Spectroscopic Detection of Alfvénic Waves in the Chromosphere of Sunspot Regions

Chae, Jongchul and Cho, Kyuhyoun and Nakariakov, Valery M. and Cho, Kyung-Suk and Kwon, Ryun-Young (2021) Spectroscopic Detection of Alfvénic Waves in the Chromosphere of Sunspot Regions. The Astrophysical Journal Letters, 914 (1). L16. ISSN 2041-8205

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Abstract

Transverse magnetohydrodynamic waves often called Alfvénic (or kink) waves have been often theoretically put forward to solve the outstanding problems of the solar corona like coronal heating, solar wind acceleration, and chemical abundance enhancement. Here we report the first spectroscopic detection of Alfvénic waves around a sunspot at chromospheric heights. By analyzing the spectra of the Hα line and Ca ii 854.2 nm line, we determined line-of-sight velocity and temperature as functions of position and time. As a result, we identified transverse magnetohydrodynamic waves pervading the superpenumbral fibrils. These waves are characterized by the periods of 2.5 to 4.5 minutes, and the propagation direction parallel to the fibrils, the supersonic propagation speeds of 45 to 145 km s−1, and the close association with umbral oscillations and running penumbral waves in sunspots. Our results support the notion that the chromosphere around sunspots abounds with Alfvénic waves excited by the mode conversion of the upward-propagating slow magnetoacoustic waves.

Item Type: Article
Subjects: Afro Asian Library > Physics and Astronomy
Depositing User: Unnamed user with email support@afroasianlibrary.com
Date Deposited: 10 May 2023 08:49
Last Modified: 18 Jun 2024 07:34
URI: http://classical.academiceprints.com/id/eprint/768

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