How do stars shape interstellar gas?

 Stars form in interstellar clouds through gravitational collapse. To remain gravitationally unstable, the clouds need to efficiently lose energy, which they do through radiative cooling. Once the stars form, they begin injecting energy back into the interstellar medium, which regulates the next-generation star-formation process. In this talk, I will review key aspects of this feedback process, focusing on the interaction of supernovae, cosmic-rays, and far-UV radiation with interstellar clouds. 

     I will discuss our recent discovery of the "Per-Tau Shell", a gigantic 3D shell of gas and dust in the solar vicinity, that is actively forming new stars. This provides the first 3D observational evidence for the constructive aspect of supernovae, where instead of destroying clouds, supernovae promote cloud-condensation and trigger the formation of a new generation of stars. Supernovae are also the dominant sites of acceleration of cosmic-rays. I will discuss a new way for constraining the proton cosmic-ray interstellar spectrum at low energies (E<GeV), which is currently highly uncertain. The James Webb Space Telescope (expected to launch in a month from now) will be a key player in this quest, shedding a new light on the generation and propagation of low-energy cosmic-rays.