Stars around planets??

[Neethis]

Hey everyone, this is my first post. Ive been using Celestia 1.3.0 for a while now, and ive made a fair few bits of my own. Ive been searching the forum for this, but to no avail, so ive decided to join up and ask

Basically, what I want to do is make a tiny "star" orbiting a planet on the edge of one of my star systems. It would be like the ultimate edge-system terraforming device hehe

I want a way to do this using my current Celestia v1.3.0, since older versions dont work on my system

Any help would be much appreicated, but if its impossible, sorry for wasting time!

-Neethis

[ajtribick]

You can't do this properly in either Celestia 1.3 series or the 1.4.0 prereleases. Stars on orbits can be defined, but only with respect to other stars.

You can define an emissive planet in orbit around another planet (add Emissive True to the definition), but this will not act as a light source.

[PlutonianEmpire]

How 'bout having a barycenter orbit a star using the same orbit as the planet you want the "mini-sun" to orbit around, and have the "mini-sun" orbit the barycenter?

[ajtribick]

Blasted crashy internet!!!

[ajtribick]

How 'bout having a barycenter orbit a star using the same orbit as the planet you want the "mini-sun" to orbit around, and have the "mini-sun" orbit the barycenter?

Yeah, you could do that. It's just a bit inelegant. Then again, the scenario is a tad unrealistic.

[Neethis]

How would I go about doing that? Ive only worked out how to edit .ssc files so far, and Ive never made a star of my own before...

(btw i meant that versions of celestia newer than 1.3.0 wouldnt work on my PC)

[ajtribick]

If you can't use newer than 1.3.0, then you can't have orbiting stars. Sorry - the feature was implemented in the 1.4.0 prereleases (can't remember which prerelease though)

[Neethis]

damn...

Well Ill try using 1.4 again once ive updated my PC

[selden]

The 1.4 prereleases should work on all systems. You just won't be able to see all of the eye candy on older graphics cards.

[Neethis]

Versions older than 1.3.0 work when I first download and install them onto my PC, but when I try to start them up a second time, this message comes up;



I was trying to run V1.4FT1.1 at the time, but it comes up if Im using 1.3.2 as well

Any help to get it working would be much appreciated

(sorry if this is a bit off topic, heh)

[selden]

Neethis,

It sounds like you are using a damaged shortcut. I don't know what might have caused it to be damaged, so I can't suggest how to prevent that.

The symptom is consistant with the quotes being missing from its "Target" field. To see the shortcut's informational fields, right-mouse-button click on the icon and select the Properties option.

The default is for Celestia to be installed in
"C:\Program Files\Celestia"
Quotes are required because of the space between Program and Files in the directory's name. Without the quotes, the space causes the two words to be treated as separate commands, which can't work.

I'd suggest de-installing Celestia and installing a new copy into a directory that has no spaces in its name. The installer will let you specify any directory you want.

[Neethis]

Excellent! That worked! Thanks very much Selden!

Right, so how would I go about making a small (250KM radius) "star" orbiting... say... Pluto, to start with?? Ive never used these Barycenter things before, but they dont look too hard...

[ajtribick]

Hmmm... choosing planets in our solar system is tricky because they have custom orbits which override the Keplerian parameters.

To do this you could try something like:

Code: Select all

Barycenter "Pluto-Bary"
{
   OrbitBarycenter "Sol"
   EllipticalOrbit
   {
   Period            248.54
   SemiMajorAxis     39.48168677
   Eccentricity       0.24880766
   Inclination       17.14175
   AscendingNode    110.30347
   LongOfPericenter 224.06776
        MeanLongitude    238.92881
   }
}

"Microstar"
{
   OrbitBarycenter "Pluto-Bary"
   EllipticalOrbit
   {
   Period      0.00336550943 # in years
   SemiMajorAxis   0.000043752813 # in AU
   Eccentricity   0
   }
   SpectralType "M"
   AbsMag 27
   Radius 250 # override as we can't set AbsMag low enough!
}

Put this in a .stc file (e.g. "pluto.stc") in your extras folder.

You will have to comment out the CustomOrbit "pluto" line in solarsys.ssc (in the data folder) to make this do what you expect however.

[Neethis]

Hey! Ive done it...the only problem is that ive lost the light of the REAL sun! Isn't it possible to have two light sources on an object? Im assuming that it must work simply by choosing the star nearest the object, and lighting it from tht point...
It certainly looks interesting though...

...Im pretty sure ive seen a planet from someones Alpha Centauri mod which was double-lit though...

[ajtribick]

You'd have to increase the value of AbsMag to make your sun dimmer, but it seems that Celestia stops drawing the star when this value gets too high, and the cutoff is too low to get this value down far enough.

[Neethis]

Wow! Ive been messing about with trial and error, and using this;

Barycenter "Pluto-Bary"
{
OrbitBarycenter "Sol"
EllipticalOrbit
{
Period 248.54
SemiMajorAxis 39.48168677
Eccentricity 0.24880766
Inclination 17.14175
AscendingNode 110.30347
LongOfPericenter 224.06776
MeanLongitude 238.92881
}
}

"Microstar"
{
OrbitBarycenter "Pluto-Bary"
EllipticalOrbit
{
Period 0.00336550943 # in years
SemiMajorAxis 0.000043752813 # in AU
Eccentricity 0
}
SpectralType "A"
AbsMag 32
Radius 50
}

I get this;



You can see the small star on the right of the image, and you can tell that Pluto is light from both the Sun (left side) and the Microstar (rightside).

All I did was change the radius to 50 and AbsMag to 32 (I tried a few values before I got that) and the Spec type to "A"

Thanks very much for the help Chaos Syndrome and Selden, Ive got a few more ideas now! Heh

[PlutonianEmpire]

Wow! Ive been messing about with trial and error, and using this;

Barycenter "Pluto-Bary"
{
OrbitBarycenter "Sol"
EllipticalOrbit
{
Period 248.54
SemiMajorAxis 39.48168677
Eccentricity 0.24880766
Inclination 17.14175
AscendingNode 110.30347
LongOfPericenter 224.06776
MeanLongitude 238.92881
}
}

"Microstar"
{
OrbitBarycenter "Pluto-Bary"
EllipticalOrbit
{
Period 0.00336550943 # in years
SemiMajorAxis 0.000043752813 # in AU
Eccentricity 0
}
SpectralType "A"
AbsMag 32
Radius 50
}

I get this;



You can see the small star on the right of the image, and you can tell that Pluto is light from both the Sun (left side) and the Microstar (rightside).

All I did was change the radius to 50 and AbsMag to 32 (I tried a few values before I got that) and the Spec type to "A"

Thanks very much for the help Chaos Syndrome and Selden, Ive got a few more ideas now! Heh

I can't see the image

[PlutonianEmpire]

Okay, I copied your star data to see it for myself, and it looks great. However, once I advance the time scale, the star completely disappears.

Must be a bug in the program.

[Neethis]

Hmm, thats strange, speeding up the time doesnt affect mine... I actually had to speed the time up to get the screenshot showing half-and-half.

I posted the picture with Imagshack.us, I dont know why you cant see it. Can anyone else??

[PlutonianEmpire]

Hmm, thats strange, speeding up the time doesnt affect mine... I actually had to speed the time up to get the screenshot showing half-and-half.

Try going to the future, like 2015 or something.

I posted the picture with Imagshack.us, I dont know why you cant see it. Can anyone else??

Actually, I can see it now. Must be something up with imageshack.