J/A+A/673/A129 Cometary dust collected by MIDAS on-board Rosetta (Kim+, 2023)
Cometary dust collected by MIDAS on board Rosetta.
I. Dust particle catalog and statistics.
Kim M., Mannel T., Boakes P.D., Bentley M.S., Longobardo A.,
Jeszenszky H., Moissl R., MIDAS team
<Astron. Astrophys. 673, A129 (2023)>
=2023A&A...673A.129K 2023A&A...673A.129K (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Comets
Keywords: catalogs - astronomical databases: miscellaneous -
comets: 67P/Churyumov-Gerasimenko - space vehicles: Rosetta -
space vehicles: instruments - planets and satellites: formation -
techniques: miscellaneous
Abstract:
The Micro-Imaging Dust Analysis System (MIDAS) atomic force microscope
(AFM) on board the Rosetta comet orbiter has been dedicated to the
collection and 3D topographical investigation of cometary dust in the
size range of a few hundreds of nanometers to tens of micrometers with
a resolution down to a few nanometers.
We aim to catalog all dust particles collected and analyzed by MIDAS,
together with their main statistical properties such as size, height,
basic shape descriptors, and collection time. Furthermore, we aim to
present the scientific results that can be extracted from the catalog,
such as the size distribution and statistical characteristics of
cometary dust particles.
Through a careful re-analysis of MIDAS AFM images, we make a
significant update and improvement to the existing MIDAS particle
catalog, resulting in the addition of more particles and newly
developed shape descriptors. The final product is a comprehensive list
of all possible cometary dust particles detected by MIDAS. The catalog
documents all images of identified dust particles and includes a
variety of derived information tabulated one record per particle.
Furthermore, the best image of each particle was chosen for subsequent
studies. Finally, we created dust coverage maps and clustering maps of
the MIDAS collection targets and traced any possible fragmentation of
collected particles with a detailed algorithm.
The revised MIDAS catalog includes 3523 MIDAS particles in total,
where 1857 particles are expected to be usable for further analysis
(418 scans of particles before perihelion + 1439 scans of particles
after perihelion, both after the removal of duplicates), ranging from
about 40nm to about 8um in size. The mean value of the equivalent
radius derived from the 2D projection of the particles is
0.91±0.79um. A slightly improved equivalent radius based on the
particle's volume coincides in the range of uncertainties with a value
of 0.56±0.45um. We note that those sizes and all following MIDAS
particle size distributions are expected to be influenced by the
fragmentation of MIDAS particles upon impact on the collection
targets. Furthermore, fitting the slope of the MIDAS particle size
distribution with a power law of a rb yields an index b of ~-1.67 to
-1.88. Lastly, based on the created dust coverage maps and clustering
maps of the MIDAS collection targets, we determined the particle
fragmentation ratio of 4.09 for nominal activity and 11.8 for the
outburst, which underlines that parent particles with faster impact
velocity are more likely to be fragmented during dust collection.
Description:
The catalog of cometary dust collected by MIDAS on-board Rosetta is
based on target exposure history and best representation of each MIDAS
particle. From the start of the Rosetta mission, 15 targets were
exposed in total. However, only 8 targets were exposed and scanned for
dust collection after the arrival of the Rosetta spacecraft at comet
67P and only 4 targets (i.e., targets 11, 13, 14, and 15) were found
to have detectable dust deposits of cometary origin.
Furthermore, the MIDAS particle catalog presented in this paper
contains in total of 3523 scans of particles. A part of those scans
are suffering from artifacts, low resolution, or represent the same
particle just with different scanning parameters. Thus, there was a
cautious selection of particles used for further scientific analysis
necessary and the full table of the ultimately chosen 1857 particles.
The steps of this selection process are described in Section 3.1.2.
Basic statistics of MIDAS particles.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
appenb.dat 70 172 Target exposure history with start and end time,
and duration, for each target with comet
activities (table B1)
appenc.dat 138 1857 Scanning time, 2D and 3D radius, location of
dust particles, and the cluster number
of best representation of each particle
(table C1)
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See also:
J/A+A/520/A92 : Global plasma parameter simulation of Comet 67P
(Gortsas+, 2010)
J/A+A/527/A113 : 67P/Churyumov-Gerasimenko R-band light curve
(Tubiana+, 2011)
J/A+A/548/A12 : 67P/Churyumov-Gerasimenko R-band light curve (Lowry+, 2012)
J/MNRAS/462/S138 : Robotic view of 67P perihelion (Snodgrass+, 2016)
J/A+A/647/A119 : Comet 67P/Churyumov-Gerasimenko FUV aurora
(Stephenson+, 2021)
Byte-by-byte Description of file: appenb.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 "datime" Start Start time of target exposure
21- 39 A19 "datime" End End time of target exposure
41- 44 I4 d Durd Duration of target exposure (day)
46- 49 A4 --- --- [days]
51- 58 A8 "h:m:s" Durt Duration of target exposure (time, hh:mm:ss)
60- 61 I02 --- Target Target number
63- 70 A8 --- Note Cometary activities
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Byte-by-byte Description of file: appenc.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- Particle Particle ID
28- 29 I02 --- Target Target number
31- 49 A19 "datime" Start Star time of scanning
51 I1 d Durd Duration of target exposure (day)
53- 56 A4 --- --- [days]
58- 72 A15 "h:m:s" Durt Duration of target exposure
(time, hh:mm:ss.ssssss)
74- 92 A19 "datime" End End time of scanning
94- 97 F4.2 um 2Drad Equivalent radius based on the 2D projection
99-102 F4.2 um 3Drad ? Equivalent radius derived from volume
104-110 F7.2 um Left Left location from the center of
the individual target
112-118 F7.2 um Right Right location from the center of
the individual target
120-126 F7.2 um Up Up location from the center of
the individual target
128-134 F7.2 um Down Down location from the center of
the individual target
136-138 I03 --- Cluster Cluster number (i.e., a reference to the
assumed cluster or parent particle family)
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Acknowledgements:
Minjae Kim, minjae.k.kim(at)warwick.ac.uk
(End) Patricia Vannier [CDS] 17-Mar-2023