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X-ray observations of the young open cluster Blanco 1
G. Micela 1,
S. Sciortino 1,
F. Favata 2,
R. Pallavicini 1 and
J. Pye 3
Received 18 August 1998 / Accepted 1 December 1998
We present results from two deep ROSAT HRI exposures on the Blanco 1 open cluster. Blanco 1 is one of the few open clusters at large distance from the Galactic Plane. This circumstance has suggested that it may have formed through a mechanism different from that responsible for the other nearby clusters. The age of Blanco 1 is rather uncertain since, depending on the adopted age indicator, it ranges between 30 and 90 Myr. Many cluster members show chromospheric emission typical of young stars. The X-ray observations presented here reveal a high number of X-ray sources, consistent with the young age of the cluster. The typical X-ray luminosity of the cluster members is consistent with that of the Pleiades and significantly lower than the Per members. These results suggest than the age of Blanco 1 is more similar to the age of the Pleiades than to that of Per.
The time sampling of the X-ray observations allows us to study the variability of the sources on time scales from hours to 6 months - 1 year.
Key words: X-rays: stars stars: coronae Galaxy: open clusters and associations: individual: Blanco 1
Send offprint requests to: G. Micela
Online publication: March 10, 1999