(updated for 2013)
- Dense cores:
- Typical ISM:
- This room: 1 mol / 22.4L
- XVH (eXtremely High Vacuum) — best human-made vacuum:
- Density of stars in the Milky Way:
In other words, most of the ISM is at a density far below the densities and pressures we can reproduce in the lab. Thus, the details of most of the microphysics in the ISM are still poorly understood. We also see that the density of stars in the Galaxy is quite small – only a few times the average particle density of the ISM.