Oh, dear, oh dear, oh dear!

It looks as if Halo globular clusters are captured objects from other nearby galaxies and did not necessarily originate in the Milky Way, after all.

In *Of Clusters and Galaxies,* by Christine M. Clement (SCIENCE, 26 July 2002, Perspectives - Astronomy, pp. 532 to 533), this subject is discussed in depth. A bottom-up theory, rather than a top-down theory in galactic formation (as is now thought to be the case) might explain the varying ages of the various globular clusters if they had actually originated separately in different nearby galaxies (such as the Sagittarius Dwarf Galaxy or the Large and Small Magellanic Clouds), and were separately captured by the Milky Way. It is difficult to adequately measure the horizontal distances to celestial objects; at present, only radial distances seem to be accurately possible.

Anyway, I always like a new slant on an old scientific idea. It cleans up the brain and throws out musty, dusty, rusty ideas.

Astronomers have made Hertzsprung-Russell (H-R) diagrams of the various globular clusters in the galactic halo and have studied the halo stars on the horizontal branch (HB) and have found that the ages in different clusters seem to vary quite a bit -- at least in those where there is a radial measurement.

So, the halo globular clusters may not be the oldest objects in our galaxy (having originated elsewhere), but may, instead, have been captured by the Milky Way as it (a/k/a The Galaxy) was developing. This will be something to keep track of and to think about when you are viewing one of these jewels in the sky.

I just love science. It always is throwing a bejeweled monkey wrench into a theory and forcing me to rethink everything! The idea of galaxies being built up through merging (bottom up) rather than having come from a primordial cloud (top down) makes sense.

Changing ideas because of new, carefully measured data, is so much fun. It is great for the brain!

ljbrs [img]/phpBB/images/smiles/icon_biggrin.gif[/img] [img]/phpBB/images/smiles/icon_smile.gif[/img] [img]/phpBB/images/smiles/icon_rolleyes.gif[/img] [img]/phpBB/images/smiles/icon_confused.gif[/img]

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"There is in the universe neither center nor circumference." Giordano Bruno Born 1548. Torched 1600.

All of them? (I ask since they are seen in other spiral galaxies, and seem to be part of the makeup of a galaxy like ours.)

This takes too long for big bangers to accept.

What takes too long? For dwarf galaxies to merge with the Milky Way? I don't think that takes too long, its probably happened several times.

I just thought that it was interesting that globular clusters might not have originated in our system (although some of them probably have done so). The idea that material pulled from other merging galaxies to form globular clusters in the Milky Way halo, which globular clusters become captured and continue on through the halo might account for globulars' non-galactic-disk paths. This makes great sense to me.

Oh, I am a steadfast Big Bang enthuiast. There has been plenty of time since the calculated Big Bang and inflationary period for mergers. After all, the bottom-up idea of galaxy formation would reflect a lot of mergers upon mergers and other kinds of interactions between neighboring galaxies. The capturing of material to make the globular clusters makes much sense to me.

I will leave it up to scientists to *duke it out* over details.

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*Nothing is more damaging to a new truth than an old error.* Goethe

<font size=-1>[ This Message was edited by: ljbrs on 2002-07-31 22:25 ]</font>

Tonight in the journal/magazine, SCIENCE (for 8-2-02 - tomorrow), there is another article about young globular clusters in other galaxies. Evidently, globular clusters are not necessarily the oldest objects in some galaxies (although, some of the globulars in the Milky Way seem to be older than the Milky Way, itself). This age discrepancy might possibly be due to previous globular capture. Then again, possibly not...

ljbrs [img]/phpBB/images/smiles/icon_smile.gif[/img] [img]/phpBB/images/smiles/icon_confused.gif[/img]

__________________
"There is in the universe neither center nor circumference." Giordano Bruno Born 1548. Torched 1600.