Linear Polarimetry Maps Complex Solar Corona Structure During 2024 Eclipse

Research utilizing high-dynamic-range (HDR) multi-band linear polarimetry during the total solar eclipse of April 8, 2024, provides a vital ground-based diagnostic tool for mapping plasma morphology and magnetic topology within the inner and middle solar corona. Observations conducted from Dallas, Texas, USA, near solar maximum, utilized a full-frame color CMOS detector paired with an 80 mm refractor to record multi-band Red, Green, and Blue (RGB) images simultaneously. To capture the extreme dynamic range of the solar disk, a 9-step exposure bracket was employed, ranging from 1/800 seconds to 1/3 second. These images were recorded across three distinct polarizer orientations: $\text{-60}^{\circ}$, $0^{\circ}$, and $+60^{\circ}$.

The study developed an end-to-end data-reduction pipeline to extract reliable polarimetric signals, which required rigorous observational calibration, spatial co-alignment, and noise reduction. The pipeline began with a novel astrometric registration framework. This framework reconstruct Sun-centric solar-disk coordinates by employing lunar-limb fitting, catalog star plate-solving, and ephemeris displacement calculations, achieving sub-pixel alignment. This precision is essential for accurately mapping fine-scale coronal structures.

Following astrometric registration, the second stage involved photometrically linear exposure-normalization HDR image synthesis. This process addresses the challenges of combining images from the 9-step exposure bracket to create a single, coherent representation of the solar disk that accurately reflects the true light distribution. The final stage of the data processing involved Multi-scale Gaussian Normalization (MGN) coupled with Polarization-to-RGB chromatic mapping. MGN enhances structural details by applying Gaussian filters at various scales, while the chromatic mapping transforms abstract polarimetric data into visually interpretable maps of magnetic topology.

The application of this sophisticated methodology revealed a complex solar-maximum coronal topology. The resulting structurally enhanced polarization composites allowed researchers to identify and trace helmet streamers, which are large-scale structures associated with coronal holes and magnetic loops. Furthermore, the analysis successfully traced fine-scale striations out to approximately 3 solar radii ($3~R_{\odot}$), providing a high-resolution view of the magnetic field organization far into the solar atmosphere. This framework establishes a high-resolution, photometrically calibrated dataset ready for subsequent analyses, including polarized brightness (pB) and electron density inversions.

This research, published in Solar Physics, Volume 301, article number 163, confirms the utility of ground-based linear polarimetry during total solar eclipses. By meticulously documenting the entire workflow—from multi-band RGB image capture to complex astrometric registration and HDR synthesis—the study provides a comprehensive blueprint for future solar physicists. This work underscores the power of combining advanced optical instrumentation with cutting-edge computational image processing techniques to unlock the secrets of the Sun’s magnetic environment.

Subject of Research: Mapping solar corona plasma morphology and magnetic topology using high-dynamic-range linear polarimetry.

Article Title: Linear Polarimetry of the Solar Corona During the Total Solar Eclipse of 8 April 2024: Multi-Band Observations and HDR Imaging

Article References: Singh, S., Sharma, P., Arora, B., Burman, S., & Gandhi, C. (2026). Linear Polarimetry of the Solar Corona During the Total Solar Eclipse of 8 April 2024: Multi-Band Observations and HDR Imaging. Solar Physics, 301(10), Article 163. https://doi.org/10.1007/s11207-026-02763-6

Image Credits: AI Generated

DOI: 10.1007/s11207-026-02763-6

Keywords: Solar Physics, Solar Corona, Total Solar Eclipse, Linear Polarimetry, HDR Imaging, Plasma Morphology, Magnetic Topology, Space Weather, Coronal Structure, Linear, Polarimetry, Solar