Speaker
Description
Studying magnetic flux ropes is crucial for understanding the origin and evolution of Coronal Mass Ejections (CMEs), as these twisted magnetic structures often serve as the core configuration driving CMEs from the solar corona. On November 9, 2021, the Metis coronagraph (Antonucci et al. 2020) on-board ESA Solar Orbiter mission, observed a slow erupting flux rope, when the spacecraft was at 0.88 AU and near the inferior conjunction with the Sun, thus enabling combined observations with SOHO/LASCO-C2. The erupting structure seems to be associated with the Active Region (AR) 12895 (26°N, 28°E), which had a simple bipolar magnetic configuration, and exhibited gradual changes in the coronal loop morphology, though no flare was detected.
The eruption manifested as a faint, bubble-like structure, slightly brighter than the surrounding ambient corona, and was observed in both visible light (VL) and ultraviolet (UV) Lyman-alpha channels of Metis. The morphology – characterized by a diffuse bright front and a weaker core - suggests that what we observed was a slowly expanding, hollow flux-rope. Base-difference images enhanced the visibility of the front and the core regions, revealing a darker cavity. The whole structure was first detected in LASCO-C2 data, with the core located at a heliocentric distance of 3.5 $R_{\odot}$ around 18:00 UT and entered in the Metis field-of-view (> 5 $R_{\odot}$) shortly after midnight.
Kinematic analysis of the Metis images indicates a propagation velocity of about 160 km/s for the core, with a weak acceleration (< 10 km/s$^2$). The flux-rope expansion was tracked across LASCO and Metis FOVs, displaying an overall elliptical geometry of both front and internal cavity. The Metis VL and UV Lyman-α images have been analysed using the direct ratio technique (Bemporad 2022) to obtain 2D maps of electron temperature inside the expanding flux-rope. The thermodynamic evolution of expanding flux ropes is indeed interesting to study, since many studies based mainly on SOHO/UVCS data have demonstrated the existence of unidentified physical processes responsible for additional heating against adiabatic cooling. Our results show – as expected – a gradual cooling of the embedded plasma during expansion, and we are now quantifying the possible additional heating during the expansion.
These preliminary results offer insights into the dynamics and thermal evolution of CMEs, which can potentially modify their interplanetary evolution and therefore their eventual impact on Earth.
| Do you plan to attend in-person or online? | In-person |
|---|
