Rotation Rates of Coronal Holes and Their Probable Anchoring Depths

Hiremath, K. M.; Hegde, M.

doi:10.1088/0004-637x/763/2/137

Cited by 33 publications

(40 citation statements)

References 82 publications

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“…We give a qualitative description of the possible physical mechanism that might provide link between CHs with deep subphotospheric layers in the conclusions. Recently, similar results were obtained by Hiremath & Hegde (2013), who investigated CHs rotation rates based on SOHO/EIT data during the years 2001-2008. Their average angular velocity (438 nHz) corresponds to the solar interior rotation rate at 0.62 (±0.10) solar radii.…”

Section: Probable Connection To the Tachocline Areasupporting

confidence: 78%

Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?

Bagashvili

Shergelashvili

Japaridze

et al. 2017

A&A

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Context. The present paper discusses results of a statistical study of the characteristics of coronal hole (CH) rotation in order to find connections to the internal rotation of the Sun. Aims. The goal is to measure CH rotation rates and study their distribution over latitude and their area sizes. In addition, the CH rotation rates are compared with the solar photospheric and inner layer rotational profiles. Methods. We study coronal holes observed within ±60 • latitude and longitude from the solar disc centre during the time span from the 1 January 2013 to 20 April 2015, which includes the extended peak of solar cycle 24. We used data created by the Spatial Possibilistic Clustering Algorithm (SPoCA), which provides the exact location and characterisation of solar coronal holes using S DO/AIA 193 Å channel images. The CH rotation rates are measured with four-hour cadence data to track variable positions of the CH geometric centre.Results. North-south asymmetry was found in the distribution of coronal holes: about 60 percent were observed in the northern hemisphere and 40 percent were observed in the southern hemisphere. The smallest and largest CHs were present only at high latitudes. The average sidereal rotation rate for 540 examined CHs is 13.86 (±0.05) • /d. Conclusions. The latitudinal characteristics of CH rotation do not match any known photospheric rotation profile. The CH angular velocities exceed the photospheric angular velocities at latitudes higher than 35-40 degrees. According to our results, the CH rotation profile perfectly coincides with tachocline and the lower layers of convection zone at around 0.71 R ⊙ ; this indicates that CHs may be linked to the solar global magnetic field, which originates in the tachocline region.

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Section: Probable Connection To the Tachocline Areasupporting

confidence: 78%

Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?

Bagashvili

Shergelashvili

Japaridze

et al. 2017

A&A

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“…Finally, we observed the magnetic diffusion that started after the wave/turbulence dissipation and the onset of CH/DR fading, as well as a magnetic realignment of the region that enclosed them. The magnetic reconnection and magnetic diffusion associated with both cases of filament eruption control the evolution of the CH area (Gutiérrez et al 2013;Hiremath & Hegde 2013).…”

Section: O N C L U S I O N Smentioning

confidence: 99%

A study of a coronal hole associated with a large filament eruption

Garro

Enacolopas

Lazarian

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We report the results of a detailed study of an equatorial coronal hole and a dimming region related to the eruptions of a nearby large filament and subsequent coronal mass ejections (CMEs). The dynamic eruptions of the filament and the associated CMEs are probably related to the magnetic reconnection involving the magnetic field lines at the filament footpoints. During the starting processes of the filament eruption, we observed several newly emerged small magnetic flux concentrations close to the filament footpoints. Disturbance increase in the prominence body was observed during the pre-eruption processes. After the filament eruption, we observed evacuated filament material from the filament channel towards the coronal hole. Thus, all the region is perturbed and EUV loops and bright points are observed before and after the eruptions. Additionally, after the CME, we observed the disappearance of the dimming region and the coronal hole, followed by photospheric magnetic diffusion. We discussed a possible magnetic reconnection scenario and MHD waves involved during these processes.

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“…1(a) illustrates a typical full disk image of sun taken on February 08, 2011, 05:11:50 UT. Following the method of Hiremath and Hegde (2013), for images of CH, in each wavelength region, threshold intensity (DN counts) for detecting CH boundary is estimated as follows.…”

Section: Data and Analysismentioning

confidence: 99%

“…One of the main reasons that CH are important to study is that they are the primary sites of acceleration of highspeed solar wind that has a significant influence on the Earth's ionosphere, auroras, and on the telecommunication systems (Hiremath and Mandi, 2004 and references there in;Hiremath, 2009;Hiremath and Hegde, 2013 and references there in), etc.…”

Section: Introductionmentioning

confidence: 99%

Coronal Hole Oscillations as inferred from SDO/AIA data

Hegde¹,

Hiremath²,

Doddamani³

2014

Advances in Space Research

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With high temporal resolution (12 s) of about two hours duration, data of a coronal hole structure in 171Å, 193Å and 211Å taken from SDO/AIA images is considered for examination of oscillations. After estimating the total DN counts of a whole coronal hole structure in three wavelength bands, the resulting time series are subjected to FFT and wavelet analysis. Significant periods in all the three wavelength bands are detected that are mainly concentrated around 500 s as a fundamental mode and its odd (167, 100, 71, 56, 46, 39, 33, 29, 26, 24 s) harmonics. Computed phases in all the three wavelengths band are estimated to be constant.

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Rotation Rates of Coronal Holes and Their Probable Anchoring Depths

Cited by 33 publications

References 82 publications

Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?

Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?

A study of a coronal hole associated with a large filament eruption

Coronal Hole Oscillations as inferred from SDO/AIA data

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