Speaker
Description
Ices are observed across the universe, including on planetary bodies, comets, within the interstellar medium (ISM), and in protoplanetary disks [1]. In these environments are subjected to a flux of UV irradiation, electron bombardment, cosmic rays bombardment, solar wind and thermal chemistry, which drive structural modifications, induce the desorption of molecules and radicals from the grains, and generate new species through radiolytic processes [2].
One of the most important constituents of these ices is methanol (CH3OH), which could have originated from surface interactions occurring in the ice mantles on the grains and is a key component in radiolytic processes due to its significant abundance in comets, in dense clouds, around low mass protostars, and around massive protostars [3]. For this reason, if this compound survived the impact processes during accretion, it would have contributed substantially to the geological and chemical evolution of large icy bodies.
Considering the above and the importance of analysing the chemical evolution of ices in the interstellar medium and and on the surfaces of planetary bodies, in this project, we simulate the conditions from icy moons, especially Enceladus surface and irradiate ices of methanol in order to analyse the changes that take place.
This project is titled “Systematic Studies of Astrophysical Ices and Materials within Simulated Space Environments” and is being carried out at the Ice Chamber for Astrophysics/Astrochemistry (ICA) at the Tandetron Accelerator, operated by the HUN-REN Institute for Nuclear Research in Debrecen under the supervision of Professor Nigel J. Mason.
In this project, we experimentally investigate how methanol ices respond to proton irradiation (simulating solar wind conditions) at different energies (250 keV, 500 keV, 750 keV, and 1 MeV). For this purpose, in an ice chamber maintained under high-vacuum conditions (10⁻⁹ mbar), we deposit methanol ices at different temperatures, obtaining crystalline ice at 130 K and amorphous ice at 20 K. Subsequently, we irradiate the samples with the required proton energy, and the infrared spectrum is obtained.
Using these infrared spectra, we proceed with the identification and quantification of the products formed by irradiation (carbon monoxide, carbon dioxide, methane, and formaldehyde), as well as the estimation of the amount of methanol destroyed during the process.
Finally, in this project we also investigates the structural changes that take place in crystalline ice when exposed to radiation through a process known as amorphization. This process is of great importance for understanding the chemical evolution of these ices on icy moons such as Enceladus, where material ejected through cryovolcanic plumes is deposited onto the surface and subsequently exposed to radiation.
These findings enhance our understanding of how ices affect the formation of icy moons and their chemical evolution and may help interpret data from upcoming space missions like JUICE.
References.
[1] Dartois, E., et al. Heavy ion irradiation of crystalline water ice Cosmic ray amorphization cross-Section and sputtering yield. Astronomy & Astrophysics 576 (2015).
[2] Boogert, AC. Adwin, Perry A. Gerakines and Douglas CB Whittet. Observations of the icy universe. Annual Review of Astronomy and Astrophysics 53.1 (2015):541-581.
[3] Cruz-Diaz, Gustavo., et al. Negligible photo desorption of methanol ice and active photon-induced desorption of its irradiation products. Astronomy & Astrophysics. 592. (2016): A68.