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Abstract We report the detection of transverse magnetohydrodynamic waves, also known as Alfvénic waves, in the chromospheric fibrils of a solar-quiet region. Unlike previous studies that measured transversal displacements of fibrils in imaging data, we investigate the line-of-sight (LOS) velocity oscillations of the fibrils in spectral data. The observations were carried out with the Fast Imaging Solar Spectrograph of the 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory. By applying spectral inversion to the Hαand Caii8542 Å line profiles, we determine various physical parameters, including the LOS velocity in the chromosphere of the quiet Sun. In the Hαdata, we select two adjacent points along the fibrils and analyze the LOS velocities at those points. For the time series of the velocities that show high cross-correlation between the two points and do not exhibit any correlation with intensity, we interpret them as propagating Alfvénic wave packets. We identify a total of 385 Alfvénic wave packets in the quiet-Sun fibrils. The mean values of the period, velocity amplitude, and propagation speed are 7.5 minutes, 1.33 km s−1, and 123 km s−1, respectively. We find that the detected waves are classified into three groups based on their periods, namely, 3, 5, and 10 minute bands. Each group of waves exhibits distinct wave properties, indicating a possible connection to their generation mechanism. Based on our results, we expect that the identification of Alfvénic waves in various regions will provide clues to their origin and the underlying physical processes in the solar atmosphere.
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This content will become publicly available on May 8, 2026
Multi-height Study of the Chromospheric Inverse Evershed Flow and its Association with Photospheric Flows
Abstract We analyzed the inverse Evershed flow (IEF) around a sunspot (NOAA 13131) using line scan observations in the Fei6173 Å and Caii8542 Å spectral lines, complemented with data products from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager. Line-of-sight (LOS) velocities were obtained for different bisector levels in both spectral lines. Additionally, the Caii8542 Å spectra were inverted using the Non-LTE Inversion COde using the Lorien Engine (or NICOLE) to retrieve the temperature and velocity stratification over different layers of the lower solar atmosphere. The IEF evolved dynamically in time and with height in the solar atmosphere. The flow speed associated with the IEF channels was on the order of 8 km s−1in the upper chromosphere, which decreased in the lower layers of the atmosphere. The flow was traced to the lower chromosphere in LOS velocity maps and the upper photosphere in intensity images. The temperature enhancements associated with the IEF were up to 300 K at logτ≈ −2 and 800 K at logτ≈ −6 near the end point of one channel. The overall appearance of the flow along the IEF channels seems consistent with a siphon flow model. We investigated the association of the IEF with the photospheric Evershed flow, but no obvious connection was found in our analysis. We also analyzed the effect of the IEF on moving magnetic features (MMF) selected near and away from IEF channels. MMFs moved radially outward with velocities in the 0.2–1 km s−1range, with no apparent association with the IEF.
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- Award ID(s):
- 2050340
- PAR ID:
- 10617178
- Publisher / Repository:
- The Astrophysical Journal
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 984
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 164
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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