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Can this star system with this configuration plausibly exist or not? If not please explain why it can't exist or explain its issues.

Planetary system

Star A 1.1 M⊙
Planets types mass semi-major axis eccentricity
B Mega-earth 10M⊕ 0.0164 Au 0.0877
C jupiter 1.3498M♃ (429M⊕) 0.1 Au 0.00838
Asteroid belt 0.5-0.8 Au
Planets types mass semi-major axis eccentricity
D Super-earth 4M⊕ 0.92 Au 0.04453
E Super-earth 3.61M⊕ 1.41 Au 0.0204
F Super-earth 3.9M⊕ 1.97 Au 0.0502
Asteroid belt 2-3.5 Au
Planets Planet types mass semi-major axis eccentricity
G jupiter 0.67017M♃ (213M⊕) 4.11 Au 0.0434
H Mini-neptune 5.11M⊕ 8.06 Au 0.0762
I Super-jupiter 3.8417M♃ (1221M⊕) 11.68 Au 0.0575
H neptune 40.3M⊕ 20.5 Au 0.0213
Asteroid belt 21-50 Au

The system is a hot Jupiter.

  • 1
    $\begingroup$ There is software which can simulate this that's quite user-friendly. If you don't want to get too technical, I believe the game "Universe Sandbox" should be able to simulate this, and it can be purchased for next to nothing on sale. If you want to go more technical, there are n-body simulation libraries and guides for Python that'd let you calculate this. $\endgroup$
    – Dragongeek
    Jan 2 at 15:02
  • $\begingroup$ I agree with @Dragongeek. You should use Universe Sandbox to test this. You should also consider the many resources in our List of Worldbuilding Resources page. $\endgroup$
    – JBH
    Jan 3 at 1:02
  • 1
    $\begingroup$ You might also consider this: "Both theory and observations concur in defining a minimum protostellar mass for the ignition of the hydrogen fusion to be around 0.08 solar mass. (Jupiter and Saturn for comparison with this limit, are only 0.001 and 0.0003 solar masses)." (Source) I point this out because the symbol you're using (M⊕) technically means "the mass of Earth" and Jupiter's mass using that symbol is 318M⊕, which makes C and G both mini-jupiters. Were you assuming M⊕ meant "times the mass of the referenced planet?" $\endgroup$
    – JBH
    Jan 3 at 1:06
  • $\begingroup$ oh i have universe sandbox 2 $\endgroup$
    – user107608
    Jan 3 at 1:20
  • $\begingroup$ ok thx for telling me $\endgroup$
    – user107608
    Jan 3 at 1:26

2 Answers 2


Just at a first look, planet C is too massive to have those neighbours so close to it.

It would kick them out of the system within few revolutions, cleaning its surroundings.

Just look at what is the distance between Jupiter and Mars/Saturn, its next door neighbours. When you are big, you want a lot of free space around you.


The probability that any well-specified set of arbitrarily selected initial conditions is the steady state which would arise from those initial conditions is zero, and the probability that it would have arisen from any plausible previous set of initial conditions is also zero.

Here, there are some obvious problems. Just to start, Planet B is much too close to its star. .016AU is about 3 solar radii. There's no way a planet would have formed there, and even if we get a wizard to put a planet there with an huge tangent velocity so that it can keep from falling into the sun, it's not long for the world. Here's a photo of our star having a coronal mass ejection with your planet's relative position edited in that should illustrate that point.

enter image description here

However, the obvious problems are ultimately secondary. The real problem, both here and in your atmospheric composition questions, is that you've come to a false intuition about how long-lasting physical systems like atmospheres and planetary systems can be specified - that the lists of facts about real systems that you can find in reference books are lists of mostly unrelated facts that could each be otherwise than it is without changing all the others. This is not an unreasonable intuition, as it's true about many things in the world of regular experience, but it is false for atmospheres and planetary systems.

If we were to reduce your solar system to just A, G, and H - which look about right to me, we would be absolutely certain to be wrong. The reason is time.

For something to be a description of a star system or an atmosphere or a planet is for it to be a description of something very, very old, which is made out of things that are themselves very, very old, as a result of processes spanning billions of years. Like a crime scene tells a story of the past few hours, a solar system or an atmosphere tells a story of the past few billion years. If you want to make up a believable crime scene, you need to be able to explain it with a believable story of how human beings and an urban environment interacted over a few hours, which you can base on an intuitive simulation of the way humans interact with their environment based on long exposure to humans and human environments. The more you specify the crime scene, the better your simulation has to be for all the facts to line up for your story.

If you want to make up a believable solar system or atmosphere or planet or star, you need to be able to explain it with a believable story based on how matter interacted with gravity, chemistry, and nuclear chemistry over a few billion years. Most people are really bad at simulating that with their intuitions, unless you're a professional astrophysicist. If you just make up numbers for planetary orbits, masses, chemical compositions, temperatures, pressures, etc, the more you specify them, the more they're simply guaranteed to be wrong. The only ways out are to be vague, to do the simulation (or ask an expert to do the simulation for you), or to not care about being right in the first place.

Realistic sci-fi is written by combining options 1 and 2. Fantastical sci-fi is written by taking option 3.

There's nothing strictly wrong with being very specific and also being completely wrong, if you don't care about being right but you want characters who care about specifics. I personally find it grating in Star Trek, but I can't argue with the fact that it's worked out reasonably well for the franchise for 60 years.

  • $\begingroup$ i took alot of inspiratioon from 55 cancri system $\endgroup$
    – user107608
    Jan 4 at 12:32

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