Momchil Molnar (Southwest Research Institute)

Date: Tue. November 11th, 2025, 11:30 am-12:30 pm

The Sun as the ultimate astrophysical laboratory in our
backyard

Our closest star, besides supporting life on our planet, is also an extremely useful
benchmark for many aspects of astrophysics, conveniently located in our Solar System’s
backyard. Moreover, the Sun can generate hazardous space weather conditions that pose risks
to our technologically dependent society, underscoring the urgent need to improve our
understanding of its behavior. In this talk, I will describe our modern understanding of the Sun
as the driver of the heliosphere — the region of space where the solar wind dominates over the
interstellar medium. I will discuss the physical processes shaping the heliosphere and driving
space weather, with an emphasis on the Sun, and how we are transitioning from gaining
fundamental physical understanding toward developing predictive capabilities for space
weather. For example, we still do not fully understand the origin of the 11-year cycle of the solar
dynamo or how its cyclic behavior manifests as differing space climate conditions over
consecutive solar cycles. Solar eruptions, driven by the solar magnetic field, produce some of
the most adverse space weather hazards, but we cannot predict them very well. Current
research on their magnetic nature is bringing us closer to understanding their triggering
mechanism, but many open questions remain. Looking farther into the Universe — to
understand other stars and their habitable zones — we need the aforementioned understanding
of how the hot outer layers of the Sun are heated (also known as the coronal heating problem),
whose magnetic origin still puzzles scientists.