The Effects of Dust Grain Surface Reactions on the HDO/H2O Ice Ratio in Protoplanetary Disks

Hebels, Tycho (2024) The Effects of Dust Grain Surface Reactions on the HDO/H2O Ice Ratio in Protoplanetary Disks. Bachelor's Thesis, Astronomy.

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Abstract

The deuterium-to-hydrogen (D/H) ratio can vary substantially in protoplanetary disks due to radial drift, turbulence and vertical settling. Molecules and atoms are able to freeze out onto the surfaces of dust grains moving through the disk. This thesis looks at the surface chemistry happening in these icy mantles, particularly the reactions that might affect the D/H ratio of water ice. We investigate their timescales and reaction rates by utilizing the Stochastic Monomer Processor (SHAMPOO) and Protoplanetary Disk Model (ProDiMo) codes to simulate H2O and HDO forming reactions at radial distances ranging from 60-60 AU from the star. We find that surface reactions with low activation energies are able to enhance the D/H ratio of water ice by a factor of ~2-5 depending on distance and the initial D/H value. Temperatures are higher closer to the star, which causes higher reaction rates, but the impact on the D/H ratio of water ice is largest when the initial value is lowest, which in our simulations is at 60 AU. Our finding suggests that surface chemistry on dust grains is able to enhance the D/H ratio of water ice, even when going far out in the protoplanetary disk.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Kamp, I.E.E. and Oosterloo, M.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	12 Jul 2024 08:11
Last Modified:	12 Jul 2024 08:11
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/33261

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