Cool Stars 14 - Submitted Abstract # 232
This version created on 05 October 2006

A Study of Angular Momentum of Pre-Main Sequence Stars in IC 348


Nairn Baliber, University of Texas at Austin
Lucas Cieza, University of Texas at Austin

We present results from an angular momentum study of the stars in the
young cluster IC 348.  We measured 105 stellar rotation periods, 75 of
which are new detections, increasing the total number of known periods
in this cluster to 143.  Stars estimated to be less massive than 0.25
solar masses show a unimodal distribution of fast rotators, peaking at
1 - 2 days, with a tail of slower rotators, while stars estimated to
be more massive than 0.25 solar masses show a bimodal distribution
with peaks at ~2 and ~8 days, resembling the distribution seen in the
heart of the Orion Nebula Cluster by Herbst and colleagues.  We
combine all published rotation periods in IC 348 with Spitzer IRAC
mid-IR photometry, an unprecedentedly efficient and reliable disk
indicator, in order to test the disk-braking paradigm.  We find no
evidence that the tail of slow rotators in low-mass stars or the long
period peak in high-mass stars are preferentially populated by objects
with disks as might be expected based on the current disk-braking
model.  We find some indication that the disk fraction decreases
significantly for stars with very short periods (P < 1.5 days), which
is the only feature of our sample that could potentially be
interpreted as evidence for disk braking.  We present preliminary
results from Monte Carlo simulations we are running to perform a
rigorous quantitative analysis of observational data from three young
clusters in order to determine if the disk-braking model is
inconsistent with these data.

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