Laboratory-based sticking coefficients for ices on a variety of small grains analogs
arXiv:2102.09862 · doi:10.1038/s41550-020-01288-7
Abstract
Abundances and partitioning of ices and gases produced by gas-grain chemistry are governed by adsorption and desorption on grains. Understanding astrophysical observations rely on laboratory measurements of adsorption and desorption rates on dust grains analogs. On flat surfaces, gas adsorption probabilities (or sticking coefficients) have been found close to unity for most gases. Here we report a strong decrease of the sticking coefficients of H2O and CO2 on substrates more akin to cosmic dust, such as submicrometer-sized particles of carbon and olivine, bare or covered with ice. This effect results from the local curvature of the grains, and then extends to larger grains made of aggregated small particles, such as fluffy or porous dust in more evolved media (e.g. circumstellar disks). The main astrophysical implication is that accretion rates of gases are reduced accordingly, slowing the growth of cosmic ices. Furthermore, volatile species that are not adsorbed on a grain at their freeze-out temperature will pertain in the gas phase, which will impact gas-ice partitions. We also found that thermal desorption of H2O is not modified by grains size, and thus the snowlines temperature should be independent on the dust size distribution.
arXiv commentManuscript : 20 pages, 3 figures, 1 table; Supplementary informations : 9 pages, 5 figures
References in corpus (12)
- Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
- New Interstellar Dust Models Consistent with Extinction, Emission, and Abundance Constraints
- Photochemistry and astrochemistry: photochemical pathways to interstellar complex organic molecules
- Atom addition reactions in interstellar ice analogues
- Dust evolution in protoplanetary discs and the formation of planetesimals. What have we learned from laboratory experiments?
- Tracing water vapor and ice during dust growth
- Sticking of molecules on non-porous amorphous water ice
- Sticking coefficient of hydrogen and deuterium on silicates under interstellar conditions
- Molecular gas freeze-out in the pre-stellar core L1689B
- Evidence of surface catalytic effect on cosmic dust grain analogues: the ammonia and carbon dioxide surface reaction
- Temperature programed desorption of water ice from the surface of amorphous carbon and silicate grains as related to planet-forming disks
- The Effective Surface Area of Amorphous Solid Water Measured by the Infrared Absorption of Carbon Monoxide