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Stars rotating around planets
- Thread starter Cooky
- Start date
Cooky
Veteran Member
Apparently not. That would be a planet.
Planets are made of stuff that was made in dying stars. You could say they used to be stars or, at least, part of stars.
Stars, themselves, are largely plasma.
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ecco
Veteran Member
How scientists took the first picture of a black hole
How scientists took the first picture of a black hole
Cooky
Veteran Member
Largely plasma due to reactions?
Subduction Zone
Veteran Member
No, too small and they will not ignite. Look at Jupiter. Big massive, but not massive enough to cause fusion to begin. And in the case of an object on the cusp of being able to fuse hydrogen its fusion would have to begin almost immediately or not at all. Two factors cause fusion, heat and pressure. The smaller a star is that hotter it would have to be at the beginning to fuse. When stars, or planets for that matter, are formed they do start with a lot of heat. The potential energy that existed before the star was formed is changed to heat as it forms. So they do get a head start. After that they continually shed heat. Jupiter is still shedding heat from its formation. When measured it appears to be a large amount to you and me. In fact it gives off twice as much heat as it receives from the Sun. That heat is from residual heat of formation, continued generation of heat from potential energy as it cools and contracts, and from radioactive decay of minerals within it. But it was nowhere near big enough to become a star itself. I have read that it would have had to have been at least eighty times as large to begin and continue to fuse hydrogen.
Subduction Zone
Veteran Member
Plasma due to their temperature. Heat hydrogen enough and its electron gets in an orbit so far out that it becomes free.
Bob the Unbeliever
Well-Known Member
If an object is large enough? The combined gravity of the mass, causes it to collapse in on itself, and become...
.... a star. Or other similar structure.
Not a planet.
Edit: I was way too late to the parade, here... but I'll leave this up anyway
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Father Heathen
Veteran Member
Shad
Veteran Member
Rogue planets are a possibility but very hard to detect. A rogue planet can be ejected just due to gravitational forces in a solar system. No galactic collision is required.
Shad
Veteran Member
White (appearance) Yellow (category) Dwarf actually.
Twilight Hue
Twilight, not bright nor dark, good nor bad.
There probably would be if planets were ever bigger than stars that didn't 'ignite'. That would be a sight.
Good question though. It makes you think about it.
Twilight Hue
Twilight, not bright nor dark, good nor bad.
Captain Obvious. *Grin*
Well, stars are typically composed mostly of hydrogen with some helium mixed in. There are other elements, but in much smaller amounts.
Larger planets, like Jupiter and Saturn, are also mostly hydrogen and helium. We call such planets 'gas giants'.
Smaller planets like the Earth are mostly rocky. They don't have enough gravity to keep the hydrogen and helium bound to the planet (those elements are very light and tend to escape the atmosphere).
Once you have something large enough for fusion reactions to happen at the core, we call the object a star. Smaller objects, like brown dwarfs, can produce a lot of heat from compression, but not enough to start nuclear reactions.
The question of composition is tricky and depends a lot on the specific star or planet discussed. The primary difference, though, is having a size that is enough to get high temperatures and pressures that can start fusion in the core.
Habitability is a *very* different issue, though, having to do with things like distance from parent star, availability of liquid water, etc.
Yep. Type G2 spectral class.
Twilight Hue
Twilight, not bright nor dark, good nor bad.
You know that would lead to another interesting speculation. Would intense mass always result in fusion?
It got me thinking if black holes could actually be regarded as a star or planet?
Like this unusual beast that goes against conventional thought.
Stars can turn into black holes without a supernova
Cooky
Veteran Member
No. i was probably either high in class or staring at Rene Perkins butt. Maybe both.
Sky Rivers
Active Member
Mass, highly compressed? As for size? Jupiter? Maybe smaller?
Father Heathen
Veteran Member
well, anyway. As others have stated, stars are massively larger than planets.No. i was probably either high in class or staring at Rene Perkins butt. Maybe both.
Bob the Unbeliever
Well-Known Member
Well, I was going to ask about 'brown dwarf' and then? It hit me: google it yerself, ya lazy bum.
So I did. Interesting read on Wiki.
Brown dwarf - Wikipedia
Edit: Go read the short section, "Theory" on that wiki page-- it briefly summarizes the differences between a brown dwarf and a normal stellar object, including the reasons for one and not the other.
Planets, naturally, are all smaller even than brown dwarfs-- which are kind of a "half way" object between planets and stars-- too big to be called "planet" (and too hot anyway) but too small to have ignited hydrogen fusion in their cores. The heat from a brown dwarf will be from pressure do to compression, and any large atomic weight elements that naturally fission (assuming the dwarf is new enough, and was made from a cloud of dust that contains such things).
Cool beans!
Also: Look at White Dwarf stars...
White dwarf - Wikipedia
Edit 2: What is denser than the matter in a White Dwarf? (which are typically dense enough that a match box sized piece would weigh more than a loaded dump truck... )
A Neutron Star... so dense that a matchbox sized piece would weigh more than the
... angular momentum is still conserved, in the formation of neutron stars, so as the giant super-star collapses, it begins to spin faster and faster-- like an ice skater pulling her arms close to her body-- so fast, that some observed spinning objects are spinning at about 1/4 the speed of light at their surfaces... which would slow relative time ... so to a theoretical observer on such a thing? The universe would seem to be whipping by at a truly frenetic pace... Oh look over there! A galaxy is forming--wait-- nevermind--it's gone.
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