Animation/visualization of galactic rotation rates (dark matter)

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Discussion Overview

The discussion revolves around the visualization and understanding of galactic rotation rates, particularly in the context of dark matter and the formation of spiral galaxies. Participants explore how galaxies maintain their structure despite stars rotating at similar rates, and seek animations or visualizations to illustrate these concepts over time.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses difficulty in visualizing how galaxies maintain their shape with stars rotating at similar rates, suggesting a tendency towards a more amorphous structure without mathematical modeling.
  • Another participant mentions being directed to the concept of "spiral density waves" as a potential explanation for the structure of spiral galaxies.
  • Several participants share links to animations and visualizations related to galaxy formation and dynamics, indicating interest in visual resources to aid understanding.
  • A participant clarifies that while stars may orbit at the same speed, they do not rotate at the same angular velocity, which affects their orbital periods.
  • It is noted that the spiral pattern in galaxies is generally considered to be a density wave, with stars and gas passing through arms, leading to temporary compression and star formation.
  • A book titled "Galactic Dynamics" is recommended for its insights into the formation of spiral structures, likening it to traffic jams.

Areas of Agreement / Disagreement

Participants generally share an interest in visualizing galactic dynamics and the role of dark matter, but there is no consensus on the best methods or resources for achieving this understanding. Multiple viewpoints on the nature of spiral structures and the effects of dark matter remain present.

Contextual Notes

Some participants highlight the complexity of modeling gravitational effects in galaxies, noting that each "point" in simulations represents a significant mass, which complicates calculations. The discussion also reflects varying levels of familiarity with the underlying physics and mathematics involved.

Who May Find This Useful

This discussion may be useful for individuals interested in astrophysics, particularly those looking to understand galaxy formation, dynamics, and the implications of dark matter in these processes.

Peeter
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I was reading the wiki page on dark matter, and have trouble visualizing how galaxies keep their shape if most of the stars rotate at the same rate. If I try to imagine this (ie: without any sort of math modelling of the gravity interactions involved) I picture everything just merging into a big amorphous disk instead of shapes like spirals.

Does anybody know of a nice animation or visualization of long term effects of a gravity model of a spiral galaxy? Ideally I'd like to see how the rotation would look over time with and without the dark matter distribution.
 
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I posted this on an astronomy forum that I found associated with the awesome "astronomy cast" podcasts. There I was recommended to look for info on "spiral density waves in galaxies" and found something pretty close to what I was looking for. Will mark thread as solved.
 
Peeter said:
...Does anybody know of a nice animation or visualization of long term effects of a gravity model of a spiral galaxy?..
I don't think these are exactly what you are looking for but these might help.

Formation of a spiral galaxy:
http://www.youtube.com/watch?v=MEEd3oOf9To&feature=related

A Galaxy is born:


Formation of a Star Cluster:
http://youtube.com/watch?v=GoQ08ONholQ

.. and of course, the Dark Matter Bullet Cluster video:
http://www.slac.stanford.edu/~jwise/research/movies/HiResBullet.mov
 
Last edited by a moderator:
thanks, those were interesting to watch. It's kind of amazing to see the dynamics of such large scale structures visualized. Looking at pictures of galaxies I never thought of them as very dynamic structures, whereas there's a massive amount of complex motion involved, with little galaxies forming and being absorbed. Modelling one of these must be interesting. Even just considering gravitational effects it's a big calculation, but when you add in the facts that each of the "points" is potentially a big nuclear engine it's quite phenomenal!
 
Peeter said:
I was reading the wiki page on dark matter, and have trouble visualizing how galaxies keep their shape if most of the stars rotate at the same rate. If I try to imagine this (ie: without any sort of math modelling of the gravity interactions involved) I picture everything just merging into a big amorphous disk instead of shapes like spirals.

Note that although stars orbit at the same speed, that doesn't mean they rotate at the same angular velocity, so stars closer to the centre still have shorter orbital periods than stars further out.

Also, the spiral pattern is generally considered to be a density wave. Stars and gas actually pass through arms, and the gas gets temporarily compressed as it passes through, which causes the star formation that makes spiral arms bright with lots of young O/B stars. Does that help you to visualise what's going on?

Peeter said:
Does anybody know of a nice animation or visualization of long term effects of a gravity model of a spiral galaxy? Ideally I'd like to see how the rotation would look over time with and without the dark matter distribution.

If you google "galaxy animation" you should find a bunch pretty easily. That or search for universities that do galaxy simulations, and find the animations on their webpages.
 
AstroDave said:
Does that help you to visualise what's going on?

Yes, thank you Dave.
 
While not video, the book Galactic Dynamics (2008) is very helpful. It shows how the spirals and whatnot form due to something that looks like traffic jams. It's pretty cool stuff.
 

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