Connecting the Scales: Large Area High-resolution Ammonia Mapping of NGC 1333
Abstract
We use NH3 inversion transitions to trace the dense gas in the NGC 1333 region of the Perseus molecular cloud. NH3 (1, 1) and NH3 (2, 2) maps covering an area of 102 square arcminutes at an angular resolution of ∼3.″7 are produced by combining Very Large Array interferometric observations with Green Bank Telescope single-dish maps. The combined maps have a spectral resolution of 0.14 km s-1 and a sensitivity of 4 mJy/beam. We produce integrated intensity maps, peak intensity maps, and dispersion maps of NH3 (1, 1) and NH3 (2, 2) and a line-of-sight velocity map of NH3 (1, 1). These are used to derive the optical depth for the NH3 (1, 1) main component, the excitation temperature of NH3 (1, 1), and the rotational temperature, kinetic temperature, and column density of NH3 over the mapped area. We compare these observations with the CARMA J = 1-0 observations of N2H+ and H13CO+ and conclude that they all trace the same material in these dense star-forming regions. From the NH3 (1, 1) velocity map, we find that a velocity gradient ridge extends in an arc across the entire southern part of NGC 1333. We propose that a large-scale turbulent cell is colliding with the cloud, which could result in the formation of a layer of compressed gas. This region along the velocity gradient ridge is dotted with Class 0/I young stellar objects, which could have formed from local overdensities in the compressed gas leading to gravitational instabilities. The NH3 (1, 1) velocity dispersion map also has relatively high values along this region, thereby substantiating the shock layer argument.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2019
- DOI:
- 10.3847/1538-4357/ab15d3
- arXiv:
- arXiv:1904.03359
- Bibcode:
- 2019ApJ...876..108D
- Keywords:
-
- ISM: clouds;
- ISM: kinematics and dynamics;
- ISM: molecules;
- ISM: structure;
- stars: formation;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- doi:10.3847/1538-4357/ab15d3