Mar-23, 07:20 AM
We've still got the chicken/egg thing going on.

Are IMBH's created by dense, massive star clusters, or are dense, massive star clusters created by IMBH's?

The starburst in the present example is a recent one, so if the cluster as a whole is an interloper, there should be an older population present with enough mass to have retained its gas to drive the starburst. Too, the motion of the cluster would be the cause of the collision shock driving the starburst, which makes the idea easily testable. The cluster as a whole would have to have a common motion with respect to the galaxy, and the shock front would be oriented with respect to that motion-- not symmetrical. No common motion was reported, and the shock front would look symmetrical only if it was oriented to our line-of-sight. This cluster was almost certainly home-grown.

Still unanswered: Why is the cluster so dense? I won't entertain clumped dark matter fantasies until a pre-existing IMBH has been ruled out. You can get that density from the ordinary sort of cloud with no BH, but not on that scale!

Fascinating. S

antoniseb
2005-Mar-24, 03:40 PM
Originally posted by wstevenbrown@Mar 23 2005, 07:20 AM
Are IMBH's created by dense, massive star clusters, or are dense, massive star clusters created by IMBH's?
These are good questions Steve. Of course if the answer for this one is that the IMBH came first, we are still left with the issue of how the IMBH was formed in the first place.

Concerning the density of the cluster... No idea. It will be interesting to see how these questions get answered over time. Obviously there IS a cluster this dense. Somehow it formed, and we may someday understand how.

Guest
2005-Mar-25, 12:06 AM
Re. the chicken/egg. Considering the data we have to date of the mass and structural/density picture of our visible universe, we have very high concentrations of mass (sheets/clusters) regions with the majority of the universal real estate void or low in mass (isolated small clusters and single galaxies) scattered about with no, or low gravitational influence or "additional" mass input from the high concentrated regions.
That said (and maybe I don't have a good grasp of the CMB et.al science results), is it possible that these "rural dwarfs" have (either started with or created later in its primordial construction?) a central black hole that simply gobbled up and exhusted their available surrouding accretion material and ended up a complete "undetectable" small to intermediate black body "wandering" sojourner?
You probably know where I'm going with this...if this now homeless rougue happens to wander close enough to a larger concentration then it may wind up being sucked into one of its galaxies (one such as ours) and become the center of a cluster concentration which is the topic under discussion here.
On the topic of "dark matter" and what it is speculated to be, includes, if I read the articles correctly, wandering black holes, brown dwarfs etc...did they include wandering /ejected neutron stars as well? Thanks for your indulgence, I'm only trying to gain some insight from the talent in this forum.

antoniseb
2005-Mar-25, 04:40 PM
Originally posted by Guest@Mar 25 2005, 12:06 AM
On the topic of "dark matter" and what it is speculated to be, includes, if I read the articles correctly, wandering black holes, brown dwarfs etc...did they include wandering /ejected neutron stars as well?
Using the cosmological definition of dark matter, it cannot be simply normal highly interactive matter that just happens not to give off light (such as neutron stars, brown dwarfs, etc). The term dark matter referes to neutrinos (hot dark matter), and some unknown particles that move more slowly, but also seldom interact with other matter except gravitationally (cold dark matter).