Changing A Star

[Dollan]

I'm trying to put together an STC file for Antares, and through trial and error I've found that I can only do it properly if I only use the following:

Code: Select all

Barycenter "Antares"

   {
   RA      247.351917
   Dec        -26.432003
   Distance        604
   }

"Alpha Scorpii B"

   {
   OrbitBarycenter    "Antares"
   SpectralType    "B4V"
   AbsMag       -0.84
   SemiAxes       [1 0.75 0.75]
   EllipticalOrbit
      {
                      Period      878
                      SemiMajorAxis         537
                      Eccentricity          0
                      Inclination           0
                      AscendingNode         0
                      ArgOfPericenter       180
                      MeanAnomaly           0
      }
   RotationPeriod    24
   }

If I try to add an entry for the A-component, I either suddenly get a triple star, or I don't get the A-component at all.

So, two questions: how can I add and change the primary star? And, if I can't do that, how can I change the appearance of the A-component? It is apparently quite egg-shaped.

...John...

[Guckytos]

Hi Dollan,

first of all did you try the updated STC-guide of mine from my homepage?
http://home.arcor.de/christianlenz/celestiae.html or
http://home.arcor.de/christianlenz/Down ... %201.1.pdf

It explains more or less the commands of the STC. If you have any comment about it, feel free to say it loud
edit: (the fully updated version will only be released after 1.4.0 final)

The egg-shape comes from your usage of the SemiAxes command. with that you define the shape of the sun-mesh [1 1 1]means perfect round
[0.1 1 1] should give you a nearly flat circle.

I think it would be best if you show the STC which makes an error to us, so it is easier to find the problem.

Anyway i hope i could help you a bit.

Regards,

Guckytos

[Dollan]

Sorry for the delay in response, but I've been gone all weekend on probably the last real vacation that I'll get until Thanksgiving. Ugh.

Anyway, this is the code that I am now using:

Code: Select all

Barycenter "Antares:HIP 80763"

   {
   RA      247.351917
   Dec        -26.432003
   Distance        604
   }


80763 "Antares A"

   {
   OrbitBarycenter    "Antares"
   SpectralType    "M1I"
   AbsMag       -5.14
   SemiAxes       [1 0.75 0.75]
   EllipticalOrbit
      {
                      Period      878
                      SemiMajorAxis         537
                      Eccentricity          0
      Inclination   82.980
      AscendingNode      67.708
      ArgOfPericenter    3.774
      MeanAnomaly        200.119
      }
   RotationPeriod    24
   }


"Antares B"

   {
   OrbitBarycenter    "Antares"
   SpectralType    "B4V"
   AbsMag       -0.84
   SemiAxes       [1 0.75 0.75]
   EllipticalOrbit
      {
                      Period      878
                      SemiMajorAxis         537
                      Eccentricity          0
      Inclination   82.980
      AscendingNode   67.708
      ArgOfPericenter 183.774
      MeanAnomaly     200.119
      }
   RotationPeriod    24
   }

This seems to do the trick, but something that I did not see in the tutorial (although I might have missed it) is the usage of the HIP number in the first entry. Is this the standard way to "over-write" the pre-existing star? If I do not use the HIP number before the entry for the A-component, then I get two red giants, with the secondary white star *Within* one of them. And if I use the HIP number for the secondary star as well, it is found by Celestia, but it is not shown.

Anyway, the point is, I did get it to work finally, but it doesn't seem to be as cut-and-dry as I thought it was.

Now my next step is to make a surrounding, faint red nebula some 5 light years in diameter.....

...John...

[Spaceman Spiff]

Hi Dollan,

I recall it's necessary to refer to stars by HIP number too. That's because the true unique identifier of all stars in the Hipparcos database that celestia uses is that very HIP number.

Spiff.

[Guckytos]

Hi Dollan,

AFAIK in the 1.4.0 pre6 and others you don't necessesarily need the HIP numbers. You need either a name for a star or a HIP number, of course you can use both.

But why you would need a HIP number for ONLY the first star and not the second baffles me. If you find anything out about, please tell me.
BTW: I created an addon with 20 orbiting stars and i don't think that i needed a HIP number for any of the orbiting ones. But i will check that out.

Regards,

Guckytos
P.S.: I should really update the STC guide once in a while, i think.

[Guckytos]

Hi Dollan,

i tried it with and without using HIP numbers by modifiing one of my binaries.
Didn't matter if i used a HIP number, worked perfect in both cases.

Anyway i hope your binary works fine.

Regards,

Guckytos