Globular Clusters, alone or part of something?

Galactic Groove · Post by **Galactic Groove** » Mon Jun 26, 2006 2:32 pm

Are Globular Clusters, such as M22, alone in space themselves? Or are they located within a galaxy?

orin stepanek · Post by **orin stepanek** » Mon Jun 26, 2006 2:45 pm

Welcome Galatic Groove! These clusters are within the Milky Way!

http://www.seds.org/~spider/spider/MWGC/mwgc.html

Orin

Galactic Groove · Post by **Galactic Groove** » Mon Jun 26, 2006 4:39 pm

Thanks Orin

.... are there any occurances of these, or anything similar, outside of our galaxy?
I'm guessing the answer is no, but i dont' want to assume anything

orin stepanek · Post by **orin stepanek** » Mon Jun 26, 2006 5:01 pm

I really don't know but here is some interesting info on clusters.

http://www.geocities.com/stellar_clusters/Globular.htm

Orin

harry · Post by **harry** » Tue Jun 27, 2006 9:45 am

Hello All

Globular clusters of stars occur in every galaxy.

Also Clusters of stars occur away from galaxies.

We even have Globular clusters of galaxies.

randall cameron · Post by **randall cameron** » Tue Jun 27, 2006 9:58 am

As far as "within" the galaxy goes, globular clusters are arranged in sort of a halo around the periphery of our galaxy and orbiting (with) it. The ones we can observe are overwhelmingly outside the spiral arms and out of the galactic plane. They are often considered (sub-galactic size) satellites of our galaxy, like the dwarf galaxies and Magellanic clouds. This is quite different from, for example, open clusters that are overwhelmingly found within the spiral arms of the galaxy.

Galactic Groove · Post by **Galactic Groove** » Tue Jun 27, 2006 3:56 pm

ahhh, excellent. I've read a bit about it but they only indrectly hinted that they were outside of our galaxy's arms. With the links below, if I had researched the difference between Open Clusters and Globular Clusters I think I would have realized the answer.
Thanks everyone!

M3 - Globular Cluster
http://antwrp.gsfc.nasa.gov/apod/ap060312.html

M22 - Globular Cluster
http://antwrp.gsfc.nasa.gov/apod/ap050627.html

NGC 290 - Open Cluster
http://antwrp.gsfc.nasa.gov/apod/ap060501.html

NGC 869 & NGC 884 - Double Open Cluster
http://antwrp.gsfc.nasa.gov/apod/ap051011.html

BMAONE23 · Post by **BMAONE23** » Tue Jun 27, 2006 11:23 pm

Sounds like a good analogy would be:

Globular Clusters are to the Galaxy what ORT Cloud bodies are to the solar system.

orin stepanek · Post by **orin stepanek** » Wed Jun 28, 2006 2:10 am

http://antwrp.gsfc.nasa.gov/apod/ap050627.html

Also suggests that 140 globular clusters orbit the center of our galaxy. This tells me that they are within our galaxy as well as outside the spiral arms of the Milky Way. Unless I interpret this wrong.
Orin

randall cameron · Post by **randall cameron** » Wed Jun 28, 2006 8:34 am

Radial velocity measurements have revealed that most globulars are moving in highly excentric elliptical orbits that take them far outside the Milky Way; they form a halo of roughly spherical shape which is highly concentrated to the Galactic Center, but reaches out to a distance of several 100,000 light years, much more than the dimension of the Galaxy's disk. As they don't participate in the Galaxy's disk rotation, they can have high relative velocities of several 100 km/sec with respect to our solar system; this is what shows up in the radial velocity measurements. Ninkovi&cacute; (1983) has estimated excentricities of globular cluster orbits.

Above quoted from http://www.seds.org/messier/glob.html

When globular clusters get to close to the major structures of the galaxy, they suffer tidal deformation, and can lose their "globular" character. GCs are overwhelmingly "population II" stars. They would stand out if found in the spiral arms, and we have found none nearby. Farther away or in the core they might well exist, but we could not see them. The reason we see the ones we do so clearly is that they are out of plane.

harry · Post by **harry** » Wed Jun 28, 2006 11:42 am

Hello All

Look at M87

Every dot is a globular cluster of stars

http://antwrp.gsfc.nasa.gov/apod/ap040616.html

These Globular clsuters in my opinion be formed by the extra ordinary ejection of material by the black hole jet stream.