New Astronomy, 9, 475-502 (2004/July-0)
On the recent star formation history of the Milky Way disk.
DE LA FUENTE MARCOS R. and DE LA FUENTE MARCOS C.
Abstract (from CDS):
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. Under the assumption that the disk has never been polluted by any extragalactic stellar populations, 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 five episodes of enhanced star formation lasting about 0.2 Gyr with production of larger clusters. This cyclic behaviour shows a period of 0.4±0.1 Gyr and could be the result of density waves and/or interactions with satellite galaxies. On the other hand, the star formation ratehis! tory from a volume-limited sample of open clusters in the solar neighbourhood appears to be consistent with the overall star formation history obtained from the entire sample. Pure continuous star formation both in the solar neighbourhood and the entire Galactic disk is strongly ruled out. Our results also indicate that, in the Milky Way disk, about 90% of open clusters are born with N1
Galaxy: kinematics and dynamics - Open clusters and associations: general - Galaxy: formation - Galaxy: evolution - Galaxy: stellar content - Galaxy: structure - Galaxy: disk