Extended Gas Giant Classification System - CLOSED

[ajtribick]

This add-on has now become part of the Celestia distribution. The latest version of extrasolar.ssc now uses these textures. The required files (exo-class1.jpg - exo-class5.jpg and associated nightside textures) can be obtained from the CVS tree. I am intending to make no further updates to this add-on for the foreseeable future.

I've created an add-on that implements the five classes of extrasolar giant planet described in Albedo and Reflection Spectra of Extrasolar Giant Planets for the gas giants in Celestia.

The planets were assigned based on their temperatures calculated for an albedo of 0.5 (Celestia default), using the star properties contained in Celestia's data files. Classes were assigned as follows:

<150K - Class I (ammonia clouds)
150-350K - Class II (water clouds)
350-900K - Class III (cloudless)
900-1500K - Class IV (sodium haze)
>1500K - Class V (silicate clouds)

Textures were created using POV-ray.

Add-on has been removed as it is now incorporated into Celestia

Download size: 154KB

Current version is v1.4

[ajtribick]

Some screenshots:

Class I gas giant (47 Ursae Majoris c)



Class II gas giant (Upsilon Andromedae A d)



Class III gas giant (Rho1 Cancri c)



Class IV gas giant (91 Aquarii b)



Class V gas giant (OGLE-TR-56 b)



Edit: updated pictures for updated textures

[Bob Hegwood]

Chaos,

Just wanted to say "Thanks" for this interesting way to look at planets
which we can't yet see. Great idea.

Take care, Bob

[danielj]

Very good!
Almost any planet texture before was simply random or very similar to gas giants in the solar system.Now the textures are based in theoretical models.
Anyway,reading the pdf,I can??t think in any variation of these types.Any idea?

[eburacum45]

Thank you very much; I am now happy to look at the various exoplanets in Celestia and be reasonably sure that they resemble reality.

I am also sure that there are many variations in detail that we will not yet be able to predict, however; different rates of rotation and turbulence, trace elements, organic and possibly biogenic compounds giving variations of colour to worlds that would otherwise be featureless.

All this remains to be seen.

[ElChristou]

Pretty cool, nice idea, nice job, TX.

Bye

[PlutonianEmpire]

Whoa! very nice!

[danielj]

Even not known,we could guess what will be the variations in these 5 subtypesn are.It??s a bit boring hundreds of planets having only 5 types of textures.And the old types gasgiant.jpg and jupiterlike.jpg still remain,or this new subtypes substitute them too?

I am also sure that there are many variations in detail that we will not yet be able to predict, however; different rates of rotation and turbulence, trace elements, organic and possibly biogenic compounds giving variations of colour to worlds that would otherwise be featureless.

All this remains to be seen.[/quote]

[Tleilax]

Even not known,we could guess what will be the variations in these 5 subtypesn are.It??s a bit boring hundreds of planets having only 5 types of textures.And the old types gasgiant.jpg and jupiterlike.jpg still remain,or this new subtypes substitute them too?

I am also sure that there are many variations in detail that we will not yet be able to predict, however; different rates of rotation and turbulence, trace elements, organic and possibly biogenic compounds giving variations of colour to worlds that would otherwise be featureless.

All this remains to be seen.

[/quote]

Actually, astronomers can get some data on the appearance of some of these worlds; judging from it's mass, orbital distance, orbital eccentricity, and (for some planets) spectrum absorbtion lines.
One example of this is the planet Osiris (HD 209458 b). Because this planet is only 0.047 AU away from it's sun, astronomers can reason that the solar winds must be stripping the planet of it's atmosphere, creating something remenicent of a comet's tail, trailing behind the planet.
Secondly, Osiris transits its sun (from our perspective) and astronomers were able to detect sodium in it's atmosphere. This infomation gives us an idea of what colors the planet probably is, etc.

[TERRIER]

Even not known,we could guess what will be the variations in these 5 subtypesn are.

Are there 5 subtypes ?

It??s a bit boring hundreds of planets having only 5 types of textures.And the old types gasgiant.jpg and jupiterlike.jpg still remain,or this new subtypes substitute them too?

It looks like all of the jupiterlike and gasgiant textures that you mention have been replaced, maybe there's an odd one or two that haven't ? But this is definately for the better.
Because this add-on is only 157kb zipped, I think there should be some consideration for these textures to be included in future versions of Celestia.

Daniel, don't forget there is also the brown dwarf, and venus-like worlds also included as standard in the Extra-solar planets, which have not been replaced.

[danielj]

But a brown dwarf is NOT A PLANET!And we are talking about gas giant subtypes.When I said that we could guess,I would like to know if I change slightly the colors of for example,class 2 or class 3,we still are following the theory.It??s because I don??t know how much of these features are directly linked to this color.If for example,I change class 3 to a lighter blue or even green,it is still possible to have the same components in the atmosphere?

Even not known,we could guess what will be the variations in these 5 subtypesn are.

Are there 5 subtypes ?

It??s a bit boring hundreds of planets having only 5 types of textures.And the old types gasgiant.jpg and jupiterlike.jpg still remain,or this new subtypes substitute them too?

It looks like all of the jupiterlike and gasgiant textures that you mention have been replaced, maybe there's an odd one or two that haven't ? But this is definately for the better.
Because this add-on is only 157kb zipped, I think there should be some consideration for these textures to be included in future versions of Celestia.

Daniel, don't forget there is also the brown dwarf, and venus-like worlds also included as standard in the Extra-solar planets, which have not been replaced.

[Beowulf01]

These are very very nice....
great work

[ajtribick]

It??s a bit boring hundreds of planets having only 5 types of textures.

Feel free to create 100+ different textures for all the exoplanets out there, but I know I'd get bored by the tenth blue class III giant which would probably be orbiting some unknown star known only by an unmemorable HD number. In any case, I don't think we know enough about these planets to create a valid scientific add-on with a different texture for each gas giant. The system I have used illustrates the data, and has the added advantage of keeping the add-on size down. (Remember dial-up? I know it's very last millennium, but some people still have it)

It looks like all of the jupiterlike and gasgiant textures that you mention have been replaced, maybe there's an odd one or two that haven't ? But this is definately for the better.

As far as I can tell I've replaced all the planets of "normal" stars, unless something's fallen through in the automation process. As stated in the readme, I have not altered the textures of brown dwarfs, pulsar planets or the "superterrestrials"/hot Neptunes, primarily because to do this accurately would require more data than is available.

As far as I am aware, the only unaltered gas giant is the planet in the PSR B1620-26 system, for which I don't have reasonable temperature data for the system components, so an attempt to apply one of the subtypes would not be justified. This planet still has its default "jupiterlike.jpg" texture.

And we are talking about gas giant subtypes.When I said that we could guess,I would like to know if I change slightly the colors of for example,class 2 or class 3,we still are following the theory.It??s because I don??t know how much of these features are directly linked to this color.If for example,I change class 3 to a lighter blue or even green,it is still possible to have the same components in the atmosphere?

It depends on what you are trying to do. If you are trying to create an artistic add-on, then sure, change the colours. The models only predict gross characteristics. The colour of a class III is determined by Rayleigh scattering in a cloudless atmosphere, however trace compounds could alter this, in the same way that trace compounds give rise to the colours of Jupiter's cloud bands. The textures I have used here are a compromise between ultra-generic textures and a reasonable idea of what a gas giant looks like - hence I've implemented cloud bands, but avoided storm systems.

I am also sure that there are many variations in detail that we will not yet be able to predict, however; different rates of rotation and turbulence, trace elements, organic and possibly biogenic compounds giving variations of colour to worlds that would otherwise be featureless.

Of course, but we don't know enough about these worlds to be able to add these yet! (Except in fictional add-ons)

Because this add-on is only 157kb zipped, I think there should be some consideration for these textures to be included in future versions of Celestia.

Hehe...

[ajtribick]

...well they had to discover some new planets eventually...

Unfortunately I can't FTP from this location, so I won't be able to update the zip file for a while, but if you add the following code to exoplanet_textures.ssc, Eta2 Hydri b will have the appropriate texture applied.

Code: Select all

Modify "b" "HD 11977"
{
   Color [0.28 0.34 0.95]
   Texture "class3.jpg"
}

I really need to find a better way of automating this - is the new stars.dat format documented anywhere?

P.S. I never heard back from the Motherlode after uploading this several months ago. I presume it was rejected on some grounds, I'd like to know what those are so I don't make the same mistake again.

[TERRIER]

I really need to find a better way of automating this - is the new stars.dat format documented anywhere?

P.S. I never heard back from the Motherlode after uploading this several months ago. I presume it was rejected on some grounds, I'd like to know what those are so I don't make the same mistake again.

Cheers for the update.
I'm suprised the Motherlode didn't accept this add-on....I was just going to say that when it becomes part of the standard Celestia release, then someone will automate the changes for you.

Just as a matter of interest, what was the previous planet texture ( I haven't had chance to look. )

regards,
TERRIER

[ajtribick]

I'm suprised the Motherlode didn't accept this add-on....I was just going to say that when it becomes part of the standard Celestia release, then someone will automate the changes for you.

I'm glad you have such faith in the validity of this that you think it is worthy of the standard distribution. I'll believe it when it happens...

Just as a matter of interest, what was the previous planet texture ( I haven't had chance to look. )

Previously Eta2 Hydri b used the "jupiterlike" texture - there is a rough correlation between my system and the standard one: planets assigned classes IV and V in my system previously used "gasgiant.jpg" in most cases, classes I, II and III were usually "jupiterlike.jpg".

[eburacum45]

It is an excellent add-on, and I would certainly recommend it as a must have. I expect it will get on the Motherlode by-and-by; they seem a little short-handed.

[Juan Marino]

Hello, Chaos Syndrome.

Very nice Textures, it is an excellent add-on:

I sent an proposal at private message..... I wait for its approval!

thanks!!

[ajtribick]

Further update: I just received a message from Grant - he's done the colour calculations for the spectra provided in that paper (something I don't know how to do, thanks Grant), and the results are very interesting. In short, the textures for classes I-III are ok, the textures and colours I've got for IV and V seem to be wildly off the mark.

At the moment I don't have time to update this right now (and even if I could I don't have FTP from where I am, so I wouldn't be able to upload anything), so you're going to have to wait a couple of weeks.

I might also have a shot at implementing albedo, if someone can come up with a reasonable way of interpolating between various star types. The main problem I see with this is that albedo affects the temperature, which could cause complications.

On the automation side of things, it would be helpful to have the format of hdxindex.dat and the new stars.dat format, as it saves manual copying of data which is prone to errors.

[ajtribick]

For those of you who like to keep this add-on up-to-date and who can't wait for the latest version, here's modifications for the latest version of extrasolar.ssc:

Code: Select all

Modify "c" "HD 217107"
{
   Color [0.78 0.74 0.72]
   Texture "class1.png"
}

Modify "c" "HD 37124"
{
   Color [0.77 0.79 0.81]
   Texture "class2.png"
}

Modify "d" "HD 37124"
{
   Color [0.78 0.74 0.72]
   Texture "class1.png"
}

Modify "c" "HD 108874"
{
   Color [0.77 0.79 0.81]
   Texture "class2.png"
}

(Note that this includes a correction for HD 37124 c - this was incorrectly assigned to class I)