The birth of binary stars via bar mode instability?

These are my old work when I first joined in LSU astrophysics group back in 2001.
A bunch of simulations were made during the past year(Nov 2001--Oct 2002) in an effort to study the dynamical bar_mode instability and the formation of binary stars. The theoretical background is built on classical work of Chandrasekhar (1969). For a rigidly rotating Maclaurin spheroid with |T/W|>0.278, it undergoes dynamical instability toward m=2 mode which will cause the initially axissymetric object to deform into an ellipsoid-like shape or bar-shape. This bar-mode instability also holds for compressible and differentially rotating configurations with |T/W|> 0.27. Cazes and Tohline(2000) has studied a paticular model with uniform vortensity, the final state of this model is in a pretty steady bar-like configuration with two off-center density maximum which leads people to believe it may break up into two parts via some physical process such as cooling. Our goal is to follow this path, trying to see if it will fission in the end. Beginning from Nov 2001, I did two simulations.
The first simulation was performed on 16 processors of LSU's IBM SP2 machine -- Casper. It started with an intitial model of resolution 130x130x128 in r, z and azimuthal direction respectively, the high value of |T/W|=0.33 implies that it is a rapidly rotating object and dynamically unstable to the bar-mode instability. The initial axissymtric structure then evolved into a elongated bar. After it became a steady bar rotating with constant pattern angluar frequency, we implemented a simple cooling mechanism to cool it.
Movies for the bar mode simulation performed on LSU CASPER
Evolution Stage Resolution # of processors computer movies comments
bar forming stage 130*130*128 16 IBM SP2 LSU Capser maya movies The axissymmetric structure evolved into a bar-shape
bar in corotating frame 130*130*128 16 IBM SP2 LSU Capser maya movies The steady bar in the corotating frame
bar in fast cooling 130*130*128 16 IBM SP2 LSU Capser maya movies bar in the quick cooling scenario
bar in slow cooling 130*130*128 16 IBM SP2 LSU Capser maya movies bar in the slow cooling scenario
In the late stage of the first simulation, the bar shrank a lot. The effective resolution decreased a lot. In order to get a better result, we swtiched our second simulation to Blue Horizon -- the IBM SP3 machine of National Supercomputing Center at University of California at San diego, so we were able to build a much larger model with resolution 258x162x256 and |T/W|=0.27, which is maginally unstable to the dynamical instability. In stage I (bar forming) and II (corotating stage), the simulation was performed on 64 processors at San diego. In the third stage (cooling), with the setup of LSU's Tera-flop Beowulf cluster -- Super-Mike (ranked 16 in the most recent top 500 world-wide super computer list), we were able to speed up our simulation here at LSU on 128 Pentinum-4 processors and able to try different parameters in the parameter space.
Movies for the bar mode simulation performed on Npaci's Blue Horizon and LSU's Beowulf cluster Super Mike
Evolution Stage Resolution # of processors computer movies comments
bar forming stage 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU SuperMike		 maya movies The axissymmetric structure evolved into a bar-shape
bar in corotating frame 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar with a steady pattern rotating speed as viewed in the corotating frame
cooling bar 1.1 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in the slow cooling scenario
cooling bar 1.2 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in the slow cooling scenario
cooling bar 2.1 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in the fast cooling scenario
cooling bar 2.2 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in the fast cooling scenario
cooling bar 3.1 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in the faster cooling scenario
cooling bar 3.2 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in the faster cooling scenario
cooling bar 3.2 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies cooling stops
cooling bar 3.2 258*162*256 64 IBM SP3,
128 Pentium 4 		NPACI Blue Horizon,
LSU Super Mike		 maya movies bar in extremly slow cooling scenario
Bar under the tidal force of a corotating massive blackhole:
The first 200 timesteps
200-3000 timesteps