Celestia Forums

To avoid loading problems on the other thread: ( http://celestiaproject.net/forum/viewtopic.php?t=12104 ), I've created this one for miscellaneous images of multiple star systems such as Castor. (Feel free to add your own).

According to: http://www.solstation.com/stars2/castor6.htm :

Stars Aa and Ab have a combined luminosity of over 34 times that of Sol's. They are separated on average by only 0.022 AUs (of a semi-major axis). Their highly eccentric orbit (e= 0.499) takes only 9.21 days to complete....Currently, the circumbinary orbit of an Earth-like planet (with liquid water) around Stars Aab may be centered just beyond 6.0 AU -- just outside the orbital distance of Jupiter in the Solar System.

I wonder what the sunrise would look like if an Earthlike planet with a moon actually did exist?
From left to right: 1. The A and M class stars of the BaBb binary appear as a single bright sun; 2. slightly higher in the sky is the moon; 3. The 2 suns of the AaAb system are clearly visible as 2 separate suns; 4. The distant CaCb flare stars appear as a single star at the far right:

http://www.solstation.com/stars2/castor6.htm also talks about the possibility of life in the YY Gem system:

Currently, the circumbinary orbit of an Earth-like planet (with liquid water) around Stars Cab may be centered around 0.23 AU -- well within the orbital distance of Mercury in the Solar System.

The 4 stars of the binary systems AaAb and BaBb rise appearing as 2 bright stars at top left of the image, followed soon after by the 2 red dwarfs of the home system:


However:

Earth-type life around flare stars may be unlikely because their planets must be located very close to dim red dwarfs to be warmed sufficiently by star light to have liquid water (around 0.23 AU for Castor Cab), which makes flares even more dangerous around such stars. In any case, the light emitted by red dwarfs may be too red in color for Earth-type plant life to perform photosynthesis efficiently.

I am trying to make a system like this around Epsilon Ceti. All three stars are really packed close together.
If an earth like planet were to orbit the barycenter then how far out would it need to be?
Do I just add up the luminosities of all thee stars and use that to calculate where the planet should go?

Reiko wrote:I am trying to make a system like this around Epsilon Ceti. All three stars are really packed close together.
If an earth like planet were to orbit the barycenter then how far out would it need to be?
Do I just add up the luminosities of all thee stars and use that to calculate where the planet should go?

I assume you're aware of this: http://en.wikipedia.org/wiki/Habitable_zone

PS. Are you sure you're talking about EPS Cet? I thought it only had 2 stars, not 3.

Chuft-Captain wrote:

Reiko wrote:I am trying to make a system like this around Epsilon Ceti. All three stars are really packed close together.
If an earth like planet were to orbit the barycenter then how far out would it need to be?
Do I just add up the luminosities of all thee stars and use that to calculate where the planet should go?

I assume you're aware of this: http://en.wikipedia.org/wiki/Habitable_zone

PS. Are you sure you're talking about EPS Cet? I thought it only had 2 stars, not 3.

I realized that 3rd star is not supposed to be there because it doesn't orbit with the other two. I'm using the 2million star extended DAT file from celestia motherload and it placed a star right next to the EPS Cet.



The binary in the center is EPS Cet, the star highlighited is TYC 6822-3356-0 and it is sitting just a few AUs from the binary.

There's a quick fix to that.
Change the designation of the dimmer star by giving it a HIP number corresponding to the TYC of the star.

TYC aaaa-bbbbb-c becomes cbbbbbaaaa

Examples
TYC 2825-3358-0-> HIP 033582825.
TYC 197-37-1-> HIP 1000370197.

If done correctly, this will override the TYC star.

Hungry4info wrote:There's a quick fix to that.
Change the designation of the dimmer star by giving it a HIP number corresponding to the TYC of the star.

TYC aaaa-bbbbb-c becomes cbbbbbaaaa

Examples
TYC 2825-3358-0-> HIP 033582825.
TYC 197-37-1-> HIP 1000370197.

If done correctly, this will override the TYC star.

I don't know how I can do that. The last time I tried to open that 2 million star DAT file my computer exploded and I had to clean computer parts off of the walls and ceiling.

Don't open the stars.dat file, but rather ths .stc that contains the information for the system. Nearstars I'm guessing? I don't know where it is exactly.

Those stars are not in the nearstars.STC file or the extrasolar.STC file.

If I make another STC file with the same name as that TYC star will it override the star in the DAT file or will it just make two stars with the same name?

Hungry4info wrote:There's a quick fix to that.
Change the designation of the dimmer star by giving it a HIP number corresponding to the TYC of the star.

TYC aaaa-bbbbb-c becomes cbbbbbaaaa

Examples
TYC 2825-3358-0-> HIP 033582825.
TYC 197-37-1-> HIP 1000370197.

If done correctly, this will override the TYC star.

By the way how do you come up with those conversions? My brain is retarded with numbers.
What would TYC 6822-3356-0 be in HIP?

I didn't come up with the conversions. Lol.
TYC 6822-3356-0 would be HIP 033566822

You basically put the last number first, then put the middle four numbers, then put the first four numbers.

I found Eps Cet defined in "visualbins.stc". To define Eps Cet B as TYC 6822-3356-0, you put it's HIP equivalent before it's name. This will eliminate the extraneous TYC star from Celestia, and Celestia will assume that EPS Cet B is that star.

Relevant (modified) stc:

Thank you much for the help it got rid of one of the stars. Instead of getting rid of that TYC star it got rid of EPS Cet B

Ok I found the trick. I just made a new STC file in the extras folder and named the star with the HIP number of that TYC star I wanted to get rid of and now it's gone.

Thanks Hungry4info!

Reiko wrote:Those stars are not in the nearstars.STC file or the extrasolar.STC file.

If I make another STC file with the same name as that TYC star will it override the star in the DAT file or will it just make two stars with the same name?

Hungry4info wrote:There's a quick fix to that.
Change the designation of the dimmer star by giving it a HIP number corresponding to the TYC of the star.

TYC aaaa-bbbbb-c becomes cbbbbbaaaa

Examples
TYC 2825-3358-0-> HIP 033582825.
TYC 197-37-1-> HIP 1000370197.

If done correctly, this will override the TYC star.

By the way how do you come up with those conversions? My brain is retarded with numbers.
What would TYC 6822-3356-0 be in HIP?

I usually go here --> http://www.rssd.esa.int/index.php?project=HIPPARCOS to look things up (cross-reference)... but I find a search on TYC 6822-3356-0 does not turn up anything (at all!).

LordFerret wrote:

Reiko wrote:Those stars are not in the nearstars.STC file or the extrasolar.STC file.

If I make another STC file with the same name as that TYC star will it override the star in the DAT file or will it just make two stars with the same name?

Hungry4info wrote:There's a quick fix to that.
Change the designation of the dimmer star by giving it a HIP number corresponding to the TYC of the star.

TYC aaaa-bbbbb-c becomes cbbbbbaaaa

Examples
TYC 2825-3358-0-> HIP 033582825.
TYC 197-37-1-> HIP 1000370197.

If done correctly, this will override the TYC star.

By the way how do you come up with those conversions? My brain is retarded with numbers.
What would TYC 6822-3356-0 be in HIP?

I usually go here --> http://www.rssd.esa.int/index.php?project=HIPPARCOS to look things up (cross-reference)... but I find a search on TYC 6822-3356-0 does not turn up anything (at all!).

I could not find anything on it either and considering it was placed just a few AUs from the EPS Cet binary I figured it was maybe a mistake.

The extra star is most likely the Tycho definition of the equivalent Hipparcos star.
Celestia's default stars.dat is based on the Hipparcos data (which is the most accurate).
I imagine the 1 million and 2 million extras by PAscall Hartmann/Grant Hutchison are probably based on the Tychos and Tychos2 data respectively (see if the README's say anything about the sources).
In this case there can obviously be duplicates because some stars were measured by both instruments, in which case the Hipparcos version should be more accurate).

See here: http://www.rssd.esa.int/index.php?project=HIPPARCOS

EDIT: I see this is the same reference LordFerret gave you.