J/A+A/671/A63 Multi-population model for Iron ions in ICMEs (Gu+, 2023)
Detailed composition of iron ions in interplanetary coronal mass ejections
based on a multi-population approach.
Gu C., Heidrich-Meisner V., Wimmer-Schweingruber R.F., Yao S.
<Astron. Astrophys. 671, A63 (2023)>
=2023A&A...671A..63G 2023A&A...671A..63G (SIMBAD/NED BibCode)
ADC_Keywords: Sun ; Models
Keywords: Sun: coronal mass ejections (CMEs)
Abstract:
Coronal Mass Ejections (CMEs) are extremely dynamical large scale
events. If a CME is detected in-situ by a spacecraft located in the
interplanetary medium, it is then called an Interplanetary Coronal
Mass Ejection (ICME).
Charge states of heavy ions reflect important information about the
coronal temperature profile due to the freeze-in effect and it is
estimated that Iron ions freeze in at the heights of ∼5 solar radii.
To identify different populations of Iron charge state composition of
ICMEs and determine their sources,we developed a model which
independently uses two, three, and four populations of Iron ions to
fit the measured charge state distribution in ICMEs detected by the
Advanced Composition Explorer (ACE) at 1AU. Three parameters are used
to identify a certain population, i.e., freeze-in temperature,
relative abundance and kappa value which together describe the
potential non-Maxwellian kappa-distributions of coronal electrons. Our
method chooses the reduced chi-squared to describe the goodness of fit
of the model to the observations.The parameters of our model are
optimized with the Covariance Matrix Adaptation Evolution
Strategy(CMA-ES).
Two major types of ICMEs are identified according to the existence of
hot material,and both cool type and hot type have two main
sub-types. Different populations in those types have their own
features related to freeze-in temperature and kappa.The electron
velocity distribution function usually contains a significant hot tail
in typical coronal material and hot material while Maxwellian
distribution appears more frequently in mid-temperature material.
Description:
This work uses the charge-state distributions of iron ions measured at
1AU by ACE/SWICS (Gloeckler et al., 1998, Space Sci. Rev., 86, 497)
from 1998 to 2011. The data are published with a cadence of 2h. All
the data are provided by the ACE Science Center
(http://www.srl.caltech.edu/ACE/ASC/level2/index.html).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 90 310 Model results of the 310 ICMEs
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Number [1/310] Case number
5- 20 A16 "datime" StartTime ICME plasma/field start time
22- 25 F4.2 [K] logT1 Temperature 1
27- 30 F4.2 [K] logT2 Temperature 2
32- 35 F4.2 [K] logT3 ?=- Temperature 3
37- 40 F4.2 [K] logT4 ?=- Temperature 4
42- 45 F4.2 --- RA1 Relative abundance 1
47- 50 F4.2 --- RA2 Relative abundance 2
52- 55 F4.2 --- RA3 ?=- Relative abundance 3
57- 60 F4.2 --- RA4 ?=- Relative abundance 4
62- 66 F5.2 --- k1 Kappa value 1
68- 72 F5.2 --- k2 Kappa value 2
74- 78 F5.2 --- k3 ?=- Kappa value 3
80- 84 F5.2 --- k4 ?=- Kappa value 4
86- 90 F5.2 --- chi2 Reduced chi square
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Acknowledgements:
Chaoran Gu, chaorangu(at)physik.uni-kiel.de
(End) Patricia Vannier [CDS] 18-Jan-2023