NPR: (Movies of jets from young stars at HubbleSite: here)
If you’re like me and maybe a little confused as to what you’re looking at, here’s some more detail (Yes, even Joe has to look stuff up sometimes):
As a star is formed from collapsing dust, ever increasing its density and energy, it begins to form a disk of dust and gas pulled in and rotated by its growing gravity. Perpendicular to this disk, like the tip of a spinning top, some gas is ejected away from the growing star in a high-energy jet. As this collides with interstellar gas, it gives off radiation, which we can observe with telescopes like Hubble.
To see the jets, we have to shift into the infrared and other spectra, as the radiation is outside normal human vision. These movies represent the first time we’ve seen the dynamics of the jets as opposed to still images. More info on protostellar jets here, you star-freaks.
In addition to being big red flags announcing the presence of young stellar objects, or YSO’s, outflows from these so-called ‘Herbig-Haro objects’ inject a considerable amount of mechanical energy into their environments. This is particularly important because stars don’t typically form alone, but rather in clusters of dozens to thousands of stars. Since stars begin as overdensities in cold molecular clouds that are unstable to collapse, even being “kicked” a little by the outflow of a neighboring YSO is enough to push these “cores” over a density threshold, causing the star formation process to formally begin. In this manner, once star formation gets started in a cloud, it can proceed in a snowball fashion as a few new stars kick off the formation of many others. -JCB