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  Dynamical properties and acceleration of hierarchical dust in the vicinity of comet 67P/Churyumov–Gerasimenko

Skorov, Y. V., Reshetnyk, V., Rezac, L., Zhao, Y., Marschall, R., Blum, J., et al. (2018). Dynamical properties and acceleration of hierarchical dust in the vicinity of comet 67P/Churyumov–Gerasimenko. Monthly Notices of the Royal Astronomical Society, 477(4), 4896-4907. doi:10.1093/mnras/sty1014.

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 Creators:
Skorov, Yuri V.1, Author              
Reshetnyk, V, Author
Rezac, Ladislav1, Author              
Zhao, Y, Author
Marschall, R, Author
Blum, J, Author
Hartogh, Paul1, Author              
Affiliations:
1Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832288              

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Free keywords: methods: numerical, comets: general, comets: individual:67P/Churyumov–Gerasimenko
 MPIS_GROUPS: Planets and Comets
 Abstract: A significant fraction of cometary dust grains leaving the nucleus surface are extremely porous and fluffy particles as revealed by recent observation from the Rosetta mission. In this paper our aim is to investigate the dynamics of such grains when subjected to a gas flow, representing the cometary outgassing. We perform numerical experiments to quantify how the internal porous texture is reflected in quantities such as effective cross-section, gas drag coefficient, and light scattering efficiency. We also derive particle speeds for the different types of aggregates as a function of radial distance and compare them to the observations by the GIADA instrument. Using our original method for constructing hierarchical aggregates we increase the level of aggregation to reach particle sizes up to few millimeters, consistent with the observations. In addition, a non-constant gas velocity is now considered in the framework of free molecular as well as fully collisional flow models, and radiation pressure calculations use the effective medium theory appropriate for such particles. These improvements lead us to conclude that dynamical models should account for accelerating gas flow, which leads to a smaller terminal speed of fluffy dust grains. Secondly, solar radiation pressure calculated based on the Mie theory approximation can lead to orders of magnitude error for the very porous particles, instead the effective medium theory should be used. Finally, although numerical simulations can reproduce the GIADA measurements of dust speeds, we cannot conclude that there exists a preferred model of porous particles build as a ballistic cluster aggregate.

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Language(s): eng - English
 Dates: 2018-06-122018
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1093/mnras/sty1014
 Degree: -

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Title: Monthly Notices of the Royal Astronomical Society
  Other : Mon. Not. R. Astron. Soc.
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Oxford : Oxford University Press
Pages: - Volume / Issue: 477 (4) Sequence Number: - Start / End Page: 4896 - 4907 Identifier: ISSN: 1365-8711
CoNE: https://pure.mpg.de/cone/journals/resource/1000000000024150