DISTANCE AND THE INITIAL MASS FUNCTION OF YOUNG OPEN CLUSTERS IN THE η CARINA NEBULA: Tr 14 AND Tr 16

We present new UBVIc CCD photometry of the young open clusters Trumpler 14 (Tr 14) and Trumpler 16 (Tr 16) in the η 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 RV,cl = 4.4 ± 0.2 was obtained for the stars in the η Carina Nebula using the 141 early-type stars with high proper-motion membership probability (Pμ gE 70%). We determined the distance to each cluster and conclude that Tr 14 and Tr 16 have practically the same distance modulus of V0 – MV = 12.3 ± 0.2 mag (d = 2.9 ± 0.3 kpc). The slope of the initial mass function was determined to be Γ = –1.3 ± 0.1 for Tr 14, Γ = –1.3 ± 0.1 for Tr 16, and Γ = –1.4 ± 0.1 for all members in the observed region for the stars with log mgE0.2. 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.