An Ammonia Spectral Atlas of Dense Cores in Perseus

TL;DR

This study provides a detailed ammonia spectral atlas of dense cores in the Perseus molecular cloud, revealing their physical properties and velocity structures through extensive radio observations.

Contribution

It presents the first comprehensive ammonia spectral atlas of dense cores in Perseus, including refined modeling of spectral lines and physical property measurements.

Findings

Most cores show ammonia emission with typical temperature of 11 K.

Velocity dispersions range from 0.07 to 0.7 km/s, with multiple components in some cores.

Many cores with higher velocity dispersions exhibit multiple velocity components.

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 NH3(1,1), NH3(2,2), CCS (2_1 -> 1_0) and CC34S (2_1 -> 1_0) transitions near 23 GHz for each of the targets with a spectral resolution of dv ~ 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=11 K, a typical column density of N(NH3)~ 10^14.5 /cm^2 and velocity dispersions ranging from sigma_v = 0.07 km/s to 0.7 km/s. However, many cores with velocity dispersions > 0.2 km/s show evidence for multiple velocity components along the line of sight.