Propagating waves in the sunspot umbra chromosphere

Кобанов, Н. И.; Makarchik, D. V.

doi:10.1051/0004-6361:20035960

Cited by 44 publications

(35 citation statements)

References 21 publications

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“…Both the early works (Sigwarth & Mattig 1997;Kobanov & Makarchik 2004;Tziotziou et al 2006) and recent publications based on SDO data analysis note that lowfrequency oscillations concentrate in regions where the magnetic field lines are significantly inclined (i.e., in the penumbra), whereas the 5 mHz and higher frequency oscillations are concentrated within the umbra boundaries.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

confidence: 99%

Oscillations above sunspots from the temperature minimum to the corona

Кобанов

Chelpanov

Kolobov

2013

A&A

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“…This way, the stratification with height of wave parameters like velocity amplitude, as well as their phase variations and their distribution with frequency can be determined. From these parameters, some authors have suggested that the three-minute chromospheric oscillations above sunspot umbrae are standing acoustic waves , while others found them to be propagating waves able to reach the upper layers of the solar atmosphere Banerjee et al, 2002;O'Shea et al, 2002;Brynildsen et al, 2003Brynildsen et al, , 2004Kobanov and Makarchik, 2004). The typical sawtooth pattern of propagating shock wave fronts has been made patent in many observations using different chromospheric and transition region lines (see, e.g., Rouppe van der Voort et al, 2003;Centeno et al, 2006;Tian et al, 2014).…”

Section: Propagation From the Photosphere To The Chromospherementioning

confidence: 98%

“…Tsiropoula et al (2000) showed several clear cases where waves that originate inside the umbra continue to propagate in the penumbra. However, the often abrupt termination of three-minute wave patterns at the umbra/penumbra boundary was noted by Kobanov and Makarchik (2004) and Kobanov et al (2006). Not all three-minute wave fronts can be traced out from the umbra into the penumbra.…”

Section: Chromospheric Running Penumbral Wavesmentioning

confidence: 99%

Oscillations and Waves in Sunspots

Khomenko

Collados

2015

Living Rev. Sol. Phys.

152

118

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A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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“…These waves, considered to be magnetoacoustic modes, were observed to propagate with a phase velocity of 10-20 km s −1 and exhibited intensity fluctuations in the range of 10%-20%. Brisken & Zirin (1997) and Kobanov & Makarchik (2004) have revealed how the frequencies and phase speeds of RPWs vary from 3 mHz, 40 km s −1 to 1 mHz, 10 km s −1 from the inner penumbral boundary to the outer penumbral edge, and becomes gradually invisible while approaching the outer boundary of the penumbra. Additionally, Kobanov (2000) has observed the propagation of RPWs in the chromosphere up to ∼15″ (∼10,000 km) from the outer edge of the penumbral boundary, suggesting the quiet-Sun p-mode oscillations dominate at greater distances, hence overpowering the signatures of any remaining RPWs.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, there is also evidence that umbral oscillatory events of the chromosphere are not the source of RPWs (Giovanelli 1972;Moore & Tang 1975;Christopoulou et al 2000Christopoulou et al , 2001Tziotziou et al 2002;Kobanov & Makarchik 2004;Bloomfield et al 2007). For example, Christopoulou et al (2001) reported that RPWs are more closely associated with photospheric umbral oscillations than the chromospheric ones.…”

Section: Introductionmentioning

confidence: 99%

Observations of Running Penumbral Waves Emerging in a Sunspot

Priya

Cao

et al. 2017

ApJ

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We present results from the investigation of 5 minute umbral oscillations in a single-polarity sunspot of active region NOAA 12132. The spectra of TiO, Hα, and 304 Å are used for corresponding atmospheric heights from the photosphere to lower corona. Power spectrum analysis at the formation height of Hα -0.6 Å to the Hα center resulted in the detection of 5 minute oscillation signals in intensity interpreted as running waves outside the umbral center, mostly with vertical magnetic field inclination >15°. A phase-speed filter is used to extract the running wave signals with speed v ph >4kms −1 , from the time series of Hα -0.4 Å images, and found twenty-four 3 minute umbral oscillatory events in a duration of one hour. Interestingly, the initial emergence of the 3 minute umbral oscillatory events are noticed closer to or at umbral boundaries. These 3 minute umbral oscillatory events are observed for the first time as propagating from a fraction of preceding running penumbral waves (RPWs). These fractional wavefronts rapidly separate from RPWs and move toward the umbral center, wherein they expand radially outwards suggesting the beginning of a new umbral oscillatory event. We found that most of these umbral oscillatory events develop further into RPWs. We speculate that the waveguides of running waves are twisted in spiral structures and hence the wavefronts are first seen at high latitudes of umbral boundaries and later at lower latitudes of the umbral center.

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Propagating waves in the sunspot umbra chromosphere

Cited by 44 publications

References 21 publications

Oscillations above sunspots from the temperature minimum to the corona

Oscillations above sunspots from the temperature minimum to the corona

Oscillations and Waves in Sunspots

Observations of Running Penumbral Waves Emerging in a Sunspot

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