Other N-Body Data Archives (excluding animations) that we know about :
NOTE: To retrieve the data through a WWW browser, you probably need to turn on some kind of option Load To local disk before you click on the datasets themself. ASCII files have normamlly been compressed with the GNU gzip program for sake of efficiency. In the examples below I have assumed that the zcat program is the version that correctly uncompresses .gz or .Z files.
mkplummer - $nbody seed=123 | snapprint - n,x,y,z,vx,vy,vz | gzip -c > tab$nbody.gzand can be read back into NEMO as follows:
gunzip -dc tab$nbody.gz | tabtos - p$nbody.snap "" mass,pos,vel nbody=$nbodyfor further visualization.
atos iau25.data snap0 snapcenter snap0 - one=t | tsf - maxprec=t hackcode1 snap0 snap1 eps=0 tol=0 tstop=0 tsf snap1 maxprec=tLookout for an upcoming updated repeat of this experiment during the 1997 IAU GA in Kyoto. This time organized by Douglas Heggie
z, y, x, vz, vy, vxbut do not always appear on the same line. The fortran statement
REAL x(43802),y(43802),z(43802),vx(43802),vy(43802),vz(43802) DO i=1,43802 READ (*,*) z(i), y(i), x(i), vz(i), vy(i), vx(i) ENDDOshould however read the data correctly. Within NEMO the program tabtos(1NEMO) can be used as follows to read in the data in snapshot(5NEMO) format:
zcat stars.dat.gz | tabtos - stars.snap block1=pos,vel nbody=43802 options=wrapfor further visualization. Some more practical information can be found in the README file.
nbodies ndim time masses x y z vx vy vz eps (and NOT the potential)
The data here may be slightly different than the ones in other similar archives (e.g. GC3). The 81920 particles are in the following order:
16384 Gal. disk 16384 And. disk 8192 Gal. bulge 8192 And. bulge 16384 Gal. halo 16384 And. haloThese initial conditions start at a point less than 1 Gyr before the collision since during the 3-4 Gyr or so leading up to the collision nothing much happens. So Andromeda should look bigger than it is at the moment. The simulation starts when Andromeda is only about 120 kpc away from the Galaxy instead of the current 700 kpc so it should look about 5 times bigger than it looks now.
In NEMO this table can be read into a snapshot as follows:
zcat dubinski.tab.gz |\ tabtos - m31.ini block1=m,pos,vel nbody=81920 times=0If you want to run a quick simulation, you could take a subset of the particles, multiply the masses appropriately and integrate, a subset of 640 particles, (320 per galaxy: 128 disk, 64 bulge, 128 halo):
zcat dubinski.tab.gz |\ tabtos - - block1=m,pos,vel nbody=81920 times=0 |\ snapcopy - - select=i%128 |\ snapscale - m31_small.ini mscale=128 hackcode1 m31_small.ini m31_small.dat tstop=80 freqout=1 > m31_small.log