Starship Asterisk*

Zooming in on Star Cluster Terzan 5

Explanation: Globular clusters once ruled the Milky Way. Back in the old days, back when our Galaxy first formed, perhaps thousands of globular clusters roamed our Galaxy. Today, there are less than 200 left. Over the eons, many globular clusters were destroyed by repeated fateful encounters with each other or the Galactic center. Surviving relics are older than any Earth fossil, older than any other structures in our Galaxy, and limit the universe itself in raw age. There are few, if any, young globular clusters in our Milky Way Galaxy because conditions are not ripe for more to form. The featured video shows what it might look like to go from the Earth to the globular cluster Terzan 5, ending with a picture of the cluster taken with the Hubble Space Telescope. This star cluster was recently found to contain not only stars formed in the early days of our Milky Way Galaxy, but also, quite surprisingly, others that formed in a separate burst of star formation about 7 billion years later.

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Last part is interesting...

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Interesting video.

Two things make Terzan 5 stand out. One, it contains ~12 billion year old stars as well as ~5 billion years old ones. That is certainly mysterious.

Two, it appears to be located relatively deep inside the Milky Way's disk.

Let's star with 2), the location of Terzan 5. I can't believe this globular has spent most of its life well inside the disk of the Milky Way. If it had been colliding with giant molecular clouds and other stuff in the disk for the better part of 12 billion years, I can't believe that Terzan 5 would still have existed as a cluster. That's why I think that Terzan 5 is just passing through.

Is it possible, though, that Terzan's probable passages through the disk of the Milky Way may have injected new gas into Terzan 5 and triggered star formation?

I'm reminded what I read about globular cluster NGC 6397 passing through the disk of the Milky Way, thereby possibly triggering the formation of massive open cluster NGC 6231.

But of course, a globular cluster forming new stars in itself is not the same thing as triggering star formation elsewhere.




















Ann

Ann wrote:Let's star with 2), the location of Terzan 5. I can't believe this globular has spent most of its life well inside the disk of the Milky Way. If it had been colliding with giant molecular clouds and other stuff in the disk for the better part of 12 billion years, I can't believe that Terzan 5 would still have existed as a cluster. That's why I think that Terzan 5 is just passing through.

When you say 'passing thru', do you mean to imply that it may be in some form of orbit around our galaxy interacting a 7 billion year intervals, or that the cluster is blasting thru only once with ballistic motion like a cluster-bullet from a universe-gun?

We need to understand how an (apparently) simpler explanation might have been excluded: that this two-population cluster formed by merger of two clusters, one of age 11-12 Gyr and one of age 4-5 Gyr. /LCS

Guest wrote:

Ann wrote:Let's star with 2), the location of Terzan 5. I can't believe this globular has spent most of its life well inside the disk of the Milky Way. If it had been colliding with giant molecular clouds and other stuff in the disk for the better part of 12 billion years, I can't believe that Terzan 5 would still have existed as a cluster. That's why I think that Terzan 5 is just passing through.

When you say 'passing thru', do you mean to imply that it may be in some form of orbit around our galaxy interacting a 7 billion year intervals, or that the cluster is blasting thru only once with ballistic motion like a cluster-bullet from a universe-gun?

"Terzan 5 probably follows an unknown complicated orbit around the center of the galaxy, but currently it is moving towards the Sun with a speed of around 90 km/s." - Wikipedia article

"Terzan 5 could be the surviving remnant of one of the primordial building blocks that are thought to merge and form galaxy bulges." - The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge

Rob

Isn't there a theory that old stars in clusters merged, thus making them look younger?

How do you tell an old star from a young star? How might you tell the old stars apart?

It gives you some sense of the scale of our Galaxy, for sure. Globular clusters are tremendously large, but microscopic in comparison.

In the completely zoomed in picture of the cluster, the entire left side appears composed of huge overlapping circular structures; like giant curved gaps, some containing lines of stars. The right side seems to have the expected appearance of a globular cluster; making an artifact unlikely as the cause of these "bubbles."

Comments? Does anyone else see / understand this, or do I need to re-install my browser again?

ok, you win. Convinced me I am just a puny something

If you're focused and patient, you can see it zoom back out after the video ends