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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

THE EFFECT OF BROADBAND SOFT X-RAYS IN SO2-CONTAINING ICES: IMPLICATIONS ON. THE PHOTOCHEMISTRY OF ICES TOWARD YOUNG STELLAR OBJECTS

Texto completo
Autor(es):
Pilling, S. [1] ; Bergantini, A. [1]
Número total de Autores: 2
Afiliação do(s) autor(es):
[1] Univ Vale Paraiba UNIVAP, Lab Astroquim & Astrobiol LASA, Sao Jose Dos Campos, SP - Brazil
Número total de Afiliações: 1
Tipo de documento: Artigo Científico
Fonte: ASTROPHYSICAL JOURNAL; v. 811, n. 2 OCT 1 2015.
Citações Web of Science: 7
Resumo

We investigate the effects produced mainly by broadband soft X-rays up to 2 keV (plus fast (similar to keV) photoelectrons and low-energy (similar to eV). induced secondary electrons) in the ice mixtures containing H2O:CO2:NH3:SO2 (10:1:1:1) at two different temperatures (50 and 90 K). The experiments are an attempt to simulate the photochemical processes induced by energetic photons in SO2-containing ices present in cold environments in the ices surrounding young stellar objects (YSO) and in molecular clouds in the vicinity of star-forming regions, which are largely illuminated by soft X-rays. The measurements were performed using a high-vacuum portable chamber from the Laboratorio de Astroquimica e Astrobiologia (LASA/UNIVAP) coupled to the spherical grating monochromator beamline at the Brazilian Synchrotron Light Source (LNLS) in Campinas, Brazil. In. situ analyses were performed by a Fourier transform infrared spectrometer. Sample processing revealed the formation of several organic molecules, including nitriles, acids, and other compounds such as H2O2, H3O+, SO3, CO, and OCN-. The dissociation cross section of parental species was on the order of (2-7) x 10(-18) cm(2). The ice temperature does not seem. to affect the stability of. SO2 in the presence of X-rays. Formation cross sections of new species. produced. were also determined. Molecular half-lives at ices toward YSOs due to the presence of incoming soft X-rays were estimated. The low values obtained. employing two different models of the radiation field of YSOs (TW Hydra and typical T-Tauri star). reinforce that soft X-rays are indeed a very efficient source of molecular dissociation in such environments. (AU)

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
Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores
Processo FAPESP: 12/17248-2 - Estudo da produção de moléculas de interesse astrobiológico em experimentos simulando a lua Encélado na presença de fótons UV, raios-X, elétrons e íons rápidos
Beneficiário:Alexandre Bergantini de Souza
Linha de fomento: Bolsas no Brasil - Doutorado