Cold Matter in Filament Channels

AbstractThe formation of cold filaments in the low corona is a central research area in solar physics. Their basic properties are not well understood, but they may be crucial for the mass and magnetic flux balance in the solar corona. The review discusses multi-wavelength observational results and theoretical modelling of filament channels and quiescent filaments.

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The formation of a penumbra as observed with the German VTT and SoHO/MDI

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311015134 ◽

2010 ◽

Vol 6 (S273) ◽

pp. 134-140 ◽

Cited By ~ 2

Author(s):

Rolf Schlichenmaier ◽

Nazaret Bello González ◽

Reza Rezaei

Keyword(s):

Magnetic Flux ◽

Solar Physics ◽

Active Regions ◽

Solar Interior ◽

Doppler Velocity ◽

Solar Photosphere ◽

Multi Wavelength ◽

2D Imaging ◽

The Magnetic Field ◽

Field Inclination

AbstractThe generation of magnetic flux in the solar interior and its transport to the outer solar atmosphere will be in the focus of solar physics research for the next decades. One key-ingredient is the process of magnetic flux emergence into the solar photosphere, and the reorganization to form the magnetic phenomena of active regions like sunspots and pores.On July 4, 2009, we observed a region of emerging magnetic flux, in which a proto-spot without penumbra forms a penumbra within some 4.5 hours. This process is documented by multi-wavelength observations at the German VTT: (a) imaging, (b) data with high resolution and temporal cadence acquired in Fe I 617.3 nm with the 2D imaging spectropolarimter GFPI, and (c) scans with the slit based spectropolarimeter TIP in Fe I 1089.6 nm. MDI contiuum maps and magnetograms are used to follow the formation of the proto-spot, and the subsequent evolution of the entire active region.During the formation of the penumbra, the area and the magnetic flux of the spot increases. The additional magnetic flux is supplied by the adjacent region of emerging magnetic flux: As emerging bipole separate, the poles of the spot polarity migrate towards the spot, and finally merge with it. As more and more flux is accumulated, a penumbra forms. From inversions we infer maps for the magnetic field and the Doppler velocity (being constant along the line-of-sight). We calculate the magnetic flux of the forming spot and of the bipole footpoints that merge with the proto-spot. We witness the onset of the Evershed flow and the associated enhance of the field inclination as individual penumbral filaments form. Prior to the formation of individual penumbral sectors we detect the existence of ‘counter’ Evershed flows. These in-flows turn into the classical radial Evershed outflows as stable penumbra segments form.

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Some Problems in Understanding the Solar Corona

International Astronomical Union Colloquium ◽

10.1017/s025292110002491x ◽

1994 ◽

Vol 144 ◽

pp. 1-9

Author(s):

A. H. Gabriel

Keyword(s):

Solar Corona ◽

Solar Atmosphere ◽

Theoretical Modelling ◽

Total System ◽

Major Advance ◽

X Ray ◽

Proper Perspective ◽

Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

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Choice of Optimum Operational Regime for Total Stations upon Making Geodetic Surveys under Heavy Aerosol Atmosphere Pollution

Geodesy and Cartography ◽

10.22389/0016-7126-2018-938-8-12-19 ◽

2018 ◽

Vol 938 (8) ◽

pp. 12-19

Author(s):

S. B. Verdiyev

Keyword(s):

Rational Choice ◽

Theoretical Modelling ◽

Total Station ◽

Visible Band ◽

Multi Wavelength ◽

Atmosphere Pollution ◽

Experimental Researches ◽

Practical Recommendations

The possibility to use multi-wavelength regime of total stations operation for making surveys under heavy aerosol atmosphere pollution is researched. The actuality of single- and multi-wavelength regimes rational choice under heavy aerosol atmosphere pollution is grounded. The task on researching the matter of operational regime choice for total stations is formulated. The method for solution of the formulated task is suggested. The theoretical modelling and experimental researches are held to formulate the criterion for choice of single- or multi-wavelength regimes. The practical recommendations for such a choice are formulated. The practical recommendations are formulated for choice of measurements regime. According to formulated recommendations if a single-wavelength total station operates in the field of longer wavelengths (R) of visible band and a three-wavelengths one operates with bias to shorter (B, G, R) wavelengths, the single-wavelength total station should be preferred. But if the single-wavelength total station operates in the field of shorter wavelengths (B) and the three-wavelengths one operates with bias to longer wavelengths (B, G, R) then the multi-wavelengths total station should be preferred. The recommendation described in this article are relevant for both the regimes of measurements with- and without reflector and can be useful for users of total stations.

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VERTICAL KINK OSCILLATION OF A MAGNETIC FLUX ROPE STRUCTURE IN THE SOLAR CORONA

The Astrophysical Journal ◽

10.1088/2041-8205/797/2/l22 ◽

2014 ◽

Vol 797 (2) ◽

pp. L22 ◽

Cited By ~ 18

Author(s):

S. Kim ◽

V. M. Nakariakov ◽

K.-S. Cho

Keyword(s):

Magnetic Flux ◽

Solar Corona ◽

Flux Rope ◽

Magnetic Flux Rope

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Emergence of small-scale magnetic flux in the quiet Sun

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936778 ◽

2020 ◽

Vol 633 ◽

pp. A67 ◽

Cited By ~ 2

Author(s):

I. Kontogiannis ◽

G. Tsiropoula ◽

K. Tziotziou ◽

C. Gontikakis ◽

C. Kuckein ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Flux ◽

Morphological Characteristics ◽

Small Scale ◽

X Rays ◽

Coronal Emission ◽

Quiet Sun ◽

Temperature Regimes ◽

Multi Wavelength ◽

Modelling Studies

Context. We study the evolution of a small-scale emerging flux region (EFR) in the quiet Sun, from its emergence in the photosphere to its appearance in the corona and its decay. Aims. We track processes and phenomena that take place across all atmospheric layers; we explore their interrelations and compare our findings with those from recent numerical modelling studies. Methods. We used imaging as well as spectral and spectropolarimetric observations from a suite of space-borne and ground-based instruments. Results. The EFR appears in the quiet Sun next to the chromospheric network and shows all morphological characteristics predicted by numerical simulations. The total magnetic flux of the region exhibits distinct evolutionary phases, namely an initial subtle increase, a fast increase with a Co-temporal fast expansion of the region area, a more gradual increase, and a slow decay. During the initial stages, fine-scale G-band and Ca II H bright points coalesce, forming clusters of positive- and negative-polarity in a largely bipolar configuration. During the fast expansion, flux tubes make their way to the chromosphere, pushing aside the ambient magnetic field and producing pressure-driven absorption fronts that are visible as blueshifted chromospheric features. The connectivity of the quiet-Sun network gradually changes and part of the existing network forms new connections with the newly emerged bipole. A few minutes after the bipole has reached its maximum magnetic flux, the bipole brightens in soft X-rays forming a coronal bright point. The coronal emission exhibits episodic brightenings on top of a long smooth increase. These coronal brightenings are also associated with surge-like chromospheric features visible in Hα, which can be attributed to reconnection with adjacent small-scale magnetic fields and the ambient quiet-Sun magnetic field. Conclusions. The emergence of magnetic flux even at the smallest scales can be the driver of a series of energetic phenomena visible at various atmospheric heights and temperature regimes. Multi-wavelength observations reveal a wealth of mechanisms which produce diverse observable effects during the different evolutionary stages of these small-scale structures.

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Magnetic Flux Emergence into the Solar Corona. II. Global Magnetic Fields with Current Sheets

The Astrophysical Journal ◽

10.1086/341800 ◽

2002 ◽

Vol 576 (2) ◽

pp. 1005-1017 ◽

Cited By ~ 8

Author(s):

M. Zhang ◽

B. C. Low

Keyword(s):

Magnetic Fields ◽

Magnetic Flux ◽

Solar Corona ◽

Flux Emergence ◽

Current Sheets

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Solar Flares, the Solar Corona, and Solar Physics

Symposium - International Astronomical Union ◽

10.1017/s007418090016348x ◽

2000 ◽

Vol 195 ◽

pp. 455-459

Author(s):

E. N. Parker

Keyword(s):

Quantum Mechanics ◽

Solar Corona ◽

Solar Flares ◽

Solar Physics ◽

The Sun ◽

Classical Physics ◽

Physics Laboratory ◽

Physical Effects

The Sun serves as the local physics laboratory for studying the suprathermal activity phenomena of stars. Scrutiny of the Sun has led to the discovery of a host of previously unknown physical effects, largely within the classical physics of Newton and Maxwell, but including quantum mechanics and lepton physics as well.

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