X-ray photolysis of CH3COCH3 ice: implications for the radiation effects of compact objects towards astrophysical ices

Autor(es)

Carvalho, G. A. ^[1] ; Pilling, S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Vale Paraiba UNIVAP, Inst Pesquisa & Desenvolvimento IP&D, Av Shishima Hifumi 2911, BR-12244000 Sao Jose Dos Campos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 498, n. 1, p. 689-701, OCT 2020.
• Citações Web of Science: 1

Resumo

In this study, we employed broad-band X-rays (6-2000 eV) to irradiate the frozen acetone CH3COCH3, at the temperature of 12 K, with different photon fluences up to 2.7 x 10(18) photons cm(-2). Here, we consider acetone as a representative complex organic molecule (COM) present on interstellar ice grains. The experiments were conduced at the Brazilian Synchrotron facility (LNLS/CNPEN) employing infrared spectroscopy (FTIR) to monitor chemical changes induced by radiation in the ice sample. We determined the effective destruction cross-section of the acetone molecule and the effective formation cross-section for daughter species. Chemical equilibrium, obtained for fluence 2 x 10(18) photons cm(-2), and molecular abundances at this stage were determined, which also includes the estimates for the abundance of unknown molecules, produced but not detected, in the ice. Time-scales for ices, at hypothetical snow line distances, to reach chemical equilibrium around several compact and main-sequence X-ray sources are given. We estimate time-scales of 18 d, 3.6 and 1.8 months, 1.4 x 10(9)-6 x 10(11) yr, 600 and 1.2 x 10(7) yr, and 10(7) yr, for the Sun at 5 au, for O/B stars at 5 au, for white dwarfs at 1 LY, for the Crab pulsar at 2.25 LY, for Vela pulsar at 2.25 LY, and for Sagittarius A{*} at 3 LY, respectively. This study improves our current understanding about radiation effects on the chemistry of frozen material, in particular, focusing for the first time, the effects of X-rays produced by compact objects in their eventual surrounding ices. (AU)

• 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
• 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: 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