Solar Disappearing Filament Inside a Coronal Hole

Abstract

Based on Y ohkoh/SXT, SOHO/EIT images and movies, as well as on Ha, He I 10830 heliograms A and other relevant data, we analyze an event of 1999 December 28, which is interesting in at least two aspects. (1) A major horseshoe-shaped Ha Ðlament appeared to be located within a large transequatorial coronal hole (CH) in the eastern hemisphere. (2) This Ðlament subsequently disappeared, with its eruption combined with a number of dynamic phenomena, including large-scale ones. The probable location of the Ðlament inside the CH was conÐrmed in detail by calculations of the open Ðeld regions and, for the Ðrst time, the quasi-separatrix layers in the global solar magnetic Ðeld. The Ðlament eruption was accompanied by signiÐcant evolution of the soft X-ray and EUV-emitting structures inside the CH as well as by a coronal mass ejection. The analysis indicates that CHs need not have the simple and uniform structure normally assumed and can sometimes contain local areas with low-altitude closed magnetic Ðelds. It demonstrates also that the erupting Ðlament inside the CH was a part of a much more global, evolving magnetic structure associated with activity extending through at least the entire eastern half of the disk.

Source-region characteristics of anemone active regions in the ascending phase of solar cycle 24

“…However, in the year 2012, this percentage was highest (Table 1); over two-thirds of the anemone regions were associated with a filament (78.57%) and nearly one-half with any flare event (50.0%), which included the two most energetic (M class) eruptive flares in our dataset. The link between anemone regions and filaments is also evident from previously reported cases for the anemone regions (Bravo et al 1998;Chertok et al 2002;Asai et al 2009). Among all the reconnection and flare events in our study, a majority of around 88.8% were C class events (16 out of 18), while only a small number of events were associated with M class events (2 out of 18).…”

“…This is primarily due to the presence of open field lines in the vicinity of AR that can influence the propagation of CMEs in the interplanetary medium with high-speed streams, and/or reconnection at the Earth's magnetosphere. Bravo et al (1998) reported cases with intense geomagnetic storms and highlighted their relationship with corresponding active regions adjacent to the coronal holes, while Chertok et al (2002) reported filament eruptions associated with the anemone regions. Furthermore, these features were also found to be linked with the disappearance of solar wind at 1 AU (Janardhan et al 2008), and generation of (slow) solar wind (He et al 2010;Macneil et al 2019) due to interaction between closed-and open-field lines in the proximity of anemone regions.…”

Is There Any Evident Effect of Coronal Holes on Gradual Solar Energetic Particle Events?

“…These so-called Kitt Peak CHs, are identified through the He 10830 8 spectral line and usually treated as the bases of CHs (Harvey & Recely 2002). Many authors use them to study the boundaries of CHs and some related phenomena (e.g., Zhao et al 1999;Chertok et al 2002). Soft X-ray data from the Yohkoh SXT instrument are also often used to study CHs.…”

“…EIT 284 8 images of CHs are almost as informative as the soft X-ray emission (Moses et al 1997;Chertok et al 2002), which also has been widely used to study CHs.…”

Characteristics of Anemone Active Regions Appearing in Coronal Holes Observed with theYohkohSoft X‐Ray Telescope

“…A small anemone AR in a CH probably evolves into a polar plume as one of their flux that has the opposite magnetic polarity to the CH gradually cancels out, and generates jets. Anemone ARs sometimes generate filament eruptions (Chertok et al 2002), and even large flares and/or coronal mass ejections (Verma 1998;Liu & Hayashi 2006;Liu 2007;Asai et al 2007). For these cases, eruptions occurring in CHs easily travel keeping the speeds by having an advantage of high speed solar wind from CHs.…”