Solar Cycle Dependence of ICME Composition

Song, Hongqiang; Li, Leping; Sun, Yanlai; Lv, Qi; Zheng, Ruisheng; Chen, Yao

doi:10.1007/s11207-021-01852-y

Cited by 16 publications

(33 citation statements)

References 100 publications

(158 reference statements)

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“…Thus the A He is available just for 420 ICMEs that are depicted with light grey in Figure 1, including 155 (37%) and 50 (12%) ICMEs with their average A He exceeding 5 and 8.5, which are displayed with the dark grey and black histograms, respectively. Figure 1 shows that ICMEs with high A He values mainly appear during solar maximum and descending phases, similar to the relative abundances of the other heavier ions (Song et al 2021a).…”

Section: Statistical Results and Comparisonssupporting

confidence: 55%

“…The quantitative comparison between the two solar maximums shows that the average A He of slow wind (ICMEs) decreases by 16.3% (11.7%), i.e. from 4.16 (6.16) to 3.48 (5.44), and the t-test (see e.g., Song et al 2021a) results illustrate that the variation is significant at the 99% confidence level. The discrepancy of A He variation trends between WIND (Alterman & Kasper 2019) and ACE should mainly result from different selections of velocity intervals.…”

Section: Statistical Results and Comparisonsmentioning

confidence: 93%

“…According to the FIP effect (Laming 2004(Laming , 2015, the Ne/O should decrease in the corona and ICMEs compared to the photosphere as the FIP of Ne (21.6 eV) is higher than O (13.6 eV). However, measurements showed the opposite case within flare regions and ICMEs (Feldman et al 2005;Song et al 2021a). Shemi (1991) has suggested that pre-flare soft X-ray can penetrate through the chromosphere and create a slab-like region with photoionization ratios at the chromosphere base.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…It is widely accepted that CMEs result from eruption of magnetic flux ropes (e.g., Chen 2011), which can form prior to (e.g., Cheng et al 2011;Patsourakos et al 2013) and during (e.g., Song et al 2014;Jiang et al 2021) eruptions. The composition (including both the charge states and elemental abundances of heavy ions) pro-vides an important avenue to analyze their eruption process (Lepri & Zurbuchen 2004;Lynch et al 2011;Gruesbeck et al 2011Gruesbeck et al , 2012Song et al 2015Song et al , 2016Song et al , 2017Song & Yao 2020;Gu et al 2020;Song et al 2021b), and supports that more CMEs come from active regions around solar maximum, whose heavy ions possess higher charge states and enriched relative abundances (Song et al 2021a).…”

Section: Introductionmentioning

confidence: 88%

“…This model connects the confinement time of plasma in a loop to its physical size, and these factors in turn influence the temperature profile, gravitational settling, and plasma composition (Kasper et al 2007). Besides, Song et al (2021a) reported that Ne/O exhibits opposite solar cycle dependence within ICMEs and solar wind, and they suggested that the photoionization might be responsible for the higher Ne/O ratios within ICMEs around solar maximum.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Helium Abundance between ICMEs and Solar Wind near 1 AU

Song,

Cheng,

et al. 2021

Preprint

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The Helium abundance, defined as A He = n He /n H × 100, is ∼8.5 in the photosphere and seldom exceeds 5 in fast solar wind. Previous statistics have demonstrated that A He in slow solar wind correlates tightly with sunspot number. However, less attention is paid to the solar cycle dependence of A He within interplanetary coronal mass ejections (ICMEs) and comparing the A He characteristics of ICMEs and solar wind. In this paper we conduct a statistical comparison of Helium abundance between ICMEs and solar wind near 1 AU with observations of Advanced Composition Explorer from 1998 to 2019, and find that the ICME A He also exhibits the obvious solar cycle dependence. Meanwhile, we find that the A He is obviously higher within ICMEs compared to solar wind, and the means within 37% and 12% of ICMEs exceed 5 and 8.5, respectively. It is interesting to answer where and how the high Helium abundance originates. Our statistics demonstrate that 21% (3%) of ICME (slow wind) A He data points exceed 8.5 around solar maximum, which decreases dramatically near minimum, while no such high A He values appear in the fast wind throughout the whole solar cycle. This indicates that the high A He (e.g., >8.5) emanates from active regions as more ICMEs and slow wind originates from active regions around maximum, and supports that both active regions and quiet-Sun regions are the sources of slow wind. We suggest that the high A He from active regions could be explained by means of the magnetic loop confinement model and/or photoionization effect.

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Section: Statistical Results and Comparisonssupporting

confidence: 55%

Section: Statistical Results and Comparisonsmentioning

confidence: 93%

Section: Discussion and Summarymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Comparison of Helium Abundance between ICMEs and Solar Wind near 1 AU

Song,

Cheng,

et al. 2021

Preprint

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A 3 Giga Sample Per Second 14-bit Digital Receiver with 9 GHz Input Bandwidth for Solar Radio Observation

Zhang¹,

Zhang²,

Shang³

et al. 2022

Res. Astron. Astrophys.

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A new digital receiver with excellent performances has been designed and developed for solar radio observation, which can receive the radio signal from direct current (DC) to 9GHz in the direct acquisition way. On the digital receiver, the analog-to-digital converter (ADC) with 14-bit, two input channels and 3 Giga Samples per second (Gsps) are used to acquire observed signal, and the field-programmable-gate-array (FPGA) chip XCKU115 acts as the processing module. The new digital receiver can be used to directly sample the solar radio signals of frequency under 9GHz. When receiving the solar radio signal above 9GHz, the new digital receiver can save 1-2 stages of frequency down-conversion, and effectively improve many indexes of solar radio observation system, i.e., the time resolution, analog front-end circuit, weight and volume of the analog circuit system. Compared with the digital receiver with sampling rate below 1 Gsps used in existing solar radio telescope, the new digital receiver reduces the frequency switching times of large bandwidth, which is beneficial to improving the frequency and time resolutions. And the ADC sampling resolution of 14 bits, providing a large dynamic range, is very beneficial to observing smaller solar eruptions. This receiver, which would be used in the solar radio observation system, well meets the latest requirements with the resolutions of time (≤1ms) and frequency(≤0.5MHz) for fine observation of radio signals.

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