Species cycling and the enhancement of ammonia in prestellar cores
| Autor: | Azrael A von Procházka, Tom J. Millar |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Astrochemistry
010504 meteorology & atmospheric sciences Population FOS: Physical sciences 01 natural sciences Reaction rate chemistry.chemical_compound Desorption 0103 physical sciences Atom education 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences Physics education.field_of_study Cyanopolyyne Astronomy and Astrophysics Observable Astrophysics - Astrophysics of Galaxies Astrophysics - Solar and Stellar Astrophysics chemistry Space and Planetary Science Chemical physics Astrophysics of Galaxies (astro-ph.GA) Cycling |
| Zdroj: | von Prochazka, A A & Millar, T J 2021, ' Species cycling and the enhancement of ammonia in prestellar cores ', Monthly Notices of the Royal Astronomical Society, vol. 501, pp. 1228-1242 . https://doi.org/10.1093/mnras/staa3650 |
| DOI: | 10.48550/arxiv.2011.07418 |
| Popis: | The quantity of NH3 produced on grain surfaces in the prestellar core is thought to be one of the determining factors regarding the chemical complexity achievable at later stages of stellar birth. In order to investigate how this quantity might be influenced by the gas-grain cycling of molecular material within the cloud, we employ a modified rates gas-grain chemical code and follow the time-dependent chemistry of NH3 as the system evolves. Our models incorporate an updated version of the most recent UDfA network of reaction rate coefficients, desorption from the grains through standard thermal and non-thermal processes, and physisorbed and chemisorbed binding of atomic and molecular hydrogen to a population of carbonaceous and siliceous grains. We find that 1.) observable abundances of NH3 can exist in the gas phase of our models at early times when the N atom is derived from CN via an efficient early-time hydrocarbon chemistry, 2.) a time-dependent gradient exists in the observational agreement between different species classes in our models, consistent with possible physical substructures within the TMC-1 Cyanopolyyne Peak, and 3.) the gaseous and solid-state abundances of NH3 are sensitive to the presence of gas-grain cycling within the system. Our results suggest that the degree of chemical complexity achievable at later stages of the cloud's chemical evolution is indeed influenced by the manner in which the gas-grain cycling occurs. Comment: 15 pages, 7 figures, to be published in Monthly Notices of the Royal Astronomical Society |
| Databáze: | OpenAIRE |
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