Wave Propagation and Shock Formation in Different Magnetic Structures

Centeno, R.; Collados, M.; Bueno, J. Trujillo

doi:10.1088/0004-637x/692/2/1211

Cited by 74 publications

(115 citation statements)

References 34 publications

(36 reference statements)

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“…Three-minute waves are generally expected to predominate at chromospheric heights in large magnetic elements (Centeno et al 2009). In this work, we have shown that the three-minute wave enhancement is confined to the region within the umbra of the pore, as seen in intensity images.…”

Section: Discussionsupporting

confidence: 56%

“…In this context, a very promising observational tool for the investigation of the propagation of waves is multi-line spectroscopy (Berrilli et al 2002;Jefferies et al 2006;Centeno et al 2009;Felipe et al 2010b), which allows the estimation of the phase lag of the waves between different layers in the solar atmosphere. In particular, Centeno et al (2009) showed that different magnetic regions have distinct power spectrum features as we move from the photosphere to the chromosphere.…”

Section: Introductionmentioning

confidence: 99%

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Three-minute wave enhancement in the solar photosphere

Stangalini

Giannattasio

Moro

et al. 2012

A&A

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It is a well-known result that the power of five-minute oscillations is progressively reduced by magnetic fields in the solar photosphere. Many authors have pointed out that this could be due to a complex interaction of many processes: opacity effects, MHD mode conversion, and intrinsically weaker acoustic emissivity in strong magnetic fields. While five-minute oscillations predominate in the photosphere, it has been shown that in the chromosphere three-minute oscillations are more common. Two main theories have been proposed to explain the presence of the latter oscillations based upon resonance filtering in the atmospheric cavity and non-linear interactions. In this work, we show, through the analysis of IBIS observations of a solar pore in the photospheric Fe I 617.3 nm line, that three-minute waves are already present at the height of formation of this line, their amplitude depends on the magnetic field strength, and they are strictly confined to the umbral region.

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Section: Discussionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Three-minute wave enhancement in the solar photosphere

Stangalini

Giannattasio

Moro

et al. 2012

A&A

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“…The reconstructed magnetic inclinations are found to be larger than the values obtained in the potential field extrapolation: the magnetic field inclination was estimated to account for about 60−80% of the decrease in cut-off frequency. This discrepancy suggests that other physics should be included, such as radiative cooling (e.g., Centeno et al 2006Centeno et al , 2009Felipe et al 2010) and MHD mode conversion (e.g., Parchevsky & Kosovichev 2009;Cally & Hansen 2011;Khomenko & Cally 2012). However, the measurement of the cut-off frequency is an alternative and useful method to reconstruct the magnetic field.…”

Section: Discussionmentioning

confidence: 99%

“…The cut-off frequency could also retrieve the plasma parameters associated with radiative losses. Centeno et al (2006Centeno et al ( , 2009) used a linear wave equation with a radiative cooling term for satisfactory fitting of the observed phase delay and wave amplitude variation with height in both sunspots and pores. The connectivity of different atmospheric layers determined by the phase difference and power amplification was demonstrated with multiple spectral line observations (Felipe et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Multi-height observations of magnetoacoustic cut-off frequency in a sunspot atmosphere

Yuan

Сыч

Reznikova

et al. 2013

A&A

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Context. The cut-off frequency of magnetoacoustic gravity (MAG) waves could be decreased by the inclined magnetic field, and therefore, low-frequency waves could penetrate into the upper atmosphere. Aims. We observe the distribution of the cut-off frequency of compressive waves at various heights and reconstruct the magnetic field inclination, according to the MAG wave theory in a stratified atmosphere permeated by a uniform magnetic field. Methods. We analysed the emission intensity oscillations of sunspot AR11131 (08 Dec. 2010) observed at the 1700 Å, 1600 Å, and 304 Å bandpasses of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO), and computed the narrow-band power maps with the pixelised wavelet filtering method. The distribution of the cut-off frequency was defined as the median contour in the azimuthally-averaged oscillation power. The magnetic field inclination was estimated with the local cut-off frequency according to the MAG wave theory in the low-β limit and was compared to the potential field extrapolation. Results. Shorter period oscillations dominate in the sunspot umbra, while longer period oscillations form an annular shape approximately concentric with the sunspot. Oscillations with longer periods are distributed further away from the sunspot centre. The 5 min oscillations appear to originate at or lower than the photosphere. The magnetic field inclinations determined with the cut-off frequency theory are about 30−40% larger than the values obtained by the potential field extrapolation. Conclusions. The oscillation power distribution in a sunspot atmosphere reflects its magnetic and thermal structure. The cut-off frequency could be used to probe the magnetic field inclination, however, other factors have to be included to fully understand this phenomenon. The existence of return magnetic flux at the outer penumbra was evidenced by the cut-off frequency distribution.

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“…In this case, one expects a positive time delay for the waves observed at the upper and lower levels. Detecting such a delay is a complex task, and the results from different authors are not always consistent with one another Centeno et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Oscillations above sunspots from the temperature minimum to the corona

Кобанов

Chelpanov

Kolobov

2013

A&A

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Context. An analysis of the oscillations above sunspots was carried out using simultaneous ground-based and Solar Dynamics Observatory (SDO) observations (Si  10827 Å, He  10830 Å, Fe  6173 Å, 1700 Å, He  304 Å, Fe  171 Å). Aims. Investigation of the spatial distribution of oscillation power in the frequency range 1-8 mHz for the different height levels of the solar atmosphere. Measuring the time lags between the oscillations at the different layers. Methods. We used frequency filtration of the intensity and Doppler velocity variations with Morlet wavelet to trace the wave propagation from the photosphere to the chromosphere and the corona. Results. The 15 min oscillations are concentrated near the outer penumbra in the upper photosphere (1700 Å), forming a ring that expands in the transition zone. These oscillations propagate upward and reach the corona level, where their spatial distribution resembles a fan structure. The spatial distribution of the 5 min oscillation power looks like a circle-shape structure matching the sunspot umbra border at the photospheric level. The circle expands at the higher levels (He  304 Å and Fe  171 Å). This indicates that the low-frequency oscillations propagate along the inclined magnetic tubes in the spot. We found that the inclination of the tubes reaches 50−60 degrees in the upper chromosphere and the transition zone. The main oscillation power in the 5-8 mHz range concentrates within the umbra boundaries at all the levels. The highest frequency oscillations (8 mHz) are located in the peculiar points inside the umbra. These points probably coincide with umbral dots. We deduced the propagation velocities to be 28 ± 15 km s −1 , 26 ± 15 km s −1 , and 55 ± 10 km s −1 for the Si  10827 Å-He  10830 Å, 1700 Å-He  304 Å, and He  304 Å-Fe  171 Å height levels, respectively.

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Wave Propagation and Shock Formation in Different Magnetic Structures

Cited by 74 publications

References 34 publications

Three-minute wave enhancement in the solar photosphere

Three-minute wave enhancement in the solar photosphere

Multi-height observations of magnetoacoustic cut-off frequency in a sunspot atmosphere

Oscillations above sunspots from the temperature minimum to the corona

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