Volume 573, January 2015
|Number of page(s)||7|
|Section||Interstellar and circumstellar matter|
|Published online||09 December 2014|
Pore evolution in interstellar ice analogues
Simulating the effects of temperature increase
1 Kapteyn Astronomical Institute,
University of Groningen, PO Box
AV Groningen, The Netherlands
2 Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
3 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
Accepted: 22 October 2014
Context. The level of porosity of interstellar ices, largely comprised of amorphous solid water (ASW), contains clues about the trapping capacity of other volatile species and determines the surface accessibility that is needed for solid-state reactions to take place.
Aims. Our goal is to simulate the growth of amorphous water ice at low temperature (10 K) and to characterise the evolution of the porosity (and the specific surface area) as a function of temperature (from 10 to 120 K).
Methods. Kinetic Monte Carlo simulations are used to mimic the formation and the thermal evolution of pores in amorphous water ice. We follow the accretion of gas-phase water molecules as well as their migration on surfaces with different grid sizes, both at the top growing layer and within the bulk.
Results. We show that the porosity characteristics change substantially in water ice as the temperature increases. The total surface of the pores decreases to a great extend while the total volume decreases only slightly for higher temperatures. This will decrease the overall reaction efficiency, but in parallel, small pores connect and merge, which allows trapped molecules to meet and react within the pores network and provides a pathway to increase the reaction efficiency. We introduce pore coalescence as a new solid-state process that may boost the solid-state formation of new molecules in space, and which has not been considered so far.
Key words: astrochemistry / ISM: abundances / ISM: molecules / stars: formation
© ESO, 2014
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.