Proper Motions of Thermal Radio Sources near HH 7-11 in the NGC 1333 Star Forming Region

TL;DR

This study measures the proper motions of thermal radio sources in NGC 1333, providing crucial data to interpret mass ejection motions and identify outflow sources in this star-forming region.

Contribution

First direct measurement of proper motions of four thermal sources in NGC 1333 using 10 years of VLA data, aiding in understanding the region's dynamics.

Findings

Mean proper motions of NGC 1333: 9 ± 1 mas/yr in RA, -10 ± 2 mas/yr in Dec.

Proper motions help distinguish between regional movement and mass ejection features.

Results assist in identifying the exciting sources of HH 7-11 outflows.

Abstract

Star forming regions are expected to show linear proper motions due to the relative motion of the Sun with respect to the region. These proper motions appear superposed to the proper motions expected in features associated with mass ejection from the young stellar objects embedded in them. Therefore, it is necessary to have a good knowledge of the proper motions of the region as a whole in order to correctly interpret the motions associated with mass ejection. In this paper we present the first direct measurement of proper motions of the NGC 1333 star forming region. This region harbors one of the most studied Herbig-Haro systems, HH 7-11, whose exciting source remains unclear. Using VLA A configuration data at 3.6 cm taken over 10 years, we have been able to measure the absolute proper motions of four thermal sources embedded in NGC 1333. From our results we have derived the mean proper motions of the NGC 1333 star forming region to be mu(alpha)cos(delta) = 9 +- 1 mas/yr and mu(delta) = -10 +- 2 mas/yr. In this paper, we also discuss the possible implications of our results in the identification of the outflow exciting sources.