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E. Flaccomio (INAF-Osservatorio Astronomico di Palermo), S.D. Vrtilek (Harvard-Smithsonian Center for Astrophysics), G. Micela (INAF-Osservatorio Astronomico di Palermo), F.R. Harnden (Smithsonian Astrophysical Observatory), S. Sciortino (INAF-Osservatorio Astronomico di Palermo), S. Wolk (Smithsonian Astrophysical Observatory), W. Herbst (Wesleyan University), F. Favata (Astrophysics Division-ESA), E.D. Feigelson (Pennsylvania State University)
We present a novel result of the Chandra Orion Ultradeep Project (COUP): the detection of rotational modulation of X-ray emission from the Orion Nebula Cluster young stars. This result is made possible by the exceptional length of the COUP observation: 10 days of ACIS integration over a time span of 13 days. We apply the Lomb Periodogram method to the X-ray light curves and find good agreement with published optically determined periods. We note that rotational modulation is often observed in stars with saturated activity levels, indicating a substantial non homogeneity in the spatial distribution of active regions on the surface of these stars. This suggests that saturation is not due to the filling of the stellar surface with active regions.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.