Energetic Processing of N-2:CH4 Ices Employing X-Rays and Swift Ions: Implications for Icy Bodies in the Outer Solar System

Autor(es)

Vasconcelos, Fredson de A. ^{[1, 2]} ; Pilling, Sergio ^{[2, 3]} ; Rocha, Will R. M. ^[2] ; Rothard, Hermann ^[4] ; Boduch, Philippe ^[4]

Afiliação do(s) autor(es)

^[1] Inst Fed Tocantins IFTO, Observ Fis Espacial, Araguatins, TO - Brazil

^[2] Univ Vale Paraiba UNIVAP, Inst Pesquisa & Desenvolvimento IP&D, Lab Astroquim & Astrobiol LASA, Sao Jose Dos Campos, SP - Brazil

^[3] Inst Tecnol Aeronaut, ITA DCTA, Sao Jose Dos Campos, SP - Brazil

^[4] Normandie Univ, Ctr Rech Ions Mat & Photon, ENSICAEN, UNICAEN, CIMAP, CIRIL, GANIL, CEA, CNRS, F-14000 Caen - France

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 850, n. 2 DEC 1 2017.
• Citações Web of Science: 3

Resumo

We experimentally address in this paper the physicochemical effects induced by ionizing photons (energies from 6 to 2000 eV) and swift heavy ions (15.7 MeV O-16(5+)) in the icy mixture containing N-2:CH4 (19:1) at 12 K and 19 K, respectively. The experiments simulate the effect of solar photons and X-rays, cosmic rays, and solar energetic particles (medium-mass ions) on the surface of icy bodies in the outer solar system, such as Triton, Titan, Pluto, and several other Kuiper Belt objects. The ice samples were analyzed by infrared spectroscopy (FTIR) at different fluences. From the energetic processing, the production of new molecules was observed. Among them, HCN, C2H4, C2H6, and N-3 have the highest production yield. Molecular half-lives of the species of interest were calculated and extrapolated to the astrophysical environment. The effective destruction yield (in molecules/ impact) of the parental species processed by the swift ions is up to six orders of magnitude higher than the value determined by employing X-rays. However, due to the differences between the fluxes of both ionizing radiation types in space, the half-lives of nitrogen and methane in the astrophysical scenarios addressed may have a huge variation. Photons dominate the chemical transformations at shorter distances from the Sun. Our results are a step toward a compilation of photochemical and radiolysis data that should allow the modeling of the abundance of astrophysical ices over long periods of time. (AU)

• Processo FAPESP: 15/10492-3 - Estudo da evolução química de gelos astrofísicos na vizinhança de objetos estelares jovens empregando dados experimentais no infravermelho e modelagem computacional
• Beneficiário: Will Robson Monteiro Rocha
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 09/18304-0 - Síntese e degradação de espécies moleculares pré-bióticas em atmosferas planetárias, cometas e gelos interestelares simulados
• Beneficiário: Sergio Pilling Guapyassu de Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 13/07657-5 - Modelagem computacional do ambiente circum-estelar de protoestrelas empregando dados de gelos bombardeados por raios cósmicos simulados em laboratório.
• Beneficiário: Will Robson Monteiro Rocha
• Modalidade de apoio: Bolsas no Brasil - Doutorado