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Typology of dust particles collected by the COSIMA mass spectrometer in the inner coma of 67P/Churyumov Gerasimenko
Tekijät: Langevin Y, Hilchenbach M, Ligier N, Merouane S, Hornung K, Engrand C, Schulz R, Kissel J, Ryno J, Eng P, Group Author(s): COSIMA Team
Kustantaja: ACADEMIC PRESS INC ELSEVIER SCIENCE
Julkaisuvuosi: 2016
Journal: Icarus
Tietokannassa oleva lehden nimi: ICARUS
Lehden akronyymi: ICARUS
Vuosikerta: 271
Aloitussivu: 76
Lopetussivu: 97
Sivujen määrä: 22
ISSN: 0019-1035
eISSN: 1090-2643
DOI: https://doi.org/10.1016/j.icarus.2016.01.027
Tiivistelmä
The COSIMA mass spectrometer on board the ROSETTA orbiter has collected dust in the near coma of comet 67P/Churyumov-Gerasimenko since August 11, 2014. The collected dust particles are identified by taking images with a microscope (COSISCOPE) under grazing incidence illumination before and after exposure of the target to cometary dust. More than 10,000 dust particles >14 mu m in size collected from August 11, 2014 to April 3, 2015 have been detected on three distinct target assemblies, including 500 dust particles with sizes ranging from 50 to more than 500 mu m, that can be resolved by COSISCOPE (pixel size 14 mu m). During this period, the heliocentric distance decreased from 3.5 AU to less than 2 AU. The collection efficiency on targets covered with "metal black" has been very high, due to the low relative velocity of incoming dust. Therefore, the COSISCOPE observations provide the first optical characterization of an unbiased sample of particles collected in the inner coma of a comet. The typology of particles >100 mu m in size is dominated by clusters with a wide range of structure and strength, most originating from the disruption of large aggregates (>1 mm in size) shortly before collection. A generic relationship between these clusters and IDPs/Antarctic meteorites is likely in the framework of accretion models. About 15% of particles larger than 100 mu m are compact particles with two likely contributions, one being linked to clusters and another leaving the cometary nucleus as single compact particles. (C) 2016 Elsevier Inc. All rights reserved.
The COSIMA mass spectrometer on board the ROSETTA orbiter has collected dust in the near coma of comet 67P/Churyumov-Gerasimenko since August 11, 2014. The collected dust particles are identified by taking images with a microscope (COSISCOPE) under grazing incidence illumination before and after exposure of the target to cometary dust. More than 10,000 dust particles >14 mu m in size collected from August 11, 2014 to April 3, 2015 have been detected on three distinct target assemblies, including 500 dust particles with sizes ranging from 50 to more than 500 mu m, that can be resolved by COSISCOPE (pixel size 14 mu m). During this period, the heliocentric distance decreased from 3.5 AU to less than 2 AU. The collection efficiency on targets covered with "metal black" has been very high, due to the low relative velocity of incoming dust. Therefore, the COSISCOPE observations provide the first optical characterization of an unbiased sample of particles collected in the inner coma of a comet. The typology of particles >100 mu m in size is dominated by clusters with a wide range of structure and strength, most originating from the disruption of large aggregates (>1 mm in size) shortly before collection. A generic relationship between these clusters and IDPs/Antarctic meteorites is likely in the framework of accretion models. About 15% of particles larger than 100 mu m are compact particles with two likely contributions, one being linked to clusters and another leaving the cometary nucleus as single compact particles. (C) 2016 Elsevier Inc. All rights reserved.
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