Radio dimming associated with filament eruptions in the meter and decimeter wavebands

¹ School of Earth and Space Sciences, Peking University, Beijing 100871, China
² Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100871, China
³ National Space Science Center, Chinese Academy of Sciences, Beijing 100871, China
⁴ Radio Science and Technology Center ( π Center), Chengdu 610041, China
⁵ Korea Astronomy and Space Science Institute, 34055 Daejeon, Republic of Korea
⁶ Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
⁷ Space Research and Technology Institute, Bulgarian Academy of Sciences, Acad. Georgy Bonchev Str., Bl. 1, 1113 Sofia, Bulgaria
⁸ School of Physics and Astronomy, Yunnan University, Kunming 650050, China
⁹ School of Space Science and Technology, Shandong University, Weihai 264209, China
¹⁰ Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS, Nanjing 210023, China
¹¹ School of Astronomy and Space Science, Nanjing University, Nanjing 210023, China

^⋆ Corresponding authors; huitian@pku.edu.cn, yanjingye@nssc.ac.cn

Received: 4 December 2024
Accepted: 17 January 2025

Abstract

Filament eruptions are considered to be a common phenomenon on the Sun and other stars, yet they are rarely directly imaged in the meter and decimeter wavebands. Using imaging data from the DAocheng solar Radio Telescope (DART) in the 150−450 MHz frequency range, we present two eruptive filaments that manifest as radio dimmings (i.e., emission depressions). Simultaneously, portions of these eruptive filaments are discernible as dark features in the chromospheric images. The sun-as-a-star flux curves of brightness temperature, derived from the DART images, exhibit obvious radio dimmings. The dimming depths range from 1.5% to 8% of the background level and show a negative correlation with radio frequencies and a positive correlation with filament areas. Our investigation suggests that radio dimming is caused by free-free absorption during filament eruptions obscuring the solar corona. This may provide a new method for detecting stellar filament eruptions.