Castor Binary (6 star hierachy) system, how is it stable?

In summary, the video shows the orbits of the 6 stars that comprise of the Castor system. Castor C (the barycenter of Castor-Ca and Castor-Cb) enters the fastest part of its orbit (between seconds 10 and 12.5 in the video), Castor B occasionally becomes closer to Castor C than Castor A. However, when Castor B becomes within very close proximity of Castor C, why doesn't Castor AB (the barycenter of Castor A and Castor B) dissolve?
  • #1
Edward Solomo
72
1
Hello, I made this video from Celestia showing the orbits of the 6 stars that comprise of the Castor system:

http://www.youtube.com/watch?v=wIWdfFG7eKw&feature=youtu.be

However, I noticed that when Castor C (the barycenter of Castor-Ca and Castor-Cb) enters the fastest part of its orbit (between seconds 10 and 12.5 in the video), Castor B occasionally becomes closer to Castor C than Castor A.

So if Castor B becomes within very close proximity of Castor C, why doesn't Castor AB (the barycenter of Castor A and Castor B) dissolve?

I understand that the differences in masses my account for it, as Castor A and Castor B are main sequence stars (Type A), and Castor C is a dwarf star, but it is still hard to imagine that Castor B wouldn't be thrown off course when the binary dwarfs (Castor Ca and Castor Cb) are practically next door.
 
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  • #2
WHat makes you think this system is stable? It might well eject a star or two over the next billion years.
 
  • #3
Perhaps you mistakenly think that Celestia simulates gravitational interactions. It does not. Whatever you set as the orbital parametres, will remain unchanged forever.

What you should do is use one of gravity simulators:
http://www.gravitation3d.com/
http://www.orbitsimulator.com/gravity/articles/what.html
http://www.andersson-design.com/gravity/

Be mindful of their limitations, though. For example, setting too high a time rate might erroneously destabilise the system.
 
  • #4
Vanadium 50 said:
WHat makes you think this system is stable? It might well eject a star or two over the next billion years.

Seeing that Castor C (Castor-Ca and Castor-Cb) complete their orbit every 10,000 - 11,000 years, I would consider a 2 billion year time frame to be relatively stable
 
  • #5
In general, I'm surprised that this system could survive even a single 10,000 cycle, and be stable enough to nearly repeat the same pattern again over the next 10,000 years.

I see Cantor AB dissolving on the first pass of Castor C, and all of them spiraling off into space.
 
  • #6
(disregard my previous post. Somehow I thought you were making a fictional system from scratch)

Have you got some more recent data that would suggest the exact configuration that you used in your visualisation?

This paper:
http://articles.adsabs.harvard.edu//full/1989SvAL...15..237A/0000240.000.html
concludes that it's quite likely(~60%) the C components are on a hyperbolic orbit(i.e., single passage), and stable elliptical with (~40%). The probability of an unstable system is very low.

Furthermore, if you look at fig.2(showing most likely configuration) from the above article, the closest approach distance of ~800AU is still huge, which should explain the stability.
 
  • #7
Why did you add music :(.
Now the video is blocked in Germany.
 
  • #8
mfb said:
Why did you add music :(.
Now the video is blocked in Germany.

Because I also happen to be an active Libertarian in the United States, are you serious? ; and since I'm also a music major (clarinet, piano and composition/arrangement have been my majors), how do they know it's not my music (even though it isn't) ?


EDIT:
Damn, you are serious:

http://en.wikipedia.org/wiki/Blocking_of_YouTube_videos_in_Germany


EDIT: No music
I'll upload a new one without music.

http://www.youtube.com/watch?v=QCV15tKFcvE&feature=youtu.be

Shame, it was a medieval chorus
 
Last edited:
  • #9
Thanks.
It would be interesting to see the 3-dimensional distances. As those stars can be separated in telescopes, their 3-dimensional positions and motions should be known.
 
  • #10
mfb said:
Thanks.
It would be interesting to see the 3-dimensional distances. As those stars can be separated in telescopes, their 3-dimensional positions and motions should be known.

I'm working on a 3D simulation right now in the Starcraft Galaxy Editor. Yes I know that sounds funny, but the video game [Starcraft II] engine is actually one of the best simulators I've ever encountered, even though it was never intended to be one.
 
  • #11
I only see 3 stars. is each star in the video actually a pair of stars? the resolution is pretty grainy on my screen to differentiate.
 
  • #12
DHF said:
I only see 3 stars. is each star in the video actually a pair of stars? the resolution is pretty grainy on my screen to differentiate.

Yeah I could zoom in if I wanted and you'd see the binary systems.
 
  • #13
it sounds fascinating. I couldn't find it in Celesta though. It only comes up as a single star system. what are the coordinates?
 
  • #14
DHF said:
it sounds fascinating. I couldn't find it in Celesta though. It only comes up as a single star system. what are the coordinates?

You'll have to download the Castor 6 pack (addon).
 
  • #15
gotcha thanks
 

1. What is a Castor Binary (6 star hierarchy) system?

A Castor Binary system is a complex stellar system that consists of six stars, arranged in a hierarchical structure. The system is named after the brightest star in the system, Castor, which is located in the constellation of Gemini.

2. How is the Castor Binary system formed?

The formation of the Castor Binary system is still not fully understood. However, it is believed that the system was formed from a large cloud of gas and dust that collapsed under its own gravity and fragmented into multiple stars.

3. What makes the Castor Binary system stable?

The Castor Binary system is considered to be stable because of the delicate balance between the gravitational forces acting on the stars and their individual motions. The gravitational pull of each star is counteracted by the movement of the other stars, keeping the system in a stable orbit.

4. How do the stars in the Castor Binary system interact with each other?

The stars in the Castor Binary system interact with each other through gravity. Each star exerts a gravitational force on the other stars, causing them to orbit around each other. The closer the stars are to each other, the stronger their gravitational pull.

5. Are there any other systems like Castor Binary?

Yes, there are other multiple star systems similar to Castor Binary in the universe. These systems are known as multiple star hierarchies and can consist of any number of stars, ranging from two to dozens. However, the Castor Binary system is one of the most well-known and studied examples of such a system.

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