Star Formation in Galactic Disks

Abstract

This review is primarily aimed as a reminder to starburst people that, besides their favourite objects which are presently forming star at the exceptional rate of 100–1000 M_⊙/year, there exists a much broader class of “normal” galaxies at z = 0 which do form stars at rates ranging from 0 (E+S0) to 10 M_⊙/year (BCDs), with the vast majority of normal disk galaxies doing it at 1 M_⊙/year. Much of what is known about the star formation properties of normal galaxies can be found in the beautiful review paper by Rob Kennicutt [14]. The Kennicutt review allows me to skip over an endless number of interesting aspects, as for example how the star formation rate varies along the Hubble sequence, and to focus on few topics that remain relatively unexplored in the literature, namely: the comparative analysis of the old stellar population indicators (NIR imaging) (Section 2) with the ongoing star formation indicators (Hα imaging) (Section 3). I will also briefly discuss an application of the population synthesis method [4] to spectrophotometric data in order to constrain the star formation history (Section 4). Moreover I will focus my analysis on the significant dependence found between the star formation history and the systemic mass and show some examples of star formation history dependences on the environmental conditions (Section 5).