Proper Motions of Young Stellar Outflows in the Mid-Infrared with Spitzer (IRAC). I. The NGC 1333 region

We use two 4.5micron Spitzer (IRAC) maps of the NGC 1333 region taken over approx. 7 yr interval to determine proper motions of its associated outflows. This is a first, successful attempt at obtaining proper motions of stellars outflow from Spitzer observations. For the outflow formed by the Herbig-Haro objects HH7, 8 and 10, we find proper motions of approx. 9-13 km/s, which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of 8 outflows, ranging from approx. 10 to 100 km/s. The derived proper motions show that out of these 8 outflows, 3 have tangential velocities less or equal to 20 km/s. This result shows that a large fraction of the observed outflows have low intrinsic velocities, and that the low proper motions are not merely a projection effect.