- #1
fab13
- 312
- 6
Hello,
I'm trying to simulate disc galaxy dynamics with a nbody code. The main problem is to get
good initial values (positions and velocities of each star) in order to reproduce the
experimental dynamics.
For the positions, I began by generating a gaussian distribution of stars on 0x and Oy plans ( with mux=muy=0.0 and sigmax != sigmay). On 0z direction, I have generated a uniform distribution whose interval is small compared to sigmax and sigmay. ( this is supposed to reproduce the thin thickness of the disc galaxy). For the velocities of each point, I simply took the Newtonian formula :
vx = - ||vnorm|| * sin(theta)
vy = ||vnorm|| * cos(theta)
vz = 0.0
with ||vnorm||=sqrt(GM/R) with R equal to the distance from the origin and M the mass parameter that we have to adjust.
Unfortunately, using the code with these initial conditions, the galaxy is not stable from a dynamics point of view.
I know the model of these conditions is too basic. Could you give me indications to generate initial conditions more accurate, which could reproduce a stable dynamics.
For example, I should take account of a central bulge.
Has anyone got some documentation on this problem and models more elaborated ?
Thanks
I'm trying to simulate disc galaxy dynamics with a nbody code. The main problem is to get
good initial values (positions and velocities of each star) in order to reproduce the
experimental dynamics.
For the positions, I began by generating a gaussian distribution of stars on 0x and Oy plans ( with mux=muy=0.0 and sigmax != sigmay). On 0z direction, I have generated a uniform distribution whose interval is small compared to sigmax and sigmay. ( this is supposed to reproduce the thin thickness of the disc galaxy). For the velocities of each point, I simply took the Newtonian formula :
vx = - ||vnorm|| * sin(theta)
vy = ||vnorm|| * cos(theta)
vz = 0.0
with ||vnorm||=sqrt(GM/R) with R equal to the distance from the origin and M the mass parameter that we have to adjust.
Unfortunately, using the code with these initial conditions, the galaxy is not stable from a dynamics point of view.
I know the model of these conditions is too basic. Could you give me indications to generate initial conditions more accurate, which could reproduce a stable dynamics.
For example, I should take account of a central bulge.
Has anyone got some documentation on this problem and models more elaborated ?
Thanks