A Variability Study of Pre–Main-Sequence Stars in the Extremely Young Cluster IC 348

The extremely young cluster IC 348 has been monitored in the Cousins I bandwith a 0.6 m telescope at Wesleyan's Van Vleck Observatory. Photometry of 150stars was obtained on 76 images taken on 27 separate nights during the periodDecember, 1998, through March, 1999. As expected, spectral characteristicslargely determine the nature of a star's variability in this cluster. None ofthe stars with H-alpha in absorption were found to be variables. On the otherhand, all 16 stars identified as CTTS by their H-alpha emission equivalentwidths and the majority of the 49 WTTS in the part of the cluster we monitoredshowed evidence of variability. Nineteen stars were found to be periodic, withperiods ranging from 2.24 to 16.2 days and masses ranging from 0.35 to 1.1M-sun. Seventeen of these are WTTS and the other 2 are of unknown spectralclass. The period distribution is remarkably similar to what is found in theOrion Nebula Cluster for stars in the same mass range. Namely, it is bimodalwith peaks at 2-3 days and 7-8 days, although there are not enough periodsknown to define these features significantly by the IC 348 data alone. Thethree fastest rotators are also the three most massive stars in the periodicsample.Comment: Scheduled for the Astronomical Journal, July 200