Why do stars form in the coldest ( or at least colder) parts of space?
from the site linked above
Is it just that “whopper” stars are born in the coldest parts of space, or is this true of all stars?
Because the warmest places already are stars.
Here’s a page on the conditions of star formation.
You actually need the temperature of the cloud to be on the “cool” side, to collapse and become a star, otherwise the molecules aren’t bound by their mutual gravity.
Thanks Bytegeist!
I guess I should have figured out that new stars form where old stars ain’t.
How do you get binary star systems then? Rogue stars travelling about and get caught? Or can two stars form in the same system?
With a bit of a different start could Jupiter have beceome a star instead of a planet? I know it’d have a ways to go yet but it has a good start (not counting black monoliths swarming Jupiter and turning it into a star).
Short answer: I don’t know.
However, I don’t think a binary star system needs to have one extant star in place while another forms nearby.
Also, from the link in the OP
emphasis mine
…maybe this is the next binary star system or, under the right conditions, a star and a gas giant type planet…
IIRC, it depends on what sort of binary system you end up with. You get some binary systems where an old, large star captures a star passing by it. However, a lot more binary stars are found in what are termed star clusters, basically, big groups of stars that formed at roughly the same time, and due to the larger number of stars there, there’s more probability of two young stars interacting with each other to make a binary system, or for two stars that form at the same time close to each other to basically capture each other as they grow.
You can also get triple star systems, and in at least one case, two pairs of binaries orbiting around each other, Epsilon Lyrae (or the Double-Double Star).
In terms of physical chemistry, the only difference between a small star and a gas giant or super-Jovian planet is size. To become a star, an accretion of hydrogen and helium with small admixtures of higher elements needs to be a large enough size where its core will reach the minimum temperature and pressure for fusion. This is somewhere between 10X and 100X Jupiter size.
Protostars are known to glow, dimly, or radiate in the infrared, as a result of gravitational energy converted to heat. Essentially, the infalling mass of the star compresses and hence heats up the core. While the “observable surface” (i.e., the cloudtops) of Jupiter is well below zero Celsius, its temperature is about 100 K higher than it “should be” purely from absorption and re-radiation of sunlight falling on it. Jupiter can therefore be regarded, from the stellar evolution perspective, as an extremely small and cold protostar, stalled at the gravitational-heat phase.
Most multiple-star systems are born that way, and as others have stated, the formation of Jupiter differs only quantitatively, not qualitatively, from the formation of a star. While it’s possible for an existing star system to capture another star, it’d be unlikely, and it would require at least two stars in the system to begin with: If there’s only one, then the “new” star would just leave at the same speed it came in, on a hyperbolic orbit. And I don’t think (though I’m not certain) that you can form a completely stable stellar system by capture: If a system is such that it could have been formed by capture, then it’s also such that it could eject one or more members some time in the future.
Multiple star systems are quite common, incidentally; I’ve heard of systems with six or more stars (Castor, one of the Gemini twins, is a 6-star system). epsilon Lyrae is notable only in that it can reasonably be resolved with a small telescope, such as an amateur might use (many binaries can only be detected spectroscopically).
Cool. I never actually realised that. I knew that binaries were fairly common, but wasn’t too sure about multiple star systems. Guess its what happens when your entire field of specialism deals with galaxies as the most basic unit!