Magellanic Interstellar Physics and Star Formation

Abstract

The mechanisms which input energy to the interstellar medium, principally supernovae and stellar mass loss, are instrumental in setting up and maintaining a multi-phase structure of the interstellar medium. In magellanic irregular galaxies such as the LMC and SMC, the dense component of the interstellar medium is triggered into star formation in a self-propagating fashion, forming so-called supergiant shells which typically reach a diameter of 1 kpc after 107 years, ejecting some 107 M⊙ of hydrogen to high altitudes above the galactic plane. In the LMC, all parts of the disk will be involved in this process in timescales of the order 1–2×108 years. From the present-day heavy-element abundances and abundance ratios we can infer that continuous star formation, rather than a violent early starburst followed by a period of less violent and continuous star formation, characterises the case of the LMC and SMC.