Universe Sandbox

Universe Sandbox Legacy => Universe Sandbox Legacy | Discussion => Topic started by: Sanduleak on May 02, 2010, 08:15:07 AM

Title: Cinderdar galaxy - Screenshots and movie
Post by: Sanduleak on May 02, 2010, 08:15:07 AM

This is Cinderdar. A Torus-shaped galaxy counting 1000 stars.

Here you will see the projected path upon initial system load (straight vectors tangential to the ring), and after some computation by US v2.

The movie  shows the galaxy spinning in a stable fashion. The stars are displayed in their "true" color, ranging from 0.015 sun (green) to 150 sun (purple) according to a Levy distribution.

Movie here : http://www.youtube.com/watch?v=p60PQc96gHM

Title: Re: Cinderdar galaxy - Screenshot and movie
Post by: atomic7732 on May 02, 2010, 10:25:34 AM

How does it do that? WOAH!!!! Hmmm, if that works maybe I can make a globular cluster...

Cool!

Title: Re: Cinderdar galaxy - Screenshots and movie
Post by: Naru523 on May 02, 2010, 01:11:30 PM

Whoa.

Title: Re: Cinderdar galaxy - Screenshots and movie
Post by: Dan Dixon on May 02, 2010, 06:21:23 PM

I love the 2nd image. That's really beautiful.

Title: Re: Cinderdar galaxy - Screenshots and movie
Post by: Sanduleak on May 03, 2010, 01:37:10 AM

I have replaced the original movie by a much neater one.
Gravity relations between stars can now be seen changing as the galaxy is spining on its center.

http://www.youtube.com/watch?v=p60PQc96gHM

Title: Re: Cinderdar galaxy - Screenshots and movie
Post by: Dan Dixon on May 03, 2010, 06:08:35 PM

How did you make these cylindrical 'galaxies'?

They're really cool.

Title: Re: Cinderdar galaxy - Screenshots and movie
Post by: Sanduleak on May 04, 2010, 05:10:50 AM

Quote from: Dan Dixon on May 03, 2010, 06:08:35 PM

How did you make these cylindrical 'galaxies'?

They're really cool.

Thank you! The most natural and simple way to make cylindrical or spherical  shapes is by using a polar system of coordinates. So I picked the equatorial coordinate system that is communly used in astronomy and that is supported by Universe Sandbox XML language.

The position data of the stars are provided through three parameters:
* The distance from observer: it is generated by a Gaussian distribution centered on the average radius of the cylinder. The standard deviation defines the thickness of the cylinder.
* The right ascension : this is a fully random angle, so that all directions are spanned around the observer
* The inclination: this angle is a gaussian centered around zero, it determines the height of the cylinder.

To obtain a perfect ring you would need to take another more complicated formula for inclination, but the approximation is good enough in most cases.

As for the velocities, I generated a norm for each star that I projected on X, Y and Z axes. The norm must be neither too small nor too big to avoid the galaxy to collapse or to scatter.

Regards,
Chris