Celestia Forums

Lately, I've been quite facinated by the program "Gravity3D" which is supposed to simulate galaxy collisions. It renders 200000 stars at interactive rates, and the reason, I found out is that it reduces the problem complexity from n^2 (stars interact with each other) to n. (stars interact only with the core of the galaxy. This makes the program pretty useless for accurate simulations of galaxy collitions, but perhaps it could be used to simulate nebulae? Since the gas from a dying star has so low density, I guess it wouldn't interact much with itself compared to the core of the remaining star. So that makes it a problem of complexity n. I've tried to experiment a little (just switching the mass of the galactic core on and off) and the results are pretty cool. It might also perhaps be used to simulate the effect of a black hole ripping a star appart. Here are a few pictures: (I'm by no means implying that this should make its way into Celestia)

http://www.stud.ntnu.no/~arneb/1.jpg
http://www.stud.ntnu.no/~arneb/2.jpg
http://www.stud.ntnu.no/~arneb/3.jpg
http://www.stud.ntnu.no/~arneb/4.jpg

Arne,

Although their gases are extremely tenuous by earthly standards, my understanding is that the bright regions of planetary nebulae are caused by shockwaves where later gas releases collide with earlier ones.

Of course, gravitational effects are in a different category.

Here's a link to the program, if anyone's curious. It's rather nifty, I could spend ages playing with that!

Ok, thanks Selden. That makes sense. After testing the program, I became convinced that the tendril like structures (is that the right word?)
were created because a thin "arm" was pulled away from the rest of the gas and slung out by the gravitational forces. But I guess that was wrong.

The great thing about this forum is that it feels almost as if I was a little kid again, and could ask my father about pretty much anything and still get proper answers. He is a physics teacher, so that helped alot Now I've finally surpassed him in some fields, and currently I've been trying to show him how to use fourier-series to solve partial differential equations. Hehe, seems appropriate to put a "nerd" emoticon here

Arne,

Well, apparently the processes that create planetary nebulae aren't very well understood. One hypothesis that I read recently is that the more beautiful (complex) ones are produced by binary systems and that individual stars outgas in rather dull patterns.

Personally, I'd guess that the interrelationships of the stars' magnetic fields would have more of an effect on the ionized gas distributions than gravity would have, but that the results would look very similar.

Oh, I didn't even think of that possibility. So a simulation would need to take in consideration both gravitational forces, direct contact and magnetic fields... I've heard that magnetic fields are very difficult to handle mathematicaly, A combination must be awful.

Here is an interesting link:

http://www.strw.leidenuniv.nl/~icke/htm ... ml#RedRect

ArneB wrote:Oh, I didn't even think of that possibility. So a simulation would need to take in consideration both gravitational forces, direct contact and magnetic fields... I've heard that magnetic fields are very difficult to handle mathematicaly, A combination must be awful.

Here is an interesting link:

http://www.strw.leidenuniv.nl/~icke/htm ... ml#RedRect

cel://Follow/Red%20Rectangle/2004-10-17T19:05:25.80759?x=AFgETuVgNDsJQqf5/////w&y=AEAt06Qudvn/xIjW/////w&z=AIC+q3KcF1j378rC/////w&ow=0.955095&ox=0.291766&oy=-0.049386&oz=-0.015085&select=Red%20Rectangle&fov=25.601799&ts=1.000000<d=0&rf=8067&lm=49152

mal solar

C'n'est pas "Mal". C'est vrai!

Mais il n'y a pas de Addon Nebula.

Si vous connaissez le plus l?ger peu de l'anglais, svp, au moins essai ! Les ?motic?nes le rendent bien plus cach? pour un Norv?gien faible qui a seulement appris l'anglais et l'allemand ? l'?cole

Vous avez su cela si vous ajoutez un "n" ; ? votre surnom, il signifie la coudre-machine dans le Norv?gien?