Helium-rich Gas Giant Formation

[Reido]

I've been doing a little reading up on Helium-rich gas giants as I've come across a few of them recently.

The theory I've found behind the creation of these bodies in real life is that a regular gas giant is formed very near it's star, or is formed farther out and migrates very close to it's star and over the course of BILLIONS of years the hydrogen which is lighter than the helium is burned off and the helium becomes more concentrated, hence the helium-rich part. They should also appear white in color.

Now the helium-rich gas giants I'm finding in the game so far have ALL been orbiting stars that are LESS 1 billion years old, they're all over the place as far as their orbits go with some of them being 1000's of Ls's from the star, and lastly they come in every color that the game produces (white, L brown, D brown, red, and blue...etc). Last, but not least the ratio of hydrogen to helium is the same as regular gas giants and this is easily seen if they're in a system with "normal" gas giants where the atmospheres are exactly the same i.e. NOT helium-rich.

I'm not here to bash on the Stellar Forge, but just wanted to ask if anybody has heard of another theory for creating helium-rich giants? My Google-fu seems to only come up with the recent theory mentioned above or hits related to Elite Dangerous, and soon probably this thread

 

[Jackie Silver]

Last, but not least the ratio of hydrogen to helium is the same as regular gas giants and this is easily seen if they're in a system with "normal" gas giants where the atmospheres are exactly the same i.e. NOT helium-rich.=

As far as I can tell the abundance of hydrogen vs helium in gas giants is set on a system-wide basis. The ratio in "helium-rich" systems is (very slightly) higher in favour of helium compared to ordinary systems (like 30:70 ish not 28:72 ish), but all gas giants in the system usually get the same ratio whatever they're marked as. In rare cases the life-bearing ones will also have a tiny fraction of Oxygen, but I don't think I've ever seen any other component.

(I have a suspicion that for ordinary planets there's a cap which means that while the atmosphere can contain more than three components, only up to three components are ever displayed, which would explain a lot.)

I think you're right that the appearance of helium-rich gas giants in Elite physics doesn't bear any relation to the appearance of helium-rich gas giants in reality...

 

[iain666]

(I have a suspicion that for ordinary planets there's a cap which means that while the atmosphere can contain more than three components, only up to three components are ever displayed, which would explain a lot.)

That certainly seems to be the case.

I'm still wondering how 90+ percent oxygen is stable on lifeless planets.

 

[Reido]

Thanks for the replies.

Despite not being very realistic, the systems containing helium-rich gas giants are often very unusual with lots of oddball planets. I enjoy coming across one of these systems now as I'm almost always rewarded with a surprise or two.

A good example was the last one I came across which had SIX helium-rich gas giants in it, they ranged in mass from 19 to over 3300 , one of the HMC planets had a mass of over 22 and a metal-rich world with a thick 100% silicate atmosphere, strange stuff.

If anybody else finds a system with any helium-rich planets I would highly recommend having a close look at the other planets as you might find a surprise or three, and the He-r systems also seem to form in clumps where the stars are young, so if you find one system with them you'll probably find more if you survey the surrounding area.

Hunting for these is the most fun I've had exploring since I started playing in mid January, it's like an Easter egg hunt , but it did take me over 2 months to find the first one though


Andrew

 

[Kalpa]

I'm pretty sure I haven't found any helium-rich system yet, except for some obvious one within civilized space. Can't remember which system it was, but it had a lot of helium giants.