I never really heard about such occurencies and now asked my self if this could be possible.

So could there be systems with a star (or black hole) that is so heavy that other less heavy stars are orbiting it?

I could imagine 2 things that would both be a no.

First, this isn't possible for so heavy objects they would just be affect each other and not one beeing a stable center.

Or the second option is this wouldn't be possible withing a galaxy since this would just form a galaxy.

So except the 2 named scenarios, could this happen within a galaxy or would this jsut form something diferent?

  • $\begingroup$ http://en.wikipedia.org/wiki/Star_system $\endgroup$ – lemon Apr 2 '16 at 10:03
  • $\begingroup$ so there are just the 2 cases possible which I named? A star system meaning stars orbiting each other or stars orbiting a center, beeing a galaxy? $\endgroup$ – Zaibis Apr 2 '16 at 10:04
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    $\begingroup$ What does the first sentence of that wiki article say? Also, the distinction between 'A orbits B' versus 'A and B orbit each other' is ill-defined since they both orbit their common centre of mass. $\endgroup$ – lemon Apr 2 '16 at 10:08
  • $\begingroup$ the first sentence says "orbiting each other" what sounds for me like the first case I emntioned in OP. Correct me if I udnerstand that wiki artcile wrong :) $\endgroup$ – Zaibis Apr 2 '16 at 10:09
  • $\begingroup$ Castor for example is a sixtuplet system where stars orbiting stars orbit stars orbiting stars, see animation at youtube.com/watch?v=bV3MrXwOU0k&t=10s $\endgroup$ – Yukterez Apr 3 '16 at 2:36

There are binary stars (orbiting around their centre of mass) and there are stars orbiting around neutron stars or black holes (or rather, again, around the centre of mass of the system).

I don't think many stars would orbit a black hole, except... There is the black hole at the centre of most galaxies, including our own. Lots of stars orbit around that - in fact the entire galaxy does. It is possible that some very small stars orbit a massive star or black hole, but I am not aware of the existence of such a system. The stars would have to be very small, possibly even brown dwarfs, as otherwise the centre of revolution of the system would be way outside the primary (as it is in the Pluto/Charon system), and your requirements would no longer be met.

SO yes, there are stars orbiting other things, be they stars, neutron stars, or black holes.

  • $\begingroup$ But my question wars about it beeing possible ecept the cases I named (beeing systems with multiple stars in tis center or systems with stars orbiting its center of mass beeing a galaxy) So I'm asking for a center of mass orbiting a galaxy, while itself is orbited by stars. $\endgroup$ – Zaibis Apr 2 '16 at 10:08
  • $\begingroup$ There cannot be "multiple stars in the centre" - they orbit their centre of mass. Are you talking about a kind of "planetary system", with one heavy star in the middle and others orbiting it? I don't think such a system exists, but it is possible. The orbiting stars would have to be very small (brown dwarfs?), otherwise they won't be orbiting around anything like the centre. Most stars are 0.1 to 10 solar masses, so the centre of mass is likely to be well away from the centre. $\endgroup$ – hdhondt Apr 2 '16 at 10:22
  • $\begingroup$ yep exactly thats what I was thinking about motivating me to ask the question. if there could be something like a planetary system just with stars. which may have their own moon like planetary system (or not) $\endgroup$ – Zaibis Apr 2 '16 at 10:25
  • $\begingroup$ I'm not aware of something like that existing, but it is possible if the orbiting stars are small enough. If they're average size, then there is no "centre", just as there is no centre in the Pluto/Charon system. $\endgroup$ – hdhondt Apr 2 '16 at 10:46
  • $\begingroup$ edit that into your answer and I can accpet it $\endgroup$ – Zaibis Apr 2 '16 at 11:01

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