On the recent star formation history of the Milky Way disk

Abstract

We have derived the star formation history of the Milky Way disk over the last 2 Gyr from the age distribution diagram of a large sample of open clusters comprising more than 580 objects. By interpreting the age distribution diagram using numerical results from an extensive library of N-body calculations carried out during the last ten years, we reconstruct the recent star formation history of the Milky Way disk. Our analysis suggests that superimposed on a relatively small level of constant star formation activity mainly in small-N star clusters, the star formation rate has experienced at least 5 episodes of enhanced star formation lasting about 0.2 Gyr with production of larger clusters. This cyclic behavior seems to show a period of 0.4+/-0.1 Gyr.Comment: Abridged abstract. Accepted by New Astronomy. Major changes. A number of figures have been added in order to improve the discussion on error