2008ApJS..175..509R

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 NH₃(1,1), NH₃(2,2), C₂ S (2₁⟶1₀), and C³⁴₂S(2₁⟶1₀) transitions near ν=23 GHz for each of the targets with a spectral resolution of δv~0.024 km/s. 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_NH3~10^14.5/cm2, and velocity dispersions ranging from σ_v=0.07 to 0.7 km/s. However, many cores with σ_v>0.2 km/s show evidence for multiple velocity components along the line of sight.