Celestia Forums

Has anyone made a stc file for these stars? I am using 1.4.1 and it doesn't show them as multi star systems.
Thanx
Tim

fungun wrote:Has anyone made a stc file for these stars? I am using 1.4.1 and it doesn't show them as multi star systems.
Thanx
Tim

Celestia includes only ~200 double stars for the simple reason that the full 3D orbit information is required for BOTH members. For most doubles/ multiple stars this information is (partially)lacking.

Bye Fridger

If you don't mind not having orbital motion, you should be able to find the right ascension and declination on SIMBAD.

You can then create a star at the specified coordinates. It won't move around, but it's a start.

I know this won't be "real" but couldn't I use the right ascension and declination of Mira and Regulus, that's already in Celestia, to make barycenters? Then I could just add the stars back in with their mates.

Thanx
Tim
ps-here is what I have found out so far.

Regulus A has relatively distant, orange-red and red dwarf binary companions BC that were last observed to be separated by around 4,200 AUs
Alpha Leonis B
Star "B" is a orange-red main sequence dwarf star of spectral and luminosity type K1-2 V. It may have around 80 percent of Sol's mass, somewhat less than its diameter, and 31 percent of its luminosity.
The orbit of an Earth-like planet (with liquid water) around Star B would be centered around 0.56 AU -- between the orbits of Mercury and Venus in the Solar System -- with an orbital period around 171 days.
Regulus A/B/C Observation data
Epoch J2000
Constellation Leo
Right ascension A: 10h 08 min 22.3s
BC: 10h 08 min 12.8/14s
Declination A: +11?° 58' 02"
BC: +11?° 59' 48"
Apparent magnitude (V) 1.35/8.14/13.5
Characteristics
Spectral type B7 V/K1-2 V/M5 V
U-B color index -0.36/0.54
B-V color index -0.11/0.87
Variable type Slightly
Astrometry
Radial velocity (Rv) +5.9 km/s
Proper motion (?µ) RA: 249 mas/yr
Dec.: 2 mas/yr
Parallax (p) 42.09 ?± 0.79 mas
Distance 77 ?± 1 ly
(23.8 ?± 0.4 pc)
Absolute magnitude (MV) -0.52/4.2/9.5
Details
Mass 3.5/0.8/0.2 M?
Radius 3.15?€“4.15/0.5/? R?
Luminosity 150/0.31 L?
Temperature 10,300?€“15,400/? K
Rotation 315 km/s. (15.9 hours)/?
Age 5 ?— 107 years



Mira B.
is most likely a main sequence star of around 0.7 solar masses and spectral type K,
it was 100 AU astronomical units from the primary;
The companion's orbital period around Mira is approximately 400 years.

I know this won't be "real" but couldn't I use the right ascension and declination of Mira and Regulus, that's already in Celestia, to make barycenters? Then I could just add the stars back in with their mates.

Yes.
Look in Celestia's own STC catalog files in the \data\ directory for examples. They use exactly that technique.

Ran into a small problem. How do I open stars.dat to get the info for Regulus and Mira? I tried Notepad, Wordpad, TextEdit Lite, Acrobat Reader. It just looks like a bunch of symbols.

Thanx
Tim

stars.dat is a binary file. You can't open it in a text reader. It probably wouldn't be particularly useful, either: it uses Celestia's internal cartesian coordinate system. STC files reuire RA and Dec.
(If you insist, though, the text version of stars.dat is available on SourceForge at
http://celestia.cvs.sourceforge.net/cel ... t?view=log )

When defining stars in STC catalog files, I find it easiest to use official coordinates, etc., obtained from Simbad.
http://simbad.u-strasbg.fr/simbad/sim-fidl

Don't forget to convert RA from HMS to fractional degrees.

fungun wrote:Ran into a small problem. How do I open stars.dat to get the info for Regulus and Mira? I tried Notepad, Wordpad, TextEdit Lite, Acrobat Reader. It just looks like a bunch of symbols.

Thanx
Tim

stars.dat IS indeed a bunch of symbols or as we say a binary file . This is done to decrease the time it takes for loading. The corresponding human-readable (Ascii) file is called stars.txt and OF COURSE can be found in the Celestia SOURCE code, along with many other goodies. Note that the Windows binary distribution is by far not the full OpenSource archive of Celestia.

I suppose you know how to find the sources.

Bye Fridger