Possibilities of a Binary Gas Dwarf-Dwarf Earth System

[Deltafang]

UPDATE: Terminology changed to reflect what we've worked on so far. Please read on! :thumbup:

Hello, all. I'm here to discuss with you the possibilities of a gas dwarf-terrestrial dwarf binary system.

Now, I've heard the term 'gas dwarf' used a lot recently, but I do not in any way take credit for that. I do however take credit for the term 'terrestrial dwarf', no matter how stupid or retarded it may (and boy do I think it does) sound.

To clarify things, I'll explain what I mean by the terms Gas Dwarf and Terrestrial Dwarf.

When a gas giant begins to form, it has a core of anywhere from 5-10 Earth masses before it begins to accrete gas from its star's protoplanetary disk. Its a slow process until it reaches about 30 Earth masses and then becomes a runaway process, eating up all the gas around it. Ice giants form in the same way, however they start the accretion process when gas giants have already finished, and accumulate less mass. It is also of note that the more massive gas giants usually have rocky cores encased in metallic hydrogen while ice giants mainly have cores of exotic forms of ice and rock.

A gas dwarf would have a core towards the lower end of the Earth mass spectrum and have accreted small amounts of gas comparative to their more massive cousins. A gas dwarf is a failed gas giant. Ice dwarfs would be the same, only differing in composition of their core and possibly atmospheric content. (Note: the term 'ice dwarf' exists already, but the IAU doesn't fully recognize its use in classifying bodies. When I say 'ice dwarf' I will be referring to what I described above.)

A terrestrial dwarf is exactly what it sounds like. A smaller terrestrial planet. The same way that gas and ice dwarfs would be sub-categories of jovian planets, terrestrial dwarfs would be a sub-category of terrestrial planets- ones primarily composed of silicon-oxygen compounds. They would have to have a metallic core of mostly iron with a surrounding silicate mantle. They would also be anywhere from 0.05-0.75 Earth masses. I know the term 'dwarf planet' already exists, but it doesn't necessarily specify what type of planet it is. Dwarf planets and terrestrial dwarfs are not the same thing. We have a lot of dwarf planets in our solar system and many more out there and not all of them would fit under these criteria.

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Now that we've defined a Gas Dwarf and a Terrestrial Dwarf, let's get down to business!

I've had it in my mind for quite a while now to write a story about mankind's first successful manned interstellar voyage. Now, in my story, we've already used probes to visit three other star systems and deemed them lifeless. We've sent a very expensive probe to Gliese 581 in the hopes that we'll find something interesting and we've found plenty. Let me introduce you to the system in order of their placement.

Gliese 581 "Tartarus" - type M3V red dwarf
Gliese 581 e "Lethe" - Superterrestrial - tidelocked, black and red molten surface with visible recent impact crater on night side
Gliese 581 b "Cocytus" - Class III Hot Neptune - moderate axial tilt and tidelocked, dark blue and featureless sunlit side with completely cloudy night side. plentiful bands of water clouds at northern pole and cloudy 'halo' around solar terminator
Gliese 581 c "Phlegethon" - Superterrestrial - thick and hazy translucent white atmosphere with high altitude, low albedo surface features.
Gliese 581 d(g) "Styx" - Ice Dwarf - Ice Dwarf (mini ice giant) in the process of warming. Hazy, dark blue lower atmosphere composed mostly of hydrogen and methane with high altitude whitish-blue water clouds. Two minor storms can be seen on its surface. In a binary relationship and tidelocked to Elysion.
Gliese 581 g(d) "Elysion" - Terrestrial Dwarf - Ocean planet with white water clouds in the atmosphere. Possesses exceptionally large ice caps with enormous free floating, migratory icebergs visible across the globe from orbit. In a binary relationship and tidelocked to Styx.
Gliese 581 f "Archeron" - Class I Cold Jupiter - standard hydrogen/ammonia gas giant with prominent banding and no visible storms

Alright, now that that's done. Questions, comments, concerns, suggestions? I'll be glad to discuss it all.

Things to discuss: Stability of orbits, weather in such a system, habitability zone implications for an ice dwarf, etc.

Thanks for all the help, I look forward to more intelligent discussion with you all.

 

[T.Neo]

Note: continued from Naming Conventions for planets thread.

The methane might be in very high amounts, but if it can't condense it won't make clouds. It might give the water ice clouds a bluish tint if there's enough of it though.

Class III planets have methane in their atmospheres, but then again so do class I and II planets, but they are not predominantly blue. Class III planets just lack worldwide cloud cover, so you're seeing deep into their atmospheres. They appear blue due to Rayleigh scattering, to which methane plays a part. Likely that if you removed all methane the hydrogen and helium would have the same effect.

Intermediate between class II and III would probably be partially clouded planets, with clouds of sulphur-rich compounds or water at cooler regions, and devoid of cloud in others. It would be featureless and blue with "ice caps" of cloud at the poles.

I've never heard of lower-mass cutoff limit for the Sudarsky model before, but the results should be similar- even on bodies with radically different characteristics like Earth, we get water clouds in the same temperatures predicted for water clouds. So for an ice giant or gas dwarf that has an outer composition similar to a larger planet, I would imagine very similar results. Temperature seems to play a bigger role then composition, at least.

 

[RisingFury]

I know the term 'dwarf planet' already exists, but it doesn't necessarily specify what type of planet it is.

A dwarf planet is any body (any body... as in... it can be an oversized pizza for all I care) that is in hydrostatic equilibrium due to it's own gravity (round due to it's own gravity) and is the primary body in orbit around it's sun (not a moon), but has not cleared it's orbit of orbital debris.

We have a lot of dwarf planets in our solar system and many more out there and not all of them would fit under these criteria.

We have a few confirmed dwarf planets in our solar system, but lots of candidates. It's hard to figure out if these bodies are in hydrostatic equilibrium due to their own gravity...


As for dwarf-Earth:
What... like... Mars-ish planet with a nice and cozy atmosphere?



As for the rest, TNeo found an interesting paper suggesting that large planets could have a moon mass limitation of around 0.1% IIRC. There are plenty of problems I could pull out of my head right now as to why...

 

[Deltafang]

The methane might be in very high amounts, but if it can't condense it won't make clouds. It might give the water ice clouds a bluish tint if there's enough of it though.

Exactly what I was thinking. The methane being released as the mantle starts to evaporate should be a large enough source.

Intermediate between class II and III would probably be partially clouded planets, with clouds of sulphur-rich compounds or water at cooler regions, and devoid of cloud in others. It would be featureless and blue with "ice caps" of cloud at the poles.

Yup. I made Gliese 581 b a class II and III intermediate with its northern pole tilted away from the sun. I can see a large 'cap' of clouds at the north pole, but what about the south pole?

I've never heard of lower-mass cutoff limit for the Sudarsky model before, but the results should be similar- even on bodies with radically different characteristics like Earth, we get water clouds in the same temperatures predicted for water clouds. So for an ice giant or gas dwarf that has an outer composition similar to a larger planet, I would imagine very similar results. Temperature seems to play a bigger role then composition, at least.

Hmm, okay. I was just noting that it seemed to be a model for predicting the appearance of gas giants based on their temperature and not Super-Earths and Ice giants. You're right, composition differences don't seem to play that much of a part in this case.

A dwarf planet is any body (any body... as in... it can be an oversized pizza for all I care) that is in hydrostatic equilibrium due to it's own gravity (round due to it's own gravity) and is the primary body in orbit around it's sun (not a moon), but has not cleared it's orbit of orbital debris.

Yes, I meant that its a rather general class of planet. The fact that it is capable of achieving hydrostatic equilibrium or not has nothing to do with the composition. I was trying to clarify and separate terms to avoid confusion. For instance, not all dwarf planets are terrestrial (composed of silicate rock and metallic cores). Many candidates so far are composed mostly of ice and rock alone.

As for dwarf-Earth:
What... like... Mars-ish planet with a nice and cozy atmosphere?

Yes, by my definition Mars would be 'Dwarf-Earth', Venus would be a 'Earth', and I'm not quite sure where that puts Mercury yet! The atmosphere doesn't have to be 'nice and cozy' though. I assume a planet of such size is still capable of maintaining fierce runaway greenhouse effects especially with intense geological activity and a strong magnetic field. Likewise, it could have a wispy, tenuous atmosphere of molecular compounds and have a very weak magnetic field, stripping it of whatever atmosphere it had managed to build. Or, it could be anywhere between.

Silicate planets are a type of terrestrial planets. Dwarf-Earths are a class of silicate planets. Dwarf-Earths don't really have the same relationship to Earth-like planets that Super-Earths do. Super-Earths aren't of any specific compositional type, but are definitely terrestrial planets.

As for the rest, TNeo found an interesting paper suggesting that large planets could have a moon mass limitation of around 0.1% IIRC. There are plenty of problems I could pull out of my head right now as to why...

Hn, really? If he remembers where he found it, could he post it here? But what would that imply exactly? That a planet whose moon is bigger than a certain mass would become gravitational unstable? Collision or being flung off into space? Nearing the Roche limit?

Gliese 581 d-g isn't a planet-moon system. Its a binary planet. Now, binary planet isn't a term recognized by the IAU yet, so the term is a bit fuzzy but we have a rough definition of what one is. One of the most commonly accepted definitions is based on their barycenter. As long as the barycenter is not under the surface of either planet, it can be called a binary planet. Apparently size has nothing to do with it it seems.

There is one more issue with deciding what constitutes a binary planet. Satellite mass ratios in our own solar system have less than .00025(1/4000) the mass of the primary planet except the Earth-Moon and Pluto-Charon system. Its estimated that the Earth and Moon could become a binary planet system in billions of years.
The Earth-Moon system has a mass ratio of approximately 0.01230(≈1/81) while the Pluto-Charon has a mass ratio of approximately 0.117(≈1/9). Assuming the Dwarf-Earth Gliese 581 g is 0.745 Earth masses and the Ice Dwarf Gliese 581 d is 7.12 Earth masses, they'd have a mass ratio of approximately 0.104(≈1/10). Closer to the Pluto-Charon binary dwarf planet system in ratio.

This raises a lot of issues with how they interact with each other as they revolve around their sun. How long can such a relationship be stable?

Thanks for the help!

Oh yeah, T.Neo, what program did you use to create the models for your version of the Gliese 581 system? I want to try and create my own models. Thanks.

 

[RisingFury]

Yes, I meant that its a rather general class of planet. The fact that it is capable of achieving hydrostatic equilibrium or not has nothing to do with the composition. I was trying to clarify and separate terms to avoid confusion. For instance, not all dwarf planets are terrestrial (composed of silicate rock and metallic cores). Many candidates so far are composed mostly of ice and rock alone.

Well, is a dwarf even less of a planet cos it's made up of ice?

Defining planet and dwarf planet to include say... chemical makeup is a very bad idea. So far we can only speculate as to what most of these bodies are made up of. And that speculation comes from their overall density, which is at times as uncertain as 50%...

Yes, by my definition Mars would be 'Dwarf-Earth', Venus would be a 'Earth', and I'm not quite sure where that puts Mercury yet!

What's the point of such a definition? Why is having it benificial for cathegorizing celestial bodies?

Hn, really? If he remembers where he found it, could he post it here? But what would that imply exactly? That a planet whose moon is bigger than a certain mass would become gravitational unstable? Collision or being flung off into space? Nearing the Roche limit?

Correction, he found an article with the summamry of a paper...
The article sugested that there's an upper limit to the mass of a moon at around 0.1% the planet's mass. And to answer your questions... if that's the case, then I assume the moon would just not form to be so big.

I think the paper only meant gas giants though. It's worth noting that our big lucky moon has about 1.2% the mass of Earth, so yea...

It is also worth noting that our best bet at explaining why Uranus has such a highly inclined axis of rotation relies on a moon with the mass of around 1% that later got lost. These two ideas are mutually exclusive though...

Its estimated that the Earth and Moon could become a binary planet system in billions of years.

If we define a binary planet as the barycentric definition, then I have to smack someone over the head for that estimate...

As the Moon slips further and further away from Earth, the barycenter will move closer and closer towards Earth's center of mass...

 

[T.Neo]

Exactly what I was thinking. The methane being released as the mantle starts to evaporate should be a large enough source.

The mantle is already at quite high temperatures. The "ices" there are not solid, but fluid (supercritical steam etc). Ice giants seem to have higher percentages of methane in their atmospheres anyway, so maybe that could be the source, if there is enough of it.

When scientists talk about "ice" they mean composition, not state. It's like stellar "metallicity"- it isn't only the metal content of the star, it's the everything above helium content of the star, which includes carbon, oxygen, etc.

Yup. I made Gliese 581 b a class II and III intermediate with its northern pole tilted away from the sun. I can see a large 'cap' of clouds at the north pole, but what about the south pole?

The winter pole is likely to have clouds then. The summer pole might not, if it is warm enough.

Although considering that Gliese 581b is most likely tidelocked, the entire farside would be covered in clouds. In both cases you'll only see a bit of the clouds, since they will mostly be on the night or farside of the planet.

As the Moon slips further and further away from Earth, the barycenter will move closer and closer towards Earth's center of mass...

So, perhaps when the Moon was closer to Earth in our distant past, the Earth-Moon system was a binary? The moon shifted away over time, and the barycenter moved beneath the surface.


Perhaps a more apt term for a "super-Earth" would be a "superterrestrial" planet. Because we don't call terrestrial planets "Earths".

 

[Deltafang]

Well, is a dwarf even less of a planet cos it's made up of ice?

Defining planet and dwarf planet to include say... chemical makeup is a very bad idea. So far we can only speculate as to what most of these bodies are made up of. And that speculation comes from their overall density, which is at times as uncertain as 50%...

What's the point of such a definition? Why is having it benificial for cathegorizing celestial bodies?

Well, I didn't say its less of a planet. I just pointed out that there's a difference in composition that defines them as different, being icy bodies and all. A terrestrial planet is defined as being composed of silicate rocks with a central metallic core with a silicate mantle. Its hypothesized that there are in fact two types of terrestrial planet. Carbon and silicate. Of course, they are just called carbon and silicate planets. While Super-Earths don't place a constraint on composition, Earth is a silicate planet specifically. I think its weird that they were to refer to it as a 'Earth' in any case. As T.Neo says below, I think it would better to refer to a 'Super-Earth' as a 'Superterrestrial'. So perhaps 'Dwarf-terrestrial' or 'Terrestrial dwarf' would be a better term. This way it doesn't have to be based on composition.

The definition of a Terrestrial dwarf would be a celestial body orbiting a star that is massive enough to be rounded by its own gravity, capable of clearing its orbit of planetesimals, yet is anywhere from 5% to 75% as massive as the planet Earth. (The lower limit for Superterrestrials seems to be anywhere from 150% to 300% as massive as Earth.)

Do you think that's a better definition? Please feel free to help me more.

If we define a binary planet as the barycentric definition, then I have to smack someone over the head for that estimate...

As the Moon slips further and further away from Earth, the barycenter will move closer and closer towards Earth's center of mass...

Hmmm, really? My apologies for posting wrong information then...I was aware that the barycenter was currently under Earth's surface but not aware it would move close to Earth's center of mass. Would that be because the Earth is more massive? I think the Moon is massive enough for the barycenter to be outside the Earth.

Oh, I found the article: http://edition.cnn.com/2006/TECH/space/08/18/moon.planet/

Its kind of dated though.

The mantle is already at quite high temperatures. The "ices" there are not solid, but fluid (supercritical steam etc). Ice giants seem to have higher percentages of methane in their atmospheres anyway, so maybe that could be the source, if there is enough of it.

When scientists talk about "ice" they mean composition, not state. It's like stellar "metallicity"- it isn't only the metal content of the star, it's the everything above helium content of the star, which includes carbon, oxygen, etc.

I understand somewhat. I read an article on exotic forms of ice like Ice VII in the ice giants as well as extrasolar planets, even though I didn't fully understand the entirety of it. When I said evaporate, I meant it a bit differently than that. The pressure at the mantle and lower atmosphere should be enough to constrain the water, ammonia, and methane. I was thinking that since it migrated from the outer solar system, it would be warmed and the volume would increase and the pressure would decrease as it lost alot of the surface gases of its atmosphere. I was thinking that maybe the decrease in pressure would allow more of the 'ice' to escape, causing it to leak into the atmosphere and tint the existing water clouds a light blue. The lower atmosphere would still be hazy and blue I think. So would it be a dark blue globe with separated thick bands of blue-whitish clouds across it from top to bottom? What other colors could whatever visible lower atmosphere be?

The winter pole is likely to have clouds then. The summer pole might not, if it is warm enough.

Although considering that Gliese 581b is most likely tidelocked, the entire farside would be covered in clouds. In both cases you'll only see a bit of the clouds, since they will mostly be on the night or farside of the planet.

Ah, that's great! At least I was right about something so far. As Cocytus is tidelocked, I would think there would be a 'halo' of clouds visible on the solar terminator from space, more so at the winter pole. Good to hear! So, the summer pole and day side would be cloudless and featureless due to Rayleigh Scattering, right?

So, perhaps when the Moon was closer to Earth in our distant past, the Earth-Moon system was a binary? The moon shifted away over time, and the barycenter moved beneath the surface.

I posted a link above to an article I had read a year or so back. They said that the Earth-Moon system could become a binary planet in the future, but nothing about it being so in the past. RisingFury did say that moving away would cause the barycenter to go further under Earth's surface and the Moon was much, much closer in the past. Either way, the Earth-Moon system would either have already been a binary planet or has the potential to become one so my statement about mass ratios of binary planet systems still stands I think.

Perhaps a more apt term for a "super-Earth" would be a "superterrestrial" planet. Because we don't call terrestrial planets "Earths".

Yeah, that seems a much better term. I suppose I could call Elysion a "Dwarf-terrestrial" or a "Terrestrial dwarf". I'm much more comfortable with my new definition of such especially since I can define planets within our own solar system as dwarf-terrestrials too.

What program did you use to make those planetary models? Do you know where I can get it?

In case anyone didn't see the names I had given them:

Gliese 581 "Tartarus" - type M3V red dwarf
Gliese 581 e "Lethe" - Superterrestrial - tidelocked, black and red molten surface with visible recent impact crater on night side
Gliese 581 b "Cocytus" - Class III Hot Neptune - moderate axial tilt and tidelocked, dark blue and featureless sunlit side with completely cloudy night side. plentiful bands of water clouds at northern pole and cloudy 'halo' around solar terminator
Gliese 581 c "Phlegethon" - Superterrestrial - thick and hazy translucent white atmosphere with high altitude, low albedo surface features.
Gliese 581 d(g) "Styx" - Ice Dwarf - Ice Dwarf (mini ice giant) in the process of warming. Hazy, dark blue lower atmosphere composed mostly of hydrogen and methane with high altitude whitish-blue water clouds. Two minor storms can be seen on its surface. In a binary relationship and tidelocked to Elysion.
Gliese 581 g(d) "Elysion" - Terrestrial Dwarf - Ocean planet with white water clouds in the atmosphere. Possesses exceptionally large ice caps with enormous free floating, migratory icebergs visible across the globe from orbit. In a binary relationship and tidelocked to Styx.
Gliese 581 f "Archeron" - Class I Cold Jupiter - standard hydrogen/ammonia gas giant with prominent banding and no visible storms

 

[T.Neo]

I understand somewhat. I read an article on exotic forms of ice like Ice VII in the ice giants as well as extrasolar planets, even though I didn't fully understand the entirety of it. When I said evaporate, I meant it a bit differently than that. The pressure at the mantle and lower atmosphere should be enough to constrain the water, ammonia, and methane. I was thinking that since it migrated from the outer solar system, it would be warmed and the volume would increase and the pressure would decrease as it lost alot of the surface gases of its atmosphere. I was thinking that maybe the decrease in pressure would allow more of the 'ice' to escape, causing it to leak into the atmosphere and tint the existing water clouds a light blue. The lower atmosphere would still be hazy and blue I think. So would it be a dark blue globe with separated thick bands of blue-whitish clouds across it from top to bottom? What other colors could whatever visible lower atmosphere be?

It's rather easy to forget that ice VII isn't the same sort of ice that floats in cocktails etc.

I doubt the planet would lose much gas (it may become a bit "puffier" due to increased temperature but not by much), and these are planetary masses and volumes so I doubt there would be much "evaporation" of methane-rich material.

The best bet is if the planet had a high amount of methane to start with, which would give you perhaps a slight bluish tinge to the water clouds.

The lower in altitude that the clouds are, the bluer they'll be due to methane.

Ah, that's great! At least I was right about something so far. As Cocytus is tidelocked, I would think there would be a 'halo' of clouds visible on the solar terminator from space, more so at the winter pole. Good to hear! So, the summer pole and day side would be cloudless and featureless due to Rayleigh Scattering, right?

They would be cloudless and mostly featureless, yes.

Don't know about axial tilt though, I think it should be possible for tidelocked planets to have at least some tilt relative to their orbits but I may be wrong.

Yeah, that seems a much better term. I suppose I could call Elysion a "Dwarf-terrestrial" or a "Terrestrial dwarf". I'm much more comfortable with my new definition of such especially since I can define planets within our own solar system as dwarf-terrestrials too.

Perhaps supermartian planet?

What program did you use to make those planetary models? Do you know where I can get it?

Do you mean the textures? I made them in GIMP (although I'd imagine photoshop would be a better alternative) and compiled them into orbiter planet .TEX files using the pltex.exe utility that comes with Orbiter.

As for the atmospheric and orbital attributes, they were a simple matter of editing .CFG files in a text editor. .DLL planets can be done but they're a bit more trouble.

If you mean the climatological and/or physics model, there isn't one. I compiled what I could from sources on the 'net.

 

[RisingFury]

Actually, my bad... I was using the wrong formula to calculate he barycenter.

As the Moon slowly escapes from Earth, the barycenter will move out. We're still talking about billions of years though.

 

[Deltafang]

It's rather easy to forget that ice VII isn't the same sort of ice that floats in cocktails etc.

I doubt the planet would lose much gas (it may become a bit "puffier" due to increased temperature but not by much), and these are planetary masses and volumes so I doubt there would be much "evaporation" of methane-rich material.

The best bet is if the planet had a high amount of methane to start with, which would give you perhaps a slight bluish tinge to the water clouds.

The lower in altitude that the clouds are, the bluer they'll be due to methane.

Yeah, I've gone through most of my life thinking that ice is ice and anything more or less is just that...What a weird and interesting universe we live in.

I also think it would lose a bit of its outer layers of gas and increase in size a bit. Hmm, there might not be much evaporation, huh? It was a bit of an assumption on my part regardless. Its been hypothesized that Neptune is an azure color compared to Uranus' aquamarine because its mantle has a higher concentration of methane that's slowly leaking into the atmosphere. I assumed that the mantle only maintained its shape because of the massive pressure on it from above and that if there was already methane leaking out, any lessening of pressure would cause more to leak out. You're right though, it would be best if Styx had had a particularly methane rich core to begin with.

As for the clouds, would there be high altitude bluish water clouds that got darker and darker until they faded into the dark blue haze of the lower atmosphere? I wonder if there could be lengthy bands of clouds with large gaps in between them that would allow you to see deep into the atmosphere. My idea of it would be a lot of bluish white cloud cover with the clouds being bluer or whiter than others in some places depending on methane contents with a few dark blue gaps where you could see the lower atmosphere.

I wonder what kind of features storms would have on Styx? Would they appear similar to Earth's spiral hurricane clouds from space or would they resemble Juptier's storms spots more? Since you can see the lower atmosphere in places, I'd assume that they would have more of a hurricane-like appearance.

They would be cloudless and mostly featureless, yes.

Don't know about axial tilt though, I think it should be possible for tidelocked planets to have at least some tilt relative to their orbits but I may be wrong.

Alright, so Cocytus would be a featureless blue globe with clouds on its night side as well as its northern pole. Some of the clouds could just barely sneak across the solar terminator before disappearing, so the sunlit side would be completely blue with white edges all around except for the south pole. I think I was rather confused about the axial tilt. You're right, I don't think it would be capable of a rather far tilt, but I just want it to tilt it just far enough that the hemisphere's have pronounced seasons when viewed from directly the poles. The northern pole and night side would be capped in clouds and the southern pole and day side would be cloudless.

Perhaps supermartian planet?

Hmmm, supermartian. I don't know what that would imply for Mercury though. I changed the definition of Dwarf-Terrestrial to having anywhere from 0.05 to 0.75 Earth masses specifically because I wanted to be able to include our smallest terrestrial planet in the mix classification. This was also meant to counter the fact that we usually consider Superterrestrials to be anywhere from 1.5 to 5.0 Earth masses.

Do you mean the textures? I made them in GIMP (although I'd imagine photoshop would be a better alternative) and compiled them into orbiter planet .TEX files using the pltex.exe utility that comes with Orbiter.

As for the atmospheric and orbital attributes, they were a simple matter of editing .CFG files in a text editor. .DLL planets can be done but they're a bit more trouble.

If you mean the climatological and/or physics model, there isn't one. I compiled what I could from sources on the 'net.

Oh, alright. I have GIMP as well. I don't know how to use for making textures at all though, I've only used it for making small edits to pictures so I could import them into games cleanly. Until I get Orbiter, I won't be compiling anything I'm afraid.

It'd be nice if there was a program that could create visual models for you. I'll be sure to be on the lookout for some.

Actually, my bad... I was using the wrong formula to calculate he barycenter.

As the Moon slowly escapes from Earth, the barycenter will move out. We're still talking about billions of years though.

Oh, alright. Still, my point is that there has to a certain mass ratio as well a barycenter in between both surfaces in order for it to be considered a binary planet. Even though Styx is a miniature Ice Giant, the barycenter between it and the Dwarf-Terrestrial Elysion isn't under either surface. Elysion is also roughly 1/10 as massive as Styx. Whereas Luna is 1/81 as massive as the Earth and Charon is 1/9 as massive as Pluto. Once determine that the barycenter of the Pluto-Charon system is not under either surface, it will almost undoubtably be considered a binary dwarf planet. Since the Styx-Elysion system is somewhere between the two, I assume it'd be a binary planet as well.

 

[RisingFury]

But what's the point? What do you gain by defining a binary (dwarf) planet?

There's a good reason why planet / dwarf planet definition was established.

Before the Hubble was launched, there wasn't anything else that we could see out there beyond Pluto. But when Hubble was launched, we started noticing a whole lot of objects that were similar in size to Pluto and behaved the same way:
- Highly inclined and eccentric orbits
- Low densities
- Same orbital region

Pluto fell well within that class and there were several objects larger then Pluto. Does that mean all of them are planets? Where do you draw the line?

For large moons, there are no real dilemmas as to what makes a moon and what makes a planet. The moon is secondary in the system and if it escapes and fulfills the criteria for a planet, then it's a planet...



As for the different phases of elements, here's a diagram that shows various phases of water in relation to pressure and temperature:

 

[Ghostrider]

Let's see... Lethe, Cocytus, Phlegethon, Styx, Acheron...

I'm so totally not going there. Especially if the ship is named "Virgil".

 

[T.Neo]

Yeah, I've gone through most of my life thinking that ice is ice and anything more or less is just that...What a weird and interesting universe we live in.

That and scientists who use names for things that really aren't what they're named after.

As for the clouds, would there be high altitude bluish water clouds that got darker and darker until they faded into the dark blue haze of the lower atmosphere? I wonder if there could be lengthy bands of clouds with large gaps in between them that would allow you to see deep into the atmosphere. My idea of it would be a lot of bluish white cloud cover with the clouds being bluer or whiter than others in some places depending on methane contents with a few dark blue gaps where you could see the lower atmosphere.

You'll get higher altitude cloud bands and lower altitude cloud bands. The high altitude bands will be whiter, and the lower ones bluer, due to being more obscured by methane.

I wonder what kind of features storms would have on Styx? Would they appear similar to Earth's spiral hurricane clouds from space or would they resemble Juptier's storms spots more? Since you can see the lower atmosphere in places, I'd assume that they would have more of a hurricane-like appearance.

I think they'll mostly be like the storms usually seen on gas giants (no eyewall, just oval storms). AFAIK hurricane-like storms are known on gas giants, but they're rare.

The atmosphere may also be turbulent to varying degrees; wavy, turbulent clouds, featureless hazy bands or almost no features due to worldwide obscuring haze.

Hmmm, supermartian. I don't know what that would imply for Mercury though. I changed the definition of Dwarf-Terrestrial to having anywhere from 0.05 to 0.75 Earth masses specifically because I wanted to be able to include our smallest terrestrial planet in the mix classification. This was also meant to counter the fact that we usually consider Superterrestrials to be anywhere from 1.5 to 5.0 Earth masses.

I was thinking more of a particular adjective for that particular planet. I'd just call it a "terrestrial" planet.

The upper limit for superterrestrials is usually stated as 10 Earth masses, with a lower limit desputed from 2 Earth masses to just above Earth mass.

It'd be nice if there was a program that could create visual models for you. I'll be sure to be on the lookout for some.

I've seen one or two, but the textures they produce are mostly fractal and not representative of anything realistic.

If you can find a program that generates good quality textures, however, please tell me about it.

 

[Deltafang]

But what's the point? What do you gain by defining a binary (dwarf) planet?

There's a good reason why planet / dwarf planet definition was established.

Before the Hubble was launched, there wasn't anything else that we could see out there beyond Pluto. But when Hubble was launched, we started noticing a whole lot of objects that were similar in size to Pluto and behaved the same way:
- Highly inclined and eccentric orbits
- Low densities
- Same orbital region

Pluto fell well within that class and there were several objects larger then Pluto. Does that mean all of them are planets? Where do you draw the line?

What do you mean what's the point in defining a binary planet? Its the same as defining anything else. A new definition arises when we achieve a better understanding of the mechanics of these sort of interactions. In that case, why define a binary star? Why not just leave us at the common knowledge of them just being two stars that are close together?

The term binary planet or double planet has been brought up numerous times. While it hasn't be officially recognized by the IAU, members have used the term on some occasions. Hell, the ESA sometimes refers to the Pluto-Charon system as a binary dwarf planet which they consider a type of binary planet. That's an additional class of planet with its own sub-class to boot.

As our understanding of these sort of mechanics increases, of course we're going to give it a different category. We like to be organized. We classify, sub-classify, cross-classify, reclassify everything. Humans are impulsive taxonomists. Look at all our biological taxonomy. Our brains are designed to make comparisons and we won't stop doing that for celestial bodies.

For large moons, there are no real dilemmas as to what makes a moon and what makes a planet. The moon is secondary in the system and if it escapes and fulfills the criteria for a planet, then it's a planet...

No, there aren't any immediate problems. But like I said, our definition is likely to change in the future. If the Pluto-Charon system is considered a binary dwarf planet by our loose, shifting standards today, the Earth-Luna system should it survive long enough, will almost definitely be considered a binary planet.

Thanks for the chart, too. That helps a lot actually.

Let's see... Lethe, Cocytus, Phlegethon, Styx, Acheron...

I'm so totally not going there. Especially if the ship is named "Virgil".

Hahaha. :lol: I was laughing for at least 5 minutes after hearing that! Maybe I should name the ISV Virgil, with the Shuttle being called Dante, eh? :thumbup:

That and scientists who use names for things that really aren't what they're named after.

That's like the basis of our existence! Lie, all lies!

You'll get higher altitude cloud bands and lower altitude cloud bands. The high altitude bands will be whiter, and the lower ones bluer, due to being more obscured by methane.

I think they'll mostly be like the storms usually seen on gas giants (no eyewall, just oval storms). AFAIK hurricane-like storms are known on gas giants, but they're rare.

The atmosphere may also be turbulent to varying degrees; wavy, turbulent clouds, featureless hazy bands or almost no features due to worldwide obscuring haze.

Ah perfect, I think it'd look really neat actually with the alternating whites to blues. Hmm, I think that we should go for either large amounts of wavy, turbulent clouds, or the featureless bands with the darker lines and gaps between them. I wonder if we could do the featureless bands with one or two minor oval storms? That would truly be perfect.

I was thinking more of a particular adjective for that particular planet. I'd just call it a "terrestrial" planet.

The upper limit for superterrestrials is usually stated as 10 Earth masses, with a lower limit desputed from 2 Earth masses to just above Earth mass.

Ohhh, I see. Silly me. I hadn't thought of an adjective like that. Terrestrial-Dwarf describes the type of planet but it doesn't seem to do so like the endings "ial" or "ian". Hmm, all terrestrial-dwarfs are terrestrial planets but not all terrestrial planets are terrestrial-dwarfs. Hmm, I heard somewhere it was anywhere from 5-10. I suppose I'm allowed some lenience there as the definition has yet to be set in stone.

If you can find a program that generates good quality textures, however, please tell me about it.

You can bet I will.

 

[T.Neo]

I'm so totally not going there. Especially if the ship is named "Virgil".

You mean the sonic-laser propelled Virgil, built from unobtanium?

Ah perfect, I think it'd look really neat actually with the alternating whites to blues. Hmm, I think that we should go for either large amounts of wavy, turbulent clouds, or the featureless bands with the darker lines and gaps between them. I wonder if we could do the featureless bands with one or two minor oval storms? That would truly be perfect.

Perhaps hazy, turbulent clouds would be better, with the occasional storm.

Pluto fell well within that class and there were several objects larger then Pluto. Does that mean all of them are planets? Where do you draw the line?

I think that the current definition of a "planet" is mostly due to covenience of not having tens of "planets" in the system, which is understandable, but I am going somewhat off-topic here.

For large moons, there are no real dilemmas as to what makes a moon and what makes a planet. The moon is secondary in the system and if it escapes and fulfills the criteria for a planet, then it's a planet...

Indeed, but "binary planet" is more of an unofficial classification, because it's cool.

 

[Deltafang]

Perhaps hazy, turbulent clouds would be better, with the occasional storm.

Woohoo! And that concludes the problems with the features and weather of Styx. Its a huge relief to know that that's over with. Thanks for all the help!

Indeed, but "binary planet" is more of an unofficial classification, because it's cool.

:lol: I can't deny that. Its a pretty cool name for a pretty cool concept.

Now we work on Elysion I guess. Do you think a planet of that size would remain geologically active under its own gravity? Or would it have to be tidal heated by Styx and its star? As an ocean world, what's a decent estimate for an average surface temp? I'm thinking between 5º C and 15º C. Its probably too cold or too hot, but I'm just throwing numbers out there. For reference: Earth is 14º C average.

I'm imagining that it would have sizable polar ice caps of free floating ice that occasionally splinter into smaller ice packs that migrate around the globe. These would be pretty large. Floating mini ice continents if you will.

 

[T.Neo]

It probably will, but tidal heating from Styx wouldn't hurt. Are there any other satellites in the system?

As for temperature I'm not sure. Depends on albedo, atmospheric density (determined mainly by pressure) and greenhouse gases. It might be a lot warmer or a lot cooler then the Earth.

Although I'm skeptical about ice "continents", it's helpful to remember that here on Earth some icebergs can be pretty large.

 

[Deltafang]

Hmm, that's an odd thought. I never considered any other satellites in the system. I was too afraid that a small moon orbiting around one of them would somehow end up careening into the other's surface. That said, is a moon even capable of holding a stable orbit in that system? When I get the chance, I have got to work on the numbers for their statistics, most importantly, their distance from each other. That would definitely be important in determining their capability of possessing moons. Styx would be a very prominent and permanent feature in Elysion's sky. (The side facing Styx of course. What would we call that?)

Hmmm, albedo eh? I never really considered that. A decent amount of large, white, water clouds and the ice caps and ice bergs would probably give it an albedo of slightly more than Earth's. Maybe 0.38 - 0.42? Atmospheric content for Styx was easy. It gets much more complicated for Elysion it seems. I'll think about it. I want it to have a surface pressure similar to Earth's but I don't know whether it would be higher or lower. I also need to establish buffer gases and the atmospheric content. I know the Armstrong Limit defines the lower limit for air pressure humans can survive without a pressure suit. Anybody know what the maximum is?

As for 'ice continents', I don't want them to be extravagantly big. I mean, one of the world's largest icebergs was bigger than the entire island of Jamaica! That's definitely visible from space. I was thinking maybe the ice caps could splinter and break occasionally, causing icebergs larger than Earth's on average to drift around the planet. Visible under the clouds would be white specks of ice varying largely in size.

If it was too warm however, I don't think the icebergs would even get too far from the poles without melting. We mentioned in my other thread that flying 'animals' could roost there and aquatic ones could possibly crawl out of the water to escape possible predators. Trying to find a balance is hard, hn.

 

[adamb193]

It'd be pretty neat to have somewhere to land and establish a research base.

 

[Deltafang]

Yeah, since my story will include the manned exploration of Elysion, its essential that they have somewhere to land. Though in all essence, some kind of floating lab would probably do the same job as one placed on drift ice. Maybe the shuttle could have aquatic abilities? All things to consider.