The relationship between the 5-min oscillation and 3-min oscillations at the umbral/penumbral sunspot boundary

Zhou, Xinping; Liang, Hong-Fei

doi:10.1007/s10509-016-3000-0

Cited by 10 publications

(4 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pronounced 3-min fluctuations have often been observed in the line-of-sight velocity and/or intensity signals, in both quiet and active regions, through chromospheric spectral lines such as Ca II H & K [27][28][29][30], Ca II infrared triplet [30][31][32][33], Hα [34], He I 1083 nm [28,35,36] and Mg II h & k [37]. In the quiet Sun, while the 3-min oscillations have been shown in many observations of the low-to-mid chromosphere (or using relatively broad-band filters), a lack of such fluctuations in intensity image sequences of Hα line-core observations have also been reported [38].…”

Section: Introductionmentioning

confidence: 99%

An overall view of temperature oscillations in the solar chromosphere with ALMA

Jafarzadeh

Wedemeyer

Fleck

et al. 2020

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

By direct measurements of the gas temperature, the Atacama Large Millimeter/submillimeter Array (ALMA) has yielded a new diagnostic tool to study the solar chromosphere. Here, we present an overview of the brightness-temperature fluctuations from several high-quality and high-temporal-resolution (i.e. 1 and 2 s cadence) time series of images obtained during the first 2 years of solar observations with ALMA, in Band 3 and Band 6, centred at around 3 mm (100 GHz) and 1.25 mm (239 GHz), respectively. The various datasets represent solar regions with different levels of magnetic flux. We perform fast Fourier and Lomb–Scargle transforms to measure both the spatial structuring of dominant frequencies and the average global frequency distributions of the oscillations (i.e. averaged over the entire field of view). We find that the observed frequencies significantly vary from one dataset to another, which is discussed in terms of the solar regions captured by the observations (i.e. linked to their underlying magnetic topology). While the presence of enhanced power within the frequency range 3–5 mHz is found for the most magnetically quiescent datasets, lower frequencies dominate when there is significant influence from strong underlying magnetic field concentrations (present inside and/or in the immediate vicinity of the observed field of view). We discuss here a number of reasons which could possibly contribute to the power suppression at around 5.5 mHz in the ALMA observations. However, it remains unclear how other chromospheric diagnostics (with an exception of H α line-core intensity) are unaffected by similar effects, i.e. they show very pronounced 3-min oscillations dominating the dynamics of the chromosphere, whereas only a very small fraction of all the pixels in the 10 ALMA datasets analysed here show peak power near 5.5 mHz. This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.

show abstract

Section: Introductionmentioning

confidence: 99%

An overall view of temperature oscillations in the solar chromosphere with ALMA

Jafarzadeh

Wedemeyer

Fleck

et al. 2020

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

show abstract

“…Moreover, the 12 mHz component exists only inside the umbra. Besides, Zhou et al (2017aZhou et al ( , 2017b [20] [21] found that the period of the running waves within the umbra is half of that within the penumbra. The former is a typical 3-min oscillation with a period of 156 s and the latter is a typical 5-min oscillation with a period of 312 s.…”

Section: Umbral Dot Penumbral Wavementioning

confidence: 99%

Research progress based on observations of the New Vacuum Solar Telescope

Yan

Liu

Zhang

et al. 2019

Preprint

View full text Add to dashboard Cite

The purpose of this paper is to introduce the main scientific results made by the one-meter New Vacuum Solar Telescope (NVST), which was put into commission on 2010. NVST is one of the large aperture solar telescopes in the world, located on the shore of Fuxian lake of Yunnan province in China, aiming at serving solar physicists by providing them with high resolution photospheric and chromospheric observational data. Based on the data from NVST and complementary observations from space (e.g., Hinode, SDO and IRIS, etc), dozens of scientific papers have been published with a wide range of topics concentrating mainly on dynamics and activities of fine-scale magnetic structures and their roles in the eruptions of active-region filaments and flares. The achievements include dynamic characteristics of photospheric bright points, umbral dots, penumbral waves, and sunspot/light bridge oscillation, observational evidence of small-scale magnetic reconnection, and fine-scale dynamic structure of prominences. All these new results will shed light on the better understanding of solar eruptive activities. Data release, observation proposals, and future research subjects are introduced and discussed.

show abstract

“…The CaII H power distribution showed the enhanced elements with the spatial scale of the umbral flashes over most of the umbra, with a region with suppressed power at the center of the umbra. The relation between the 3-min and 5-min oscillation in sunspots has been studied by Zhou & Liang (2017), who showed that the running waves are propagating across the umbra-penumbra as 3-min oscillations when they are located at the umbra region, and 5-min oscillations in the penumbra region.…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic wave mode identification in circular and elliptical sunspot umbrae: evidence for high order modes

Albidah,

Fedun,

Aldhafeeri

et al. 2022

Preprint

View full text Add to dashboard Cite

In this paper we provide clear direct evidence of multiple concurrent higher order magnetohydrodynamic (MHD) modes in circular and elliptical sunspots by applying both Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) techniques on solar observational data. These techniques are well documented and validated in the areas of fluid mechanics, hydraulics, and granular flows, yet are relatively new to the field of solar physics. While POD identifies modes based on orthogonality in space and it provides a clear ranking of modes in terms of their contribution to the variance of the signal, DMD resolves modes that are orthogonal in time. The clear presence of the fundamental slow sausage and kink body modes, as well as higher order slow sausage and kink body modes have been identified using POD and DMD analysis of the chromospheric Hα line at 6562.808 Å for both the circular and elliptical sunspots. Additionally, to the various slow body modes, evidence for the presence of the fast surface kink mode was found in the circular sunspot. All the MHD modes patterns were cross-correlated with their theoretically predicted counterparts and we demonstrated that ellipticity cannot be neglected when interpreting MHD wave modes. The higher-order MHD wave modes are even more sensitive to irregularities in umbral cross-sectional shapes, hence this must be taken into account for more accurate modelling of the modes in sunspots and pores.

show abstract

The relationship between the 5-min oscillation and 3-min oscillations at the umbral/penumbral sunspot boundary

Cited by 10 publications

References 27 publications

An overall view of temperature oscillations in the solar chromosphere with ALMA

An overall view of temperature oscillations in the solar chromosphere with ALMA

Research progress based on observations of the New Vacuum Solar Telescope

Magnetohydrodynamic wave mode identification in circular and elliptical sunspot umbrae: evidence for high order modes

Contact Info

Product

Resources

About