Spectropolarimetric fluctuations in a sunspot chromosphere

Stangalini, M.; Baker, D.; Valori, G.; Jess, D. B.; Jafarzadeh, S.; Murabito, M.; To, Andy S. H.; Brooks, David H.; Ermolli, I.; Giorgi, F.; MacBride, Conor D.

doi:10.1098/rsta.2020.0216

Cited by 19 publications

(39 citation statements)

References 75 publications

(109 reference statements)

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“…IBIS full Stokes spectropolarimetric scans were used to identify possible signatures of magnetic field oscillations in circular polarization (CP) measurements in the umbra. A full account of the observations and data reduction techniques is provided in Stangalini et al (2018), Murabito et al (2020), Houston et al (2020), andStangalini et al (2021). Here, we precis the aspects that are relevant to this analysis.…”

Section: Ibis Observations and Methodsmentioning

confidence: 99%

“…To identify possible intrinsic magnetic field oscillations in the same IBIS data set, Stangalini et al (2021) performed a specific phase lag analysis between the CP and the core intensity of the Ca II. Figure 2(c) shows the Stokes V max /I cont CP map saturated at 0.3.…”

Section: Ibis Observations and Methodsmentioning

confidence: 99%

“…4. Alfvénic Perturbations in the sunspot Chromosphere Stangalini et al (2021) found the presence of Alfvénic perturbations in the sunspot chromosphere in the 3 minute band of the IBIS Ca II time series (see Section 2.2). The frequency band corresponding to this period, which is also the dominant period in the solar chromosphere (e.g., Khomenko & Collados 2015, and references therein), is smaller than the ion-cyclotron frequency, and thus in the regime appropriate for the model of Laming (2015).…”

Section: Coronal Loop Connectivitiesmentioning

confidence: 98%

“…The detection of magnetic oscillations associated with MHD modes is a difficult task, as opacity effects or instrumental crosstalk with other physical quantities can easily mimic the effect of these oscillations (e.g., Khomenko & Collados 2015;Joshi & de la Cruz Rodríguez 2018, and references therein). One way to disentangle intrinsic magnetic oscillations in the solar atmosphere is through the investigation of the phase lag between the polarization signals associated with magnetic field disturbances and other physical quantities such as intensity and Doppler velocity (Stangalini et al 2018(Stangalini et al , 2021. Oscillating physical quantities associated with MHD waves may have different phase relations depending on the MHD mode and the propagation state of the wave (Fujimura & Tsuneta 2009;Hinode Review Team et al 2019), thus the analysis of the phase relations between them can be exploited for their identification (Stangalini et al 2018) as well as the identification of the specific mode producing them.…”

Section: Introductionmentioning

confidence: 99%

“…We find that the elemental abundance variation in the corona above the sunspot is highly structured, with extremes in the level of fractionation among the distinct loop populations. The distribution of the highly fractionated plasma appears to be correlated with the spatial locations at which intrinsic magnetic oscillations are identified in nearly simultaneous high spatial resolution spectropolarimetric observations of the solar chromosphere (Stangalini et al 2021). Magnetic field modeling is used to investigate the connectivities of the loop populations within the sunspot in order to seek an understanding of the distribution of plasma composition observed there.…”

Section: Introductionmentioning

confidence: 99%

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Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona

Baker

Stangalini

Valori

et al. 2021

ApJ

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In this study, we investigate the spatial distribution of highly varying plasma composition around one of the largest sunspots of solar cycle 24. Observations of the photosphere, chromosphere, and corona are brought together with magnetic field modeling of the sunspot in order to probe the conditions that regulate the degree of plasma fractionation within loop populations of differing connectivities. We find that, in the coronal magnetic field above the sunspot umbra, the plasma has photospheric composition. Coronal loops rooted in the penumbra contain fractionated plasma, with the highest levels observed in the loops that connect within the active region. Tracing field lines from regions of fractionated plasma in the corona to locations of Alfvénic fluctuations detected in the chromosphere shows that they are magnetically linked. These results indicate a connection between sunspot chromospheric activity and observable changes in coronal plasma composition.

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Section: Ibis Observations and Methodsmentioning

confidence: 99%

Section: Ibis Observations and Methodsmentioning

confidence: 99%

Section: Coronal Loop Connectivitiesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona

Baker

Stangalini

Valori

et al. 2021

ApJ

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Waves in the lower solar atmosphere: the dawn of next-generation solar telescopes

Jess

Jafarzadeh

Keys

et al. 2023

Living Rev Sol Phys

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Waves and oscillations have been observed in the Sun’s atmosphere for over half a century. While such phenomena have readily been observed across the entire electromagnetic spectrum, spanning radio to gamma-ray sources, the underlying role of waves in the supply of energy to the outermost extremities of the Sun’s corona has yet to be uncovered. Of particular interest is the lower solar atmosphere, including the photosphere and chromosphere, since these regions harbor the footpoints of powerful magnetic flux bundles that are able to guide oscillatory motion upwards from the solar surface. As a result, many of the current- and next-generation ground-based and space-borne observing facilities are focusing their attention on these tenuous layers of the lower solar atmosphere in an attempt to study, at the highest spatial and temporal scales possible, the mechanisms responsible for the generation, propagation, and ultimate dissipation of energetic wave phenomena. Here, we present a two-fold review that is designed to overview both the wave analyses techniques the solar physics community currently have at their disposal, as well as highlight scientific advancements made over the last decade. Importantly, while many ground-breaking studies will address and answer key problems in solar physics, the cutting-edge nature of their investigations will naturally pose yet more outstanding observational and/or theoretical questions that require subsequent follow-up work. This is not only to be expected, but should be embraced as a reminder of the era of rapid discovery we currently find ourselves in. We will highlight these open questions and suggest ways in which the solar physics community can address these in the years and decades to come.

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Large scale coherent magnetohydrodynamic oscillations in a sunspot

et al. 2022

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Although theoretically predicted, the simultaneous excitation of several resonant modes in sunspots has not been observed. Like any harmonic oscillator, a solar magnetic flux tube can support a variety of resonances, which constitute the natural response of the system to external forcing. Apart from a few single low order eigenmodes in small scale magnetic structures, several simultaneous resonant modes were not found in extremely large sunspots. Here we report the detection of the largest-scale coherent oscillations observed in a sunspot, with a spectrum significantly different from the Sun’s global acoustic oscillations, incorporating a superposition of many resonant wave modes. Magnetohydrodynamic numerical modeling agrees with the observations. Our findings not only demonstrate the possible excitation of coherent oscillations over spatial scales as large as 30–40 Mm in extreme magnetic flux regions in the solar atmosphere, but also paves the way for their diagnostic applications in other astrophysical contexts.

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Spectropolarimetric fluctuations in a sunspot chromosphere

Cited by 19 publications

References 75 publications

Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona

Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona

Waves in the lower solar atmosphere: the dawn of next-generation solar telescopes

Large scale coherent magnetohydrodynamic oscillations in a sunspot

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