- #1
VladZH
- 56
- 1
Do all stars orbit around the black hole in the same plane? Or some stars can have the same orbital radius but slightly different orbital inclinations?
Inclinations of star orbits in the Milky Way
Click For Summary
Discussion Overview
The discussion revolves around the inclinations of star orbits in the Milky Way, specifically whether all stars orbit around the central black hole in the same plane or if some can have varying inclinations. It touches on the complexity of star distributions in different galactic structures, including the disc, bulge, and halo of the galaxy.
Discussion Character
- Exploratory, Technical explanation, Conceptual clarification, Debate/contested
Main Points Raised
- Some participants question whether all stars orbit the black hole in the same plane or if there are variations in orbital inclinations among stars with similar radii.
- One participant highlights the existence of a galactic spheroid, suggesting that many stars exist outside the galactic plane, complicating the understanding of star orbits.
- Hypervelocity stars are mentioned as potentially having trajectories that do not relate to the center of mass of the galaxy, indicating a complexity in their motion.
- Another participant outlines their understanding of spiral galaxies, noting that stars in the disc have slight inclinations, while stars in the bulge can have any inclination, and questions the existence of stars that follow a galaxy without orbiting a center.
- It is noted that even stars that appear to be in the galactic plane do not orbit in flat circles, as they move up and down through the plane.
Areas of Agreement / Disagreement
Participants express differing views on the nature of star orbits, with no consensus reached regarding the inclinations of stars in relation to the black hole or the existence of stars that do not orbit a center.
Contextual Notes
Some claims depend on the definitions of orbital motion and the structures of galaxies, which may not be fully resolved in the discussion.
- #2
jim mcnamara
Mentor
- 4,789
- 3,852
It is more complex than that: https://en.wikipedia.org/wiki/Spiral_galaxy#Galactic_spheroid
The galactic spheroid is a ball-shaped halo of stars that extends in all directions, not just the galactic plane. This is a LARGE number of stars out there.
In terms of the galactic core: https://en.wikipedia.org/wiki/Sagittarius_A*
The black hole is part of a small clusters of smaller stars with orbits thought to be in many different highly elliptical orbits due to the BH there.
Hypervelocity stars are 'rogue' stars with very high velocities relative to all their neighboring stars.
https://www.space.com/19748-hypervelocity-stars-milky-way.html
There was a paper published lately about the origin of some of these hypervelocity stars: the Lesser Magellanic Cloud - smallish galaxy that orbits the Milky Way. Preprint only so far:
https://arxiv.org/abs/1704.01373
Kind of cool!
The galactic spheroid is a ball-shaped halo of stars that extends in all directions, not just the galactic plane. This is a LARGE number of stars out there.
In terms of the galactic core: https://en.wikipedia.org/wiki/Sagittarius_A*
The black hole is part of a small clusters of smaller stars with orbits thought to be in many different highly elliptical orbits due to the BH there.
Hypervelocity stars are 'rogue' stars with very high velocities relative to all their neighboring stars.
https://www.space.com/19748-hypervelocity-stars-milky-way.html
There was a paper published lately about the origin of some of these hypervelocity stars: the Lesser Magellanic Cloud - smallish galaxy that orbits the Milky Way. Preprint only so far:
https://arxiv.org/abs/1704.01373
Kind of cool!
- #3
VladZH
- 56
- 1
Thanks for reply. What I figured out about spiral galaxies:
1) The stars in a disc incline slightly
2) There is a center bulge where stars can have any inclinations
3) And a galaxy has a halo where stars are gathered in globular clusters orbiting a galactic center
Are there stars just following a galaxy, not orbiting a center?
1) The stars in a disc incline slightly
2) There is a center bulge where stars can have any inclinations
3) And a galaxy has a halo where stars are gathered in globular clusters orbiting a galactic center
Are there stars just following a galaxy, not orbiting a center?
- #4
jim mcnamara
Mentor
- 4,789
- 3,852
I do not know. It appears to me: Hypervelocity stars can have trajectories or orbits unrelated to the center of mass of a galaxy. Per the last paper cited above.
- #5
newjerseyrunner
- 1,532
- 637
Even a star that is more or less in the plane, does not orbit in a flat circle. Stars bob up and down through the galactic plane, sort of like this:
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