J/ApJ/900/123 Abundances of heavy ions in ICMEs from 1998-2011 (Gu+, 2020)
Abundances and charge states of heavy ions in ICMEs highly related to speed and
solar activity.
Gu C., Yao S., Dai L.
<Astrophys. J., 900, 123 (2020)>
=2020ApJ...900..123G 2020ApJ...900..123G
ADC_Keywords: Sun; Abundances
Keywords: Solar coronal mass ejections ; Solar cycle
Abstract:
This statistical work studies the abundances and the charge states of
the carbon, oxygen, and iron ions in 281 interplanetary coronal mass
ejections (ICMEs) measured at 1 au by ACE spacecraft from 1998 to
2011. The Gaussian distribution test is applied, and the analysis of
variance is used to quantify the similarity between two distributions
of ionic charge states and abundances. The correlation coefficient is
calculated to reveal the dependence of the abundances and the mean
charge of heavy ions on the solar activity. The results show that the
mean charge, the abundance, and the speed at 1 au are highly related
to the sunspot number (SN). The O7+/O6+ shows statistical difference
between the high speed and the low speed groups of ICMEs. Different
from the cold materials inside ICMEs, the mean charge of carbon ions
shows a positive relation to that of oxygen ions. The Mg/O in the
studied ICMEs are much higher than that in the solar wind. Three types
of charge distribution of C, O, and Fe ions are summarized. The
fraction of each of the three types is related to the solar minimum or
the solar maximum. The mean charge and the flux of oxygen ions show
quasi-linear relations to the SN during solar minimum, and show
fluctuations during maximum. The results reveal that the solar
activity, which represents the solar magnetic field status by nature,
controls the composition of heavy ions in ICMEs.
Description:
This work uses the interplanetary magnetic field, the proton speed
(V), the number density and speed of He2+ (Na, Va), the
elemental abundances, and the charge distributions of heavy ions
measured at 1au by ACE spacecraft from 1998 to 2011.
See Section 2.1.
The ICMEs studied in this work are listed by
Cane & Richardson (2003JGRA..108.1156C 2003JGRA..108.1156C),
Richardson & Cane (2010SoPh..264..189R 2010SoPh..264..189R), and
by the ACE Science Center at
http://www.srl.caltech.edu/ACE/ASC/DATA/level3/index.html
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 78 281 The studied 281 ICMEs from 1998 to 2011
--------------------------------------------------------------------------------
See also:
J/ApJ/868/124 : ICMEs events from 1998 to 2011 with ACE and WIND (Feng+, 2018)
J/ApJ/891/79 : Single storms and the related ICMEs from 1998-2011 (Li+, 2020)
J/ApJ/896/133 : ICME associated Forbush decrease events (Light+, 2020)
http://www.srl.caltech.edu/ACE/ASC/level2/index.html : ACE science center
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/281] Internal index number
5- 8 I4 yr Obs.Y [1998/2011] Year of the observation
start time
10- 11 I2 "month" Obs.M Month of the observation start time
13- 14 I2 d Obs.D Day of the observation start time
16- 17 I2 h Obs.h Hour of the observation start time
19- 20 I2 min Obs.m Minute of the observation start time
22- 24 I3 km/s Vmean [270/900] Mean velocity of ICME
26- 31 F6.2 --- He/O [20/378.7] The He/O abundance ratio
33- 36 F4.2 --- Fe/O [0.05/0.66] The Fe/O abundance ratio
38- 41 F4.2 --- Mg/O [0.1/0.63] The Mg/O abundance ratio
43- 46 F4.2 --- avQC [4.54/5.82] Mean Carbon charge state
48- 51 F4.2 --- avQO [6.01/7.24] Mean Oxygen charge state
53- 57 F5.2 --- avQFe [8.27/15.33] Mean Iron charge state
59- 62 F4.2 --- O7+/O6+ [0.04/2.5] The O7+/O6+ abundance ratio
64- 67 F4.2 10+5/cm2/s OFlux [0.04/2.6]? Oxygen ion flux
69- 70 A2 --- f_OFlux Flag on OFlux (1)
72- 78 A7 --- Type The C/O/Fe charge distribution type (2)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
ND = No alpha particle number density data.
DR = Number density of alpha particle used to calculate the O flux
is not reliable.
Note (2): Classification criteria of charge distribution types (Table 1):
---------------------------------------------------------------------------
Type Criteria
---------------------------------------------------------------------------
C1 Fr(C5+)) is the maximum and Fr(C5+)>2Fr(C4+) and
Fr(C5+)>2Fr(C6+)
C2 |Fr(C5+)-Fr(C6+)|<0.5Max(Fr) and Fr(C6+)≤0.5 and Fr(C4+)<0.2
C3 Fr(C6+) is the maximum and Fr(C6+)>0.5
O1 Fr(O6+) is the maximum and Fr(O6+)>2Fr(O7+) and
Fr(O6+)+Fr(O7+)>1-t
O2 |Fr(O6+)-Fr(O7+)|<0.5Max(Fr) and Fr(O8+)<t
O3 Fr(O8+)≥t
Fe1 QMax(Fr)<10 and Fr(Fe16+)<0.5Max(Fr)
Fe2 Dual-peaked and |Peak1-Peak2|<0.5Max(Fr)
Fe3 Fr(Fe16+) is the maximum and Peak2<0.5Fr(Fe16+)
ND no charge distribution data
NA the types are not applicable to the ICM
---------------------------------------------------------------------------
Note. Fr represents the fraction of the charge distribution.
QMax(Fr) represents the charge state having the maximum fraction.
And t=0.1367 is the mean fraction plus standard deviation of O8+
in the 278 ICMEs with charge distribution data.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Dec-2021