Jupiter and the Failed Star Theory

[Debostar]

I have read that some astronomers believe that Jupiter could have been a star, had it been slightly more massive..

In the case that it had been a star, would we have two suns? Would we orbit Jupiter or the Sun?? Would Jupiter and our sun be a double star? Would Jupiter still behave as a planet??

[FraserClarke]

Jupiter would have to be about 80 times more massive to be a star, so it's quite a long way off really.

If that were the case, it would change the dynamics of the solar system, but the dominant mass would still be the sun (which is about 1000x more massive than Jupiter). So we, and Jupiter, would still be orbiting the Sun. Whether the Earth's orbit would still be stable is a more complex question.

[Tadakun]

Funny I just read that today in an old national geographic book my wife found in her grandparents house (they are both deceased now so cleaning up is going on so the house sells)

[Macavity]

Hardly science, but for SciFi (and Jimi Hendrix) fans:

The Sands of Mars - Wikipedia, the free encyclopedia

Unlikely(!), but some NICE ideas though...

[brianb]

Jupiter might yet become a star ... if it captures a significant amount of the intense solar wind that the sun will emit when it becomes a red giant, it could start to gain mass at a significant rate & would also move closer to the sun as its orbital momentum is distributed across a larger mass ... of course the closer it gets, the faster the capture rate.

Poor Earth - it will lose its atmosphere, its crust and its mantle, and it core will be slung off into interstellar space in the unlikely event that it manages to avoid colliding with & being swallowed up by either the Sun or Jupiter ... still, all that's five billion years in the future, plenty of time for another drink or two!

[johankj]

Actually, if I remember correctly, Jupiter already emits more energy than it receives from the sun. Doesn't make it a star thought, and I'm not sure of what the definition of a brown dwarf is...

[brianb]

Jupiter already emits more energy than it receives from the sun.

Yes, about half its radiated energy is the residual from the accretion 4.5 billion years ago.

I'm not sure of what the definition of a brown dwarf is

As usual, wikipedia is your friend linky

"Currently, the International Astronomical Union considers an object with a mass above the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) to be a brown dwarf, whereas an object under that mass (and orbiting a star or stellar remnant) is considered a planet"

[johankj]

..."Currently, the International Astronomical Union considers an object with a mass above the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) to be a brown dwarf, whereas an object under that mass (and orbiting a star or stellar remnant) is considered a planet"

I guess the limiting mass for thermonuclear fusion is the key here, unlike the minimum diameter for a planet, which is more arbitrary

I'm glad we only have one (very stable) star. Having two, especially in such a close orbit as Jupiter, would have been devastating.

[johankj]

Planets could orbit either 'star', but it really depends on the two stars. Jupiter already have some very sizeable moons. I think there are some other stable orbits, if you look up something called Lagrange points.

To us, it would look like two suns, and if we kept our current orbit, Jupiter would look like sun number two. So, when you see Jupiter, that would be Jupiter day. But because Jupiter would have to be more massive, the orbits we have today could not be the same I think.

If Jupiter suddenly acuired more mass, by currernt theory, it could become a star.

If by Jupiter behaving like a planet you mean that Jupiter would appear to orbit the sun, then yes. But even in out system, the orbits are not at the centre of the sun, but slighty shifted away from the larger body centre. If you look up the model for a two-body system, you can read more about that. Three or more body systems are very-very complex...