The Origin of Solar Filament Plasma Inferred from In Situ Observations of Elemental Abundances

Abstract

Solar filaments/prominences are one of the most common features in the corona, which may lead to energetic coronal mass ejections (CMEs) and flares when they erupt. Filaments are about one hundred times cooler and denser than the coronal material, and physical understanding of their material origin remains controversial. Two types of scenarios have been proposed: one argues that the filament plasma is brought into the corona from photosphere or chromosphere through a siphon or evaporation/injection process, while the other suggests that the material condenses from the surrounding coronal plasma due to thermal instability. The elemental abundance analysis is a reasonable clue to constrain the models, as the siphon or evaporation/injection model would predict that the filament material abundances are close to the photospheric or chromospheric ones, while the condensation model should have coronal abundances. In this letter, we analyze the elemental abundances of a magnetic cloud that contains the ejected filament material. The corresponding filament eruption occurred on 1998 April 29, accompanying an M6.8 class soft X-ray flare located at the heliographic coordinates S18E20 (NOAA 08210) and a fast halo CME with the linear velocity of 1374 km s −1 near the Sun. We find that the abundance ratios of elements with low and high First

Interchange Reconnection Associated with a Confined Filament Eruption: Implications for the Source of Transient Cold-dense Plasma in Solar Winds

“…Yet, it is reasonable that they remain similarly cold and dense, especially when the mixing with the background plasma is not very effective. Thus, the study provides a possible mechanism for the origin of the transient cold-dense plasma that is sometimes detected in the solar wind by spacecrafts (Yao et al 2010;Lepri & Zurbuchen 2010;Song et al 2017). …”

“…Though it is rare, the transient cold-dense plasma is sometimes detected in the solar wind with in situ observations. Most of the cases are associated with interplanetary coronal mass ejections (ICMEs) or magnetic clouds (MCs), and the cold-dense plasma is identified as the ICME core consisting of filament material that shows a low proton temperature, a high proton density, a flux rope, and the ions with low charge states (Yao et al 2010;Lepri & Zurbuchen 2010;Song et al 2017). On the other hand, for normal solar winds not associated with ICMEs/MCs, the origin of their cold-dense plasma are not resolved.…”

The Distributions of Iron Average Charge States in Small Flux Ropes in Interplanetary Space: Clues to Their Twisted Structures

“…Similar to the case no. 8 as shown in Figure a, Song et al () also found the Q <Fe> in one case decreasing from high to low level, and this could be a manifestation of cold filament material in MCs (Song et al, ). However, cases with three peaks higher than 12 (similar to case no.…”

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

“…For example, the bimodal profile implies that the MFR exists prior to eruption; see Figure 8 in [37] for more details. In addition, the elemental abundances are not uniform within one cross section either [39]. Therefore, a spacecraft can detect different composition profiles when it crosses one MC along the blue and black arrows as shown in Figure 1B, which are located in the same cross section perpendicular to the axis but with different impact factors.…”

“…The charge states within ICMEs are frozen-in near the Sun [33], and the relative abundances of elements with different first ionization potentials (FIPs) are different obviously in the corona and photosphere [34,35]. As the composition does not alter during CME propagation to 1 AU and beyond [36], the in situ data are also employed to analyze the MFR formation [28,37,38] and plasma origin [39,40] of CMEs. So far, the most complete composition data of ICMEs are provided by the solar wind ion composition spectrometer (SWICS) aboard Advanced Composition Explorer (ACE) and Ulysses, which can provide the charge states and elemental abundances of ∼10 elements [41].…”