5 ms·
> Gas physics suggests you shouldn't be able to make objects with the mass of Jupiter on their own This is new to me. I always imagined that on the way to star
by jl6 3y ago
> Gas physics suggests you shouldn't be able to make objects with the mass of Jupiter on their own
This is new to me. I always imagined that on the way to star formation the coalescing gas would start as a small central mass and grow larger and larger, passing through a Jupiter-mass stage and eventually igniting. I also imagined that the process could involve several small central masses which would variously end up as binary/ternary/++ star systems and all manner of brown dwarves/planets/debris in orbit around the center. And I also imagined that this process would stop at whatever point the gas supply ran out.
So in my mind, a pair of Jupiters would be a failed binary star system that didn’t quite have enough mass to achieve ignition as a pair of stars.
But maybe I’m missing a gas-physics reason why it couldn’t happen like this.
- macintux 3y agoIt would be interesting to hear more. My only (completely uneducated) guess is that if you don’t have enough gas to form a star, the density isn’t sufficient to begin the process at all.
- misja111 3y agoThat's a fascinating thought actually. Why does a mass of gas always have to materialize into a solar system? Why not into one or more planets, if the amount is too low? Or also the other way around: what if there is so much gas that it's too much to fit into a single star, what would it materialize into then? A twin star solar system, or something else?
- samus 3y agoThere is no "too much". The result would simply be a larger star.
- dougmwne 3y agoThere is a theorized “Eddington Limit” that stars can only grow to a certain mass before the power of their fusion reactions counterbalance gravity and they blow off additional matter instead of absorbing it. It’s approximately a few hundred solar masses.
- liotier 3y agoHow does the Eddington Limit relate to black hole formation ? Does it means that accretion is slow until the star's matter has finished fusing ?
- samus 3y agoBlack holes form when there is insufficient force to counter accretion and subsequent compression by gravity. There are a few forces that act as a counter: - thermally generated pressure as a result of exothermic reactions (like nuclear fusion), - Coulomb pressure (atomic nuclei opposing each other), or - quantum-mechanical degeneracy pressure (keeps white and brown dwarfs and neutron stars from collapsing)
- andrewflnr 3y agoIf you have a really big gas cloud I think you just get multiple stars, not particularly in a "solar system". There are some telescope images of stellar nurseries where you can see several young stars in the same gas cloud.
- dotancohen 3y agoYou can see the Pleiades with the naked eye.
- ngcc_hk 3y agoSurprise so many uncertainties of the age and even distance of them https://en.wikipedia.org/wiki/Pleiades https://en.wikipedia.org/wiki/Pleiades
- dotancohen 3y agoMost of the distance measurements are within a percent of each other, except for a single survey with is 10% off all the others. That is not such a large uncertainty as to be of significant note.
- mesebrec 3y agoStars are formed when clouds of gas and dust collapse into themselves. Either the cloud is big and dense enough to collapse into a star, or it will remain as a cloud. Our Jupiter was created when, during the collapse, other forces pulled part of the collapsing cloud away from the sun, into a stable orbit. > Stars form when the dust and gas clouds in a nebula cool, progressively fragment and eventually collapse under their own gravity. The smallest stars are about 80 Jupiter masses, below which the core is not dense enough to fuse hydrogen, but smaller objects can coalesce through the same process, including dimly glowing brown dwarfs – sometimes called failed stars – and, below about 13 Jupiter masses, planetary-mass objects. But theoretical predications suggest that the lower boundary for an object forming through a star-like gravitational collapse is about three to seven Jupiter masses. https://www.theguardian.com/science/2023/oct/02/jumbos-jupiter-mass-binary-objects-discovery-orion-nebula-new-astronomical-category https://www.theguardian.com/science/2023/oct/02/jumbos-jupit...
- mesebrec 3y agoDon't quote me on this but I think the limiting factor is that gravitational pull needs to be stronger than the expansion of the universe.
- danparsonson 3y agoThe expansion of the universe isn't really related to the formation of individual stars.
- mbrumlow 3y agoBut it sounded cool.
- danparsonson 3y agoThat it did
- jl6 3y ago> Either the cloud is big and dense enough to collapse into a star, or it will remain as a cloud. Why is this? Why can’t a small molecular cloud coalesce into small objects?