The role of the JWST in understanding how stars are created. How and where do stars form, and what determines how many of them form and their masses?
Birth and formation of stars
Stars are the "witches' cauldrons of the Universe" - they transform the simple light elements into heavier elements and spread them among the stars.
The heavier elements are crucially important for the creation of planets, and in turn, for life itself. The birth of the first stars triggered the continuing chain of cosmic recycling to which we owe our existence. The processes by which stars and planets are made are still poorly understood.
When stars are formed they are usually nestled inside a dusty cocoon. These cocoons prevent much of the visible light from young, proto-stellar objects (stars in the early stages of formation) ever reaching us.
Using the infrared part of the spectrum, the JWST will be able to penetrate the dusty envelopes around newborn stars and take a closer look at the stars themselves.
The JWST will also be sensitive enough to study very small objects that are not massive enough to become stars. These objects - brown dwarfs and Jupiter-sized planets - will become the targets of intensive study with the JWST.
In this way, the JWST will enable observations crucial to our further understanding of star and planet formation.
The JWST will investigate the distribution of stellar masses found in star-forming clusters to try to answer such key questions as: What are the parameters establishing the mass of a forming star? How do we know if the star will be like our Sun, or a blue giant like Rigel, the blue star at the foot of Orion?