Is there a plausible way to have a Gas Giant with two or more earth to mars sized moons orbiting it in the Habitable zone?

A hypothetical scenario I'm batting around in my head is a Habitable Gas Giant system consisting of a roughly Saturn sized body orbiting a sun like star at a comfy goldilocks zone distance. Orbiting this planet are two Massive moons, one roughly 70-80% the mass of the earth and the other between 20-30% of earth's mass. Additionally there may be some smaller moons that are still large enough to be spherical, roughly in the ballpark of size between Enceladus and Europa, along with all the minuscule asteroid sized moons, so overall there's about an Earth's mass worth of material orbiting around this planet spread out over multiple large bodies.

Now, I'm mostly interested in the two large moons, and them being Earth like bodies in a lot of ways that could both support life. There's a few issues I've been made aware of for this. First of all, if the moons formed alongside the planet in situ, and then moved with it towards a more habitable area closer to the sun, as I understand would need to happen under our current understandings of Gas Giant formation, would this mean that the moons would just turn into water planets with no hard surfaces, based on the fact that they're made of ices found outside the frost line? Is it at all conceivable they could have a silicate crust with a light covering of water that still allows for large continents like with Earth in this scenario at all? Or is them being drenched in giant oceans unavoidable?

Second, is an earth sized total of mass orbiting a Gas Giant about Saturn's size plausible in itself? I find it hard to find reliable information on the relationship in size between Gas Giant's and their moons, but I understand that some people have taken the maximum size of the Gas Giant moons in our solar system to be indicative of the limits in size that the moons could reach generally. Is this something that's considered a hard limit, or is it conceivable that there's a lot more wiggle room and our current solar system is just a bit unlucky when it comes to massive moons?

Next, if it is the case that this setup is unlikely to have happened with natural moon evolution from accretion around the planet, what about capturing large bodies as moons after both have already been formed elsewhere? I presume that worlds created closer to the sun would be better placed to have earth like characteristics, but would it be conceivable that multiple large bodies can be caught into the same system and create a stable setup, or would it rapidly turn into a planetary scale game of billiards? Is there any possibility that the chaos of the giant planet moving inward could destroy and break up a larger planet, maybe from catastrophic collisions with pre-existing large moons it brought with it, which could then re-accrete into multiple smaller worlds to better fit this scenario?

I'll admit that I would prefer the first scenario for the stories I have in mind, where Earth like moons form with the planet and move with it, mostly because it would seem to lead to a 'neater' system than a captured moon scenario, but I can understand if this is extremely implausible and can't really be justified. Many thanks for your time.

posted over 4 years ago

Khwarezm‭

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