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Astronomers Find Star-Within-a-Star, 40 Years After First Theorized
derekmead writes: After 40 years, astronomers have likely found a rather strange celestial body known as a Thorne–Zytkow object (TZO), in which a neutron star is absorbed by a red supergiant. Originally predicted in the 1970s, the first non-theoretical TZO was found earlier this year, based on calculations presented in a paper forthcoming in MNRAS.
TZOs were predicted by astronomer Kip Thorne and Anna Zytkow, who wasthen postdoctoral fellow at CalTech. The pair imagined what might happen if a neutron star in a binary system merged with its partner red supergiant. This wouldn't be like two average stars merging. Neutron stars are the ancient remnants of stars that grew too big and exploded. Their cores remain small — about 12.5 miles across — as they shed material out into space. Red supergiants are the largest stars in the galaxy, with radii up to 800 times that of our sun, but they aren't dense.
TZOs were predicted by astronomer Kip Thorne and Anna Zytkow, who wasthen postdoctoral fellow at CalTech. The pair imagined what might happen if a neutron star in a binary system merged with its partner red supergiant. This wouldn't be like two average stars merging. Neutron stars are the ancient remnants of stars that grew too big and exploded. Their cores remain small — about 12.5 miles across — as they shed material out into space. Red supergiants are the largest stars in the galaxy, with radii up to 800 times that of our sun, but they aren't dense.
Just imagine a block of the most dense visible thing in the universe crashing into a star so large you could fit a good chunk of the inner solar system in.
I can't be the only person who'd want to watch that firework display.
Sounds like a mixed-drink with specific gravity setup...
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I was thinking the same thing, it would be an interesting event to witness. The only sad thing about living when we do, is we will never get to watch solar collisions from under 100 AU.
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- Is the research reliable?
Well, the Monthly Notices of the Royal Astronomy Society is one of the longest running astronomy journals in the world, and, to my knowledge, has never done anything substantial to impugn its reputation. It also has a comparatively large impact factor. All signs that the peer review is considered of good quality.
- How can such a thing be stable? Is there any particular process that keeps one star inside the other?
Why wouldn't it be stable? More gravity means more fusion, not less.
The theory says it's a companion star that goes nova, and then is gradually de-orbitted into the larger gas giant.
- What even /is/ such a body? If you were to travel from the outside to the midpoint of the body, would you encounter two barriers of destructing heat, with some emptiness (I'd like to say "vacuum" but of course space is not exactly a vacuum) in between?
Or is it actually just something entirely unlike what you would imagine when someone says "star within a star"?
Oh, and just now I realize you hadn't read the summary. It's a neutron star inside a star. A neutron star is essentially a block of neutronium(essentially a gigantic neutron only nucleus) with some attached hanger on high energy plasma around.
It lasts for several hundred thousand years but the red giant is eventually absorbed into the neutron star which becomes a slightly larger neutron star or possibly a black hole.
So the red giant is just a big meal that takes a while to eat. But if you look around enough, you can find one in the middle of its course.
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One is a neutron Star. So a object multiple times more dense than the Sun but only a 5-15 miles wide. The other a red giant (when our Sun becomes a red giant it'll be as big as Earth's orbit). So the first barrier you would cross working for the middle is a iron polymer a million times stronger than steel as you crossed out of the tiny tiny neutron star into the absolutely enormous red giant. An analogy would be a BB gun pellet inside of a balloon.
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^^^ That's a place where "average" can be quite deceiving. The sun's atmosphere is rarefied but its core's density is up to 150 g/cm3, or 150x that of water.
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Yeah I clicked through to the article. No idea why I did that but:
It's red supergiant with too much lithium, molybdenum and other metals. There's 'something' in there.
Gravity keeps one star inside the other, as in, the neutron star fell into the supergiant. It sank to the center.
Around the surface of the neutron star is now where the 'core' of the red supergiant is, still burning hydrogen (or was it helium?) as a red supergiant should.
Sounded like some subtle measurements to distinguish this one from all the other red supergiants they looked at.
I should get karma for this. Just sayin'.
That would be a bummer man. Let's go with the star in a star thing. Almost as cool as guns that shoot guns.
...a BB gun pellet...
Typical scientist. Explain away all these "hard-to-understand" principals, but totally crash on a simple analogy. ;)
I'm assuming that you meant "BB".
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I think it should have been multiple times more massive then the sun.
Actually if the neutron star is in the center then the added gravity in the layer near it will cause greater fusion, when increases pressure causing the layer to expand outward. As it expands it encounters the next layer, which will absorb the energy and begin the same process on a smaller scale. So forth untill it reaches the photosphere. In the mean time the inner layer has transfer excess momentum, has cooled some from it's expansion, it rate of fusion decreases and it collapses to the point it was before, actually a little less. Then it begins the process again. The result is a slightly variable vibrating star. I wonder is it might be possible to create sympathetic vibrations that way. Probably not, It would be most interesting.
There is however one major flaw in the above model. Supposedly the neutron star was once part of binary system with the red giant. It is not suddenly going to appear in the core. Instead, it is going to slowly absorb material until it's orbit "decays" into one below the photosphere. I don't know if parts of star will be eject when gases impinge. Certainly tides on the star will help. ( Also the neutron star will generate tides on the giant affecting it's weather. )
So the neutron star will act like a giant stirring, slowly stirring up layers of the gas. The romantic in me would like to think this is going to generate some massive and quite interesting effects. The realist though says that any effects will probably be small and hardly noticeable after a few millennium.