Star formation is relevant to nearly every area in astrophysics, from planetary science to galaxy evolution. Yet the physical processes that determine the rate of star formation and its spatial and temporal distribution are still poorly understood. IAU Symposium 373 will focus on the impact that resolved studies of galaxies, both observational and theoretical, are having on the understanding of star formation on all scales. With improvements in spatial resolution, new multi-wavelength capabilities (including ALMA and soon JWST), and our ability to probe strongly lensed systems at high redshift, the characterization of star-forming regions is no longer limited to the nearest galaxies. Furthermore, advances in imaging spectroscopy (particularly integral field units, IFUs) are providing key diagnostics across galaxy bulges and disks, overcoming the aperture limitations of previous spectroscopic surveys. At the same time, our ability to model the coupled evolution of gas, stars, and dark matter has grown dramatically. Improvements in data and theory are also propelling improvements in inference that can exploit the synergies of multiple lines of evidence, for instance past and present star formation rates. The goal of the meeting will be to update the community on the latest advances in understanding star formation in its galactic context (via resolved studies) and how it drives galaxy evolution.
Tentative Session Titles:
- Session 1: Scales of Star Formation: From Molecular Cores to Galaxies
- Session 2: Sustaining Star Formation: Gas Conditions & Environment
- Session 4: The Decline of Star Formation: Feedback, Fuel Shortage or Inefficiency?
- Session 5: The Rise and Fall of Star Formation Across Cosmic Time
- Session 6: Regulation of Star Formation and the Evolution of Galaxies
A full understanding of star formation requires considering vastly different scales, from individual star-forming regions to galaxy-wide environments, all of which may exhibit different characteristics at different redshifts. In this initial session we aim to determine to what extent we understand the basics of star formation and can extrapolate what we know over different spatial (and temporal) scales.
The efficiency of the star formation process is observed to vary as a function of galactic environment and to be influenced by conditions in the interstellar medium. Since star formation itself is closely linked to the availability of cold, dense molecular gas, we will explore in this session the conditions that enable star formation: the supply of gas, the ability of the gas to collapse, and the ability to recover from disruptions to these prerequisites.
Today, and even at early epochs, there exists a population of galaxies in which star formation is either in decline, or has almost entirely ceased. The decline of star formation is also witnessed on kpc-scales, whereby a given galaxy may be actively forming new stars in some locations, but failing to do so in other regions. Untangling the role of the various internal processes, as well as the role of external environmental factors, remains a major challenge for interpreting these results.
The processes which ignite and extinguish star formation on local scales will, over time, transform entire galaxies. We witness this transformation as we observe galaxies across cosmic time, and under favorable conditions we are starting to resolve the physical processes at work. As we begin to tackle the biases imposed by limited sensitivity and resolution while tracing more accurately the evolution of gas reservoirs, we gain new perspectives on the connection between “local” and “global” star formation.
How do we reconcile star formation as a “sub-grid” process that occurs locally within galaxies with it also being a driver of change in galaxies and across the galaxy population? A new conceptual framework has emerged that treats galaxies as open systems and star formation as a kind of “metabolic” activity that is regulated by both internal and external processes. Advances in large-scale surveys and numerical simulations will enable us to test and flesh out these ideas.