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Distance and the Initial Mass Function of Young Open Clusters In The Eta Carina Nebula: Tr 14 and Tr 16

We present new UBVI_C CCD photometry of the young open clusters Trumpler 14 (Tr 14) and Trumpler 16 (Tr 16) in the eta Carina nebula. We also identify the optical counterpart of Chandra X-ray sources and Two Micron All Sky Survey point sources. The members of the clusters were selected from the proper motion study, spectral types, reddening characteristics, and X-ray or near-IR excess emission. An abnormal reddening law R_V,cl=4.4\pm0.2 was obtained for the stars in the eta Carina nebula using the 141 early-type stars with high proper motion membership probability (P_u\geq70). We determined the distance to each cluster and conclude that Tr 14 and Tr 16 have practically the same distance modulus of V_0-M_V=12.3\pm0.2 mag (d=2.9\pm0.3 kpc). The slope of the initial mass function was determined to be Γ=-1.3\pm0.1 for Tr 14, Γ=-1.3\pm0.1 for Tr 16, and Γ=-1.4\pm0.1 for all members in the observed region for the stars with log m\geq0.2. We also estimated the age of the clusters to be about 1 -- 3 Myr from the evolutionary stage of evolved stars and low-mass pre-main-sequence stars.