SIMBAD references

We present the results of a very deep ROSAT HRI X-ray observation of the highly active star forming region NGC 1333. In total we could detect 20 X-ray sources, 16 of which we assume to be members to the cluster of pre main sequence stars. Since most of the stars in NGC 1333 are still deeply embedded in the molecular cloud (A_V≲5-30mag), we use near infrared data to estimate individual extinctions for the calculation of X-ray luminosities. One of the X-ray sources is identified with the optically invisible, very deeply embedded (A_V≃28mag) infrared class I source SVS16, for which we find an extremely high X-ray luminosity of 2.8x10³²erg/sec, making this object one of the most X-ray luminous pre main sequence stars known to date. Since we have already performed similar sensitive ROSAT observations of the young cluster IC 348 (the second active star forming region in the Perseus molecular cloud complex), we compare the X-ray properties of the young stars in NGC 1333 to those in IC 348. We find no evidence for a significant change of the X-ray luminosity function during the first few million years in the life of the pre main sequence stars.