Name/Affiliation: John Stauffer (Caltech)
Possible Detection of Dust in the Accretion Columns of YSOs in NGC2264
We have identified a half dozen YSOs in the NGC 2264 star-forming region whose optical (CoRoT) light curves are dominated by short- duration, shallow, often nearly gaussian-shaped, periodic flux dips. The flux dips have FWHM generally less than one day, depths almost always less than 15%, and periods consistent with the keplerian rotation period of the inner disk wall (P < 7 days). The flux dips vary considerably in their depth from epoch to epoch, but are usually persistent for several weeks and in two cases were present in data collected on successive years. Presumably these flux dips are due to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In general, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns but with lower amplitudes. We characterize the properties of these dips, and compare the stars whose light curves exhibit this behavior to other classes of YSOs in NGC 2264. One possible physical explanation for the flux dips is that they are due to dust entrained in the accretion columns connecting the inner disk to the stellar photosphere.