Starship Asterisk*

Some time this fall, I saw a fascinating text at arXiv.org about globular clusters. The text said that tremendously large star clusters formed normally inside spiral galaxies about twelve billion years ago. But since these clusters formed inside spiral galaxies out of giant molecular clouds, the newborn clusters kept colliding with other giant molecular clouds, and as a result, most of them were disrupted and destroyed.

But this was an era when the universe was much smaller and galaxies kept colliding with each other. During galactic collisions, large clusters are easily knocked out of the plane of the spiral galaxy and sent into the galactic halo. Here they are safe from collisions with giant molecular clouds, and therefore they can survive for billions of years, only shrinking slowly by regularly shedding some of their constituent stars.

To me, this paper was extremely interesting. It seemed to explain how globular clusters formed (normally, inside spiral galaxies), why basically none of them seem to orbit in the galactic plane (those that did were disrupted and destroyed by giant molecular clouds soon after their formation) and why we find them in galactic halos (they were knocked into the halos by galactic collisions, and once they got into the halo they were pretty much safe from violent disruption and could survive until today).

So I found this arXiv paper very interesting and would like to read it again, but now I can't find it. Does anyone else recognize it?

Ann

Do you happen to remember a specific object contained in the paper?

Unfortunately, what I said in my post above is all I can remember.

Ann

Can you remember the names of any of the astronomers in the paper?

Ann wrote:So I found this arXiv paper very interesting and would like to read it again, but now I can't find it. Does anyone else recognize it?

No, but you might have some luck if you can recreate the path toward finding it in the first place. For instance, if you go to the Wikipedia page for globular clusters, and look at the references in the formation section, there are some arXiv papers that deal with similar material- large clusters colliding with each other in galaxies. A few author names seem to show up pretty commonly. Maybe that would give you a start at finding the specific paper you're interested in. Also, if you do a Google search for globular clusters or globular cluster formation, it should give you the opportunity to restrict the search to "scholarly articles".

I found it. Thanks for your help. The ArXiv article is called Globular clusters as the relics of regular star formation in ‘normal’
high-redshift galaxies, and it was written by J. M. Diederik Kruijssen, Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching, Germany; kruijssen@mpa-garching.mpg.de. It was printed on September 9, 2015.

J. M. Diederik Kruijssen wrote:
The results of this section show that the observed properties of GCs
at z = 0 are reproduced by our model, indicating that GCs are
fully consistent with being the products of the regular star and cluster
formation process in the high-pressure environments of z > 2
galaxies. These clusters were saved from tidal destruction in their
dense natal environments by the redistribution of matter (and hence
their ‘liberation’ into the galaxy halo) during hierarchical galaxy
formation.

There is lots and lots of math in that article that I don't understand and can't explain, sorry. But I think the gist of the article is that the author defends his hypothesis that globular clusters are the result of normal star formation in gas-rich galaxies in the early, high-pressure universe. Most giant clusters that were formed back then were disrupted and destroyed by interaction with giant molecular clouds, but some clusters were redistributed into the halo of their parent galaxy, where they were safe from the disruptive influence of the crowded disk, and could age gracefully and survive until this day.

Very interesting, I think.

Ann

Ann wrote:I found it. Thanks for your help. The ArXiv article is called Globular clusters as the relics of regular star formation in ‘normal’
high-redshift galaxies, and it was written by J. M. Diederik Kruijssen, Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching, Germany; kruijssen@mpa-garching.mpg.de. It was printed on September 9, 2015.

J. M. Diederik Kruijssen wrote:
The results of this section show that the observed properties of GCs
at z = 0 are reproduced by our model, indicating that GCs are
fully consistent with being the products of the regular star and cluster
formation process in the high-pressure environments of z > 2
galaxies. These clusters were saved from tidal destruction in their
dense natal environments by the redistribution of matter (and hence
their ‘liberation’ into the galaxy halo) during hierarchical galaxy
formation.

There is lots and lots of math in that article that I don't understand and can't explain, sorry. But I think the gist of the article is that the author defends his hypothesis that globular clusters are the result of normal star formation in gas-rich galaxies in the early, high-pressure universe. Most giant clusters that were formed back then were disrupted and destroyed by interaction with giant molecular clouds, but some clusters were redistributed into the halo of their parent galaxy, where they were safe from the disruptive influence of the crowded disk, and could age gracefully and survive until this day.

Very interesting, I think.

Ann

I love a happy ending! Another interesting fact is that the most distant globular cluster in the Milky Way, AM 1 has a distance of 390 000 light years!!