39 | | The field starts with a Beta=0.5 everywhere in the box. We see early on the NTSI develops and grows for the first 20 frames or so. By about 2 Myr, it seems the NTSI begins to collapse back toward the midplane. Without the troughs of the NTSI for the material to funnel toward, the material is instead splashed laterally in the y-direction. This creates large shear that excites KH modes especially at the tops and bottoms of the colliding streams. The first core (sink particle) forms late in the simulation, by 15 Myr, in the center of the slab corresponding to the global potential minima. Peak densities at this time are ~12,000 /cc << 10^21^ number densities Heitsch et al. regarded previously as the threshold when H2 can appreciably form in the clouds due to effective shielding. |
| 39 | The field starts with a Beta=0.5 everywhere in the box. We see early on the NTSI develops and grows for the first 20 frames or so (~2 Myr). By about this time, it seems the NTSI begins to collapse back toward the midplane. Without the troughs of the NTSI for the material to funnel toward, the material is instead splashed laterally in the y-direction. This creates large shear that excites KH modes especially at the tops and bottoms of the colliding streams. The first core (sink particle) forms late in the simulation, by 15 Myr, in the center of the slab corresponding to the global potential minima. Peak densities at this time are ~12,000 /cc << 10^21^ number densities Heitsch et al. regarded previously as the threshold when H2 can appreciably form in the clouds due to effective shielding. |