CN in prestellar cores

Abstract

Determining the structure of and the velocity field in prestellar cores is essential to understanding protostellar evolution.} {We have observed the dense prestellar cores L 1544 and L 183 in the $N=1\to 0$ rotational transition of CN and \thcn in order to test whether CN is depleted in the high--density nuclei of these cores.} {We have used the IRAM 30 m telescope to observe along the major and minor axes of these cores. We compare these observations with the 1 mm dust emission, which serves as a proxy for the hydrogen column density.}{We find that while CN\jone is optically thick, the distribution of \thcn\jone intensity follows the dust emission well, implying that the CN abundance does not vary greatly with density. We derive an abundance ratio of $\rm [CN]/[\hh]=\dix{-9}$ in L 183 and 1-3\tdix{-9} in L 1544, which, in the case of L 183, is similar to previous estimates obtained by sampling lower--density regions of the core.}{We conclude that CN is not depleted towards the high--density peaks of these cores and thus behaves like the N-containing molecules \nnhp and \nhhh. CN is, to our knowledge, the first C--containing molecule to exhibit this characteristic.

Accepted for publication in A&A Letters

References in corpus (12)

• Systematic Molecular Differentiation in Starless Cores
• N2H+ and C18O Depletion in a Cold Dark Cloud
• Observing the gas temperature drop in the high-density nucleus of L 1544
• SCUBA Polarization Measurements of the Magnetic Field Strengths in the L183, L1544, and L43 Prestellar Cores
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• Depletion and low gas temperature in the L183 prestellar core : the N2H+ - N2D+ tool
• A High Resolution Study of the Slowly Contracting, Starless Core L1544
• Disappearance of N2H+ from the Gas Phase in the Class 0 Protostar IRAM 04191
• Freeze-out and coagulation in pre-protostellar collapse
• Line profiles of molecular ions toward the pre-stellar core LDN 1544
• The depletion of NO in pre-protostellar cores
• Disappearance of N2H+ from the Gas Phase in the Class 0 Protostar IRAM 04191

Cited by in corpus (23)

• Chemistry of Dark Clouds: Databases, Networks, and Models
• Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes
• Chemical modeling of L183 (= L134N) : an estimate of the ortho/para H2 ratio
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• Interstellar chemistry of nitrogen hydrides in dark clouds
• Nitrogen chemistry and depletion in starless cores
• The 15N-enrichment in dark clouds and Solar System objects
• Nitrogen hydrides and the H2 ortho-to-para ratio in dark clouds
• Discovery of interstellar isocyanogen (CNCN): further evidence that dicyanopolyynes are abundant in space
• Chemistry in Disks. V: CN and HCN in proto-planetary disks
• CCH in prestellar cores
• The CN/C15 N isotopic ratio towards dark clouds
• Hydrogen cyanide and isocyanide in prestellar cores
• Isocyanogen formation in the cold interstellar medium
• Hyperfine excitation of N${}_2$H${}^{+}$ by H${}_2$: Toward a revision of N${}_2$H${}^{+}$ abundance in cold molecular clouds
• ALMA view of the ${}^{12}$C/${}^{13}$C isotopic ratio in starburst galaxies
• Abundance of HCN and its C and N isotopologues in L1498
• CN Zeeman and dust polarization in a high-mass cold clump
• An Interferometric View of H-MM1. I. Direct Observation of NH3 Depletion
• Chemical tracers in proto-brown dwarfs: CN, HCN, and HNC observations
• Structure and Composition of Molecular Clouds with CN Zeeman Detections I: W3OH
• The spatial correlation between CN line and dust continuum emitting regions in high-mass star-forming cloud
• Hyperfine transitions of 13CN from pre-protostellar sources