Alternate Planets, Suns, Stars, and Solar Systems Thread

any advice on positioning the day-night divide of a tidally locked world on a Winkel Tripel projection?
I think it depends on a couple of things. If the subsolar point (or an area within the inner hemisphere) is most habitable, and the rest is frozen, then you could put the terminator (day-night divide) at 90º E and W, so that the important areas are displayed in the center. If it's the region along the terminator in a narrow band that's habitable, maybe put the terminator along the equator line (0º N/S), with the subsolar point at one of the "poles".
If you don't have focus on any one region in particular, or if you want to highlight the whole world, both of these options are also good, but you might also consider placing your terminator at the prime meridian (0º and 180º E/W). Like the option of using the equator, this divides your map neatly in half into the day and night hemispheres.

It's also, of course, possible to use other projections.
 
Don't know if Universe Sandbox 2 images are good enough. But I played with the idea of Venus turning into a hotter TTL's Mars.
It would have a 24.36 sidereal rotation period. Roughly 0.9 bar atmosphere with +90% if it being Co². An axial tilt of around 25°. I think the mean temp. would be around 30°C. It's magnetosphere would look like a somewhat weaker version of Earth's.
I'd imagine this planet would be a muddy desert planet. So no to very little surface water but the earth itself is wet enough to support life thanks to subsurface lakes, rivers and all that.

Over all it would be a bigger and hotter version of Mars, and not the literal hell that is OTL's Venus.

Do you think this Venus could take Mars's place as the favorite child of scientific and public interest?
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Don't know if Universe Sandbox 2 images are good enough. But I played with the idea of Venus turning into a hotter TTL's Mars.
It would have a 24.36 sidereal rotation period. Roughly 0.9 bar atmosphere with +90% if it being Co². An axial tilt of around 25°. I think the mean temp. would be around 30°C. It's magnetosphere would look like a somewhat weaker version of Earth's.
I'd imagine this planet would be a muddy desert planet. So no to very little surface water but the earth itself is wet enough to support life thanks to subsurface lakes, rivers and all that.

Over all it would be a bigger and hotter version of Mars, and not the literal hell that is OTL's Venus.

Do you think this Venus could take Mars's place as the favorite child of scientific and public interest?
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Even if the magnetosphere is weaker than Earth's, a lot of the atmosphere would still have been blown off over billions of years since the solar wind is much stronger at Venus's location.

I'd think the life that evolves there (which would probably be related to Earth/Mars life via panspermia) would be useful in testing hypotheses regarding the early Earth before the emergence of the oxygen atmosphere.
 
Even if the magnetosphere is weaker than Earth's, a lot of the atmosphere would still have been blown off over billions of years since the solar wind is much stronger at Venus's location.
If that’s true, since Venus’s atmosphere is 90 bar right now, how much thicker was it eons ago, then?
 
Wait, so Venus back then had around 340 bar?
If we evaporate Earth Ocean and decompose carbonates by heating we would have near 320 bar in Earth


Wonder how much that would increase the temp.
I don't know. And we should remember that a disproportionately large part of Venus' atmospheric loss is water, which is greenhouse gas too



Over all it would be a bigger and hotter version of Mars, and not the literal hell that is OTL's Venus.
Is this clouds in south hemisphere? ATL Venus should be pretty dry, because wet Venus with fast rotation will have runaway greenhouse effect by water.
 
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If we evaporate Earth Ocean and decompose carbonates by heating we would have near 320 bar in Earth



I don't know. And we should remember that a disproportionately large part of Venus' atmospheric loss is water, which is greenhouse gas too




Is this clouds in south hemisphere? ATL Venus should be pretty dry, because wet Venus with fast rotation will have runaway greenhouse effect by water.
So dry and thinner atmosphere are more likely with OTL Venus orbit?
 
So dry and thinner atmosphere are more likely with OTL Venus orbit?
It depends from first off all magnetosphere, temperature and initial composition of planet.


Roughly 0.9 bar atmosphere with +90% if it being Co².
I thought again and I have doubts. I not sure that 0.8 bar CO2 don't warm planet by greenhouse effect. And ATL Venus atmosphere should have more Nitrogen. OTL Venus nas 3 bar N2 and Martian N2 escaped or turned into nitrates
 
It depends from first off all magnetosphere, temperature and initial composition of planet.



I thought again and I have doubts. I not sure that 0.8 bar CO2 don't warm planet by greenhouse effect. And ATL Venus atmosphere should have more Nitrogen. OTL Venus nas 3 bar N2 and Martian N2 escaped or turned into nitrates
Maybe 1/3 Co² like pre life Earth?
 
Maybe 1/3 Co² like pre life Earth?
It is not the thing I can calculate on a napkin. We need to take into account Venudune's surface radiation spectrum and CO2 absorption window.
Venus with Martian albedo already has 304K effective temperature. So, on first look, Venudune's atmosphere should have pretty little of greenhouse gases but as I said it need more calculations
 
Would it have been possible for a Ceres mass dwarf planet to form between the Sun and Mercury in a stable orbit, in a small asteroid belt?
 
Would it have been possible for a Ceres mass dwarf planet to form between the Sun and Mercury in a stable orbit, in a small asteroid belt?
Maybe. The Yarkovsky–O'Keefe–Radzievskii–Paddack effect prevents anything small from remaining stable so close to the Sun, but Ceres is about 7 times larger than the theoretical limit of destruction. As for a belt, probably not, for the same reason.
 
Maybe. The Yarkovsky–O'Keefe–Radzievskii–Paddack effect prevents anything small from remaining stable so close to the Sun, but Ceres is about 7 times larger than the theoretical limit of destruction. As for a belt, probably not, for the same reason.

Would it then be possible for there to be various smaller bodies larger than 100km in that proximity to the sun? Like around a dozen or so...forming a belt, of sorts?
 
Would it then be possible for there to be various smaller bodies larger than 100km in that proximity to the sun? Like around a dozen or so...forming a belt, of sorts?
Possibly. We’re still looking for Vulcanoids, but the length and scope of the search has led people to think there may be fewer than 100, if there are any at all. They seem possible, it’s just we haven’t found any.
 
Possibly. We’re still looking for Vulcanoids, but the length and scope of the search has led people to think there may be fewer than 100, if there are any at all. They seem possible, it’s just we haven’t found any.
I am more or less speaking in the context of an alternate solar system, where such objects did exist in our solar system. Would they be stable and able to exist in an interior orbit to that of Mercury?

Here is a description of what I have set up for that alternate universe.

The Planet Vulcan is the largest object in the Vulcanoid Belt, at about the mass of Pluto. It's composition is almost entirely of Iron, nicknaming it the 'anvil' of the solar system. Because of it's small size, and close proximity to the Sun (0.14 AU), it has an orbital period of 19 days, and 17 hours. The planet is also rather dark for a planetary body, so any observation of the planet was made even more difficult thanks to the planet's dark appearance. Thanks to this, the planet was only discovered by Le Verrier (the same astronomer who discovered Neptune), in 1860. The planet has been visited a few times by spacecraft, although it is difficult to get there.
 
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What do you think of the rest of these here for my idea?



Mars is discovered to have life on it's surface by the early 2000's, when a successful sample return had returned samples of microbes in the Martian soil. Further follow up missions have confirmed this is not because of contamination. Rover missions on mars in the late 2010's have proved the existence of fossilized plant and animal life on Mars, which is hypothesized to have gone through a mass extinction event in the early days of the solar system because of the planet's inability to sustain life and a proper atmosphere. The discovery of underground lakes on Mars through orbiting probes gives many the idea that animal life could still exist in those lakes, but as they are underneath the poles of Mars, discovery of that life will likely have to wait decades. Because of this discovery, scientists have taken prominent care of the samples to avoid any potential biohazards, and also have made careful sure to not contaminate Mars with Earth bacteria either.

The Rings of Ceres were discovered in the 1980's through occultation, as astronomers were measuring the planet's size, shape, and albedo. It is the only object in the asteroid belt classified as a planet, as no other object in the asteroid belt is gravitationally rounded by it's own gravity.

The Moon Rhea of Saturn, is the second largest moon of Saturn. Discovery of it's rings proved to be an impressive moment in scientific history, as no other moon has been observed in the solar system to have rings. It's rings orbit quite close in to the Moon.

Titan was the first Moon of Saturn that was discovered, in 1655. It is about the mass of Mars (1/10th the mass of Earth), giving it the position of the largest Moon in the solar system, with Propserina (Minthe's largest Moon) as the second largest moon in the solar system, followed by Ganymede. Titan has oceans of hydrocarbons on it's surface through scientific analysis. Titan's physical appearance from space is the same as it is OTL, a hazy moon. It's atmosphere is more or less the same as OTL. Awaiting discovery on Titan is unique coral-like lifeforms in it's oceans, and patches of simple Moss and Plant like organisms on it's surface.

The Planet Minthe orbits the Sun in a roughly circular orbit, but inclined by 17 degrees to the orbital plane of the planets. The closest the planet comes to the sun is 340 AU, and the furthest it is at 360 AU, making it's orbit somewhat eccentric. It is around 7.7 to 8.1 times as far away as the Kuiper Belt, rendering it having no gravitational impact on it. OTL objects such as Sedna will not exist in this system, due to the presence of Nemesis.

The planet is a superterran ice world with a confirmed ring system, with a mass of 6.3 times that of Earth. Despite it's large size, due to the distance from the sun, the planet has close to no atmosphere which makes any hypothetical landings quite challenging. It would take a spacecraft many decades to arrive, at the very least.

The planet has 5 confirmed Moons. Persephone, Hecae, Nox, Mors, and Prosperina. They are similar in size to Pluto, Eris, Ceres, Pluto, and Mars respectively, with large spaces between each orbits, meaning the 5 moons of Minthe do not enact tidal forces on each other. Only the moons Persephone and Hecate are close enough to Minthe to be tidally locked, while the rest are far enough away to have their own rotation rates. Because of the distance from Earth, the planet Minthe and it's Moons are known only by their size, mass, and orbital configurations.

Visual images of them are pixelated and blurry because of the distance, this may change in future decades with the advent of more advanced telescopes. Because of Minthe's distance form the sun, many astronomers have theorized that the planet could have the most moons of any planet in the solar system. Minor moons are not able to be observed around Minthe because of the distance, future telescopes and advances in technology will yield more results about this, while the rest is scientific theory.

Nemesis is an ultra-cool red dwarf star a planetary system of seven known planets. It has a mass about 9% of the Sun's, a radius slightly larger than the planet Jupiter, and a surface temperature of about 2,904 K (2626.85 °C). This gives it a stellar classification of M7V. This makes Nemesis rather similar to the star known as Teegarden's Star. Nemesis is a "Safe" star, meaning it is not subject to massive stellar flares like other red dwarfs are known to have.

Observations of the planets around Nemesis have been made. No visual images of any real meaningful value have been made, however some characteristics about the planets have been recorded through observations by long range telescopes. Moons around these planets have not been discovered either.

Phlegethon is the first planet around Nemesis. It is 0.81 Earth Masses. Observations of the planet have confirmed that it likely has a thick Venus like atmosphere, making the planet similar to Venus. Due to close proximity to Nemesis, it is likely much hotter than Venus is. It orbits Nemesis every 1.2 Earth days. It is tidally locked. The planet is not within the habitable zone as its expected irradiation is more than 4 times that of Earth.

Acheron is the second planet around Nemesis. It is 1.04 Earth Masses. Observations of the planet confirm that it is in the habitable zone around Nemesis and is host to liquid water. It orbits Nemesis every 5.7 days. Compared to other exoplanets around other stars, Acheron is the most Earth-Like exoplanet currently known by mankind. It is not currently known if the planet is host to life by humans. The planet is also tidally locked.

Cocytus is a low density world as big as Venus but just 0.5 Earth mass and 5/8 Earth's gravity. It's like a much bigger Titan on a balmy interglacial day: warmer and wetter, 'wetter'. If you could call gasoline wet, that is. Air pressure at sea level is 4 atmospheres. It's atmosphere is mostly hazy with hydrocarbons evaporating off of ethane seas. Rain won't be a rarity, as on Titan in OTL. If life is found to exist here, it may exist in similar forms to Titan's life. Life here would likely still be evolving very slowly, thanks to how cold the planet is. Cocytus goes around Nemesis every 30 days.

The final planet of Nemesis discovered to date is Lethe. A large mini-Neptune about 5.2 Earth masses. Not much is known about it other than that it exists, and takes 21 years to go around Nemesis. It exists within darkness with both the Sun and Nemesis respectively as the brightest objects in the skies of those planets.

Nemesis should be at around 5,000 AU out. Doing some research, other stars have come into the Oort cloud in the past, so I wanted to state a more realistic margin for distances from other stars to where it wouldn't have been dislodged from the solar system.
 
What do you think of the rest of these here for my idea?
I want to procrastinate on a different project, so I can maybe give some thoughts here.
Mars is discovered to have life on it's surface by the early 2000's, when a successful sample return had returned samples of microbes in the Martian soil. Further follow up missions have confirmed this is not because of contamination. Rover missions on mars in the late 2010's have proved the existence of fossilized plant and animal life on Mars, which is hypothesized to have gone through a mass extinction event in the early days of the solar system because of the planet's inability to sustain life and a proper atmosphere. The discovery of underground lakes on Mars through orbiting probes gives many the idea that animal life could still exist in those lakes, but as they are underneath the poles of Mars, discovery of that life will likely have to wait decades. Because of this discovery, scientists have taken prominent care of the samples to avoid any potential biohazards, and also have made careful sure to not contaminate Mars with Earth bacteria either.​
We're doing Mars sample returns by the early 2000s? That's great!
How do we discover the lakes under the ice caps?
The Rings of Ceres were discovered in the 1980's through occultation, as astronomers were measuring the planet's size, shape, and albedo. It is the only object in the asteroid belt classified as a planet, as no other object in the asteroid belt is gravitationally rounded by it's own gravity.​
Are you sure you don't mean a dwarf planet, or is the IAU definition of a planet different ITTL? The asteroid belt does still exist, so it hasn't cleared its orbit.
The Moon Rhea of Saturn, is the second largest moon of Saturn. Discovery of it's rings proved to be an impressive moment in scientific history, as no other moon has been observed in the solar system to have rings. It's rings orbit quite close in to the Moon.​
Sure, that's not far off from reality anyway
Titan was the first Moon of Saturn that was discovered, in 1655. It is about the mass of Mars (1/10th the mass of Earth), giving it the position of the largest Moon in the solar system, with Propserina (Minthe's largest Moon) as the second largest moon in the solar system, followed by Ganymede. Titan has oceans of hydrocarbons on it's surface through scientific analysis. Titan's physical appearance from space is the same as it is OTL, a hazy moon. It's atmosphere is more or less the same as OTL. Awaiting discovery on Titan is unique coral-like lifeforms in it's oceans, and patches of simple Moss and Plant like organisms on it's surface.​
So Titan is scaled up by ~4.5x and life-infused, but otherwise similar to OTL. Doesn't sound too unreasonable. Since methane and ethane are non-polar, the chemistry of this life must be very different from Earth; I don't know very much about this, but I'm sure it would be fascinating to flesh out.
The Planet Minthe orbits the Sun in a roughly circular orbit, but inclined by 17 degrees to the orbital plane of the planets. The closest the planet comes to the sun is 340 AU, and the furthest it is at 360 AU, making it's orbit somewhat eccentric. It is around 7.7 to 8.1 times as far away as the Kuiper Belt, rendering it having no gravitational impact on it. OTL objects such as Sedna will not exist in this system, due to the presence of Nemesis.​
That orbit gives it a period of ~6550 years. Where in its orbit is it currently? Nearer to perihelion or aphelion? Is it close to ascending or descending node, or is it currently far out of the ecliptic?
The planet is a superterran ice world with a confirmed ring system, with a mass of 6.3 times that of Earth.​
What ices is it made of? What's the radius? About 2.6 times Earth's is my estimate, given icy composition and mass.
Is all of this material just created ex nihilo (which would be fine), or is there an explanation? This alone is more than three times the total mass of the Oort cloud and Kuiper belt.
Despite it's large size, due to the distance from the sun, the planet has close to no atmosphere which makes any hypothetical landings quite challenging. It would take a spacecraft many decades to arrive, at the very least.​
No kidding - Voyager 1 launched half a century ago and is only 160 AU away, and this is more than twice that!
The planet has 5 confirmed Moons. Persephone, Hecae, Nox, Mors, and Prosperina. They are similar in size to Pluto, Eris, Ceres, Pluto, and Mars respectively, with large spaces between each orbits, meaning the 5 moons of Minthe do not enact tidal forces on each other. Only the moons Persephone and Hecate are close enough to Minthe to be tidally locked, while the rest are far enough away to have their own rotation rates. Because of the distance from Earth, the planet Minthe and it's Moons are known only by their size, mass, and orbital configurations.​
When you say "similar in size", do you mean mass or radius? I assume all of these moons are icy as well.
Based on this spreadsheet, Nox would have an absolute magnitude of almost 27 - close to the limit of what our telescopes could probably find.
Visual images of them are pixelated and blurry because of the distance, this may change in future decades with the advent of more advanced telescopes. Because of Minthe's distance form the sun, many astronomers have theorized that the planet could have the most moons of any planet in the solar system. Minor moons are not able to be observed around Minthe because of the distance, future telescopes and advances in technology will yield more results about this, while the rest is scientific theory.​
I think Nox is a good estimate for the minimum resolvable size. Do Minthe's moons orbit in the same plane as it?
Nemesis is an ultra-cool red dwarf star a planetary system of seven known planets. It has a mass about 9% of the Sun's, a radius slightly larger than the planet Jupiter, and a surface temperature of about 2,904 K (2626.85 °C). This gives it a stellar classification of M7V. This makes Nemesis rather similar to the star known as Teegarden's Star. Nemesis is a "Safe" star, meaning it is not subject to massive stellar flares like other red dwarfs are known to have.​
You say seven planets, but I think you only list four. A typical M7V star has a luminosity around 6.5 * 10^-4 Lsol, for reference.
Observations of the planets around Nemesis have been made. No visual images of any real meaningful value have been made, however some characteristics about the planets have been recorded through observations by long range telescopes. Moons around these planets have not been discovered either.​
Have most of our observations been using transits then? Do the planets transit?
Phlegethon is the first planet around Nemesis. It is 0.81 Earth Masses. Observations of the planet have confirmed that it likely has a thick Venus like atmosphere, making the planet similar to Venus. Due to close proximity to Nemesis, it is likely much hotter than Venus is. It orbits Nemesis every 1.2 Earth days. It is tidally locked. The planet is not within the habitable zone as its expected irradiation is more than 4 times that of Earth.​
This orbital period with this star gives about 0.00990 AU for orbital radius.
Acheron is the second planet around Nemesis. It is 1.04 Earth Masses. Observations of the planet confirm that it is in the habitable zone around Nemesis and is host to liquid water. It orbits Nemesis every 5.7 days. Compared to other exoplanets around other stars, Acheron is the most Earth-Like exoplanet currently known by mankind. It is not currently known if the planet is host to life by humans. The planet is also tidally locked.​
The distance to the star would be 0.0280 AU. How did we confirm water? Spectra? The planet is too small and close to its star to resolve. I really like this idea. Do we know if the liquid water is exclusively on the terminator? What's the temperature differential like?
Cocytus is a low density world as big as Venus but just 0.5 Earth mass and 5/8 Earth's gravity. It's like a much bigger Titan on a balmy interglacial day: warmer and wetter, 'wetter'. If you could call gasoline wet, that is. Air pressure at sea level is 4 atmospheres. It's atmosphere is mostly hazy with hydrocarbons evaporating off of ethane seas. Rain won't be a rarity, as on Titan in OTL. If life is found to exist here, it may exist in similar forms to Titan's life. Life here would likely still be evolving very slowly, thanks to how cold the planet is. Cocytus goes around Nemesis every 30 days.​
30. days -> 0.0847 AU
This is a fun concept for a planet. The gravity, mass, and radius more or less check out; Venus radius and 0.5 earth mass gives 0.55 g, while 0.5 earth mass and 0.625 g gives 0.94 Venus radius.
The final planet of Nemesis discovered to date is Lethe. A large mini-Neptune about 5.2 Earth masses. Not much is known about it other than that it exists, and takes 21 years to go around Nemesis. It exists within darkness with both the Sun and Nemesis respectively as the brightest objects in the skies of those planets.​
21 years -> 3.4 AU
If these planets were discovered with transits - how long have we been watching Nemesis, to have confirmed a 21-year-period planet? If it's some other method we're using to discover planets, which? They don't appear to have any resonance, which could be something to consider given how close in the inner planets orbit.
Nemesis should be at around 5,000 AU out. Doing some research, other stars have come into the Oort cloud in the past, so I wanted to state a more realistic margin for distances from other stars to where it wouldn't have been dislodged from the solar system.​
Sounds fine.
 
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@Epsilon Tauri

I will try to provide good responses to your statements, I really appreciate the interest. Do be known, that this is an alternative history timeline, which I am not going into, until it is posted by the person who covered the map and lore of it. I requested all this information, and the majority of the lore behind it, I just had someone compile it and map out the alternative history portion of it. You won't be seeing this on a map, but hopefully what you see will be interesting enough.
We're doing Mars sample returns by the early 2000s? That's great!
How do we discover the lakes under the ice caps?
I would imagine the lakes discovered under the ice caps are done by orbital probes scanning the poles. I do not know much about this, but, I would assume that it would be something we would be capable of knowing. Best guess I can give for what the life on Mars would be like - think about under the ice of Antarctica.
Are you sure you don't mean a dwarf planet, or is the IAU definition of a planet different ITTL? The asteroid belt does still exist, so it hasn't cleared its orbit.
It is different. Any object that is gravitationally round by it's own gravity is considered a planet in this timeline (think Pluto, Ceres, Eris, Sedna, etc, added to the planet list) I have always very much disagreed with the IAU standards. I will not accept the idea of Dwarf Planets not being considered planets. Personal bias and subjectivity, I know, but, it's the way I see these things.
Sure, that's not far off from reality anyway
There even exists possible evidence of it in this timeline, as far as I know. In this timeline, the Moon Rhea's rings are quite prominent. They are not small arcs like the rings of Neptune. They are a relatively solid, and visible ring system like that of Saturn's, but on a far smaller scale, of course. Existing well within Rhea's sphere of influence, their prominence would indicate they formed in the past few million years or so, so are relatively young in the scheme of the solar system.

https://en.wikipedia.org/wiki/Rings_of_Rhea

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So Titan is scaled up by ~4.5x and life-infused, but otherwise similar to OTL. Doesn't sound too unreasonable. Since methane and ethane are non-polar, the chemistry of this life must be very different from Earth; I don't know very much about this, but I'm sure it would be fascinating to flesh out.
I do not know exactly how this life would look. I have been imagining Fractal like structures, like plants, almost. Living crystals, so to speak. Perhaps they would take thousands of years to fully mature, if conditions get right. Titan does not have intelligent life. Animal life would likely be small, and focus on conserving energy. Perhaps organisms that blurr the lines between plants and animals. Titan is very cold. Life must conserve energy and heat. By not moving. Perhaps the skies of Titan are filled with small floating plant-like creatures that have a life cycle up in the sky as the wind currents carry them about.

Unlike the Titan of our world, it's liquid lakes and oceans are not confined to the Equator. I would imagine roughly 60% land and 40% ocean.

This Titan, as it is much larger than our Titan - I'll say the outer Moons of Saturn are different. Titan orbits where it sits currently, while Hyperion and Iapetus exist further out from Saturn. How much further out, and how their orbits would differ - I don't know. Stable orbits, with Hyperion existing in a resonance with it.

Something else has crossed my mind about Hyperion. Maybe Hyperion could be a smaller version of Titan, roughly the mass of our Moon. Imagine the two Moons with similar biospheres via panspermia? Just a proposal, not sure how realistic that would be.

That orbit gives it a period of ~6550 years. Where in its orbit is it currently? Nearer to perihelion or aphelion? Is it close to ascending or descending node, or is it currently far out of the ecliptic?

What ices is it made of? What's the radius? About 2.6 times Earth's is my estimate, given icy composition and mass.
I do not know about that. It's orbital period means, at least in my eyes, it would not affect the orbits of the other planets or Kuiper belt. Minthe, in mind, as a large super-terran iceworld - it has a fairly cratered appearance. Minthe exists in such a cold region of the solar system, that I can imagine it has a thin atmosphere. Minthe's atmosphere does not sublimate, like that of Pluto. It is simply too far away for it's atmosphere to change that much. Good luck landing on Minthe. There won't be that much of an atmosphere to slow you down.

Minthe, likely does have a global ocean underneath it's surface. Far more expansive than that of any ocean elsewhere in the solar system. Tons, and tons more water than that is on the Earth. By how much, I don't know.

No kidding - Voyager 1 launched half a century ago and is only 160 AU away, and this is more than twice that!

Best I could think would be sending lightsail probes out to do a fly by of it, but even then, we may not see pictures of it up close within our lifetime.

When you say "similar in size", do you mean mass or radius? I assume all of these moons are icy as well.
Based on this spreadsheet, Nox would have an absolute magnitude of almost 27 - close to the limit of what our telescopes could probably find.

Similar in Mass. If you are saying that Nox is the only one that would be large enough to be visible, I do not know about that. I do not know anything about orbital mechanics or how visible these sorts of things would be in space, that's for someone with more talent and knowledge than I to figure out.

I think Nox is a good estimate for the minimum resolvable size. Do Minthe's moons orbit in the same plane as it?
Yes they do. I imagine Minthe's main moons are similar in composition to that of Kuiper belt objects. All icy, with the major ones being cryovolcanic like Enceladus. I am also imagining that because of Minthe's lack of a substantial atmosphere, the rings themselves extend fairly close down to the planet. I would imagine that the record of "Moon with a shortest orbital period around a planet" would be one of Minthe's inner minor moons, likely a small moon similar to that of the moons of Saturn that inhabit it's rings. Going around the planet in mere hours.

You say seven planets, but I think you only list four. A typical M7V star has a luminosity around 6.5 * 10^-4 Lsol.
There should have been 5, but you are right, I only listed four. The main 4 I listed are the names that matter. Perhaps I can think of more planets for Nemesis, but I am not sure what else to add to it. What magnitude would Nemesis be?

Have most of our observations been with transits then? Do the planets transit?
Perhaps they would. We can say that the orbital plane of the Nemesis system is tilted so transits are able to be observed like around other stars.

This orbital period with this star gives about 0.00990 AU for orbital radius.

My intentions for the first planet is for it to be a hothouse world similar to Venus. Intense atmospheric pressure. Intense heat. Thick atmosphere. Likely hotter than Venus, possibly.

The distance to the star would be 0.0280 AU. How did we confirm water? Spectra? The planet is too small and close to its star to resolve. I really like this idea. Do we know if the liquid water is exclusively on the terminator? What's the temperature differential like?

I would propose that this planet is in a 2:3 resonance, so for every 2 times it orbits, it rotates 3 times. But I do not know if this is possible. If it's not, then we'd have a terminator line where liquid water is present.

30. days -> 0.0847 AU
This is a fun concept. The gravity, mass, and radius more or less check out; Venus radius and 0.5 earth mass gives 0.55 g, while 0.5 earth mass and 0.625 g gives 0.94 Venus radius.
0.5 Earth mass, but similar in radius to Venus, yes.

If these planets were discovered with transits - how long have we been watching Nemesis, to have confirmed a 21-year period? If it's some other method, which? They don't appear to have a resonance, which somewhat surprises me given how close in they orbit.
I simply put that "21 years" in since I didn't know what else to put. I wanted to have a resonance, but I do not have the manners to calculate that. Perhaps you could help me with these planets, and we can create a solid groundwork for the Nemesis system, you seem to know more than me.
 
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