Jupiter was formerly twice its current size, had a much stronger magnetic field
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Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#2Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#3Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
A prepublished version of the paper is available on arxiv [1]
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#4Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
It was hotter, a lot hotter.
Like stars, radius for a gas giant is increased by heat, and decreased by increased mass.
These two factors are rarely completely independent, of course, so it gets complicated. Especially in a star where masses are large enough to result in densities sufficient to cause fusion - and large releases of heat, which then cause decreased density, etc.
But all other factors being constant, the volume of a gas increases (and density decreases) as temperature increases.
See page 6 and the first couple paragraphs of page 7 in the paper for a breakdown.
Eventually Jupiter will cool enough it will be a small fraction of it’s current size, assuming that our understanding is correct and it doesn’t have enough mass to meaningfully result in fusion regardless of how dense it gets. [https://www.pas.rochester.edu/~blackman/ast104/jinterior.htm...]
In theory, it will even eventually cool to the point all those clouds and atmosphere are liquid (or even solid!) gas oceans. That is going to take awhile.
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#5Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
Not larger mass. Simply, was less dense. In layman terms, and if I understand correctly, was the result of the interactions of Jupiter, Jupiter's magnetosphere and Jupiter's circumplanetary disk.
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#6Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
Probably contracted as it's mostly gas.
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#7Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
The mass did not differ much from the present mass, but the planet was less dense and with a more rapid rotation.
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#8Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
Not larger mass. Simply, was less dense. In layman terms, and if I understand correctly, was the result of the interactions of Jupiter, Jupiter's magnetosphere and Jupiter's circumplanetary disk.
aka "fluffier"
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#9Couldn't read the actual paper as it is paywalled, but does "twice its current radius" mean that it had a larger mass, and if so what happened to all that extra mass?
It was hotter, a lot hotter. Like stars, radius for a gas giant is increased by heat, and decreased by increased mass. These two factors are rarely completely independent, of course, so it gets complicated. Especially in a star where masses are large enough to result in densities sufficient to cause fusion - and large releases of heat, which then cause decreased density, etc. But all other factors being constant, the…
> Like stars, radius for a gas giant is [..] decreased by increased mass.
If this is the case then do you have any intel on why do the gas giants in our system appear to more closely directly correlate mass with radius instead of inversely?
https://nssdc.gsfc.nasa.gov/planetary/factsheet/ Mass: Jupiter = 3.3 x Saturn = 22 x Uranus = 19 x Neptune Radius: Jupiter = 1.2 x Saturn = 3 x Uranus = 3 x Neptune
I mean Saturn's density is far less than either of the other three planets, despite being smaller and less massive than Jupiter but larger and more massive than Uranus/Neptune, as well as slightly cooler than Jupiter and far warmer than Uranus/Neptune. And Saturn has the lowest angular velocity among the four, which it would make sense might have the opposite relative effect on density.
Re: Jupiter was formerly twice its current size, had a much stronger magnetic field
#10How is the size defined for a gas planet? The gas density just keeps dropping, where do you draw the line (isosurface, rather)? Earth's radius is always the one without earth's atmosphere.