While stars are a classic topic of astronomy, only in recent times have we begun to understand them with detailed observations and computer simulations. A hundred years ago we did not know that they are powered by nuclear fusion, and 50 years ago we did not know that stars are continually being formed. We still do not know the details of how they are formed from clouds of gas and dust, or why most stars form in groups, or how planets form with them. We also do not know the details of how they evolve and liberate the “metals” back into space for recycling into new generations of stars and planets. In many cases these old stars have major effects on the formation of new ones.
Observations show that most stars are formed in multiple star systems and that many have planets. However, there is little agreement about how this occurs, and the discovery of large numbers of massive planets in very close orbits around their stars was very surprising. We also know that planets are common around late-type stars (cooler and less massive than the Sun), and that debris disks might signal their presence.
The JWST Birth of Stars and Protoplanetary Systems theme goal is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars, to the genesis of planetary systems. JWST is uniquely primed to solve these mysteries given the combination of its high resolution observing modes, imaging, spectroscopy, and coronographic capabilities, and superb near and mid-IR sensitivity.