HR: 15:00h
AN: SH43B-05    [Abstracts]
TI: Solar-Wind Drag on Fluffy Dust Particles
AU: * Minato, T
EM: minato@eps.nagoya-u.ac.jp
AF: Dept. of Earth and Planetary Sciences, Nagoya University, Chikusa-ku, Forou-cho, Nagoya, 464-8604 Japan
AU: * Minato, T
EM: minato@eps.nagoya-u.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita-ku, Kita19, nishi8, Sapporo, 060-0819 Japan
AU: Koehler, M
EM: koehlert@uni-muenster.de
AF: Institut fuer Planetologie, Westfaelische Wilhelms-Universitaet, Wilhelm-Klemm-strasse, Muenster, D-48149 Germany
AU: Kimura, H
EM: kimura@uni-muenster.de
AF: Institut fuer Planetologie, Westfaelische Wilhelms-Universitaet, Wilhelm-Klemm-strasse, Muenster, D-48149 Germany
AU: Mann, I
EM: imann@uni-muenster.de
AF: Institut fuer Planetologie, Westfaelische Wilhelms-Universitaet, Wilhelm-Klemm-strasse, Muenster, D-48149 Germany
AU: Yamamoto, T
EM: ty@lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita-ku, Kita19, nishi8, Sapporo, 060-0819 Japan
AB: The impact of solar-wind particles on dust grains exerts not only a repulsive force but also a drag force on the grains, called the plasma Poynting-Robertson effect. The drag force decreases the orbital angular momentum of the grains and limits their lifetime in a manner similar to the photon Poynting-Robertson effect. We study the solar-wind drag and the lifetime of fluffy silicate and carbon dust aggregates. We calculate the momentum transfer cross section of the fluffy dust aggregate for the impinging solar wind taking into account the penetration of incident solar wind ions. We find that 1) the cross section of very small aggregates is approximately proportional to the volume of the grains and independent of their shape, while 2) the cross section of large aggregates approaches the geometrical cross section. The lifetime of the aggregates against both plasma and photon drag forces is shorter than that of spherical particles of the same mass. We show that the plasma Poynting-Robertson effect for aggregates is comparable to and in some cases more effective than the (photon) Poynting-Robertson effect. The importance of the plasma drag compared to the photon drag increases as the size of constituent particles of the aggregate decreases, irrespective of the passage of solar-wind ions through the dust grains. This contradicts the general understanding that the lifetime of dust particles is limited by the photon Poynting-Robertson effect.
DE: 2100 INTERPLANETARY PHYSICS
DE: 2129 Interplanetary dust
DE: 2164 Solar wind plasma
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting