An Ammonia Spectral Atlas of Dense Cores in Perseus

Abstract

We present ammonia observations of 193 dense cores and core candidates in the Perseus molecular cloud made using the Robert F. Byrd Green Bank Telescope. We simultaneously observed the NH 3 (1,1), NH 3 (2,2), C 2 S (2 1 → 1 0 ), and C 34 2 S(2 1 → 1 0 ) transitions near ν = 23 GHz for each of the targets with a spectral resolution of δ v ≈ 0.024 km s −1 . We find ammonia emission associated with nearly all of the (sub)millimeter sources, as well as at several positions with no associated continuum emission. For each detection, we have measured physical properties by fitting a simple model to every spectral line simultaneously. Where appropriate, we have refined the model by accounting for low optical depths, multiple components along the line of sight, and imperfect coupling to the GBT beam. For the cores in Perseus, we find a typical kinetic temperature of T k = 11 K, a typical column density of N NH 3 ≈ 10 14.5 cm −2 , and velocity dispersions ranging from σ v = 0.07 to 0.7 km s −1 . However, many cores with σ v > 0.2 km s −1 show evidence for multiple velocity components along the line of sight.