PROPER MOTIONS OF YOUNG STELLAR OUTFLOWS IN THE MID-INFRARED WITH SPITZER (IRAC). I. THE NGC 1333 REGION

We use two 4.5 μm Spitzer (IRAC) maps of the NGC 1333 region taken over a ∼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 ∼9–13 km s−1, which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of eight outflows, ranging from ∼10 to 100 km s−1. The derived proper motions show that out of these eight outflows, three have tangential velocities ⩽20 km s−1. 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.