An Ammonia Spectral Atlas of Dense Cores in Perseus

By Erik Rosolowsky, J. Pineda, J. Foster, Michelle A. Borkin, Jens Kauffmann, P. Caselli, P. Myers, A. Computing, Harvard University Department of Physics, Astronomy and 1 more. 2007

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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), C2S (21→ 10), and C342S(21→ 10) 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 Tk = 11 K, a typical column density of NNH3 ≈ 1014.5 cm −2, and velocity dispersions ranging from σv = 0.07 to 0.7 km s−1. However, many cores with σv > 0.2 km s−1 show evidence for multiple velocity components along the line of sight.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers (2015, background): “…1992, Mangum & Wootten 1993, Plume et al. 1997, Jijina et al. 1999, Savage et al. 2002, Pirogov et al. 2003, Purcell et al. 2006, Blair et al. 2008, Rosolowsky et al. 2008, Falgarone et al. 2008, Hily-Blant et al. 2010, Barnes et al. 2011, Dunham et al. 2011, Ginsburg et al. 2011, Reiter et al.…”
LOW VIRIAL PARAMETERS IN MOLECULAR CLOUDS: IMPLICATIONS FOR HIGH-MASS STAR FORMATION AND MAGNETIC FIELDS (2013, methodology): “In Perseus, we have combined masses from Bolocam dust continuum data (Enoch et al. 2006) with gas temperatures and velocity dispersions gleaned from GBT NH3 (1,1) data (Rosolowsky et al. 2008).”
FILAMENTARY ACCRETION FLOWS IN THE EMBEDDED SERPENS SOUTH PROTOCLUSTER (2013, methodology): “…HCN, and H13CN), we substitute the Gaussian model with a single uniform slab model with the appropriate hyperfine emission information (adapted from Rosolowsky et al 2008), and again use MPFIT to find the best fitting line parameters – in this case, the velocity centroid, velocity dispersion (in…”
Physical Processes in the Interstellar Medium (2014, background): “This indicates that the gas motions inside the cores are subsonic or at best transsonic, with Mach numbers less than ∼2 (Kirk et al., 2007; André et al., 2007; Rosolowsky et al., 2008).”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, methodology): “Both dense cores (André et al. 2007; Kirk et al. 2007; Rosolowsky et al. 2008a) and stars (Fűrész et al. 2008; Tobin et al. 2009) show systematically smaller velocity dispersions than the diffuse gas in the same region.”
The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus (2008, methodology): “— Kinetic temperatures (TK) and linewidths (σH2) are derived from the NH3 observations of Perseus cores completed by Rosolowsky et al. (2008).”
The RMS Survey: Ammonia and water maser analysis of massive star forming regions. ⋆ (2011, result): “…0.6 respectively, with a mean value of∼0.3; this compare well to the values reported by Pillai et al. (2006) (ηff ∼0.3–0.5) from ammonia mapping observations of a small sample of infrared dark clouds (IRDCs) and Rosolowsky et al. (2008) (ηff ∼0.3) from GBT observations of dense cores in Perseus.”
DIRECT OBSERVATION OF A SHARP TRANSITION TO COHERENCE IN DENSE CORES (2010, methodology): “Foster et al. (2009) shows that 81 out of the 83 cores in Perseus observed by Rosolowsky et al. (2008) display subsonic non-thermal motions at their center, while in Klessen et al. (2005) only a 12–52% of the identified objects (which depends on the nature of the driv- ing mechanism) display…”
Hierarchical fragmentation and differential star formation in the Galactic ‘Snake’: infrared dark cloud G11.11−0.12 (2014, methodology): “For details of the method see Rosolowsky et al. (2008).”
How to Calculate Molecular Column Density (2015, methodology): “At Tex = 10K, a common value found in NH3 studies (see Rosolowsky et al. 2008), the thin+RJ+noBG approximation results in a systematic 30% underestimate of the column density.”