Salvato in:
| Autori principali: | , , , |
|---|---|
| Natura: | Preprint |
| Pubblicazione: |
2025
|
| Soggetti: | |
| Accesso online: | https://arxiv.org/abs/2512.21872 |
| Tags: |
Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
|
| _version_ | 1866918264028790784 |
|---|---|
| author | Kumar, Aman Priyadarshi M. Shetye, Juie Sellers, Sean G. Christian, Damian J. |
| author_facet | Kumar, Aman Priyadarshi M. Shetye, Juie Sellers, Sean G. Christian, Damian J. |
| contents | We present a uniform analysis of compact Ca II K (3934 Å) brightenings that occur near flare kernels and assess their value as short-lead indicators of solar flare onset. Using high-cadence imaging from the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument at the Dunn Solar Telescope (DST), we examine eight flare sequences (seven C-class and one B-class) obtained between 2021 and 2025. Fixed, detector-coordinate regions of interest are used to generate mean-intensity light curves, which are detrended and smoothed to isolate impulsive brightenings. In every event, a compact Ca II K brightening is detected within or adjacent to the flaring region that peaks 10--45 min before the primary kernel and the corresponding rise in GOES 1--8 Å flux. The measured temporal offsets scale with the deprojected separation between the brightening and flare kernels, implying an apparent propagation speed of $\sim$30--35 km s$^{-1}$ that is consistent with chromospheric reconnection. Complementary Spectropolarimeter for Infrared and Optical Regions (SPINOR) spectropolarimetry for one event shows topological reconfiguration from closed to open or extended connectivity, supporting a reconnection-driven origin. These results demonstrate that compact Ca II K brightenings are reproducible, physically meaningful precursors to flare onset. Their simplicity and cadence make them attractive chromospheric indicators, and future work will evaluate their predictive skill alongside established UV/EUV and magnetic diagnostics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_21872 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Compact Ca II K Brightenings Precede Solar Flares: A Dunn Solar Telescope Pilot Study Kumar, Aman Priyadarshi M. Shetye, Juie Sellers, Sean G. Christian, Damian J. Solar and Stellar Astrophysics We present a uniform analysis of compact Ca II K (3934 Å) brightenings that occur near flare kernels and assess their value as short-lead indicators of solar flare onset. Using high-cadence imaging from the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument at the Dunn Solar Telescope (DST), we examine eight flare sequences (seven C-class and one B-class) obtained between 2021 and 2025. Fixed, detector-coordinate regions of interest are used to generate mean-intensity light curves, which are detrended and smoothed to isolate impulsive brightenings. In every event, a compact Ca II K brightening is detected within or adjacent to the flaring region that peaks 10--45 min before the primary kernel and the corresponding rise in GOES 1--8 Å flux. The measured temporal offsets scale with the deprojected separation between the brightening and flare kernels, implying an apparent propagation speed of $\sim$30--35 km s$^{-1}$ that is consistent with chromospheric reconnection. Complementary Spectropolarimeter for Infrared and Optical Regions (SPINOR) spectropolarimetry for one event shows topological reconfiguration from closed to open or extended connectivity, supporting a reconnection-driven origin. These results demonstrate that compact Ca II K brightenings are reproducible, physically meaningful precursors to flare onset. Their simplicity and cadence make them attractive chromospheric indicators, and future work will evaluate their predictive skill alongside established UV/EUV and magnetic diagnostics. |
| title | Compact Ca II K Brightenings Precede Solar Flares: A Dunn Solar Telescope Pilot Study |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2512.21872 |