The Green Bank Ammonia Survey: Data Release 2

Abstract We present an overview of the final data release (DR2) from the Green Bank Ammonia Survey (GAS). GAS is a large program at the Green Bank Telescope to map all Gould Belt star-forming regions with A V ≳ 7 mag visible from the Northern Hemisphere in emission from NH 3 and other key molecular tracers. This final release includes the data for all the regions observed: Heiles Cloud 2 and B18 in Taurus; Barnard 1, Barnard 1-E, IC 348, NGC 1333, L1448, L1451, and Per7/34 in Perseus; L1688 and L1689 in Ophiuchus; Orion A (North and South) and Orion B in Orion; Cepheus; B59 in Pipe; Corona Australis East and West; IC 5146; and Serpens Aquila and MWC297 in Serpens. Similar to what was presented in GAS DR1, we find that the NH 3 emission and dust continuum emission from Herschel correspond closely. We find that the NH 3 emission is generally extended beyond the typical 0.1 pc length scales of dense cores, and we find that the transition between coherent core and turbulent cloud is a common result. This shows that the regions of coherence are common throughout different star-forming regions, with a substantial fraction of the high column density regions displaying subsonic nonthermal velocity dispersions. We produce maps of the gas kinematics, temperature, and NH 3 column densities through forward modeling of the hyperfine structure of the NH 3 (1,1) and (2,2) lines. We show that the NH 3 velocity dispersion, σ v , and gas kinetic temperature, T K , vary systematically between the regions included in this release, with an increase in both the mean value and spread of σ v and T K with increasing star formation activity. The data presented in this paper are publicly available via doi: 10.11570/24.0091 .