Asking help for a sci-fi book

[Bea_Res]

I am writing a sci-fi book and I need a stable simulation of a solar system with specific features.
The star has to be a M dwarf with the 1st planet uninhabitable (too close, too hot, etc).
The second planet needs to be in the Goldilocks zone, with habitable conditions, water and atmosphere, yet it needs to have much stronger gravity than Earth (from 1.5 to 2 times the weight felt on Earth, with a metal core that also produces a strong magnetic field). It also needs to have 1 day corresponding to about 4.5 Earth days.
The third planet needs to be habitable too, even if with colder temperatures. The size can be about that of the Earth.
There has to be a fourth planet (uninhabitable), Further planets can be there or not.
I have run a series of stable simulations my own but I don't know how much forgiving Universe Sandbox is in regards of my mistakes (that wouldn't really allow life, for saying one).
If any of you can provide me with such a simulation I'd be very grateful and add you in my book's aknowledgments, which will be hopefully published next year in Italy.

[Thundercracker]

Originally posted by Bea_Res:

The star has to be a M dwarf with the 1st planet uninhabitable (too close, too hot, etc).
The second planet needs to be in the Goldilocks zone, with habitable conditions, water and atmosphere, yet it needs to have much stronger gravity than Earth (from 1.5 to 2 times the weight felt on Earth, with a metal core that also produces a strong magnetic field). It also needs to have 1 day corresponding to about 4.5 Earth days.

this is going to be very hard to do. the habitable zone of a dwarf star is VERY close compared to our own. when you put planets that close to a star, they generally get tidally locked. this means that a year is the same length of a day, and the result of this is that one side of the planet will ALWAYS face the sun. think of how our moon always has the same side pointed at earth.

this has dramatic effects on a planet, though. the side facing the sun is going to get too hot, and the side facing away will get too cold. life, and liquid water, will only be possible on the "twilight zones" on the sides.

another thing to consider is that red dwarfs are generally "flare stars," they have much more, and more intense solar flares than our sun. it would be hard for planets around such a star to keep atmosphere and develop life. assuming your life on this planet evolved naturally.

you might consider going the other way, using a giant star. with a giant star, the habitable zone is going to be far away you can avoid tidal locking. it can go both ways, but generally speaking, a larger star can gravitationally hold on to more heavy elements, like metals.

a metal rich terrestrial planet isnt the most believable orbiting a low-mass dwarf, unless the planet did not form in the system, or the system itself formed in a nebula very rich in heavy elements. both possible, but we tend to observe less heavy elements in dwarf star systems.

[IT's CHEESASAURUS REX!]

The setting sounds solid, like some thorough thought was put into it. Though I can guess the plot weighs on the nature of said solar system given there isn't any context as to what the story is about, which in any story should be of great focus by it's writer.

Along with that is how exactly the story is conveyed with your use of words. My suggestion is to just go to the Wikipedia article on figures of speech and write down notes on each type and scheme.
https://en.wikipedia.org/wiki/Figure_of_speech
At least that's what I've been doing off and on.

Aside that if it is how planets work I'd look at the ones we know like ours, Alpha Centari or Proxima Centari (Probably not too exciting but at a start no less).

[Bea_Res]

Terrosaur yes, I was thinking about tidal lock today and I may avoid that problem making the planet orbiting another bigger planet, so that it becomes a moon orbiting around a planet. Flares are another problem indeed, maybe with a strong magnetic field life can still exist. I will think about your suggestion about a giant star, I didn't consider the different distribution of elements in dwarf systems. Thank you for your answer.

[Bea_Res]

Rear admiral Heroin needle, I am writing the book in my native language as I wrote, but thank you anyway for your link about the grammar in your language. I do not provide context or an excerpt of my story for obvious reasons. Or not so obvious probably. Thank you for your answer.

[IT's CHEESASAURUS REX!]

Originally posted by Bea_Res:

Rear admiral Heroin needle, I am writing the book in my native language as I wrote, but thank you anyway for your link about the grammar in your language. I do not provide context or an excerpt of my story for obvious reasons. Or not so obvious probably. Thank you for your answer.

That's understandable then, apologies for my first point.
Also here's the page for rhetorical speech in Italian:
https://it.wikipedia.org/wiki/Figura_retorica
Not as extensive as the English one (In fact quite different overall) but it is what I found.

[Thundercracker]

Originally posted by Bea_Res:

Terrosaur yes, I was thinking about tidal lock today and I may avoid that problem making the planet orbiting another bigger planet, so that it becomes a moon orbiting around a planet. Flares are another problem indeed, maybe with a strong magnetic field life can still exist. I will think about your suggestion about a giant star, I didn't consider the different distribution of elements in dwarf systems. Thank you for your answer.

a gas giant could shield a terrestrial planet-like moon from stellar radiation, yes.... but it itself is a dangerous source of radiation. jupiter's radiation belts are extremely lethal to most life on earth. one of the reasons we think there may be life in subsurface oceans on europa, the moon of jupiter, is that the ice and ocean itself would shield hypothetical life from jupiter's radiation.

a tidal lock does not mean you have to discard the idea. i've read a few scifi stories set at least in part on a tidally locked planet. it does give you a planet with a lot of biomes that have no analog on earth. a tidally locked planet located just outside the "traditional habitable zone" might have a star-facing side that would not be boiling hot. pretty sure in this case, though, the away-facing side will be a solid icecap, though.


if you want to get really exotic, you could have a unique host star. perhaps one that started as a low mass dwarf, but collided and merged with some stellar remnant like a white dwarf before the planets were all formed. this could get you the heavy elements you want, while keeping a relatively low mass dwarf star.

[Craz Zero]

I have an idea for my book but i wanted to know if there was any such logical science to it

as my book is a sci fi fantasy

The question is, Would there be a way to Simulate a Planet with a radius 3x that of Earth that could be habitable with an orbit of 120 days to a Year
with 30 days to 4 months

and still have an solar eclipse which would block the sun?

Can such a thing be done in game?

[Thundercracker]

Originally posted by GCT:

I have an idea for my book but i wanted to know if there was any such logical science to it

as my book is a sci fi fantasy

The question is, Would there be a way to Simulate a Planet with a radius 3x that of Earth that could be habitable with an orbit of 120 days to a Year
with 30 days to 4 months

and still have an solar eclipse which would block the sun?

Can such a thing be done in game?

well, first off, a rocky planet 3x earth's radius is going to be a tough one. at 1.5x the earth's radius, the planet is so massive that it would grab an extended hydrogen atmosphere during planetary formation. you'd end up with a mini-neptune. 2x earth's radius is the extreme upper limit to having a terrestrial planet. at this size, you've got about 5x earth's mass, and surface gravity is ~3g or 3x earth's gravity.

having an eclipse cycle that blocks the sun depends on the size and distance of the moon, more than anything else. earth is a bit strange because from our vantage, the moon takes up almost exactly as much sky as the sun. however, a visibly larger moon still blocks the sun.

now, i'm not very good at these kind of geometric calculations, i suspect trigonometry is involved.

next is your year. at 120 days, it's got to be fairly close to its sun. i'd estimate an orbit a bit smaller than that of venus. the smaller the star, the closer the habitable zone, so you might actually need a shorter year, or a longer one. depending on if you want a smaller or larger star.

by "month" do you mean "lunar orbit"? tracking the lunar orbit is the main purpose of our months. kind of highlights how weird it is that we use a combined solar and lunar calendar. figuring out how big the moon needs to be in the sky is that geometry problem i mentioned. you're probably going to need a moon that's a significant portion of the planet's mass, and it's going to probably be near the margin for close orbits. almost a binary planet.

this is of course assuming a planet with earthlike temperature ranges. you could move toward the edges of the habitable zone, rendering the poles much too cold, or the equator much too hot, for earthlike life to exist.

[Craz Zero]

thx for relating to the comment, I since changed the conception to 2x the Earth

But still the same orbit

However a planet is blocking the sun's rays on every 12th day of the 2nd month said planet is called Sarash

While the other is the 5th planet lets call Eal, Eal is 120 days in orbit

But I am not sure a Planet like Sarash being able to block a Dwarf star would even be possible?

[Thundercracker]

Originally posted by GCT:

thx for relating to the comment, I since changed the conception to 2x the Earth

But still the same orbit

However a planet is blocking the sun's rays on every 12th day of the 2nd month said planet is called Sarash

While the other is the 5th planet lets call Eal, Eal is 120 days in orbit

But I am not sure a Planet like Sarash being able to block a Dwarf star would even be possible?

it depends on the apparent sizes of the objects in the sky. i'm not good with the geometry/ trigonometry needed to calculate the apparent sizes of objects in the sky.

i would assume that one of two things is true, though. either a dwarf star is much smaller in the skies of planets in their habitable zones than i would assume, or the secondary planet is very big or very close.

considering how packed-in things are in the inner solar system of a dwarf star, planets could be found much closer together than we see here in our own solar system. i think at least one of the gelsie systems has something like 3 mini-jupiters and one terrestrial planet in an area smaller than the orbit of mercury.

[DmAnd]

Originally posted by Terrorsaur:

Originally posted by Bea_Res:

The star has to be a M dwarf with the 1st planet uninhabitable (too close, too hot, etc).
The second planet needs to be in the Goldilocks zone, with habitable conditions, water and atmosphere, yet it needs to have much stronger gravity than Earth (from 1.5 to 2 times the weight felt on Earth, with a metal core that also produces a strong magnetic field). It also needs to have 1 day corresponding to about 4.5 Earth days.

this is going to be very hard to do. the habitable zone of a dwarf star is VERY close compared to our own. when you put planets that close to a star, they generally get tidally locked. this means that a year is the same length of a day, and the result of this is that one side of the planet will ALWAYS face the sun. think of how our moon always has the same side pointed at earth.

this has dramatic effects on a planet, though. the side facing the sun is going to get too hot, and the side facing away will get too cold. life, and liquid water, will only be possible on the "twilight zones" on the sides.

another thing to consider is that red dwarfs are generally "flare stars," they have much more, and more intense solar flares than our sun. it would be hard for planets around such a star to keep atmosphere and develop life. assuming your life on this planet evolved naturally.

you might consider going the other way, using a giant star. with a giant star, the habitable zone is going to be far away you can avoid tidal locking. it can go both ways, but generally speaking, a larger star can gravitationally hold on to more heavy elements, like metals.

a metal rich terrestrial planet isnt the most believable orbiting a low-mass dwarf, unless the planet did not form in the system, or the system itself formed in a nebula very rich in heavy elements. both possible, but we tend to observe less heavy elements in dwarf star systems.

With a very intense magnetic field, a planet could survive all those flares being so close to a red star, no?

[76561198025051992]

I took some time to read this all, and if one planet is going to cause a total eclipse, the star has to be very far away or the planet need to be extremely large, maybe larger than the star. The only way I see this possible for a habitable planet with a 120 day orbit is if it's a post fusion solar system, where the planets formed after the star collapsed into a white dwarf.

[Thundercracker]

Originally posted by Captain Obvious:

With a very intense magnetic field, a planet could survive all those flares being so close to a red star, no?

then we come to the problem of what is generating that field, and if the field is strong enough to actually be harmful to life.

[Craz Zero]

Very very interesting

as per said Eclisping planet I worked out... A planet to Eclispe... it would be 60 days of orbit

To hit on the same day of the 2nd month

So effectively the 30th day of the 2nd month and then the last day of the 4th month

But you all raise such very interesting questions

[76561198025051992]

If the two planets are in a 2 to 1 resonance, one with a 120 day orbit and one with a 60 day orbit, the eclipse would happen once every 120 days. If you wanted an eclipse twice per orbit, the inner planet would need to be in a 40 day orbit. Either way, you need the inner planet to be larger than the star, so it would need to be a white dwarf system.