44 Bootis

[Dollan]

Maybe it is the late hour. maybe I'm terminally stupid. But I've been trying to get an STC file for the triple system 44 Bootis for the last couple of hours, and I'm at my wit's end. Plus, it is nearly 4am, and it is time for me to go home and sleep!

Can anyone give me a hand? I've been following Selden's STC definitions, and though everything is looking absolutely proper, I'm getting nowhere. I'm using 1.4.0 pre5, BTW.

I'd cut and paste what I'm doing, but I'm actually working on a different computer than that which I'm currently posting this message with, and I don't have time to run up and bring down a copy of the STC file I'm wrestling with (I know, I know, I should have brought it down with me in the first place).

Anyway, any help would be highly appreciated!

...John...

[selden]

Exactly what kinds of problems are you having?

What informational sites are you using to develop your system?

[Dollan]

Hi Selden...

I'm a little more clear-headed after about 4 hours of sleep, even though I spent most of that time putting together ssc and stc files in my dreams. Can we say "obsessive"?!

Anyway, I'm going off of your STC file definitions located here. 44 Bootis consists (as you probably know) of three components; the A-BC pair are widely seperated by about 40 AU, while the BC pair themselves are either close to, or *are* a contact binary.

My first step is to make the A and B components (figuring I could add the C component later). Now, I can get the barycenter established, but only one component will show up at a time. I named the barycenter 44 Boo:HIP 73695 (or whatever its HIP number is; I really wish I'd brought home the file that I was working on).

I know that this could be considered a cop-out, but if you (or someone) could make an STC for the triple system, I could "reverse engineer" it and hopefully, through studying it, figure out how to make future STC files. I tried pulling some out of the stars.dat file, but that file always comes up as a bunch of gibberish when I try to open it via notepad or even Word.

At any rate, whatever help you can give, I greatly appreciate it (clearly I didn't study this aspect of Celestia enough when it first became available)!

...John...

[Dollan]

A quick extra question: Do I *need* ArgOfPericenter and MeanAnomaly in the stc definitions?

...John...

[Dollan]

Okay, I'm confident that this is a reconstruction of the code that I made last night.

Code: Select all

Barycenter "44 Boo:HIP 73695:i Boo"
{
   RA 225.947083
   Dec 47.654061
   Distance 41.6
}

44 Boo A
{
   OrbitBarycenter  "44 Boo"
   SpectralType "F9V"
   AppMag 5.19

   EllipticalOrbit  {
      Period      225
      SemiMajorAxis   48.1
      Eccentricity   0.43
      Inclination   0.00
   }
}

44 Boo B
{
   OrbitBarycenter  "44 Boo"
   SpectralType "G2V"
   AppMag 6.00

   EllipticalOrbit  {
      Period      225
      SemiMajorAxis   48.1
      Eccentricity   0.43
      Inclination   82.00
   }
}

All that I get is a barycenter with one star, the G2 V component that comes by default with Celestia.

...John (going to deal with a sudden lack of water and screaming tenants)...

[selden]

You need to put double-quotes around the star names, just as you do with Barycenter names.

If you want, you can prefix them by Star to remind yourself:

Code: Select all

Barycenter "44 Boo:HIP 73695:i Boo"
{
   RA 225.947083
   Dec 47.654061
   Distance 41.6
}

Star "44 Boo A" {   
   OrbitBarycenter  "44 Boo"
   SpectralType "F9V"
   AppMag 5.19

   EllipticalOrbit  {
      Period      225
      SemiMajorAxis   48.1
      Eccentricity   0.43
      Inclination   0.00
      ArgOfPericenter 0.0
  }
}

Barycenter "44 Boo BC" {
   OrbitBarycenter  "44 Boo"

    EllipticalOrbit  {
      Period      225
      SemiMajorAxis   48.1
      Eccentricity   0.43
      Inclination   0.00
       ArgOfPericenter 180
  }
}

Star "44 Boo B" {
   SpectralType "G2V"
   AbsMag 8

    OrbitBarycenter "44 Boo BC"
    EllipticalOrbit  {
      Period      0.00034
      SemiMajorAxis   0.001
      Eccentricity   0.0
      Inclination   0.00
       ArgOfPericenter 0.0
  }
}
Star "44 Boo C" {

   SpectralType "G6V"
   AbsMag 9

   OrbitBarycenter "44 Boo BC"
    EllipticalOrbit  {
      Period      0.00034
      SemiMajorAxis   0.001
      Eccentricity   0.0
      Inclination   0.00
       ArgOfPericenter 180.0
  }
}


Within the EllipticalOrbit definitions, Celestia only requires Period plus one of SemiMajorAxis or PericenterDistance. Of course, you'll need to add other parameters with appropriate values to make what Celestia shows agree with observations.

Note that I've have not tried to provide accurate values above, just something that works.

Does this help?

[Dollan]

That *does* help! I can't believe I missed the quotes... oof.

I'll play around with this today as I can, but I won't be able to do any meaningful experimentation until I get to work tonight. But for now, *thank* you, Selden! I truly appreciate this.

...John...

[Dollan]

Oop... one thing. the A-BC components come up just fine, thank you! but off to the side, about 900 AU away, the original 44 Bootis is still there.

Here's my code thus far:

Code: Select all

Barycenter "44 Boo:HIP 73695:i Boo"
   {
   RA 225.947083
   Dec 47.654061
   Distance 41.6
   }

Star "44 Boo A"
   {
   OrbitBarycenter  "44 Boo"
   SpectralType "F9V"
   AppMag 5.19

   EllipticalOrbit
       {
      Period      225
      SemiMajorAxis   48.1
      Eccentricity   0.43
      Inclination   0.00
      ArgOfPericenter   0.00
      }
   }

Barycenter "44 Boo BC"
   {
   OrbitBarycenter "44 Boo"

   EllipticalOrbit
      {
      Period      225
      SemiMajorAxis   48.1
      Eccentricity   0.43
      Inclination   0.00
      ArgOfPericenter   180
      }
   }

Star "44 Boo B"
   {
   OrbitBarycenter  "44 Boo BC"
   SpectralType "G2V"
   AppMag 6.00

   EllipticalOrbit
       {
      Period      0.2677903
      SemiMajorAxis   0.008
      Eccentricity   0.00
      Inclination   0.00
      }
   }

Star "44 Boo C"
   {
   OrbitBarycenter "44 Boo BC"
   SpectralType "G2V"
   AppMag 6.00

   EllipticalOrbit
      {
      Period      0.2677903
      SemiMajorAxis   0.008
      Eccentricity   0.00
      Inclination   0.00
      ArgOfPericenter   180.00
      }
   }

Is there maybe a problem with the naming convention I'm using?

...John...

[selden]

To cause one of Celestia's predefined stars to be replaced, you should use its HIP number by itself, not the textual name "HIP nnnn"

e.g.

Code: Select all

Barycenter 73695 "44 Boo:i Boo"
{
   RA 225.947083
   Dec 47.654061
   Distance 41.6
}


[Dollan]

Ah, understood. Thanks again.

...John...