Chinese researchers from the Yunnan Observatories of the Chinese Academy of Sciences have made a groundbreaking discovery in the study of sunspots. By uncovering the structure of waves within sunspots, specifically in the chromosphere—the sun's outer layer—they have identified the forces driving what are known as 'umbral waves'.
Understanding umbral waves is crucial for enhancing our knowledge of solar magnetic field dynamics, energy transfer mechanisms, and space weather forecasting. These insights could lead to more accurate predictions of solar activity and its impacts on Earth.
Previously, scientists were uncertain whether these waves originated from external forces, such as sound waves traveling through air, or from the sunspot’s own magnetic and fluid movements. To investigate, the team employed the Interface Region Imaging Spectrograph alongside data from other telescopes to closely examine the waves in two sunspots.
In a pioneering discovery, the researchers identified two one-armed spiral wave patterns coexisting in the umbra—the dark center of the sunspot. These patterns can rotate in either the same direction or opposite ones.
Further analysis of the spatial distribution of the oscillation centers of these spiral wave patterns revealed that the chromospheric umbral waves repeatedly originate from areas with strong wave activity, particularly within the sunspot's darkest and most magnetically intense regions.
The study concludes that chromospheric umbral waves are likely excited by p-mode oscillations within the sun, similar to the resonant vibrations of a musical instrument initiated by the plucking of its strings.
This significant research was published in the journal Solar Physics on May 29.
Reference(s):
Secrets of sunspots: Chinese study uncovers force behind umbral waves
cgtn.com
