AN X-RAY STUDY OF THE YOUNG OPEN CLUSTER IC-2602

We present the results of ROSAT PSPC observations of the 30 Myr old IC 2602 cluster; for the X-ray detected objects the results of a CCD pho tometric survey are also given. In X-rays, we detect a total of 110 ob jects within a 11 deg(2) area, above a threshold of typically 3-5 x 10 (28) erg/sec. 68 of the detected objects have been identified with at least one optical counterpart; 44 of these are new optical candidates for cluster membership provided by our CCD photometry. Stars of all sp ectral types have been detected, from the very early-types to the late -M dwarfs. Soft X-ray luminosities range between about 10(29) erg/sec to a few 10(30) erg/sec, with the maximum and average L(x) decreasing with spectral type for B-V larger than similar to 0.8. Many of the sta rs redder than B-V similar to 0.8 show a L(X)/L(bol) ratio at about th e saturation level of 10(-3). We construct X-ray luminosity distributi on functions for objects in different color ranges and we compare them with those for the Pleiades. F, G, and early-K type candidates in IC 2602 appear to be more X-ray luminous than in the Pleiades, while no s ignificant difference is seen among late-K and M dwarfs. Under the ass umption that our IC 2602 sample is not severely affected by incomplete ness, we argue that the above finding is related to the distribution o f rotational velocities in the two clusters, with most of the late-typ e stars being fast rotators in both clusters, while, due to different spin-down timescales, the earlier type stars in IC 2602 are likely to rotate more rapidly than their counterparts in the Pleiades.