Orion Nebula Cluster PMs with HST Treasury Program

Our catalog contains 2454 objects in the magnitude range of 14.2<m_F775W_<24.7, thus probing the stellar masses of the ONC from ~0.4M{sun} down to ~0.02M{sun} over an area of ~550arcmin^2^. We provide a number of internal velocity dispersion estimates for the ONC that indicate a weak dependence on stellar location and mass.

There is good agreement with the published velocity dispersion estimates, although nearly all of them (including ours at {sigma }_{v,x}_=0.94 and {sigma}_{v,y}_=1.25mas/yr) might be biased by the overlapping young stellar populations of Orion A. We identified four new ONC candidate runaways based on HST and the Gaia DR 2 data, all with masses less than ~1M{sun}. The total census of known candidate runaway sources is 10-one of the largest samples ever found in any Milky Way open star cluster.