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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.)

Processing of analogues of plume fallout in cold regions of Enceladus by energetic electrons

Texto completo
Autor(es):
Bergantini, A. [1] ; Pilling, S. [1] ; Nair, B. G. [2] ; Mason, N. J. [2] ; Fraser, H. J. [2]
Número total de Autores: 5
Afiliação do(s) autor(es):
[1] Univ Vale Paraiba UNIVAP, Inst Pesquisa & Desenvolvimento IP&D, BR-12244000 Sao Jose Dos Campos, SP - Brazil
[2] Open Univ, Dept Phys Sci, Milton Keynes MK7 6AA, Bucks - England
Número total de Afiliações: 2
Tipo de documento: Artigo Científico
Fonte: Astronomy & Astrophysics; v. 570, OCT 2014.
Citações Web of Science: 12
Resumo

Context. Enceladus, a small icy moon of Saturn, is one of the most remarkable bodies in the solar system. This moon is a geologically active object, and despite the lower temperatures on most of its surface, the geothermally heated south polar region presents geysers that spouts a plume made of water (similar to 90%), carbon dioxide, methane, ammonia, and methanol, among other molecules. Most of the upward-moving particles do not have the velocity to escape from the gravitational influence of the moon and fall back to the surface. The molecules in the ice are continuously exposed to ionizing radiation, such as UV and X-rays photons, cosmic rays, and electrons. Over time, the ionizing radiation promotes molecular bond rupture, destroying and also forming molecules, radicals, and fragments. Aims. We analyse the processing of an ice mixture analogue to the Enceladus fallout ice in cold resurfaced areas (north pole) by 1 keV electrons. The main goal is to search for complex species that have not yet been detected in this moon, and to determine relevant physico-chemical parameters, such as destruction and formation cross-sections and the half-life of the studied molecules in the ice. Methods. The experiment consisted of the electron irradiation of an Enceladus-like ice mixture (H2O: CO2: CH4: NH3: CH3OH) in an ultra-high vacuum chamber at 20 K. The analysis was made by infrared spectrometry in the mid-infrared region (4000-800 cm(-1) or 2.5-12.5 mu m). Results. The absolute dissociation cross-sections of the parent molecules, the formation cross-section of daughter species, and the half-life of the parental species in a simulated Enceladus irradiation scenario were determined. Among the produced species, CO (carbon monoxide), OCN- (cyanate anion), HCONH2 (formamide), and H2CO (formaldehyde) were tentatively detected. (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