Why studying star formation?
One of the major challenges in modern astrophysics is understanding the processes that regulate star formation and determine the properties of the resulting stars, how these processes vary with environment and epoch, and what observational signatures of the process are detectable with modern telescopes. Star formation is not only fascinating for its own sake, but also because it is a key ingredient of many other areas of astronomical research, regulating – for example – the environments in which planets form, the formation, structure and evolution of galaxies, and the build-up of the heavy elements
The big picture: Molecular Clouds
On the largest scales diffuse atomic gas undergoes compressive motions, for example as it flows into a spiral arm (as observed in external galaxies) and forms massive clouds. As the density increases, the cooling processes become more efficient. The gas thermal pressure decreases, the gas becomes even denser and starts to shields itself against Ultra Violet (UV) radiation. This then favours the transition from atomic to molecular hydrogen, which is the most abundant molecule formed in molecular clouds
As a result of the interplay between turbulence, magnetic fields and gravity, a highly complex structure with a mixture of physical conditions is produced. Molecular clouds themselves consist of an interwoven mixture of cold and dense gas (known as cold neutral medium or CNM for short), and warm and diffuse gas (the warm neutral medium or WNM), which co-exist in approximate pressure equilibrium.
Zooming into low mass star formation: Young Stellar Objects
The clumpy and filamentary CNM structures, by virtue of being colder and more compact, are prone to fragment into even more compact dense cores, where, if self-gravity is able to overcome the thermal and magnetic pressure forces, new stellar systems will be formed.
But the process is not that simple. If the angular momentum is conserved during the collapse, the rotation of the proto-star would disrupt it and prevent the formation of a star. This is known as the “Angular momentum problem”. In order to form a star, as the gravitational collapse proceeds, the gas must evacuate more than 99.999% of its initial angular momentum during the short main accretion phase. Magnetic fields might hold the key to solve the angular momentum problem.
High-sensitivity, high-resolution polarization observations along with new techniques are providing a unique insight into the morphology of magnetic fields in star forming regions. Understanding how magnetic fields regulates the star formation process is the main goal of the MagneticYSOs project (PI: Anaelle Maury).
