2017/03/14 by Zainab Awad, Osama M. Shalabeia
Physics and Astronomy · #Astrochemistry #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #COSMIC cancer database #Core (optical fiber) #Cosmic ray #Cosmochemistry #Cosmology #Ionization #Millimeter #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.1007/s10509-017-3061-8
published as Astrophys Space Sci (2017) 362:83 · 24 pages, 4 figures, 3 Tables. Accepted for publication in Astrophysics and Space Science
arxiv created 2017/03/14 · openalex publication_date 2017/03/17 · arxiv updated 2017/03/21 · openalex created_date 2017/03/23 · openalex updated_date 2026/08/05
We present the first gas-grain astrochemical model of the NGC 2264 CMM3 protostellar core. The chemical evolution of the core is affected by changing its physical parameters such as the total density and the amount of gas-depletion onto grain surfaces as well as the cosmic ray ionisation rate, ζ. We estimated ζ_\text CMM3 = 1.6 × 10-17 s-1. This value is 1.3 times higher than the standard CR ionisation rate, ζ_\text ISM = 1.3 × 10-17 s-1. Species response differently to changes into the core physical conditions, but they are more sensitive to changes in the depletion percentage and CR ionisation rate than to variations in the core density. Gas-phase models highlighted the importance of surface reactions as factories of large molecules and showed that for sulphur bearing species depletion is important to reproduce observations. Comparing the results of the reference model with the most recent millimeter observations of the NGC 2264 CMM3 core showed that our model is capable of reproducing the observed abundances of most of the species during early stages (≤ 3×104 yrs) of their chemical evolution. Models with variations in the core density between 1 - 20 × 106 cm-3 are also in good agreement with observations during the early time interval 1 × 104 < t (yr) < 5 × 104. In addition, models with higher CR ionisation rates (5 - 10) × ζ_\text ISM are often overestimating the fractional abundances of the species. However, models with ζ_\text CMM3 = 5 ζ_\text ISM may best fit observations at times ∼ 2 × 104 yrs. Our results suggest that CMM3 is (1 - 5) × 104 yrs old. Therefore, the core is chemically young and it may host a Class 0 object as suggested by previous studies.