High-resolution Imaging Spectroscopy of a Tiny Sigmoidal Minifilament Eruption

Document Type

Article

Publication Date

10-1-2024

Abstract

Minifilament eruptions producing small jets and microflares have mostly been studied based on coronal observations at extreme-ultraviolet and X-ray wavelengths. This study presents chromospheric plasma diagnostics of a quiet-Sun minifilament of size ∼ 2″ × 5″ with a sigmoidal shape and an associated microflare observed on 2021 August 7 17:00 UT using high temporal and spatial resolution spectroscopy from the Fast Imaging Solar Spectrograph (FISS) and high-resolution magnetograms from the Near InfraRed Imaging Spectropolarimeter (NIRIS) installed on the 1.6 m Goode Solar Telescope at Big Bear Solar Observatory. Using FISS Hα and Ca ii 8542 Å line spectra at the time of the minifilament activation we determined a temperature of 8600 K and a nonthermal speed of 7.9 km s−1. During the eruption, the minifilament was no longer visible in the Ca ii 8542 Å line, and only the Hα line spectra were used to find the temperature of the minifilament, which reached 1.2 × 104 K and decreased afterward. We estimated thermal energy of 3.6 × 1024 erg from the maximum temperature and kinetic energy of 2.6 × 1024 erg from the rising speed (18 km s−1) of the minifilament. From the NIRIS magnetograms we found small-scale flux emergence and cancellation coincident with the minifilament eruption, and the magnetic energy change across the conjugate footpoints reaches 7.2 × 1025 erg. Such spectroscopic diagnostics of the chromospheric minifilament complement earlier studies of minifilament eruptions made using coronal images.

Identifier

85206452955 (Scopus)

Publication Title

Astrophysical Journal

External Full Text Location

https://doi.org/10.3847/1538-4357/ad74f3

e-ISSN

15384357

ISSN

0004637X

Issue

1

Volume

974

Grant

AGS-2114201

Fund Ref

Seoul National University

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