Estimating the early propagation direction of the coronal mass ejection with DIRECD during the severe event on May 8 and for the follow-up event on June 8, 2024

¹ Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, 121205 Moscow, Russia
² University of Graz, Institute of Physics, Universitätsplatz 5, 8010 Graz, Austria
³ University of Graz, Kanzelhöhe Observatory for Solar and Environmental Research, Kanzelhöhe 19, 9521 Treffen, Austria
⁴ University of Zagreb, Faculty of Geodesy, Hvar Observatory, Kaciceva 26, HR-10000 Zagreb, Croatia
⁵ NorthWest Research Associates, 3380 Mitchell Lane, Boulder, 80301 CO, USA

^⋆ Corresponding author; shantanu.jain@skoltech.ru

Received: 20 September 2024
Accepted: 22 October 2024

Abstract

Context. On May 8, 2024, the solar active region 13664 produced an X-class flare, several M-class flares, and multiple coronal mass ejections (CMEs) directed towards Earth. The initial CME resulted in coronal dimmings, which are characterized by localized reductions in extreme-ultraviolet (EUV) emissions and are indicative of mass loss and expansion during the eruption. On June 8, 2024, after one solar rotation, the same active region produced another eruptive M-class flare that was followed by coronal dimmings that were observed by the Solar Dynamics Observatory (SDO) and the Solar Terrestrial Relations Observatory (STEREO) spacecraft.

Aims. We analyzed the early CME evolution and propagation direction from the expansion of the coronal dimming observed low in the corona using the method called dimming inferred estimation of the CME direction (DIRECD).

Methods. DIRECD derived the key parameters of the early CME propagation from the expansion behavior of the associated coronal dimming at the end of its impulsive phase by generating a 3D CME cone model whose orthogonal projection on the solar sphere matches the dimming geometry. To validate the resulting 3D CME cone, we compared the CME properties derived in the low corona with white-light coronagraph data.

Results. Using DIRECD, we find that the CME on May 8, 2024 expands close to radially, with an inclination angle of 7.7°, an angular width of 70°, and a cone height of 0.81 R_sun, which was derived at the end of the impulsive dimming phase, and for which the CME showed connections to the dimming and still left footprints in the low corona. It was inclined 7.6° north in the meridional plane and 1.1° east in the equatorial plane. The CME on June 8, 2024, after one solar rotation, was inclined by 15.7° from the radial direction, had an angular width of 81°, and had a cone height of 0.89 R_sun. The CME was inclined 6.9° south in the meridional plane and 14.9° west in the equatorial plane. A validation with white-light coronagraph data confirmed the accuracy of the 3D cone by matching the CME characteristics and projections with STEREO-A COR2 observations.

Conclusions. Our study demonstrates that by tracking low coronal signatures such as the coronal dimming expansion in 2D for the May and June 2024 CMEs, we can estimate the 3D CME direction early in the CME evolution. This provides early lead times for mitigating adverse space weather impacts.