Abstract: 

The formation of stars and star clusters is one of the most important events that shape the physical, chemical, and dynamical properties of their host galaxy, influencing the formation of subsequent generations of stars and planetary systems. Due to the high extinction of optical light by dust grains mixed with the gas, the birth of stars must be studied at infrared and longer wavelengths that can penetrate clouds. In the last few years, the field of star formation has experienced significant advances thanks to the major improvement of instrumentation. The increase in angular resolution and sensitivity of single-dish telescopes, radio interferometers, and space satellites make it now possible to study with unprecedented detail the obscured regions in the Milky Way. The early stages of star and planet formation involve a balance between accretion and ejection of material during the gravitational collapse. There is hence an underlying accretion-ejection connection that governs and keeps track of the protostellar evolution, crucial in determining the final properties of stars and their planetary systems. In this contact, both mass accretion rate and mass-loss rate are fundamental, albeit still uncertain, quantities in star formation.

In this context, I will present the VLA Large Project VOLS (The VLA Orion A Large Survey), which has been granted with 306 hours of observing time with the Karl G. Jansky Very Large Array to observe the molecular cloud Orion A and investigate how the mass accretion and mass loss rated proceed with protostellar evolution and how they depend on the birth environment and on the mass of the star. Orion A is the nearest star-forming complex containing a broad range of environments populated by protostars and Young Stellar Objects with different masses and evolutionary stages, representing a testbed for star formation theories