Solar eruptions: preparing for the next generation multi-waveband coronagraphs
Although CMEs have been intensively studied in the past, their origin is still not fully understood: CMEs are associated with regions of strong magnetic field (e.g. active regions), but we still have very little information on the properties of the source magnetic structure and plasma within the CME source region, and on the precise sequence of events leading to an eruption. in the intermediate corona (above ~ 1.7 solar radii) CMEs have been observed mainly from space-based (e.g. SOHO/LASCO, STEREO/COR1-2) and ground-based (e.g. Mauna Loa MarkIV and CoMP) coronagraphs, primarily in the polarized and unpolarised VL emission from coronal plasmas. Only the SOHO/UVCS provided the UV spectra in a limited field-of-view (FOV) and usually not accompanied by VL observations, and revealed unexpected thermodynamic behaviours, with plasma heating processes exceeding adiabatic cooling whose origin is still unidentified. Nevertheless, the only CME plasma physical parameters usually investigated with coronagraphic data are limited to the electron density, and to large-scale CME kinematical properties, even if spectro-polarimetric observations have proven their capability to derive other plasma parameters. For the above reasons, many science questions on CMEs remain open.
Currently available coronagraphic data have already proven their potential, but also their limits. Fortunately this situation will change in the near future with the new generation multi-waveband coronagraphs, whose new data will allow to answer most of the above questions. In particular, over the next few years, the following new coronagraphic instruments (among others) will become operational in space and on-ground:
Thanks to their multi-wavelength capabilities, all the above instruments will really enable a new perspective on solar eruptions. However, only the combination of these data with new observations acquired at the same time in different EUV, UV and visible spectral ranges can really enrich our knowledge of solar eruptions.
To efficiently extract new information from data of the future coronagraphs listed above and to answer the aforementioned compelling science questions which drive this Project, it is necessary to develop new diagnostic techniques and tools, which are anchored in the existing data. For this reason, the Project will focus on the early phases of the CME formation and propagation in the corona, a field where extended data archives from space-based SOHO, STEREO, SUVI, and ground-based COMP, KCOR, etc, can be effectively explored. Moreover, because many different spectral bands will be observed, it is necessary to provide and analyse synthetic observables from various MHD simulations. These main objectives will be achieved with the goals listed below.
Due to the ongoing pandemic emergency, the first meetings have been organized remotely with Zoom. The regular "face-to-face" meetings will be organized as soon as possible; we plan to meet for two one-week meetings at ISSI-Beijing.
Remote meetings: January 13, January 20, January 27
Almost all the Team members are actively involved and have important roles in the different instruments/projects mentioned above, and in particular in Solar Orbiter/Metis (Bemporad, Heinzel, Pagano, Susino, and Jejcic), PROBA-3/ASPIICS (Bemporad, Heinzel, Jejcic, and Mierla), ASO-S/LST (Feng, and Li), Aditya-L1/VELC (Banerjee), and UCoMP (Tian). Moreover, the Team members have great experience in many different research fields including the analysis of coronagraphic VL images and EUV-UV images and spectra of CMEs (Banerjee, Bemporad, Feng, Mierla, Susino), analysis of prominence observations and non-LTE radiative transport modelling (Heinzel, Jejcic), numerical simulations and synthetic data (Pagano, Lin), derivation of coronal magnetic fields (Tian).
