Celestia Forums

I'm releasing one STC file defining 1 million stars in the Andromeda galaxy (M31).

Take note that Celestia takes much more time to load, with this file in its extras folder (a few minutes more, on my 2010 Mac mini).
Frame rate may also drop significantly, depending on your setup.

Also, the STC file has a size of 145.3 MB on disk.

Have fun :

http://fsgregs.startlogic.com/Public_Fi ... _stars.zip (31.3 MB zip file)

Pictures of the distribution (the planet and nebulae aren't included in the addon above) :

Excellent. It does cause my Celestia to take more time loading (A useful feature for a new version would be the ability to properly minimise that loading screen one gets when executing), but framerates are fine, although I do have a pretty awesome computer.

I can't wait to start putting planets and stuff around these stars...

NoXion wrote:I can't wait to start putting planets and stuff around these stars...

Take note that the stars in this STC file are mostly of spectral class O and B (very luminous stars), so we could see them at some distance.

For Sol like stars (F, G and K), you should use the database I published in another thread.

Cham wrote:Take note that the stars in this STC file are mostly of spectral class O and B (very luminous stars), so we could see them at some distance.

For Sol like stars (F, G and K), you should use the database I published in another thread.

Thanks. Although I thought that O and B (and possibly A) stars were only really problematic for Earthlike planets, since they don't last long enough for life (as we know it) to evolve?

Unless of course, somebody artificially constructs or places an Earthlike planet around an O/B/A star...

Hi, Martin: FYI, it doesn't work on my system. It take up about 3.5 min. to load Celestia at Sol (Earth, in my case) and another 3.15 min. to be ready for the console. Then, when I go to one M31's star, I'm able to see it, but soon after Celestia does crash.

Fenerit,

this may be a memory problem on your system.

You can try removing half of the stars in the STC file. You'll still have 500 000 stars, randomly placed in the galaxy !
Or even 100 000 stars (1/10 of the file) is a lot.

Editing the file is easy, especially since all the stars are numbered from 1 to 1000000.
Their locations are fully random inside the M31 galaxy : they aren't sorted by location.

Thank you for this!
Long ago a made a 100,000 star STC file for Andromeda using and old globular cluster generator but could never make them distribute along the galactic plane.

Reiko wrote:but could never make them distribute along the galactic plane.

This is exactly the non-trivial nature of making stellar distributions for galaxies in Celestia. The distribution must be properly aligned with the galactic model. This asks for LOTS of non-trivial mathematics (rotation matrices, with knowledge of Celestia's way to orient the axes in its virtual space). I even discovered that one of the axes used by Celestia is actually reversed, compared to the usual conventions in science and maths.

A maths program like Mathematica or Maple is really necessary for that stuff.
In theory, it could also be done with software like OpenOffice or Excel, but it would be a huge pain in the butt !

--- edit ---

Yes, Celestia need a tool to build binary STC files.
Currently, it recognize only one binary file, and it must be placed in its data folder.

Very sad.

john Van Vliet wrote:for people on "lower end" less than 4 gig ram

a 145 Meg TEXT file WILL TAKE FOREVER to load !!!
so be warned

in contrast the 2c star db
"Version 2.1 C contains 2072867 stars."

is a BINARY file and loads VERY fast

Even with Notepad++ I can't manage such file while I did managed with easyness the NOAA ETOPO files with tenth millions of lines. I think these are MAC-Win issues.

OK, found the issue with Notepad++ (v. 5.8 ): no formatting language must be used with such big file. Only "normal text" option.

As I already stated before, that huge file is usefull just to do some nice screen captures.
I don't use it for other things, so it's not in my extras folder.
I use it only when I want to do some special screen captures.

I don't have any problem loading it on my 2010 Mac mini with 4 GB ram, and it's working very well.

And the user is free to truncate the file so it loads in less time :
using a word processor, remove 99% of its stars, and you'll still get 10 000 stars in M31 !
You wont notice any problem while Celestia is loading.

--- edit ---

Cham wrote:

NoXion wrote:I can't wait to start putting planets and stuff around these stars...

Take note that the stars in this STC file are mostly of spectral class O and B (very luminous stars), so we could see them at some distance.

For Sol like stars (F, G and K), you should use the database I published in another thread.

Do you have a link to that thread?

omega13a wrote:Do you have a link to that thread?

Two threads, actually :

viewtopic.php?f=23&t=16624

viewtopic.php?f=23&t=16626

The file looks corrupted. I tried to open the file, but then there was an error and after that, the file vanished.Is there another link where I can download it?

danielj wrote:The file looks corrupted. I tried to open the file, but then there was an error and after that, the file vanished.Is there another link where I can download it?

The file isn't corrupted. You simply don't have enough memory on your computer to open a text file of 145 MB. Or the software you're using is a piece of crap.

On a Mac with just 4 GB of memory, I can open the file easily using TextEdit.

--- edit ---

Cham wrote:I even discovered that one of the axes used by Celestia is actually reversed, compared to the usual conventions in science and maths.

Would that be the same axes Fridger and and Ajtribick had a standoff over in the Binary Radial Velocities thread, by any chance?