Fluid motions in the solar chromosphere-corona transition region. III - Active region flows from wide slit Dopplergrams

1983 ◽  
Vol 269 ◽  
pp. 706 ◽  
Author(s):  
R. G. Athay ◽  
J. B. Gurman ◽  
W. Henze
Keyword(s):  
Active Region ◽  
Transition Region ◽  
Solar Chromosphere ◽  
Wide Slit

The nature of moss and lower atmospheric seismology

2005 ◽  
Vol 364 (1839) ◽  
pp. 383-394 ◽  
Author(s):  
B De Pontieu ◽  
R Erdélyi
Keyword(s):  
Active Region ◽  
Numerical Modelling ◽  
Recent Work ◽  
Transition Region ◽  
Solar Atmosphere ◽  
Solar Chromosphere ◽  
Structure Dynamics ◽  
Oscillations And Waves ◽  
Lower Solar Atmosphere

The discovery of so-called solar ‘moss’, i.e. dynamic and bright upper transition region emission at chromospheric heights above active region plage, provides a novel diagnostic to probe the structure, dynamics, energetics and coupling of the magnetized solar chromosphere and transition region. We briefly review observations of the morphology and connectivity in the low solar atmosphere, with a particular focus on the propagation of oscillations and waves in the moss. We also present recent work that combines moss observations and numerical modelling, and which sheds light on the (quasi-periodic) formation of dynamic jets (spicules), and the propagation of normally evanescent oscillations into the corona. We also briefly explore how coronal oscillations could be exploited to determine the connectivity between photosphere and corona, i.e. perform seismology of the lower solar atmosphere.

scholarly journals Experiment to Determine the Temperature Structure in the Solar Chromosphere and Corona

1972 ◽  
Vol 14 ◽  
pp. 668-669
Author(s):  
C. R. Negus
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Research Unit ◽  
Emission Lines ◽  
Solar Chromosphere ◽  
Temperature Structure ◽  
Ultraviolet Emission ◽  
Ionization Temperature ◽  
Intensity Ratios

An experiment is in course of preparation at the Astrophysics Research Unit at Culham for flight on a Sun-pointing rocket. It is designed to determine the ionization temperature and electron density as a function of height in the temperature range of about 8 × 104 K to 3 × 106 K by measuring limb to disk intensity ratios of extreme ultraviolet emission lines in the 170 to 850 Å region. The work is an extension of current experiments in which normal-incidence spectrographs are used to determine the structure lower in the chromosphere-corona transition region.

scholarly journals ACTIVE REGION TRANSITION REGION LOOP POPULATIONS AND THEIR RELATIONSHIP TO THE CORONA

2009 ◽  
Vol 695 (1) ◽  
pp. 642-651 ◽  
Author(s):  
Ignacio Ugarte-Urra ◽  
Harry P. Warren ◽  
David H. Brooks
Keyword(s):  
Active Region ◽  
Transition Region ◽  
Region Loop

scholarly journals Joint Discussion 3 Solar active regions and 3D magnetic structure

2006 ◽  
Vol 2 (14) ◽  
pp. 139-168
Author(s):  
Debi Prasad Choudhary ◽  
Michal Sobotka
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Large Scale ◽  
Focal Point ◽  
Active Regions ◽  
Theoretical Modelling ◽  
Solar Chromosphere ◽  
Origin And Evolution ◽  
Solar Active Regions ◽  
The Magnetic Field

AbstractKeeping in view of the modern powerful observing tools, among othersHinode(formerlySOLAR-B),STEREOand Frequency-Agile Solar Radiotelescope, and sophisticated modelling techniques, Joint Discussion 3 during the IAU General Assembly 2006 focused on the properties of magnetic field of solar active regions starting in deep interior of the Sun, from where they buoyantly rise to the coronal heights where the site of most explosive events are located. Intimately related with the active regions, the origin and evolution of the magnetic field of quiet Sun, the large scale chromospheric structures were also the focal point of the Joint Discussion. The theoretical modelling of the generation and dynamics of magnetic field in solar convective zone show that the interaction of the magnetic field with the Coriolis force and helical turbulent convection results in the tilts and twists in the emerging flux. In the photosphere, some of these fluxes appear in sunspots with field strengths up to about 6100 G. Spectro-polarimetric measurements reveal that the line of sight velocities and magnetic field of these locations are found to be uncombed and depend on depth in the atmosphere and exhibit gradients or discontinuities. The inclined magnetic fields beyond penumbra appear as moving magnetic features that do not rise above upper photospheric heights. As the flux rises, the solar chromosphere is the most immediate and intermediary layer where competitive magnetic forces begin to dominate their thermodynamic counterparts. The magnetic field at these heights is now measured using several diagnostic lines such as CaII854.2 nm, HI656.3 nm, and HeI1083.0 nm. The radio observations show that the coronal magnetic field of post flare loops are of the order of 30 G, which might represent the force-free magnetic state of active region in the corona. The temperatures at these coronal heights, derived from the line widths, are in the range from 2.4 to 3.7 million degree. The same line profile measurements indicate the existence of asymmetric flows in the corona. The theoretical extrapolation of photospheric field into coronal heights and their comparison with the observations show that there exists a complex topology with separatrices associated to coronal null points. The interaction of these structures often lead to flares and coronal mass ejections. The current MHD modelling of active region field shows that for coronal mass ejection both local active region magnetic field and global magnetic field due to the surrounding magnetic flux are important. Here, we present an extended summary of the papers presented in Joint Discussion 03 and open questions related to the solar magnetic field that are likely to be the prime issue with the modern observing facilities such asHinodeandSTEREOmissions.

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