Questions tagged [stellar-dynamics]
10 questions
20
votes
1 answer
Do gravitational many-body systems fall apart eventually?
Imagine an $N$-body problem with lots of particles of identical mass (billions of them).
I saw several simulations on the Internet, where the particles first form small clumps, then bigger clumps, then finally one huge globular cluster like clump…
Calmarius
- 8,428
6
votes
1 answer
What prevents stars in globular clusters from merging over time to form a black hole?
Globular clusters are apparently very very old, and the density of these clusters appears to increase as one approaches the center of a cluster. Orbits are bound to be chaotic, since there is no particular orbital plane, unlike a spiral galaxy. From…
Cyberherbalist
- 559
5
votes
2 answers
Population I and II stars
I have been thinking about the formation of the galaxy. I can easily understand that old, low-metallicity stars are in the halo, but I'm missing something when it comes to the disk.
If slowly-rotating gas settled into the disk, formed stars, then…
Gigi Giles
4
votes
1 answer
What is the most commonly used density model for globular clusters?
It is possible to model a globular cluster using a number of different density models:
Plummer model
King model
Isothermal sphere
. . .
They all have advantages and disadvantages, depending on whether you want to fit a law to a specific cluster or…
HDE 226868
- 10,934
3
votes
1 answer
Population II star orbits
Ok so they are usually found in globular clusters and can consider orbits in a static spherically symmetric gravitational field. The orbits are randomly scattered. Would these be considered to be collisional or collisionless orbits?
SFL
- 57
3
votes
2 answers
Why do clusters of stars eventually dissipate?
Why don't the stars in a star cluster attract each other gravitationally, forming one big star? What causes a cluster to disperse the stars in it?
james
3
votes
2 answers
What are the proposed models for the existence of bars in galaxies?
What are the current explanations and models for the formation of a central bar in some galaxies, and what is the difference that can produce a barred galaxy instead of a spiral one ?
Stefano Borini
- 3,970
1
vote
2 answers
How does the energy of a solar flare propagate?
Does it radiate outward, spherically, or is it more directed? Is there some opening angle? Is it more complex than this?
user213717
- 11
1
vote
2 answers
Could a viable solar system work with a cluster of dwarf stars in center? And would it last longer than a single stellar mass star?
So, I was watching various sci channel shows, and they touch on how extremely massive stars live only 100k years, vs the sun which lives ~10 billion years, and dwarf stars live some unspecified time longer.
So, lets say you have a galactic…
Charles Teague
- 367
0
votes
1 answer
Intuition for the velocity ellipsoid
The velocity ellipsoid is a quantity that comes up in the kinematic modelling of N-body systems, e.g. stars in a galaxy. The velocity dispersion tensor describes the local distribution of velocities at each point:
\begin{align}\sigma_{ij}^2({\bf…
Kyle Oman
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