Introduction and Motivation

• Review/overview of star formation histories (not structural, kinematics, etc.). Complementary (contradictory?) talks by Smecker-Hane, Venn, Ferguson, Harris, Grebel, Olszewski, Mayer
  • Components of star formation histories:
    • Star formation rate as function of lookback time

    • Initial mass function

    • Chemical evolution

• Star formation histories of Local Group galaxies as a cosmological training sample and cosmological probe?
  • Parameterization of star formation in models. Role of various factors in triggering/regulation of star formation:
    • Internal processes, e.g. gas density, gravitational instability, supernovae

    • Internal-dynamics triggered, e.g. bars and spiral structure

    • External-dynamics triggered, e.g. interactions and mergers

    • External-radiation triggered, e.g. ionizing background

  • Local Group as a key to helping to understand galaxies at higher redshift:
    • Initial mass function: affects rate of luminosity evolution, chemical evolution . High mass end important for chemical evolution, star formation histories. Low mass end important for mass-to-light, star formation histories.

    • History of star formation rate: dominates rate of luminosity evolution, galaxy counts. Constrains star formation mechanism. Key point for both issues is burstiness.

• Recent observational progress has been largely incremental; possibly some overgeneralizations, e.g:
  • The IMF is universal with some scatter and with a few possible exceptions

  • Star formation is bursty in a minority of galaxies studied

  • Metallicities are correlated with absolute magnitude except there is a range of metallicities in all systems studied

• Time may be ripe for fruitful interchange between observations and models
  • Modellers need constraints for free parameters

  • Observers need justification for more telescope time

  • What are the best points for comparison?