How do stars form from gas? This question lies at the heart of astrophysics, as star formation is the key process governing the evolution of baryons. Star formation converts interstellar matter into stars and their planetary systems, depletes galaxies of gas, and feeds back metals, energy, and momentum into the interstellar medium, which may reach the halos of galaxies and beyond. In turn, this feedback, together with galactic-scale inflows and dynamics, impacts the state of the gas and the future of star formation.

With new observational data and highly improved simulations, it is becoming clear that scaling relations commonly used for, e.g., the star formation process, star formation synthesis models, feedback models etc. are no longer sufficient. Progress needs to take into account how the environment present within galaxies may connect to the small-scale physics of the star formation process. Further observations at cloud-scales, for example, could inform our understanding of the physics acting in galaxies out to cosmic noon and implemented in state-of-the-art simulations.

This workshop aims to bring together experts on the observation and theory of the star formation process to discuss the current state-of-the-field and identify promising ways forward to address pressing questions. The workshop hopes to follow the spirit of the 2013 Ringberg meeting on “Regulation of star formation in molecular gas: from galactic to sub-cloud scales”.

Topics

I. Cold gas properties and structure

• Which physical processes and parameters (e.g. host galaxy, time, environment) control/set the state of the molecular gas? Are GMCs or only their substructures bound? How does temperature/excitation state of gas vary with galactic environment, and what physically sets this (gas heating)?

II. Structure linked to galactic potential and star formation process

• What role does the galactic potential play in regulating star formation? How similar are the molecular reservoir and subsequent star formation from disks to centers to U/LIRGs to high-z galaxies?

III. Star clusters and associations

• What are star clusters and associations, and what fraction of star formation occurs in that population? Given that star clusters are the tip of the iceberg of the star formation hierarchy, why are they useful to study for gaining insight into the overall star formation process? What are the observational and theoretical constraints on how and when young star clusters feed back energy and momentum into the ISM? How can studies of star clusters and GMCs be optimally combined to provide insight into star formation timescales?

IV. Physical drivers of depletion, time-average scaling relations

• What physical parameters control/set the depletion time (or star formation efficiency)? Is there a dependence on scale probed? How does time evolution affect our understanding?

V. Feedback: physics, sources stirring turbulence, stochastic star formation process, violent cycling

• What is the physical origin of turbulence in cold gas? How can different drivers for turbulence (e.g. winds, supernovae, spiral arms) be discriminated? What is the connection of turbulence to star formation? What role does feedback play in the regular of star formation in galaxies? How well do we understand the violent cycling of the ISM, including GMC destruction?