Solar flares are the most powerful explosions in our solar system, releasing up to 10³²–10³³ ergs of energy within ~10–1000 seconds. These events are driven by the sudden release of energy stored in non-potential magnetic fields, triggered by magnetic reconnection. The Standard Flare Model—a two-dimensional (2D) framework—has significantly advanced our understanding of the physical processes occurring across various layers of the solar atmosphere during flares.

In the first part of this seminar, I will present representative observations that highlight both the strengths and limitations of the standard flare model, along with discussions on key magnetic field topologies. Special focus will be placed on circular ribbon flares (CRFs), a morphologically distinct class of events often accompanied by parallel ribbons, remote brightenings, and jet activity. The complex morphology of CRFs will be examined within the context of three-dimensional (3D) magnetic null-point topologies, offering insight into the physical conditions that govern whether an eruption manifests as a jet, a confined flare, or a coronal mass ejection (CME).

In the latter part of the seminar, I will focus on contemporary X-ray observations of solar flares. I will emphasize high spectral resolution measurements from the Solar X-ray Monitor (XSM) onboard Chandrayaan-2, which enable the investigation of multi-scale phenomena ranging from microflares to large eruptive flares. Notably, XSM has detected intriguing sub-A-class microflares occurring outside active regions, which will also be briefly discussed. Recent collaborative efforts using XSM/Chandrayaan-2 and STIX/Solar Orbiter to study flares across different scales further enrich our understanding of flare energetics and dynamics.