THE PAST, PRESENT AND FUTURE OF THE SUN'S MAGNETISM

2012 ◽  
Vol 18 ◽  
pp. 130-135
Author(s):  
J. D. DO NASCIMENTO
Keyword(s):  
Magnetic Fields ◽  
Global Scale ◽  
Evolutionary Stage ◽  
The Sun ◽  
Fundamental Parameters ◽  
The Past ◽  
Bona Fide ◽  
The Subject ◽  
Solar Analogs ◽  
Active Investigation

Magnetic field in the Sun is produced through the dynamo process in a way that is not yet completely understood. The question whether the Sun is peculiar as compared with other stars has been the subject of active investigation over the past 5 decades, but no studies have been focused on the properties of rotation and surface magnetic fields. The availability of ESPaDOnS offers an exceptional possibility to study the specificity of rotation and magnetic properties of Sun-like stars by means of spectropolarimetric observations. In this review, we present some results concerning the investigation of magnetic fields and dynamo evolution in cool active solar-like stars. Our results are based on the systematic searching for genuine solar analogs and observation of a sample of bona fide solar twins and solar analogs, whose fundamental parameters and evolutionary stage was determined in our previous studies. Our main aim is to investigate how rotation and magnetism evolve and how the depth of the convection zone may influence the global-scale toroidal magnetic fields at the stellar surface.

scholarly journals Small Scale Solar Magnetic Fields: Theory

1977 ◽  
Vol 4 (2) ◽  
pp. 241-250 ◽  
Author(s):  
N. O. Weiss
Keyword(s):  
Magnetic Fields ◽  
Field Strength ◽  
Solar Physics ◽  
Small Scale ◽  
The Sun ◽  
Solar Magnetic Fields ◽  
Solar Granulation ◽  
The Past ◽  
Maximum Field Strength ◽  
Maximum Field

One of the most exciting developments in solar physics over the past eight years has been the success of ground based observers in resolving features with a scale smaller than the solar granulation. In particular, they have demonstrated the existence of intense magnetic fields, with strengths of up to about 1600G. Harvey (1976) has just given an excellent summary of these results.In solar physics, theory generally follows observations. Inter-granular magnetic fields had indeed been expected but their magnitude came as a surprise. Some problems have been discussed in previous reviews (Schmidt, 1968, 1974; Weiss, 1969; Parker, 1976d; Stenflo, 1976) and the new observations have stimulated a flurry of theoretical papers. This review will be limited to the principal problems raised by these filamentary magnetic fields. I shall discuss the interaction of magnetic fields with convection in the sun and attempt to answer such questions as: what is the nature of the equilibrium in a flux tube? how are the fields contained? what determines their stability? how are such strong fields formed and maintained? and what limits the maximum field strength?

Introductory remarks

1994 ◽  
Vol 346 (1678) ◽  
pp. 1-2 ◽  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Neutrino Flux ◽  
The Sun ◽  
Gamma Ray Astronomy ◽  
The Past ◽  
The Subject ◽  
Neutrino Astronomy ◽  
The Universe ◽  
Particle Physicist

Nearly twenty years ago, G. D. Rochester and I organized a Discussion Meeting here on the origin of the cosmic radiation. P art of that meeting was devoted to primary gamma rays, and this meeting was followed a few years later by a meeting devoted entirely to gamma ray astronomy. At that time gamma rays represented a ‘new window on the Universe’. Now it is the turn of neutrinos to move into that slot, although it must be said that neutrino astronomy is not as far on as gamma ray astronomy was at that stage. Nevertheless, the subject has started and has already thrown up some dramatic questions, questions of interest to both astronomer and elementary particle physicist. In the more conventional astronomies, the Sun appears to be quite well behaved, and reasonably understood, with the interests of many centring on more distant and ‘dramatic’ objects, such as supernovae and extragalactic sources. With neutrinos, however, supernovae seem to be well behaved — at the superficial level, at least and based on one event — but the Sun does not. The remarkable deficit in solar neutrino flux recorded by Davis and collaborators over the past decades has been confirmed and we look forward to hearing the details of these confirmations, as well as the energy dependence of the flux and its comparison with expectation.

scholarly journals Exeter Book Riddle 95: ‘The Sun’, a New Solution

2019 ◽  
Vol 137 (4) ◽  
pp. 612-638
Author(s):  
Dieter Bitterli
Keyword(s):  
Tenth Century ◽  
Exeter Book ◽  
The Sun ◽  
Anglo Saxon ◽  
The Past ◽  
The Earth ◽  
English Verse ◽  
Isidore Of Seville ◽  
The Subject ◽  
The One

Abstract Elusive and fraught with textual difficulties, Riddle 95, the ‘last’ of the Old English verse riddles preserved in the tenth-century Exeter Book, has long baffled modern readers as one of a handful of thorny items in the collection that have so far defied solution. ‘Book’ is the answer that has found most acceptance with critics in the past, yet the speaking subject of Riddle 95 is unlike anything described in those items of the collection that actually deal with writing and the tools of the monastic scriptorium. Rather, the linguistic and thematic parallels between Riddle 95 on the one hand, and the cosmological riddles and poems in the Exeter Book on the other, strongly suggest that the subject of Riddle 95 is the sun, a frequent topic of early medieval enigmatography. The poem obliquely relates how the rising sun installs itself in the sky to shed its welcome light upon the earth before it sets and vanishes from sight, completing its daily orbit along unknown paths. The main clues helping to secure the solution ‘sun’ are based upon what was known in Anglo-Saxon England about the solar course and the planetary motions, especially from the astronomical writings of Isidore of Seville and Bede. Further evidence is provided by several analogues in the Anglo-Latin riddle tradition, including the Enigmata of Aldhelm and his followers.

scholarly journals Between Secularity and Post-Secularity: Critical Appraisal of Charles Taylor's Account

2019 ◽  
Vol 79 (2) ◽  
pp. 411-423 ◽  
Author(s):  
Bojan Žalec
Keyword(s):  
Final Section ◽  
Critical Appraisal ◽  
Special Section ◽  
Global Scale ◽  
The Past ◽  
The Usa ◽  
The Subject ◽  
Secular Age ◽  
Definition Of ◽  
Narrative Account

The article deals with Charles Taylor's account of the secular age. In the first part, the main constituents of Taylor's narrative account are presented: the central concepts, distinctions, definition of the subject, the aims etc. The author pays special attention to the notions of secularity, secular age, religion, and transcendence. In the second part, Taylor's genealogy of the secular age is outlined and comparatively placed in the context of other main relative forms of genealogical account. Because our age is an age of authenticity, a special section is devoted to it. The final section presents some reproaches to Taylor and evaluates their strength and the value of Taylor's contribution. Besides, some speculative »forecasts« about secularity and post-secularity in Europe, the USA, and at the global scale are presented (by reference to Taylor's account). The author concludes that despite some (serious and cogent) reproaches and second thoughts about Taylor's account, it is doubtless one of the major achievements in the area that manifests features of a paradigmatic work. It helps us a lot to understand the condition of religion not only in the past and today, but also gives us directions and guidelines, conceptual and methodological tools, and ideas to more clearly discern the forms and condition of religion in the future.

Fundamental parameters of x-ray microanalysis: A brief introduction

1990 ◽  
Vol 48 (2) ◽  
pp. 2-3
Author(s):  
Peter Duncumb
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
X Rays ◽  
X Ray ◽  
Fundamental Parameters ◽  
The Past ◽  
Basic Physics ◽  
The Subject ◽  
Almost All ◽  
Physical Laws

It is indeed fortunate that nature has provided us with such well-defined physical laws governing the generation of x rays and their interaction with matter. This benefit has given electron microprobe analysis two major advantages over many other techniques of analysis: it can be applied to almost all elements in the periodic table and it can be applied quantitatively. Nevertheless, we are continually striving for better and better quantitation over a wider range of conditions, and there is a corresponding pressure to improve our knowledge of the physics. The purpose of this session is to identify the fundamental parameters by which these physical laws are expressed, and to explore their relative importance in determining the accuracy of which the technique is capable.The essential link between the basic physics of microprobe analysis and its useful application is the physical model used to represent the process numerically. Many such models have been proposed in the past 40 years and these are properly the subject of a separate session on quantitative analysis.

The Elemental Past

2014 ◽  
Vol 44 (2) ◽  
pp. 262-279 ◽  
Author(s):  
Ted Toadvine
Keyword(s):  
The Body ◽  
The Sun ◽  
Human Beings ◽  
Contemporary Philosophy ◽  
The Past ◽  
Phenomenology Of Perception ◽  
Continental Divide ◽  
The World ◽  
The Subject ◽  
Quentin Meillassoux

In a 1951 debate that marked the beginnings of the analytic-continental divide, Maurice Merleau-Ponty sided with Georges Bataille in rejecting A. J. Ayer’s claim that “the sun existed before human beings.” This rejection is already anticipated in a controversial passage from Merleau-Ponty’s Phenomenology of Perception, where he claims that “there is no world without an Existence that bears its structure.” I defend Merleau-Ponty’s counterintuitive position against naturalistic and anti-subjectivist critics by arguing that the world emerges in the exchange between perceiver and perceived. A deeper challenge is posed, however, by Quentin Meillassoux, who argues that the “correlationism” of contemporary philosophy rules out any account of the “ancestral” time that antedates all subjectivity. Against Meillassoux, and taking an encounter with fossils as my guide, I hold that the past prior to subjectivity can only be approached phenomenologically. The paradoxical character of this immemorial past, as a memory of the world rather than of the subject, opens the way toward a phenomenology of the “elemental” past. Drawing on Merleau-Ponty’s descriptions of the absolute past of nature and the anonymity of the body, as well as Levinas’ account of the elements at the end of the world, I argue that our own materiality and organic lives participate in the differential rhythms of the elements, opening us to a memory of the world that binds the cosmic past and the apocalyptic future.

2. The Sun’s life-cycle

2020 ◽  
pp. 42-64
Author(s):  
Philip Judge
Keyword(s):  
Life Cycle ◽  
Magnetic Fields ◽  
Main Sequence ◽  
Milky Way ◽  
The Sun ◽  
Centre Of Mass ◽  
Fusion Reactions ◽  
The Past ◽  
Nuclear Fusion Reactions ◽  
The Universe

‘The Sun’s life-cycle’ describes the birth of the Sun out of the debris of stars which exploded early in the life of the Milky Way. When stars form, they employ a disc structure, with matter spinning around the centre of mass like a carousel, aided by magnetic fields. At four and a half million years old, the Sun, like most stars in the Universe, is on the main sequence stage of its life. In this stage, nuclear fusion reactions in its core fuse hydrogen into helium. Both observations and theory infer that the Sun spun faster in the past and was both hotter and less luminous.

scholarly journals The Coronal Responses to the Large-Scale and Long-Term Phenomena of the Lower Layers of the Sun

1980 ◽  
Vol 91 ◽  
pp. 87-104 ◽  
Author(s):  
J. Sýkora
Keyword(s):  
Magnetic Fields ◽  
Solar Corona ◽  
Large Scale ◽  
The Sun ◽  
Solar Cycles ◽  
The Past

Based on the assumption, generally accepted over the past decade, that all the forms of solar and interplanetary activity are responses to the magnetic fields generated initially in the subphotosphere, some characteristics of the large-scale and long-term behaviour of the solar corona during the last three solar cycles are presented.

scholarly journals Poetic Lithuania of Miłosz

2016 ◽  
Vol 38 (8) ◽  
Author(s):  
Maria Berkan-Jabłońska
Keyword(s):  
Real World ◽  
The Sun ◽  
Symbolic Form ◽  
The Waste Land ◽  
Waste Land ◽  
The Past ◽  
Starting Point ◽  
The Subject ◽  
Gradual Transformation ◽  
Hostile Attitude

The article deals with the images of Lithuania found in Czesław Miłosz’s poetry. The novels and essays have only been used to confirm the conclusions drawn from the interpretation of selected poems. Despite the frequently-declared unwillingness of the author of Dolina Issy (The Valley of the Issa) to accept and use any autobiographical elements in literature, the land of his childhood has always been present in all the poet’s works. The explanation of this fascination with nostalgia seems to be unsatisfactory. The author of the article perceives the poetic images of Lithuania created by the uprooted immigrant as a symbol of his inner, not purely geographical, settlement. The subject of the discussion is the ever-changing perception of the Eastern-Borderland, which corresponds to particular stages of the protagonist’s journey through life. The starting point is the experience of eviction. It modifies the originally idealized vision of the “little homeland” and makes the hero’s attempt to reject or “amputate” it. The poems from the Światło dzienne (Daylight) collection surprise the reader by a hostile attitude towards the poet’s youth spent in Lithuania and the perception of those early memories as some destructive forces threatening the artist. It is only after a many years’ quest that the borderland heritage is appreciated and conquered again. Now, however, it acquires a different, more symbolic form. The cycle Miasto bez imienia (A Town without a Name) and the poem Gdzie wschodzi słońce i kędy zapada (Where the Sun Rises and Sets) are evidence of a gradual transformation. The faithful recreation in the poet’s memory of particular places and people changes into the construction of some outside religious space, built from the traces of the real world. Lithuania changes into a perfect reality, a Super-Land, capable of retaining the past and combining it with the present. It is a prop freeing the poet from the waste land of Urizen.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Sign in / Sign up

Export Citation Format

Share Document