2024/03/15 by Yingjie Zhu, Zhu, Yingjie, S. R. Habbal +13 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2403.10363
openalex publication_date 2024/03/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The spectroscopic observations presented here were acquired during the 2017 August 21 total solar eclipse with a three-channel partially multiplexed imaging spectrometer (3PAMIS) operating at extremely high orders (> 50). The 4 R_\odot extent of the slit in the North-South direction scanned the corona starting from the central meridian out to approximately 1.0 R_\odot off the east limb throughout totality. The line widths and Doppler shifts of the Fe X (637.4 nm) and Fe XIV (530.3 nm) emission lines, characteristic of 1.1 × 106 K and 1.8 × 106 K electron temperatures respectively, varied across the different coronal structures intercepted by the slit. Fe XIV was the dominant emission in the closed fields of an active region and the base of a streamer, with relatively constant 20 - 30 km s-1 line widths independent of the height. In contrast, Fe X emission exhibited broader (>40 km s-1) line widths in open fields which increased with height, in particular in the polar coronal hole. Inferences of line widths and Doppler shifts were consistent with extreme ultraviolet (EUV) observations from Hinode/EIS, as well as with the near-infrared Fe XIII 1074 nm line observed by CoMP. The differences in the spectral line widths between distinct coronal structures are interpreted as an indication of the predominance of wave heating in open structures versus localized heating in closed structures. This study underscores the unparalleled advantages and the enormous potential of TSE spectroscopy in measuring line widths simultaneously in open and closed fields at high altitudes, with minimal exposure times, stray light levels, and instrumental widths.