Small-scale eruptions in the Sun   --- an ISSI team led by Jie Chen, Robertus Erdely and Nour Rawafi

Aim and Goals

Our over-arching aim with this ISSI programme is to leap forward in understanding the dynamic processes of different types of small-scale solar eruptions through the combined analysis of observations with high spatial, high temporal, and high spectral resolution with advanced numerical modeling. Specific goals to achieve this aim are:

(1) Study the formation mechanism of spicules, jets and brightening events.
(2) Analyze the relationship between spicules and plasma outflow and link it to the origin of solar wind.
(3) Identify the fine structures of spicules and brightenings, and pinpoint the key difference between spicules and jets.
(4) Clarify the heating mechanism of small-scale eruptions and the physics behind it.

Timeliness

The proposed work is extremely important and timely mainly because the necessary high-quality observations are only just becoming available. Data with unprecedented high-quality and high-resolution provided by a fleet of space telescopes (with support from ground-based telescopes) were very scarce in the past, but hold the key to uncover the different aspects of different types of small-scale eruptions. The unique combination of in-situ and remote sensing telescopes with a broad temperature coverage is paramount for this project and has only been available now. Combined with recent progress in models and ongoing research carried out by team members makes this project most timely. This ISSI team is uniquely positioned to undertake the challenging tasks proposed here.

Expected outcome

Besides the scientific progress made during the collaboration, the Team expects to publish 2-3 research papers in leading field-specific journals (e.g., ApJ(L), A&A, Solar Physics, JGR or PRL) and 1-2 reviews. If it is possible, we also aim for one more comprehensive view is in Year 1 in the Chinese international journal of Res. Astron. Astrophys, and a more concise one in is in Year 2 in Space Sci. Rev.

We also anticipate that our project will facilitate further funded scientific collaborations and joint grant proposal activities at bi- or multi-lateral levels between Team members, which will allow the participants to continue partnership through, e.g., Horizon Europe or Lorentz/Kavli Center projects, or various national collaborative programmes (e. g. Royal Society/UK, NSFC or PIFI in China). The resulting long-term collaborations would enable i) further leaps forward and new insights into deeper understanding of plasma-astrophysical dynamics, and ii) a further enhanced capability of grasping the observational constraints of space- and ground-based observations.

The two years of this coordinated international effort will provide us with a sought-after opportunity to, first, set up a discussion on the above problems among leading experts and, second, considerably improve our insight into the formation of an astrophysical (solar) plasma jet.

Team

Twelve (12) international scientists with complementary expertise (plus 2-3 additional early-career researchers through the Young Scientist [YS] scheme, as per guidelines, once the proposal is approved).

List of confirmed participants: Chen, Jie (China); Erdélyi, Robertus (UK) ; Rawafi, Nour (USA); Chatterjee, Piyali (India); Korsos, Marianna Brigitta (Hungary); Kuridze, David (USA); Liu, Jiajia (China); Nelson, Chris (ESA); Pereira, Tiago (Norway); Sterling, Alphonse (USA); Su, Jiantao (China); Tian, Hui China)

   Picture 1: A group photo of some members in June 2024

Project schedule

The 2-yr project is proposed to begin Jan 2025. Two one-week meetings are planned, one in Beijing in Year 1 and another in Bern in Year 2.

We anticipate the first meeting taking place in the first half of 2025. Between the first and second meeting we will address O1 and O2 to achieve the most promising observational and modelling (data or computational) approaches to be agreed upon in the first meeting. The investigation findings will be consolidated during the second meeting. The outcome of this synergy will form the basis of the proposed second article intended for Space Sci. Rev. The Team Leaders, each with their own expertise as, but in coherence with the others, will monitor the progress. If necessary, additional e-conference calls will be arranged for coordination. At the second meeting, we will also analyze and synthesize the results of the research devised since the first meeting, and compile the outline of the second review text. It is also proposed to hold an invitation-only externally funded workshop adjacent to the second one-week ISSI meeting where we will further discuss with external experts the open issues and their potential solutions.

Added value provided by ISSI

The Team consists of scientists from a carefully selected but wide range of institutions from all over the world, located in seven different countries. The stimulating research environment and excellent facilities provided by ISSI, already experienced by several Team Members, together with the convenient geographical location for the Chinese/Asian participants, makes this site ideal for the proposed programme. We feel that, the most important benefits are to i) get together face-to-face and exploit the ii) complementary expertise of the team (e.g., MHD modelling, image analysis and processing) to stage focused and detailed discussions dedicated to the aims/objectives iii) in a relaxed and friendly environment. Such an environment is often most beneficial to make true progress, ironing out differences in views and raising in-depth further questions, not to mention getting down and resolving the most challenging details that impede progress today. The progress made will be exploited for further synergistic activities, possibly at a much higher effort level. Previous remarkable examples of successful collaborations are the two Chinese-European solar meetings (2017 and 2019) that signaled a new era in Chinese-European collaborations. Last, but not least, our Team proposes to lay the groundwork towards another joint Chinese-European gathering, more focused on the dynamics of astrophysical plasmas.

Venue

The Team will have its two scheduled Project Meetings (PMs) at ISSI/ISSI-BJ, respectively, while adjacent to the second meeting we propose to hold a closed, by invitation only, externally funded 3-day mini-Workshop (max 25 participants in total) in Beijing, to shape a view on the future course of the initiative. Invitation of a few self-supported experts is envisaged.

References:

1. Brueckner, G. E., & Bartoe, J. D. F. 1983, ApJ, 272, 329
2. Chen, J., Su, J., Yin, Z., et al. 2015, ApJ, 815, 71
3. Chen, J., Su, J., Deng, Y., and Priest, E. R. 2017, ApJ, 840, 54
4. Chen J, Erdélyi R, Liu J, Deng Y, et al. 2022, Front. Astron. Space Sci., 8:786856
5. Cirtain, J. W., Golub, L., Lundquist, L., et al. 2007, Sci, 318, 1580
6. Dey, S., Chatterjee, P., O. V. S. N., M., et al. 2022, Nat. Phys., 18, 595
7. De Pontieu, B., et al. 2011, Science, 331, 55–58
8. Ellerman, F. 1917, ApJ, 46, 298
9. Harrison, R. A. 1997, Sol. Phys., 175, 467
10. Nelson, C., Auchère, F., Aznar Cuadrado, R. 2023, A&A, 676, A64
11. Pereira, T. M. D., De Pontieu, B., Carlsson, M. 2012, ApJ, 759, 18
12. Samanta, T., Tian, H., Yurchyshyn, V., et al. 2019, Science, 366, 890–894
13. Schmieder, B., Guo, Y., Moreno-Insertis, F., et al. 2013, A&A, 559, A1
14. Shen, Y. 2021, Proc. R. Soc. A, 477:20200217
15. Shibata, K., Nitta, N., Strong, K. T., et al. 1994, ApJL, 431, L51
16. Shibata, K., Ishido, Y., Acton, L. W., et al. 1992, PASJ, 44, 173
17. Sterling, A. C., Moore, R. L., Falconer, D. A., & Adams, M. 2015, Natur, 523, 437
18. Sterling, A. C., Moore, R. L., Panesar, N. K., et al. 2020, ApJ, 889, 187
19. Sterling, A. C., Schwanitz, C., Harra, L. K., et al. 2022, ApJ, 940, 85
20. Young, P. R., Tian, H., Peter, H., et al. 2018, Space Sci. Rev., 214, 120
21. Zhang, Q. M., Ji, H. S., and Su, Y. N. 2016, Sol. Phys., 291, 859–876