AAS 207th Meeting, 8-12 January 2006
Session 74 Planets in Binary Star Systems, Young Stars and Jets
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[74.07] Accretion Rates for Classical T Tauri Stars in NGC 2264

K.E. Lockhart, C.M. Johns-Krull (Rice University), C.M. Hamilton (Mount Holyoke College)

We present a study of 35 T Tauri stars in NGC 2264 using spectra in the optical range obtained with the Large Cass Spectrometer on the 2.7 m Harlan J. Smith telescope at McDonald Observatory and the RC Spectrograph on the 4 m Mayall telescope at Kitt Peak National Observatory. We also obtained spectra of 18 template stars without accretion disks with the same spectral types as our targets in NGC 2264. We use Rc-Ic colors from the literature to determine the reddening, radius, and luminosity of each of the stars in our sample. We fit a model to each spectrum consisting of a template star spectrum plus a model spectrum of boundary layer consisting of a slab of hydrogen in LTE meant to represent the heated photosphere resulting from shocks at the base of the accretion column. This boundary layer is partially optically thin and is used to fit the Balmer jump and certain Balmer emission lines in the observed spectra. Using these fits, we re-evaluate the Rc-Ic colors for only the star. We use these values to calculate new values for the reddening, radius, and luminosity of each star and compare these values to those obtained ignoring the accretion shock emission. Finally, we calculate accretion rates for the stars in our sample. This research was supported in part by a NASA Origins grant to Rice University.

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