Celestia Forums

HI.
First of all:
WHAT A COOL PIECE OF SOFTWARE IS THIS ???!!!
Hey, I really love it (always dreamed of flying through the stars...)

Just one Question:
As I know, Alfa UMi is at least a double star (perhaps even triple, but i'm not sure, i think no one really is).

" The Pole Star alpha UMi, commonly called Polaris, is a Cepheid variable star. Within a period of 4 days the brightness varies between 2.1 mag and 2.2 mag. Additionally alpha UMi is a double star; the companion, a star of 9th mag, can be separated with small telescopes (the separation is 18"). The F7 supergiant Polaris is famous because is lies just one degree away from the true pole."

I don't think it's in Celestia. (Not in nearest stars from Polaris / cannot access by console (tested alf2 umi - no result)
I'm not sure how to add stars (does it work through an .ssc file ? - and if: how ?)

Well if there isn't Alfa UMi B yet, i think it should be there, because Polaris is a very (the most) famous star and the double star feature is well known since (at least) about 10 years. (I'm not sure about Alfa UMi C, but you can differ Alfa UMi A and Alfa UMi B with a small telescope.)

If i'm wrong anyway - correct me.

thanks

thomas

I don't believe Celestia supports multiple-star systems yet. It seems to be a feature a lot of people want, so I'm sure they'll be in a future version.

Although there is Alpha Centurai A and B. Is this something else?

nope.
Alfa Centauri is a double star. (Although i've never tested if they're rotating across each other in Celestia)
So I wondered why Polaris is not (at least in Celestia

Thomas

Celestia seems to adjust stars to be physically multiples even if they are only catalogued as multiple but happen to be coincidentally aligned.
Also, Celestia only has multiple stars which appear in the Hipparcos catalog, one example of which is Alpha Centauri A/B. This is presumably because Hipparcos was only able to resolve certain multiple stars.

On a related note, does anyone know where the Hipparcos parallax measurement procedure is outlined in more detail? I'd be interested in knowing exactly what the reference "background" is for parallax motion.

@ Paul:
Google for "Hipparcos parallax" and someone called "Leeuwen" (& Evans)
There should be serveral Articles for download, so you can read out as much and deep as you want (or can.. )

Thomas