# Alternate Planets, Suns, Stars, and Solar Systems Thread

#### Dibwys

Let's assume two differing scenarios.

One scenario is Valey-Shinespark are both the same. 5/8ths the mass of the sun.
Second scenario is Shinespark has the exact specifications of the sun, with Valey being one quarter of the mass of the Sun.

What is different between the two?

The second is going to be brighter. The first one would probably be about the same overall as Sol is.

#### CarnelianClout

The second is going to be brighter. The first one would probably be about the same overall as Sol is.
I am not so sure. If they both are 5/8ths the mass of the Sun, the two of them will both be as bright as the sun, combined, is what you are saying?

#### Workable Goblin

I don’t think so. A K7V with 62.5% of the Sun’s mass (i.e. about 5/8ths) will only shine with about 9% of the Sun’s luminosity, so their combined brightness will only be about 18% of the Sun’s.

#### Pax_Nihil

Would it be alright if I ask a physics question here as it relates to a planet that would hypothetically exist?

See above…yes.

#### Pax_Nihil

Well I was watching a video of some guy playing this game called Solar Smash on YouTube and he was trying to hollow the world out by creating a blackhole in the center of the Earth, and then burning through one side to access the void that the games mechanics didn't accurately portray how I think it should have, so, heres my question...

If somehow an ASB magically made the Earth's core go poof and suddenly nothing would be there but a void, wouldn't the principle of hydrostatic equilibrium and gravity cause the Earth to shrink and conform to the most perfect sphere possible? Or would the sudden 'removal' (effectively teleportation) of the densest and most significant part of Earth's gravity leave Earth as basically a hollowed out orb?

#### CarnelianClout

I don’t think so. A K7V with 62.5% of the Sun’s mass (i.e. about 5/8ths) will only shine with about 9% of the Sun’s luminosity, so their combined brightness will only be about 18% of the Sun’s.
How close would a planet have to orbit to both of them in order to be habitable? Another question, what if Shinespark was 0.85 solar masses, while Valey was 0.4? What would the stellar classifications and luminosities be? I think it would be interesting to have them both have different masses, but different than the ones I had described originally.

I think that having a K class star system would be a bonus, because of their life spans - and Halycon would not have to orbit as close to the point where it is tidally locked?

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#### Workable Goblin

How close would a planet have to orbit to both of them in order to be habitable? Another question, what if Shinespark was 0.85 solar masses, while Valey was 0.4? What would the stellar classifications and luminosities be? I think it would be interesting to have them both have different masses, but different than the ones I had described originally.

I think that having a K class star system would be a bonus, because of their life spans - and Halycon would not have to orbit as close to the point where it is tidally locked?
Wikipedia has tables for each stellar class that provide information on mass and luminosity, so you can pick and choose from there (make sure to click through to the articles on each individual stellar class, which provides more fine-grained information). I will note that luminosity is a strongly nonlinear function of mass, so seemingly small decreases in mass will result in relatively large decreases in luminosity (for example, a K0V star has about 88% of the mass of the Sun, but 46% of its luminosity!)

#### Dibwys

How close would a planet have to orbit to both of them in order to be habitable? Another question, what if Shinespark was 0.85 solar masses, while Valey was 0.4? What would the stellar classifications and luminosities be? I think it would be interesting to have them both have different masses, but different than the ones I had described originally.

I think that having a K class star system would be a bonus, because of their life spans - and Halycon would not have to orbit as close to the point where it is tidally locked?

http://www.stellar-database.com/ Most of the entries for the stars has a 'comfort zone' listed.

#### CarnelianClout

Wikipedia has tables for each stellar class that provide information on mass and luminosity, so you can pick and choose from there (make sure to click through to the articles on each individual stellar class, which provides more fine-grained information). I will note that luminosity is a strongly nonlinear function of mass, so seemingly small decreases in mass will result in relatively large decreases in luminosity (for example, a K0V star has about 88% of the mass of the Sun, but 46% of its luminosity!)
So it seems like Shinespark will be a K1V class star with 0.86 solar masses with a luminosity of 41% of the Sun's luminosity, while Valey will be an M3V class star with a mass of 0.37 solar masses with a luminosity of 1.6% that of the Sun. So combined, the two stars will have a luminosity of 42.6% that of the Sun. This means that both stars will be relatively long lived in comparison to that of the sun.

The two stars will be 0.02 AU seperated from each other. This setup seems satisfactory for me so far. So with that in mind, what do you think the planetary system could potentially be like?

http://www.stellar-database.com/ Most of the entries for the stars has a 'comfort zone' listed.

The one I have in mind as an analog for Shinespark (107 Piscium) doesn't seem to show up there.

#### Dibwys

So it seems like Shinespark will be a K1V class star with 0.86 solar masses with a luminosity of 41% of the Sun's luminosity, while Valey will be an M3V class star with a mass of 0.37 solar masses with a luminosity of 1.6% that of the Sun. So combined, the two stars will have a luminosity of 42.6% that of the Sun. This means that both stars will be relatively long lived in comparison to that of the sun.

The two stars will be 0.02 AU seperated from each other. This setup seems satisfactory for me so far. So with that in mind, what do you think the planetary system could potentially be like?

The one I have in mind as an analog for Shinespark (107 Piscium) doesn't seem to show up there.

http://www.stellar-database.com/Scripts/search_star.exe?Catalog=HD&CatNo=10476 They list lots of things by their Henry Draper Catalog number. Try looking that up in the bottom of the right-side box on the Wikipedia entry for the star.

In "The Teddy Invasion and What Happened Next" I have a lot of mining going on in the 107 Piscis system (but no naturally habitable planet or moon).

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#### CarnelianClout

http://www.stellar-database.com/Scripts/search_star.exe?Catalog=HD&CatNo=10476 They list lots of things by their Henry Draper Catalog number. Try looking that up in the bottom of the right-side box on the Wikipedia entry for the star.

In "The Teddy Invasion and What Happened Next" I have a lot of mining going on in the 107 Piscis system (but no naturally habitable planet or moon).
Very very interesting. So what would the CZ be for the two stars with a combined luminosity of 42.6% ?

#### Dibwys

Very very interesting. So what would the CZ be for the two stars with a combined luminosity of 42.6% ?

I would assume 85.2%.

#### CarnelianClout

I would assume 85.2%.
More or less referencing the AU / size of it here.

#### Pragmatic Progressive

Would a planet which rotates significantly slower (i.e. where the seasons are a year each or longer in a temperate climate zone) be liveable for humanity? What - except for crops - would have to change? I plan for a planet to be somewhat further out than Earth - maybe further than Mars(?) but by far not as far out as Jupiter -, the sn correspondingly brighter and/or hotter, and its orbital period significantly longer - not quite Atlacamani

Atlacamani's is 64 TY

The axial tilt goes through revolutions. It stays at the same angle, but through a 13 TY cycle moves in a circle so that the hemispheres swap directions (and therefore winter/summer) every 6.5 TY. In the temperate zones, there are rough analogues of the four familiar seasons.
-In winter, snow falls and plants go into dormancy
-In spring, the snow melts and plants regrow their foliage
-In summer, plants release fruit and most fungi release spores
-In autumn, the leaves of the plants turn yellow, green, blue, and violet, before falling to the earth and providing detritus for the growing fungi

In the tropics, there is a wet season, where the wet-weather plants thrive. Towards the end of the season, they release fruit, and seeds go into the ground and lay dormant.
-Then there is a dry season, during which wet weather plants suffer a massive dieback and dry weather flora take over. Cactus-like organisms as well as bulbous balls of orange photosynthesizing flesh bloom and cover the dry landscape. Before this season ends, they release fruit and/or put down deep roots for asexual reproduction. The seeds and roots lay dormant.
-When the rains come again, the dry weather plants die off and are washed into the inland seas by torrential floods and refilled rivers, where they fertilize the sea and allow for an algal and fungal bloom

In the steppe, there is a cold-dry season where the ground is covered in frost, the grasses die, and the sky throws down freezing rain and hail. This is followed by a warm-wet season where grasses and small trees bloom. After that is a third, cold-wet season where grasses grow extremely tall, cold rains fall as the trees fan out their leaves to gain as much sunlight as possible. Then the cold-dry season begins again.

In the tundra, there is a season of relative warmth where small shrubs manage to grow above the permafrost, followed by a very harsh winter.

This happens over a period of 13 years.

It is also of note that the true orbital year of 64 TY also affects the seasons, which go through subtle changes in length and intensity as the perihelion and aphelion are reached.

but maybe five to eight years. This planet is planned to already have native life (but no intelligent life). What would humanity have to mind?

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#### mrmandias

Another one to play with is a red dwarf orbiting a star in that star's habitable zone. Then, either a tidally-locked planet orbiting the red dwarf would have one side with a very long day/night cycle, and the inner hemisphere would have constant daylight, with periods of additional light from the system primary. Alternatively you could have a habitable planet in the same orbit as the red dwarf, but in either the leading or trailing trojans. The red dwarf would rise at noon and be visible until midnight....
COOL!

#### CarnelianClout

I would assume 85.2%.
I misread that earlier. I will write out my ideas for the planets soon.

#### Ekg

an interesting video about newly discovered effect that could possibly affect tidally locked planets : they can erratically flip multiple times in their lifetime, meaning that the side facing the sun can suddenly become the cold one
it's not a good news for the potential life evolving here, even if some organisms could perhaps adapt

#### CarnelianClout

Here is a list of the planets and stars so far. This is just the first two planets, so far, what do you think?

@Workable Goblin @Dibwys

Shinespark will be a K1V class star with 0.86 solar masses with a luminosity of 41% of the Sun's luminosity, while Valey will be an M3V class star with a mass of 0.37 solar masses with a luminosity of 1.6% that of the Sun. So combined, the two stars will have a luminosity of 42.6% that of the Sun. This means that both stars will be relatively long lived in comparison to that of the sun.

The two stars will be 0.02 AU seperated from each other. The two stars will revolve around each other at a distance of 0.02 AU - meaning that they would both be tidally locked to each other, share the same axis of rotation. This will also mean that the two stars will eclipse each other regularly, once a day. Because of how close the two stars are to each other - they will both have a roughly oval shape. Both stars formed together from the same accretion Disk. Because both stars are of different masses, it is likely they will have differing solar cycles - meaning that there will be time periods in which both of their magnetic fields are aligned, and when there are periods where their magnetic fields are opposite - this will mean there will be more solar flare activity and solar activity than we experience with our Sun.

The first planet is named Ruby, at about 3.6 Earth masses, with a similarity to Venus. A hot, extremely reflective, hell world. Ruby has no moons, and is tidally locked to both stars. It's atmosphere is extremely dense, toxic. Imagine Venus, but worse. Potentially a crushing atmosphere 400 times that of Earth's in terms of pressure. Would this make sense, or would Ruby's atmosphere have been blown away by the combined stars?

Second planet is named Halycon. It is 0.93 the mass of Earth. Halycon has an axial tilt of 24 degrees. Rotation period - unsure of. It's single large Moon (which is Lunar Mass) is a captured Moon, and orbits in the opposite direction of Halycon's rotation. Like that of Triton. Corsica is the name of this Moon. Corsica is doomed to collide with Halcyon due to it moving closer and closer each year - on the scale of mere centimeters. In a few billion years, Corsica will enter Halcyon's roche limit and break up, forming a ring system. Corsica was once a binary planet, the secondary object was lost as it became captured by Halcyon.

What would Halcyon's rotation period be like, assuming Corsica was captured in the past billion year? Corsica will likely not be tidally locked, due to the capture. It will not rotate with the same axial plane as Halcyon.

Halcyon has a thin ring system of rock, indicating that when Corsica was captured, it pushed a smaller moon inward, causing it to break up into a ring system. Said ring system is very faint.

#### CarnelianClout

More on my system.

Garshova Is a fairly large Jovian planet, at about 84% the mass of Jupiter. Garshova has a fairly reflective ring system and an entourage of moons. The planet's ring system is similar to that of Saturn but thanks to the size of the planet, it's ring system is much more extensive. The planet, much like Jupiter itself is host to various massive planet-sized storms. Garshova has a vast amount of minor moons - so I'll only really list the major moons.

Ironia - Is a barely spherical Moon that orbits just beyond Garshova's rings. It is roughly the mass of Ceres and consisted almost entirely of iron - hence it's name.

Meltdown - A Mars mass world similar to that of Io. It has major and regular eruptions thanks to the tidal interactions between other Moons. Unlike our Io, Meltdown has a rather thick atmosphere of sulfur. It has a rather active Magnetic field that produces global auroras. Due to it's magnetic interactions with Garshova, it produces a flux tube similar to that of Io.

Aramo - Aramo is an Earth mass moon. It's atmosphere however, is not breathable to humans thanks to the large amount of Carbon Dioxide and Ammonia. It's oceanic nature means that there is ample room for hurricanes to form. There is ammonia rain and ammonia snow. Aramo is fairly cold in comparison to Meltdown. It's atmosphere is mostly of nitrogen (N2) and oxygen (O2 with variable amounts of ammonia (NH3) and trace amounts of carbon dioxide (CO2) and other gases. There is roughly 80% ocean and 20% land.

Maple - Maple is a half-Earth mass world, similar to that of Mars. Unlike our Mars it is host to a slightly thicker atmosphere, though it's atmospheric pressure is negligible in comparison to that of Earth (0.03). Maple is fairly cratered and Barren, with many similar features to Mars. Due to it's larger mass, it's magnetic field is still active.

Ancel - A distant Lunar mass Moon, it's elliptical and inclined orbit leads some to believe that it's a captured planet. Some circles suggest it was once Corsica's binary companion before Corsica was captured into orbit around Halycon.

Beyond Garshova is an asteroid belt with a small planet named Edgelwonk that has a small ring system. Edgelwonk is roughly about the mass of Pluto and has 6 small asteroidal moons (each less than 10km in size).

After the asteroid belt is a three Earth mass world named Larceny. Larceny rotates on it's side like Uranus, and has a fairly reflective ring system. Larceny is in a binary pair with a Mercury mass moon named Senescey and many other minor moons. Both Larceny and Senescey have large internal oceans that may very well be host to life. Senescey has a thin atmosphere and outgassing similar to that of Triton/Enceladus, just on a much larger scale. Nehaly is the third Moon, orbiting far out, which is about the Mass of Mars, having a similar look to that of Europa.

Leitmotif is world similar to that of Titan. It's a hazy world with it's thick atmosphere that conceals the surface. It is roughly about twice the mass of Earth though it's low density means that surface gravity is lower than on Earth. It is host to a large internal ocean, and has a complex biosphere. Life on Leitmotif will be slow evolving and slow moving thanks to the low amount of Sunlight. Leitmotif's Moons are named Graygarden (Ceres Mass), Iconia (Pluto Mass), and Aldera (Lunar Mass), thanks to Leitmotif's large hill sphere, the three moons orbit quite far apart from each other. Leitmotif has a visible ring system, as well.

The next planet after Leitmotif is Sosa - which is a Neptune mass / type world with a deep blue color. Sosa has many Moons and a vibrant ring system. Sosa's first Moon is about the Mass of our Moon, named Snowdrop. Snowdrop orbits fairly close into Sosa, giving it a good view of the ring system. There is also Crystal, Papyrus, Unless, and Gerdo (Pluto, Moon, Eris, Ceres and mass respectively)

There is also a third Sun, orbiting at 500 AU out. It is named Aegis. Aegis has a spectral type of M7.7V. It has a luminosity of 0.00076 that of the Sun - making it very similar to Teegarden's star. Aegis has some planets, as well.

The first planet around Aegis is the only one in the habitable zone, named Indus. It is roughly 10% more massive than Earth, and has a somewhat eccentric orbit, negating some of the effects of tidal locking. Indus is Earth like.

The second planet is a sub-Neptune mass world about 6 times the mass of Earth, it may very well be an oceanic world - named Vortex. Vortex has no moons, nor does Indus.

The third planet is named Chauncey, it is a fairly strange planet with a very low density despite it's large radius about twice that of Earth's. It has a dark ring system, with many minor moons.