Fate of Jupiter when our sun dies

Question

Five billion years from now, the sun will have grown into a red giant star, more than a hundred times larger than its current size. While this metamorphosis into the giant star will change the solar system, scientists are unsure what will happen to the third rock from the sun.We already know that our sun will be bigger and brighter, so that it will probably destroy any form of life on our planet. But whether the Earth's rocky core will survive is uncertain. At the end of its evolution, seven billion years from now, the sun will become a tiny white dwarf star.

_{(by Leen Decin, professor at the KU Leuven Institute of Astronomy (source))}

When our sun runs through its last phase of its life it will expand and tremendous solar flares will flow out of it. Earth will end up getting baked and will lose its atmosphere.

Jupiter is a gas giant planet, a GAS GIANT. So,

What will happen in Jupiter? Will it evolve into a star since it contains hydrogen and helium? How will the atmosphere deal with the extreme heat?

Answer 1

Jupiter won't evolve into a star, it is not big enough. A body would have to have about 80 times the mass of Jupiter for there to be significant fusion occurring in the core. The end of life of the Sun won't change the mass of Jupiter.

Jupiter will continue to orbit the Sun as it evolves into a red giant. Although the solar wind will be much much more powerful, it won't have a significant effect on the overall mass of Jupiter.

When the Sun loses its outer layers it will, in the last million years or so of its life, lose about half its mass. This will have a significant effect on the orbit of Jupiter, causing Jupiter to migrate outwards. While it is possible that some planet's orbits may become unstable and get ejected from the solar system, it is more likely that Jupiter will settle into a new, wider orbit around the white dwarf.

Answer 2

How will the atmosphere deal with the extreme heat?

Using this article as a guide

During most of the red giant lifetime, the sun will be only 30 times brighter than its current state. Toward the end of the red giant phase the sun will grow more than 1,000 times brighter, and occasionally release pulses of energy reaching 6,000 times current brightness.

Jupiter is about 5 times further from the Sun than the Earth, so it receives 1/25th the solar energy per area. If the Sun emits 30 times as much energy during most of its red-giant phase, and if we assume that Jupiter will migrate outwards some, that puts Jupiter (and its moons) probably somewhere in or close to the habitable zone.

Hydrogen and Helium are pretty inert, but Jupiter has enough Methane and Water vapor in its upper atmosphere to experience a greenhouse effect and gradually heat up, so it will likely grow hot given enough time, even at what we might consider a comfortable distance for a planet. The Red-giant stage of the Sun will last a couple hundred million years and Jupiter is very large and will take a long time to trap enough solar energy to really start to heat up, but I think that's the outcome. It would be a good place to put Earth during that time, but Jupiter would probably become a heat trap or run-away greenhouse planet at a certain point.

Even with heating up, Jupiter is massive enough that it probably won't lose much of its hydrogen.

A final point to make is that Jupiter will probably absorb a small percentage of the matter that the sun loses. Our Sun is estimated to lose about 54% of its mass by the time it becomes a white dwarf and much of (some of?) that matter loss will happen during the red giant stage. That's about 560 Jupiter masses.

Most of that ejected material will just form a planetary nebula or leave the solar system. A tiny percentage of it will be absorbed by Jupiter. I don't expect it will be much, but Jupiter will probably (could?) add some mass during the red giant stage of the sun. I don't expect it would be close to enough to become a brown dwarf star, but I think there will be some added hydrogen and helium during that time.

The heat will make it expand a bit and it will probably get darker. Losing its lighter bands which are lighter in color due to ice. But it'll still basically be Jupiter. Hotter around the surface but otherwise not very different.

Europa, however, will probably become an ocean moon instead of an ice moon, at least for a while.

Answer 3

https://en.wikipedia.org/wiki/Hot_Jupiter

For a much hotter Jupiters, a mass loss is estimated as 5-7% over the star lifetime. Our rather cold one (even with Sun as a red giant), being exposed to the heat much less time, will lose probably way less.

Capturing a significant amount of the Sun ejected matter will probably not happen. The matter is too hot and too fast, so the net result will be probably a constant mass loss. Contact binary stars do exchange mass, but the receiving star is way heavier and orbits closer.