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Forum » SpaceEngine » Archive » Hypothetical solar system, what do you guys think? (Alternate history)
Hypothetical solar system, what do you guys think?
steeljaw354Date: Tuesday, 15.12.2015, 20:29 | Message # 1
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Hytheria: A cthonian planet that circles the sun in 3 days, about half the mass of earth.
Vulcan: A world about the size of earth's moon inside mercury's orbit has an orbital period of 51 days. Has oceans of lava and no
moons. Largest among the vulcaniods
Mercury: Same as present day but with a moon the size of phobos that orbits at about 1000 Miles
Eos: A planet the size of mars in venus's orbit but with less greenhouse gasses so it is a desert world, a lot colder than venus but still hot in earthly terms.
Earth: Same as present day but with 2 moons each about half the size of earth's moon.
Mars: A world with Rings made of iron oxide, makes them red, mars itself is the same as the present day but with no moons.
Ceres An asteroid-like object but with 10x it's current mass, heavily cratered and has 3 small moons. (No asteroid belt)
Jupiter: A gas giant about 75% it's current mass has 4 moons (galiean ones)
Saturn A gas giant with the mass of uranus and neptune combined with swirling clouds of methane and water vapor, has 2 volcanic moons including titan which has about 50% the mass of earth.
Ra: An earth sized world with no atmosphere with 1 moon. Orbits where uranus is.
Pluto: An ice planet the size of venus with a moon the size of mars. Orbits where neptune is.
Planet X: A planet the mass of 3 earths on the the inner oort disc, has 10 icy moons, that include all dwarf planets and sedna (not pluto)
Tyche: A Y dwarf of the very outer rim of the solar system and has 4 planets.
No such thing as the asteroid belt or the kuiper belt. The oort disc is a rim of icy objects about where the Kuiper belt is. But a little further out.
There is a sparce population of vulcanoids inside the orbit of mercury, most are small rocks but vulcan is an exception. Only a few hundred are known.


Edited by steeljaw354 - Tuesday, 15.12.2015, 23:03
 
SpaceEngineerDate: Wednesday, 16.12.2015, 16:24 | Message # 2
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Quote steeljaw354 ()
Mercury: Same as present day but with a moon the size of phobos that orbits at about 1000 Miles

It's moon will have unstable orbit.

Quote steeljaw354 ()
Mars: A world with Rings made of iron oxide, makes them red, mars itself is the same as the present day but with no moons.

Rings will be unstable due to Poynting-Robertson and Yarkovsky effects.

Quote steeljaw354 ()
Jupiter: A gas giant about 75% it's current mass has 4 moons (galiean ones)

Then you must reduce moons mass to 75%. Gas giants have total mass of satellites system of 0.02% of planet's mass (empiric law).

Quote steeljaw354 ()
Saturn A gas giant with the mass of uranus and neptune combined with swirling clouds of methane and water vapor, has 2 volcanic moons including titan which has about 50% the mass of earth.

Such low-mass Saturn can't have such high-mass moon, unless it was captured.

Quote steeljaw354 ()
Ra: An earth sized world with no atmosphere with 1 moon. Orbits where uranus is.

With this size (mass) and this far distance from the Sun, it MUST have an atmosphere.

Quote steeljaw354 ()
Planet X: A planet the mass of 3 earths on the the inner oort disc, has 10 icy moons, that include all dwarf planets and sedna (not pluto)

It is too massive for such distance. It can exist there only if it was formed closer to Sun and get ejected out. In this case it must have highly eccentric orbit.

Quote steeljaw354 ()
There is a sparce population of vulcanoids inside the orbit of mercury, most are small rocks but vulcan is an exception. Only a few hundred are known.

Yarkovsky effect will reduce asteroids orbits until they crush into Sun. Also Yarkovsky–O'Keefe–Radzievskii–Paddack effect will be strong there. Asteroids will increase their rotation speed, broke to smaller parts, they broke to evens smaller etc. Small debris will crush into Sun even faster.





 
steeljaw354Date: Saturday, 19.12.2015, 01:57 | Message # 3
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Mars rings removed,Lets make Jupiter the size of neptune, change the moons to about the size of Ceres. They Will form differently and look differently than in our timeline.Add an atmosphere to Ra made of thin whispy clouds of methane. The methane is made by small organisms floating around in it's atmosphere. Planet X is a gas dwarf that formed where the kuiper belt would be in this system, but it's further out. Titan is reduced to 10% of earth's mass, orbits a 50000KM outside the Roche radius and is slowly moving towards saturn which it will slowly get ripped apart and made into a ring just like triton in our timeline but neptune doesn't exist.

Vulcanoids removed for simplicity Mercury's moon was captured and will be stable for a few thousand years, it will collide with mercury or get ejected. Now for Tyche's planets, they are mostly barren lifeless worlds, Frigid dark worlds made of ice and rock, Tyche can't warm these planets because it isn't bright enough, Tyche has it's own asteroid belt about where the orbit of mercury is, called the Tychoid ring, keep in mind the 4 planets won't affect the ring since they are so small.

Brahman: A moon sized planet orbiting close to tyche, mostly volcanic, devoid of life. (orbits .2 million miles out)
Marduk: Marduk is a bleak, rocky world with a wide elliptical orbit. Moon sized. (orbits .4 million miles out)
Roni: A planet the size of Ganymede, has no atmosphere and 1 moon. (orbits .7 million miles out) Surface is barren and pluto like, it is a binary like pluto and it's moon is about 1/3 the mass, it warms up the inside and has a small subterranian ocean, with aquatic life.
Tiamat: A mars sized planet, mostly barren and lifeless also has a look similar to earth's moon. (orbits 1 million miles out)

I will try to make this in universe sandbox. It's easier to make it there then in space engine.


Edited by steeljaw354 - Saturday, 19.12.2015, 15:11
 
FaceDeerDate: Tuesday, 22.12.2015, 02:01 | Message # 4
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Quote SpaceEngineer ()
Rings will be unstable due to Poynting-Robertson and Yarkovsky effects.


Wouldn't these effects only have a net impact on dust that's orbiting the Sun directly? If it's orbiting Mars I would expect that half the time the effect would slow the dust down and half the time it'd speed it up, with a net effect of close to zero.

Quote SpaceEngineer ()
Then you must reduce moons mass to 75%. Gas giants have total mass of satellites system of 0.02% of planet's mass (empiric law).


I'd say that we don't have a large enough sample size to make this a universal statement. Even within our own solar system we've got a real oddball case, Neptune's captured moon Triton, that shows a mechanism by which this could be violated even if there's an insurmountable limitation on moon formation.

Quote SpaceEngineer ()
With this size (mass) and this far distance from the Sun, it MUST have an atmosphere.


If it was formed closer to the Sun and had its light volatiles baked off before being ejected into the outer solar system it could have a fully frozen atmosphere at that distance. Maybe a bit of nitrogen hanging on.

This article suggests that Vulcanoid asteroids larger than 0.1km in diameter could endure in long-term orbits as close as 0.09 AU despite various drag effects and evaporation.
 
WatsisnameDate: Tuesday, 22.12.2015, 02:39 | Message # 5
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Quote FaceDeer ()
Wouldn't these effects only have a net impact on dust that's orbiting the Sun directly? If it's orbiting Mars I would expect that half the time the effect would slow the dust down and half the time it'd speed it up, with a net effect of close to zero.


You would think, but no -- Poynting-Robertson drag is a special relativistic effect which always works against the orbital motion. In the particle's rest frame, the radiation it re-emits is isotropic. But in the frame of the body the particle orbits, the radiation carries more momentum in the direction it is orbiting. This causes the particle to lose orbital energy and spiral inward, regardless of whether the particle be orbiting the Sun or a planet.

Some formulas and a plot of the decay timescale for planetary rings by this effect can be found in this paper (section 2.2).





 
FaceDeerDate: Tuesday, 22.12.2015, 05:54 | Message # 6
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Huh, neat. I would have thought only the orbital velocity around the Sun would count, which is much higher than orbital velocity around Mars.

However, when I look at the graph it appears that the effect is only significant for rings around planets that are extremely close to their primaries - at 0.3 AU the ring lasts about a billion years (and this is possibly an underestimate since a ring inclination of 45 degrees was assumed, a lower-inclination ring lasts longer). So a ring around Mars or even around Earth looks like it'd stick around for the lifetime of the solar system, discounting other sources of orbital decay. At 0.05 AU they last a hundred million years so you might even see rings around hot jupiters if they're young enough or recently disrupted a moon.
 
steeljaw354Date: Tuesday, 22.12.2015, 11:06 | Message # 7
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Won't really matter on a ring thats 1000KM away from mars and ends 1100KM away.

For vulcanoids I was thinking (between 0.1 - 0.3 AU)


Edited by steeljaw354 - Tuesday, 22.12.2015, 11:39
 
WatsisnameDate: Wednesday, 23.12.2015, 07:31 | Message # 8
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Quote FaceDeer ()
I would have thought only the orbital velocity around the Sun would count, which is much higher than orbital velocity around Mars.


The heliocentric velocity is indeed significantly greater than the primary velocity (about the planet) for the inner solar system. However, this turns out to not be an important factor to the PR drag. It is a lower-order term than that from the primary velocity about the planet, as shown here.

Quote FaceDeer ()
However, when I look at the graph it appears that the effect is only significant for rings around planets that are extremely close to their primaries - at 0.3 AU the ring lasts about a billion years (and this is possibly an underestimate since a ring inclination of 45 degrees was assumed, a lower-inclination ring lasts longer).


Correct, but we have to be really careful here: the graph in figure 4 assumes the ring is optically thick. Otherwise, we use formula (3), which gives much shorter timescales in line with what SpaceEngineer was saying.

A good rule of thumb that I like to use with figuring the decay timescale for ring particles is that it is approximately the time that it takes for the particle to absorb its own mass worth of radiant energy. This allows us to do a fairly simple derivation, which will differ from a rigorous derivation only by numerical constants:

The mass of the particle is 4/3*pi*s^3*density, where s is its radius.
The rate of energy absorbed is the solar flux at its heliocentric distance, times the particle's cross sectional area, times some efficiency factor of order unity.
To convert energy absorbed to mass, divide by c^2.
The decay timescale is then the particle mass times c^2 divided by the energy absorption rate, which yields



where rho is the particle density, a is the heliocentric orbital distance, L* is the star's luminosity, and QPR is the efficiency. Notice this is functionally the same as formula (3) and gives similar answers. We can quickly see that the decay timescale is proportional to particle size, density, square of orbital distance, and inversely with star luminosity. For a Mars analogue with optically thin silicate rings, this timescale is less than 100,000 years for micrometer sized particles. The particles would need to be several cm in size to survive for the lifetime of the solar system.

I'm not sure if we can realistically expect optically thick rings in this scenario or not, but it makes a really big difference for its lifetime. We could just assume that it is largely made of pretty big pieces, but that would also imply it is optically thin.





 
DiakonovDate: Sunday, 17.01.2016, 19:06 | Message # 9
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I found this:



THIS is the ultimate better solar system version! biggrin
 
AlekDate: Monday, 18.01.2016, 04:45 | Message # 10
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Quote Diakonov ()
this


Is a good way to say buh-bye to Earth. Jupiter's gravity would either tear Earth apart, send it too close to the sun, or eject it from the solar system completely. I can do a simulation of this just to prove what I'm saying, if needed





Living among the stars, I find my way. I grow in strength through knowledge of the space I occupy, until I become the ruler of my own interstellar empire of sorts. Though The world was made for the day, I was made for the night, and thus, the universe itself is within my destiny.
 
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