Comment on if jupiter gained enough mass to trigger fusion and ignite into a star...

• Apollo42@lemmy.world ⁨5⁩ ⁨months⁩ ago

  The moons would almost certainly fall into Jupiter or be thrown from its orbit if itsuddenly gained enough mass to become a star.

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  • SorteKanin@feddit.dk ⁨5⁩ ⁨months⁩ ago

    I assumed in this scenario that orbits would be left unchanged aside from orbital velocity - if we can magic Jupiter much bigger, we can magic the orbits too :P

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    • Apollo42@lemmy.world ⁨5⁩ ⁨months⁩ ago

      I mean if we’re talking magic now, then all bets are off haha

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      • SorteKanin@feddit.dk ⁨5⁩ ⁨months⁩ ago

        Not sure how else you would increase Jupiter’s mass that much :P

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• Skua@kbin.earth ⁨5⁩ ⁨months⁩ ago

  The sun and Jupiter are pretty close in terms of density, and Jupiter would need to get at least an order of magnitude heavier to start fusion. I think it's just a coincidence that the outward pressure of the sun's fusion makes these numbers roughly line up.

  Thirteen Jupiters seems to be a commonly-given lower limit for fusion, so let's go with that. To increase mass by thirteen times while maintaining density (and assuming the whole thing is a perfect sphere, which it obviously isn't), Jupiter needs to increase its radius by a factor of about 2.35. This increases its equatorial radius to about 168,000 km, which does swallow up the three innermost moons, but leaves the four big ones alones

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  • Davel23@fedia.io ⁨5⁩ ⁨months⁩ ago

    For the four remaining do you know if they'd be clear of the Roche Limit?

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    • Skua@kbin.earth ⁨5⁩ ⁨months⁩ ago

      Oh, good call, I didn't think of that! Assuming I did my sums right, the Roche limit probably destroys the fourth innermost moon, but it still leaves the big four (which are the fifth through to ninth in ascending order of size of orbit). They're quite substantially farther out than the prior four

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• SzethFriendOfNimi@lemmy.world ⁨5⁩ ⁨months⁩ ago

  They’re in an orbit that works with jupiters current mass. If Jupiter gained enough mass to trigger fusion then I would think that many of them would with fall in or be slung out of orbit.

  I’d be interested to see if anybody has done the math though to see how that would all play out.

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• Rhaedas@fedia.io ⁨5⁩ ⁨months⁩ ago

  Aside from the orbit change mentioned, the huge increase in stellar radiation would certainly blow much of the lighter elements including water away. The core and some residuals that might remain on the far sides would be all that's left.

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