Celestia Forums

Hi all,
Is there a chance to see in Celestia this new planet with its 3 suns ?
http://www.jpl.nasa.gov/news/news.cfm?release=2005-115
That will be very nice

This has been posted several times before.

e.g. http://www.celestiaproject.net/forum/viewtopic.php?t=8335

Yes you are right
But my question was "can we expect to see this 3 suns system in Celestia"
It's a good example to see how the planet (moon) will be colored according to the modifications made by Chris on the v1.4.0pre6 and 7

I'm going to hazard a guess that the multiple star lighting would not have much of an effect in this system - the planet is a hot Jupiter, so it will probably be receiving thousands of times as much light from the primary than it would from the binary pair.

I'm not sure what the plans for extrasolar.stc are, there are definitely some long overdue updates needed (e.g. Gamma Cephei, 55 Cnc B), but from what I've seen the current priority is dealing with t00fri's large catalogue-derived binary stars files rather than the "pick and choose" approach of the extrasolar.stc and nearstars.stc files.

So, it's not so a "good example"
Thanks Chaos Syndrome for your reply

What update is required for the Gamma Cephei system, Chaos?

eburacum45 wrote:What update is required for the Gamma Cephei system, Chaos?

It should be a double star system (with a planet) but it doesn't appear to be shown as such in Celestia (not even in FT1.1).

http://www.astro.uiuc.edu/~kaler/sow/gammacep.html
http://www.solstation.com/stars2/errai2.htm

Malenfant wrote:

eburacum45 wrote:What update is required for the Gamma Cephei system, Chaos?

It should be a double star system (with a planet) but it doesn't appear to be shown as such in Celestia (not even in FT1.1).

http://www.astro.uiuc.edu/~kaler/sow/gammacep.html
http://www.solstation.com/stars2/errai2.htm

Unfortunatley, we require full kinematical information for binaries in order to display them in 3d. Unfortunately that system is lacking data...The planet is there, but not the other star

Bye Fridger

t00fri wrote:Unfortunatley, we require full kinematical information for binaries in order to display them in 3d. Unfortunately that system is lacking data...The planet is there, but not the other star

Bye Fridger

What info do you need, specifically?

Is there anything useful in this paper?

Malenfant wrote:

t00fri wrote:Unfortunatley, we require full kinematical information for binaries in order to display them in 3d. Unfortunately that system is lacking data...The planet is there, but not the other star

Bye Fridger

What info do you need, specifically?

Is there anything useful in this paper?

Well for a binary system with /comparable/ masses we need

a) the usual orbit parameters ( Period, SemiMajorAxis_1 , SemiMajorAxis_2, Eccentricity, Inclination, AscendingNode, ArgOfPericenter_1, ArgOfPericenter_2 and MeanAnomaly)

b) the barycenter's (RA, DEC and distance)

c) the color classes of both stars.

That's quite a lot, even if we are ready to guess a few or use mass-luminosity relations and the like.

That's why so far we only have a fairly "compact" set of ~200 binaries in Celestia...

Bye Fridger

PS: That paper is interesting, but not as to the binary orbit issue.

The systems could be handled until better data are available by having the secondaries fixed, e.g. the current handling of Gliese 86, where the white dwarf orbit is not known, but we do have the position.

Ok, ok,I will be patient

Thank you. I asked because I have a small add-on for the Gamma Cephei system (a terraformed moon); but if I add any more planets and moons I'll put a red dwarf in as well- using the best data available which no doubt will not include the inclination, argument of pericentre and so on. I note that this information is not available for most of the exoplanets either...

Hmm... the Sixth Catalog of Orbits of Visual Binary Stars gives elements for Gamma Cephei AB and HD 188753 AB:

HD 188753 B:
Magnitude of primary: 7.41
Magnitude of secondary: 8.09
Period: 25.7 years
Semimajor axis: 0.27 arcseconds
Inclination: 34 degrees
Node (Omega): 43 degrees
Time of periastron passage: 1988.2 (fractional Besselian year)
Eccentricity: 0.50
Longitude of periastron (w): 236 degrees
Equinox: 2000
Orbit grade: 1 (definitive)

I haven't found any information on the Ba-Bb pair's orbit, so for now we might have to do with representing it as a single star - HD 188753 has an entry in the Eighth Spectroscopic Binary Catalogue, but it lists it as a B-class star with a period of 155.1 years... hmmm...

Gamma Cephei B:
Magnitude of primary: 3.23
Magnitude of secondary: ?
Period: 44.5 years
Semimajor axis: 0.60 arcseconds
Inclination: 158 degrees
Node (Omega): 318 degrees
Time of periastron passage: 1958 (fractional Besselian year)
Eccentricity: 0.4
Longitude of periastron (w): 174
Equinox: 1991
Orbit grade: 9 (astrometric fit, poor)

Apparently not a particularly good set of orbital elements, and it is lacking information on the companion magnitude, but I guess it's better than nothing...

I don't have the know-how to convert these to barycentre-relative orbits and translating the orbital elements however.

Hmm... I have found some orbital data on the BC pair in the HD 188753 system here:

HD 188753 C
Period: 156.0 days
Semimajor axis: 0.67 AU
Node (Omega): 10 degrees
Time of periastron: 2453198 (HJD)
Eccentricity: 0.1
Mass ratio: 0.96:0.67

Inclination information is not available, presumably because this is a spectroscopic binary.

If anyone knows how to convert all this into a format suitable for Celestia, help would be much appreciated!

Ok, I have implemented the triple system based on the information we know. Go here for more details.