Solar Prominences

Tandberg-Hanssen, E.

doi:10.1007/978-94-010-2136-4

Cited by 277 publications

(90 citation statements)

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“…Using Greenwich photoheliographic results, Jensen et al (1955), Tandberg-Hanssen (1956), and Ringnes (1964) reported a weak tendency for the average penumbra-to-umbra radius to change in phase with the solar cycle. Steinegger et al (1990) and Brandt et al (1990) found umbra-penumbra area ratios of 0.24 and 0.32 for small and large spots, respectively.…”

Section: Introductionmentioning

confidence: 99%

Properties of sunspot umbrae observed in cycle 24

Kiess

Rezaei

Schmidt

2014

A&A

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Aims. There is an ongoing debate whether the solar activity cycle is overlaid with a long-term decline that may lead to another grand minimum in the near future. We used the size, intensity, and magnetic field strength of sunspot umbrae to compare the present cycle 24 with the previous one. Methods. We used data of the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and selected all sunspots between May 2010 and October 2012, using one image per day. We created two subsets of this dataset with a manual tracking algorithm, both without duplication. One contains each sunspot (910 umbrae within 488 spots) and was used to analyze the distribution of umbral areas, selected with an automated thresholding method. The other subset contains 205 fully evolved sunspots. We estimated their magnetic field and the total magnetic flux and discuss the relations between umbral size, minimum continuum intensity, maximum field strength, and total magnetic flux. Results. We find non-linear relations between umbral minimum intensity and size and between maximum magnetic field strength and size. The field strength scales linearly with the intensity and the umbral size scales roughly linearly with the total magnetic flux, while the size and field strength level off with stronger flux. When separated into hemispheres and averaged temporally, the southern umbrae show a temporal increase in size and the northern umbrae remain constant. We detected no temporal variation in the umbral mean intensity. The probability density function of the umbral area in the ascending phase of the current solar cycle is similar to that of the last solar cycle. Conclusions. From our investigation of umbral area, magnetic field, magnetic flux, and umbral intensity of the sunspots of the rising phase of cycle 24, we do not find a significant difference to the previous cycle, and hence no indication for a long-term decline of solar activity.

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Section: Introductionmentioning

confidence: 99%

Properties of sunspot umbrae observed in cycle 24

Kiess

Rezaei

Schmidt

2014

A&A

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“…Quoting Einar Tandberg-Hanssen (1974), "the single, physically most important parameter to study in prominences may be the magnetic field. Shapes, motions, and in fact the very existence of prominences depend on the nature of the magnetic field threading the prominence plasma".…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, being low β structures, the channeling of plasma motions and of thermal conduction are controlled by the magnetic field, and it provides also support to the prominence material against gravity (Démoulin 1998). Details and further references can be found in the reviews of Leroy (1989) and Landi Degl'Innocenti (1990), as well as in Tandberg-Hanssen (1974, 1995.…”

Section: Introductionmentioning

confidence: 99%

Full-Stokes spectropolarimetry of solar prominences

Paletou

Ariste²,

Bommier³

et al. 2001

A&A

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Abstract. We report on first spectropolarimetric observations of solar prominences made at THEMIS. Hereafter we shall emphasis on the preliminary analysis of He i D3 full-Stokes observations. Our measurements clearly show manifestations of both the Hanle and Zeeman effects. More generally, we demonstrate the very favourable performances of the THEMIS multi-line spectropolarimetric mode for further new investigations of the magnetic field in solar prominences.

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“…These models have better withstood the test of time and are the basis for much work on quiescent prominences. For detailed accounts of the history and physics of prominences see the books "Solar Prominences" by Tandberg-Hanssen (1974) and "Dynamics and Structure of Quiescent Solar Prominences" edited by Priest (1989). e-mail: tcmckai@tc.cc.va.us Marvelous photographs of these magnificent structures can also be found on the internet -see for example http://mesola.obspm.fr (a site run by INSU/CNRS France) and http://sohowww.estec.esa.nl (the web site of the Solar and Heliospheric Observatory).…”

Section: Prominence Modelsmentioning

confidence: 99%

Solar prominence magnetic configurations derived numerically from convection

McKaig

2001

A&A

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Abstract. The solar convection zone may be a mechanism for generating the magnetic fields in the corona that create and thermally insulate quiescent prominences. This connection is examined here by numerically solving a diffusion equation with convection (below the photosphere) matched to Laplace's equation (modeling the current free corona above the photosphere). The types of fields formed resemble both Kippenhahn-Schlüter and KuperusRaadu configurations with feet that drop into supergranule boundaries.

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Solar Prominences

Cited by 277 publications

References 0 publications

Properties of sunspot umbrae observed in cycle 24

Properties of sunspot umbrae observed in cycle 24

Full-Stokes spectropolarimetry of solar prominences

Solar prominence magnetic configurations derived numerically from convection

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