four suns of HD 98800 (APOD 30 July 2007)

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Expand view Topic review: four suns of HD 98800 (APOD 30 July 2007)

Chaotic planets? (30 July image)

by Cherax » Tue Jul 31, 2007 3:31 am

In a two - or even more a four sun system, I presume the orbits of planets might look really bizarre. Has anybody modelled this?

by Qev » Mon Jul 30, 2007 8:47 pm

I believe that each pair of stars consists of a K-type and an M-type star, all of which are 'pre-main sequence stars'. The Ba component (K7) is 0.7-0.95 M(s), and the Bb component (M-type) is 0.5-0.65 M(s). The larger Aa component (K5) is around 1.1 M(s), and I can't seem to find anything about the mass of the Ab component.

by bystander » Mon Jul 30, 2007 8:04 pm

I would think the rings would be elliptical, much the same as the orbits of the planets and asteroids around Sol. One focus of the ellipse would be the center of mass of the inner pair of stars. The motion of the inner pair around their center of gravity would probably perturb the rings, but stability could probably be acheived. Modeling it mathematically would probably be quite a chore.

I think it's strange that only one pair has rings. Maybe the other pair has fainter rings like Neptune and Uranus.

Ringworlds

by oldgeezer » Mon Jul 30, 2007 4:37 pm

Its funny that Larry Niven never told us in RINGWORLD that there were two suns!

by rigelan » Mon Jul 30, 2007 4:25 pm

Relooking at the picture, it shows two dust rings. The outer one might be fine, if as you said, with much less defined borders. But I would venture a guess that the inner one would not be able to exist in such a stable orbit.

by rigelan » Mon Jul 30, 2007 4:20 pm

If you get out far enough on the orbit, the two stars act as one point mass. And if the dust pattern is as far out as the picture shows, it could very well be similar to a circular dust ring. It might have eddys, but would be generally circular.

It would not be circular, however, if the other pair of stars happened to sweep closely to the dust ring.

by orin stepanek » Mon Jul 30, 2007 12:18 pm

I'M sure the star pair orbit each other. I'd be curious as to what the seasons would be like on the planets that may be orbiting them. Probably from the furnace to the deep freeze! :D
Orin

by l3p3r » Mon Jul 30, 2007 6:31 am

http://apod.nasa.gov/apod/ap070730.html

It is incredible that we actually have observed a system like this to exist! Be a good place for a hotel :)

I have doubts about the actual nature of the dust rings as well, for starters I very much doubt it would have such well defined edges.

Does anyone have any info on the relative masses (solar masses) of each start in this system? I had a quick look at some of the links but couldn't find anything...

four suns of HD 98800 (APOD 30 July 2007)

by AZJames » Mon Jul 30, 2007 6:01 am

In today's artist conception of the quadruple star system HD 98800
http://apod.nasa.gov/apod/ap070730.html
the dust clouds appear to be in a circular orbit. I'm wondering, however, whether dust orbiting any double star system ought to exhibit a more complex pattern. I have no idea what that pattern would look like.

Nevertheless, it's a very striking image.

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