Modelling of the gas dynamics in the inner-coma and the composition of comet 67P/Churyumov-Gerasimenko

Pinzón Rodriguez, Olga Janeth (2021). Modelling of the gas dynamics in the inner-coma and the composition of comet 67P/Churyumov-Gerasimenko (Unpublished). (Dissertation, Physikalisches Institut, Phil.-Nat.)

Preview

Text Pinz_n_Olga_Defense.pdf - Other Available under License BORIS Standard License. Download (23MB) | Preview

This thesis presents a study of the gas dynamics of cometary nuclei with a focus on the target
of the Rosetta mission, comet 67P/Churyumov-Gerasimenko. We therefore apply the 3D Direct
Simulation Monte Carlo (DSMC) method to different distributions of H2O and CO2-ice source on
the surface of the nucleus in order to model the inner-coma of 67P/CG. The sublimation rates and
temperatures at the surface are calculated using a balance equation that takes into account the
solar radiation at the surface and the energy losses due to thermal emission, sublimation of ices
and thermal conduction. This has been done for a spherical nucleus comet of 2km, and a comet
that takes into account the real shape of 67P/CG.
The ultimate goal of this work is to find a link between remote sensing observations at
large distances and the relative abundances of major volatiles in the nucleus. Therefore, for the
complex shape of the nucleus, we validate our surface boundary condition by comparing the
simulation results with local measurements of the gas properties obtained by ROSINA, MIRO
and VIRTIS-M.
The targeted times in this work are May 10, 2015, when the comet was at its spring equinox
at 1.67AU; and July 10, 2015, when the comet was at 1.67AU and the global production rates
were high enough to study the increasingly emissions from the southern hemisphere of the comet
as it approached perihelion.
We have found that different distribution of H2O and CO2 sources at the surface are difficult
to detect using ROSINA data alone. Comparison with multiple instruments are found to be
necessary to better constrain the thermophysical models that link comae measurements with
the nucleus near-surface structure and composition. CO2 has been found to be the most likely
candidate for nightside activity in multiple tests that include thermal inertia values between 40 -
80 J/(m2K
p
s ). There is a strong indication that the heat exchange between the dust mantle and
the sublimating gas can have a strong effect on the expansion velocities of the gas measured by
MIRO on both dates.

Interest & Impact

Downloads

2 since deposited on 07 Jun 2024
2 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item