Triggered Star Formation in the Sco OB2 Association

Thomas Preibisch, Eike Guenther, & Hans Zinnecker

talk presented at the meeting "Modes of Star Formation and the Origin of Field Populations" eds. E.K. Grebel and W. Brandner, ASP Conference Series, Vol. 285, p. 97-104 (2002)


We explore the star formation history of the Upper Scorpius OB association, the youngest part of large Sco OB2 association. After an initial wide field (160 square-degree) survey for solar-mass pre-main sequence (PMS) stars in Upper Scorpius, we have performed a deeper survey for low-mass (~ 0.1 - 0.7 M_sun) PMS stars, covering a 6 square-degree area. Our current PMS sample contains nearly 200 stars. In a detailed analysis of the locations of these stars in the HR diagram, taking proper account of the uncertainties and the effects of unresolved binaries, we find a mean stellar age of about 5 Myr and no evidence for a significant age dispersion among these stars. This implies that the star formation history of the Upper Scorpius association was dominated by a short star-burst, which started about 5 Myr ago and ended probably not more than one or two Myr later. This result strongly suggests that the shock wave of a supernova explosion in the nearby Upper Centaurus-Lupus association, that crossed Upper Scorpius just about 5 Myr ago, triggered the star-burst in Upper Scorpius.

To get a preprint of this paper click here

For further information see our paper published in the Astronomical Journal, (in press)

and also the previous paper on the survey for young stars in Upper Scorpius.

Some nice images of the Upper Scorpius association can be found here .

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