Why globular clusters don't collapse.

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Jordi Heguilor
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I asked Bard that question and it responded (among other things) that a) globular clusters are spherical and b) that they are spinning rapidly. Aren't those two things contradictory, as in they should be flattened by centrifugal forces?
 
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If Bard is some sort ofg AI Chatbot, don't believe it.

Globular clusters are not rigid, so they do not rotate like rigid objects. Further, they are pressure supported, which means that the individual stars rotation parameters are fairly random, unlike spirals.
 
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openai gave a lot more considerations: (bound together by their mutual gravitational attraction.) Gravitational balance, Stellar Velocity Dispersion, mass segregation, tidal effects, a broad distribution of kinetic energies within the cluster, higher energy orbits, Stellar Collisions and re-balancing, mass loss and gravity reduction, dark matter gravitational attraction, high mass-to-light ratio, yet low contamination levels of gas, dust prevent mass clouds that promote collapse. May contain intermediate black holes.

Like rain drops with "like charges", stars repel each other
- while in random kinetic motion
- to contain 10k to 10m stars in a cluster from 3.2 ly across or 100 ly across and up.
- 150m clusters in Milky Way each very dense. Living inside a Globular Cluster
- from Fraser Cain: Publisher Universe Today ...
 
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  • #4
Jordi Heguilor said:
I asked Bard that question and it responded (among other things) that a) globular clusters are spherical and b) that they are spinning rapidly. Aren't those two things contradictory, as in they should be flattened by centrifugal forces?
Welcome to PF, Jordi. :smile:

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FAQ: Why globular clusters don't collapse.

Why don't globular clusters collapse under their own gravity?

Globular clusters don't collapse under their own gravity because they are in a state of dynamic equilibrium. The gravitational forces pulling the stars inward are balanced by the kinetic energy of the stars moving in their orbits. This balance prevents the cluster from collapsing.

What role does stellar velocity dispersion play in preventing the collapse of globular clusters?

Stellar velocity dispersion refers to the range of velocities at which stars in a globular cluster move. This dispersion creates a dynamic pressure that counteracts the gravitational forces trying to pull the stars together, thereby preventing the cluster from collapsing.

How does the mass distribution within a globular cluster affect its stability?

The mass distribution within a globular cluster is generally more concentrated towards the center, but it is still distributed in such a way that the gravitational forces are balanced by the kinetic energy of the stars. This distribution helps maintain the cluster's stability and prevents collapse.

What is the role of two-body relaxation in the stability of globular clusters?

Two-body relaxation is a process where stars in a globular cluster exchange energy through gravitational interactions. Over time, this process leads to a more uniform distribution of kinetic energy among the stars, which helps to stabilize the cluster and prevent collapse.

Can external tidal forces influence the stability of globular clusters?

Yes, external tidal forces from the host galaxy can influence the stability of globular clusters. These forces can strip away outer stars and alter the cluster's shape, but they generally do not cause the entire cluster to collapse. Instead, they can contribute to the long-term evolution and potential dissolution of the cluster over billions of years.

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