<p><em>Isotropic</em> means <em>the same in all directions</em>. If all galaxies you observe move in random directions, their velocities are isotropic. If most galaxies appear to be moving in the same direction, then the velocity distribution is <em>anisotropic</em>, i.e. there is a preferred direction to the velocity vectors.</p>

CC BY-SA 4.0
2024-07-29T19:06:22.987Z
I'm sorry, the previous version of the question was not very clear. Now I tried to explain myself better; it's not about galaxy groups or anything like that, more on the internal velocities of matter in a single galaxy
jack_O'Dim
CC BY-SA 4.0
2024-07-26T11:48:00.863Z
2024-07-26T11:48:00.863Z
Lenard Kasselmann
<p>I came across this term in this <a href="https://iopscience.iop.org/article/10.1086/310095/pdf" rel="nofollow noreferrer">paper</a>, where the authors propose using galaxy velocity anisotropy to classify galaxies.
What does this term refer to?
Is it just the difference between stars and gases velocities at different distances from the galactic centre? Or does it refer to another thing?</p>
<p>Thanks in advance</p>

CC BY-SA 4.0
2024-07-26T18:00:10.390Z
Are you talking about velocities of galaxies or velocities of stars inside a galaxy?
Sten
CC BY-SA 4.0
2024-07-29T19:04:32.007Z
The previous version of the question was not very clear; now I tried to explain myself better
jack_O'Dim
CC BY-SA 4.0
2024-08-06T10:53:51.470Z
The question is substantially improved, and clearlhy answerable now. Boting to **leave open**.
uhoh
<galaxy><galactic-dynamics><velocity><kinematics>
What is galaxy internal velocity anisotropy?
jack_O'Dim
# What is galaxy internal velocity anisotropy?

(Asked by: username_0 on 2024-07-26)

I came across this term in this [paper](https://iopscience.iop.org/article/10.1086/310095/pdf), where the authors propose using galaxy velocity anisotropy to classify galaxies.
What does this term refer to?
Is it just the difference between stars and gases velocities at different distances from the galactic centre? Or does it refer to another thing?

Thanks in advance

**Tags:** galaxy, galactic-dynamics, velocity, kinematics
> **Comments:**
> **username_1**: Are you talking about velocities of galaxies or velocities of stars inside a galaxy?  
> **username_0**: The previous version of the question was not very clear; now I tried to explain myself better  
> **username_2**: The question is substantially improved, and clearlhy answerable now. Boting to **leave open**.  

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## 1 answers

### Answer by username_3 on 2024-07-26. Score: 1

*Isotropic* means *the same in all directions*. If all galaxies you observe move in random directions, their velocities are isotropic. If most galaxies appear to be moving in the same direction, then the velocity distribution is *anisotropic*, i.e. there is a preferred direction to the velocity vectors.

> **Comments:**
> **username_0**: I'm sorry, the previous version of the question was not very clear. Now I tried to explain myself better; it's not about galaxy groups or anything like that, more on the internal velocities of matter in a single galaxy  

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