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We present results from 1351 high resolution spectra of 1215 stars in theOrion Nebula Cluster (ONC) and the surrounding Orion 1c association, obtainedwith the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. Weconfirmed 1111 stars as members, based on their radial velocity and/or H-alphaemission. The radial velocity distribution of members shows a dispersion of 3.1km/s. We found a substantial north-south velocity gradient and spatiallycoherent structure in the radial velocity distribution, similar to that seen inthe molecular gas in the region. We also identified several binary and highvelocity stars, a region exhibiting signs of triggered star formation, and apossible foreground population of stars somewhat older than the ONC. Starswithout infrared excesses (as detected with the IRAC instrument on the SpitzerSpace Telescope) exhibit a wider spread in radial velocity than the infraredexcess stars; this spread is mostly due to a blue-shifted population of starsthat may constitute a foreground population. We also identify some accretingstars, based on H-alpha, that do not have detectable infrared excesses withIRAC, and thus are potential transitional disk systems (objects with inner diskholes). We propose that the substructure seen both in stellar and gaseouscomponent is the result of non-uniform gravitational collapse to a filamentarydistribution of gas. The spatial and kinematic correlation between the stellarand gaseous components suggests the region is very young, probably only ~1crossing time old or less to avoid shock dissipation and gravitationalinteractions which would tend to destroy the correlation between stars and gas.

Kinematic Structure of the Orion Nebula Cluster and its Surroundings