The theoretical world of Hēdran is the 2nd planet of a 7 planet system. It lies within its star's (G1.4) habitable zone, but with a hot jupiter gas giant only ~1 AU away it experiences heavy gravitational flux.

It has been brought to my attention in a previous question that this closeness is unlikely. I have had difficulty finding information as to the limits of planet spacing within a solar system. Outside of that I have found some supporting data that earth-like planets could exist in Hot Jupiter systems. From my knowledge one only had to be outside the hill sphere to be free of significantly dangerous gravitational effects.

Looking at this question posted sometime earlier has helped but not provided concrete answers one way or another.

This article states that hot jupiters between .1 and .5 AU are systems that can contain earth-like planets, and generally have a lower mass for a gas giant.

Is there something I'm not understanding? If I am wholesale wrong about my gas giant being so close to the homeworld I would appreciate as to why and will gladly make changes.

Apologies for the disjointed question and lack of knowledge on the subject. And thank you for any and all help!

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    $\begingroup$ Hmm... Perhaps let's think the other way around : The answer you linked already tells that your planet risk to be thrown like discuses are thrown in the olympic games. Then, wouldn't it be more interesting to you if you asked "how can I make this planet so close to the gas giant?" or as a more general thought "How close can I put this planet to this gas giant, and how?". Well, unless you didn't grasp L.Dutch answer, in which case the current question is fine 🐶. $\endgroup$ Aug 30, 2022 at 14:32
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    $\begingroup$ Hi Austinman42. I hope you'll forgive me, but I'd like to make a point. We're not perfect and you don't need our permission to make a great world or write a good story. Do you expect your readers to include PhD astrophysicists? Well... we'd all love that, but if that's the issue, don't be afraid of their judgement. A lot of good stories and great worlds have languished because the worldbuilder was too worried they weren't "realistic" or "plausible." Except the universe shows us almost daily that what we think is realistic and plausible is very limited. (*Continued*) $\endgroup$
    – JBH
    Aug 30, 2022 at 16:01
  • $\begingroup$ What I recommend is that you visit our List of Worldbuilding Resources and scroll down until you find the solar system simulators. Skip the first one, it's too simple for what you need. Pick the third one. It'll take a bit for you to get used to how it works (drop two suns directly onto the default sun to get a yellow star similar to what you want), but it will also prove that what you're looking for isn't impossible. Note that a Jupiter-class planet that close to a star causes the star to move, which causes your (*continued*) $\endgroup$
    – JBH
    Aug 30, 2022 at 16:03
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    $\begingroup$ ... habitable planet to have a wonky orbit. But it's not impossible. Give it a try, have a ton of fun goofing around with it. Remember to switch between Cam mode and Place mode to get a 3D feel for things! But finally, remember that you don't need our permission to do anything with your world or its universe. Reality is a bit overrated, and our current understanding of science is so honking limited that it's more rare than you might think that we can factually tell you something is impossible. $\endgroup$
    – JBH
    Aug 30, 2022 at 16:06
  • $\begingroup$ @JBH I really appreciate your comment. I don't expect a dissertation or anything from users here, that would be nice. The thing is I trust L.Dutch's comment, they got that reputation for a reason. I'm still new to Stackexchange and thought it was common practice to provide answer as to why I'm wrong. Thank you for the list of resources, it has already been extremely helpful. $\endgroup$ Aug 31, 2022 at 0:01

1 Answer 1


Maybe hot Jupiters help with the formation of water rich terrestrial planets!

On the formation of terrestrial planets in hot-Jupiter systems

These researchers modelled what would happen to the protoplanetary disc as a hot Jupiter in the making moved through on its way to its place by the fire. The whole article is available full text at the above link.

Results.We find that ≳60% of the solids disk survives by being scattered by the giant planet into external orbits. Planetesimals are scattered outward almost as efficiently as protoplanets, resulting in the regeneration of a solids disk where dynamical friction is strong and terrestrial planet formation is able to resume. A simulation that was extended for a few Myr after the migration of the giant planet halted at 0.1 AU, resulted in an apparently stable planet of ∼2 forming in the habitable zone. Migration–induced mixing of volatile-rich material from beyond the “snowline” into the inner disk regions means that terrestrial planets that form there are likely to be water-rich.

Conclusions.We predict that hot-Jupiter systems are likely to harbor water-abundant terrestrial planets in their habitable zones. These planets may be detected by future planet search missions.

Hottie helped your planet form! It dragged in a bunch of outer ring wet goodness and so your world was extra wet. Plus Hottie looks good when seen from the beach at night; a little bit incandescent from its hotness.


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