scholarly journals Corona during the total solar eclipse on March 20, 2015, and 24 cycle development

2016 ◽  
Vol 2 (2) ◽  
pp. 3-14
Author(s):  
Сергей Язев ◽  
Sergey Yazev ◽  
Александр Мордвинов ◽  
Aleksandr Mordvinov ◽  
Антонина Дворкина-Самарская ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Solar Eclipse ◽  
Large Scale ◽  
Magnetic Activity ◽  
Total Solar Eclipse ◽  
Asynchronous Development ◽  
Current Cycle ◽  
Polar Magnetic Fields ◽  
Using Data ◽  
Northern And Southern Hemispheres

We analyzed the structure of coronal features, using data on the March 20, 2015 total solar eclipse. The Ludendorff index characterizing the flattening of the corona is 0.09. The solar corona structure in the Northern and Southern hemispheres corresponds to the maximum and post-maximum phases of solar activity, respectively. The asynchronous development of magnetic activity in the Sun’s Northern and Southern hemispheres caused a substantial asymmetry of coronal features observed at the reversal of polar magnetic fields in the current cycle. The polar ray structures in the Southern Hemisphere are associated with the polar coronal hole, while in the Northern Hemisphere a polar hole has not been formed yet. We examine the relation between large-scale magnetic fields and location of high coronal structures.

scholarly journals Corona during the total solar eclipse on March 20, 2015, and 24 cycle development

2016 ◽  
Vol 2 (2) ◽  
pp. 3-11
Author(s):  
Сергей Язев ◽  
Sergey Yazev ◽  
Александр Мордвинов ◽  
Aleksandr Mordvinov ◽  
Антонина Дворкина-Самарская ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Solar Eclipse ◽  
Large Scale ◽  
Total Solar Eclipse ◽  
Asynchronous Development ◽  
Current Cycle ◽  
Corona Structure ◽  
Polar Magnetic Fields ◽  
Using Data ◽  
Northern And Southern Hemispheres

We analyzed the structure of coronal features, using data on the March 20, 2015 total solar eclipse. The Ludendorff index characterizing the flattening of the corona is 0.09. The solar corona structure in the Northern and Southern hemispheres corresponds to the maximum and post-maximum phases of solar activity, respectively. The asynchronous development of mag-netic activity in the Sun’s Northern and Southern hemi-spheres caused a substantial asymmetry of coronal features observed at the reversal of polar magnetic fields in the current cycle. The polar ray structures in the Southern Hemisphere are associated with the polar cor-onal hole, while in the Northern Hemisphere a polar hole has not been formed yet. We examine the relation between large-scale magnetic fields and location of high coronal structures.

scholarly journals Magnetism Science with the Square Kilometre Array

Galaxies ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 53
Author(s):  
George Heald ◽  
Sui Mao ◽  
Valentina Vacca ◽  
Takuya Akahori ◽  
Ancor Damas-Segovia ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Dark Matter Annihilation ◽  
New Techniques ◽  
Square Kilometre Array ◽  
New Radio ◽  
Recent Developments ◽  
Using Data ◽  
The Impact

The Square Kilometre Array (SKA) will answer fundamental questions about the origin, evolution, properties, and influence of magnetic fields throughout the Universe. Magnetic fields can illuminate and influence phenomena as diverse as star formation, galactic dynamics, fast radio bursts, active galactic nuclei, large-scale structure, and dark matter annihilation. Preparations for the SKA are swiftly continuing worldwide, and the community is making tremendous observational progress in the field of cosmic magnetism using data from a powerful international suite of SKA pathfinder and precursor telescopes. In this contribution, we revisit community plans for magnetism research using the SKA, in light of these recent rapid developments. We focus in particular on the impact that new radio telescope instrumentation is generating, thus advancing our understanding of key SKA magnetism science areas, as well as the new techniques that are required for processing and interpreting the data. We discuss these recent developments in the context of the ultimate scientific goals for the SKA era.

scholarly journals X-rays from magnetic massive OB stars

2013 ◽  
Vol 9 (S302) ◽  
pp. 330-333
Author(s):  
V. Petit ◽  
D. H. Cohen ◽  
Y. Nazé ◽  
M. Gagné ◽  
R. H. D. Townsend ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Massive Stars ◽  
Magnetic Activity ◽  
Magnetic Characteristics ◽  
Driving Mechanism ◽  
X Rays ◽  
X Ray ◽  
Ob Stars ◽  
Strong Winds

AbstractThe magnetic activity of solar-type and low-mass stars is a well known source of coronal X-ray emission. At the other end of the main sequence, X-rays emission is instead associated with the powerful, radiatively driven winds of massive stars. Indeed, the intrinsically unstable line-driving mechanism of OB star winds gives rise to shock-heated, soft emission (~0.5 keV) distributed throughout the wind. Recently, the latest generation of spectropolarimetric instrumentation has uncovered a population of massive OB-stars hosting strong, organized magnetic fields. The magnetic characteristics of these stars are similar to the apparently fossil magnetic fields of the chemically peculiar ApBp stars. Magnetic channeling of these OB stars' strong winds leads to the formation of large-scale shock-heated magnetospheres, which can modify UV resonance lines, create complex distributions of cooled Halpha emitting material, and radiate hard (~2-5 keV) X-rays. This presentation summarizes our coordinated observational and modelling efforts to characterize the manifestation of these magnetospheres in the X-ray domain, providing an important contrast between the emission originating in shocks associated with the large-scale fossil fields of massive stars, and the X-rays associated with the activity of complex, dynamo-generated fields in lower-mass stars.

scholarly journals CHAMP observation of intense kilometer-scale field-aligned currents, evidence for an ionospheric Alfvén resonator

2007 ◽  
Vol 25 (7) ◽  
pp. 1603-1615 ◽  
Author(s):  
M. Rother ◽  
K. Schlegel ◽  
H. Lühr
Keyword(s):  
Large Scale ◽  
Field Vector ◽  
Auroral Oval ◽  
Magnetic Activity ◽  
Current Strength ◽  
Champ Satellite ◽  
Scale Field ◽  
Flux Level ◽  
Polar Orbiting Satellite ◽  
Using Data

Abstract. Bursts of very intense kilometer-scale field-aligned currents (KSFACs) are observed quite frequently by the CHAMP satellite when passing through the auroral region. In extreme cases estimated current densities exceed 3 mA/m². Typical scale sizes of these KSFACs are 1 km. The low-Earth, polar orbiting satellite CHAMP allows one to assess KSFACs down to scales of a couple of 100 m based on its high-precision magnetic field vector data sampled at 50 Hz. Using data from 5 years (2001–2005) details of these currents can be investigated. In our statistical study we find that most of the KSFAC bursts and the strongest events are encountered in the cusp/cleft region. Significantly fewer events are found on the nightside. The affected region is typically 15°–20° wide in latitude. There seems to be some dependence of the current intensity on the level of magnetic activity, Kp. On the other hand, no dependence has been found on sunspot number, the solar flux level, F10.7 or the solar zenith angle. The latitude, at which KSFAC bursts are encountered, expands equatorward with increasing Kp. This trend follows well the auroral oval expansion during enhanced magnetic activity. These KSFACs are generally accompanying large-scale FAC sheets, and they are predominantly associated with Region 1 currents. We propose an explanation of the KSFACs in terms of Alfvén waves trapped in a ionospheric resonator, which is initiated when the convection electric field or current strength surpasses a critical value. Many properties of such a resonator are in agreement with our KSFAC results.

scholarly journals Polar magnetic fields and coronal holes during the recent solar minima

2011 ◽  
Vol 7 (S286) ◽  
pp. 101-112 ◽  
Author(s):  
Giuliana de Toma
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Coronal Holes ◽  
Magnetic Activity ◽  
Fast Solar Wind ◽  
The Earth ◽  
Slow Decline ◽  
Polar Magnetic Fields ◽  
Cycle 24 ◽  
The One

AbstractThe slow decline of solar Cycle 23 combined with the slow rise of Cycle 24 resulted in a very long period of low magnetic activity during the years 2007–2009 with sunspot number reaching the lowest level since 1913. This long solar minimum was characterized by weak polar magnetic fields, smaller polar coronal holes, and a relatively complex coronal morphology with multiple streamers extending to mid latitudes. At the same time, low latitude coronal holes remained present on the Sun until the end of 2008 modulating the solar wind at the Earth in co-rotating, fast solar wind streams. This magnetic configuration was remarkably different from the one observed during the previous two solar minima when coronal streamers were confined near the equator and the fast solar wind was mainly originating from the large coronal holes around the Sun's poles. This paper presents the evolution of the polar magnetic fields and coronal holes during the past minimum, compare it with the previous minima, and discuss the implications for the solar wind near the Earth. It also considers the minimum of Cycle 23 in an historical perspective and, in particular, compares it to the long minima at the turn of the 19th century.

scholarly journals XVIII. The Bakerian lecture.—On the total solar eclipse of July 18th, 1860, observed at Rivabellosa, near Miranda de Ebro, in Spain

1862 ◽  
Vol 152 ◽  
pp. 333-416 ◽  
Keyword(s):  
Solar Eclipse ◽  
Large Scale ◽  
Total Solar Eclipse ◽  
The State ◽  
Central Path ◽  
Southern Side

My attention was first called to the Solar Eclipse of 1860, in the latter part of the year 1858, on the occasion of my visiting Russia, when Dr. Medler placed in my hands a copy of his anticipative pamphlet, entitled “L’ Eclipse Solaire du 18 Juillet, 1860.” This paper contained a Map of Spain, with certain lines indicating the position of the central path of the moon’s shadow, the limits of totality, and its epoch at various localities; and it occurred to me, on perusing it, that, if circumstances should permit of my observing the eclipse, Santander would be very convenient for the disembarcation and erection of the instruments I should, in all probability, require for photographic observations, to the prosecution of which my successful researches in astronomical photography led me to think I ought to devote myself. On communicating my plans to Mr. Vignoles, he strongly recommended me to cross to the southern side of the Pyrenees in order to avoid the mists which are caused by the condensation of vapours from the ocean against the northern slopes of the mountains. Subsequently Mr. Vionoles published an eclipse-map of Spain on a very large scale, and I selected Miranda for my station; but he suggested that I should place my observatory at Rivabellosa, about two miles from that town. It is fortunate that I changed my station from Santander to Rivabellosa, as many of those astronomers who selected the former place were prevented by the state of the atmosphere from observing the eclipse.

scholarly journals Total eclipse of the sun, 1900, May 28. Preliminary account of the observations made at Ovar, Portugal

1901 ◽  
Vol 67 (435-441) ◽  
pp. 392-402
Keyword(s):  
Solar Eclipse ◽  
Large Scale ◽  
Total Solar Eclipse ◽  
Time Signal ◽  
The Sun ◽  
Structural Detail ◽  
Royal Observatory ◽  
Preliminary Account ◽  
Taking Charge ◽  
Daily Time

An expedition to observe the total solar eclipse of May 28 having been sanctioned by the Admiralty, it was arranged, in concert with the Joint Permanent Eclipse Committee, that the Royal Observatory party should take photographs of the corona on a large scale for structural detail, and on a smaller scale for the coronal streamers, and should also photograph the spectrum of the “flash” and of the corona. The programme thus naturally divided itself into two parts, Mr. Christie, assisted by Mr. Davidson, taking charge of the first part, and Mr. Dyson of the second. The party are much indebted to the Portuguese Government for the liberal arrangements made for the conveyance of the observers and their instruments in Portugal free of all charge to and from their observing station at Ovar, and for the great assistance rendered in erecting the instruments, and for a daily time-signal from the Lisbon Observatory direct to the observing station.

scholarly journals Global Evolution of Photospheric Magnetic Fields

1990 ◽  
Vol 138 ◽  
pp. 281-295
Author(s):  
V. I. Makarov ◽  
K. R. Sivaraman
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Active Regions ◽  
Magnetic Activity ◽  
Field Pattern ◽  
The Sun ◽  
Coronal Emission ◽  
Global Magnetic Field ◽  
Global Modes

The main features concerning the evolution of the large scale photospheric magnetic fields derived from synoptic maps as well as from H-alpha synoptic charts are reviewed. The significance of a variety of observations that indicate the presence of a high latitude component as a counterpart to the sunspot phenomenon at lower latitudes is reviewed. It is argued that these two components describe the global magnetic field on the sun. It is demonstrated that this scenario is able to link many phenomena observed on the sun (coronal emission, ephemeral active regions, geomagnetic activity, torsional oscillations, polar faculae and global modes in the magnetic field pattern) with the global magnetic activity.

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