scholarly journals On Activities of UV Cet-Type Flare Stars and of T Tau-Type Stars

1983 ◽  
Vol 71 ◽  
pp. 487-495
Author(s):  
R.E. Gershberg
Keyword(s):  
Solar Activity ◽  
Magnetic Fields ◽  
Physical Nature ◽  
The Other ◽  
Stellar Surface ◽  
The Sun ◽  
T Tau Type Stars ◽  
Flare Stars ◽  
Local Magnetic Fields ◽  
T Tau

Comparisons of the activities of UV Cet-type flare stars and of T Tau-type stars with solar activity permits the conclusion that non-sta-tionary processes in the UV Cet-type stars and in the Sun are of an indent ical physical nature but that they differ qualitatively from active events in the T Tau-type stars. The identity of the activity in flare stars and the Sun makes it possible to study successfully stellar activity with the help of known models of various solar events and, on the other hand, to have a more general approach to the physics and evolution of solar activity on the basis of established features of numerous flare stars of different ages and masses. The hypothesis on hydromagnetic activity of the T Tau-type stars is sketched; within this framework, one supposes that the main feature of such stars is an occurrence at every point of the stellar surface, of conditions necessary for the existence of dark spots, i.e. a lowering of the photospheric brightness due to strong local magnetic fields.

About the Relation Between the Limb Effect of the Redshift on the Sun and the Large-Scale Distribution of Solar activity

1976 ◽  
Vol 71 ◽  
pp. 113-118
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Magnetic Fields ◽  
Interplanetary Magnetic Field ◽  
Large Scale ◽  
The Sun ◽  
Limb Effect

The measurement of the magnitude of the limb effect was homogenized in time and a recurrent period of maxima of 27.8 days was found. A relation was found between the maximum values of the limb effect of the redshift, the boundaries of polarities of the interplanetary magnetic field, the characteristic large-scale distribution of the background magnetic fields and the complex of solar activity.

scholarly journals Analog Video Magnetograms in Real Time

1971 ◽  
Vol 43 ◽  
pp. 76-83 ◽  
Author(s):  
R. C. Smithson ◽  
R. B. Leighton
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Magnetic Field ◽  
Solar Spectrum ◽  
Zeeman Splitting ◽  
The Other ◽  
Line Of Sight ◽  
Zero Field ◽  
The Sun ◽  
Solar Magnetic Fields

For many years solar magnetic fields have been measured by a variety of techniques, all of which exploit the Zeeman splitting of lines in the solar spectrum. One of these techniques (Leighton, 1959) involves a photographic subtraction of two monochromatic images to produce a picture of the Sun in which the line-of-sight component of the solar magnetic field appears as various shades of gray. In a magnetogram made by this method, zero field strength appears as neutral gray, while magnetic fields of one polarity or the other appear as lighter or darker areas, respectively. Figure 1 shows such a magnetogram.

Planetary Modulation of Solar Activity

1967 ◽  
Vol 1 (2) ◽  
pp. 53-54 ◽  
Author(s):  
E. K. Bigg ◽  
P. S. Mulhall
Keyword(s):  
Solar Activity ◽  
Solar Surface ◽  
Relative Equilibrium ◽  
High Tide ◽  
The Other ◽  
The Sun ◽  
Sunspot Numbers ◽  
Tidal Forces ◽  
Wide Range ◽  
Degree Of Control

It has recently been shown that the planet Mercury exerts a small control on relative sunspot numbers, the degree of control depending on the positions of the other planets.This paper describes the results of extending the work to include all the planets.As a working hypothesis we have assumed that gravitational tidal forces induced on the Sun by the planets may modulate solar activity and have accordingly calculated relative equilibrium ‘high tide’ displacements of the solar surface for each day from the positions, masses and distances of the first six planets. Although the tides are very slight, the mass of displaced material is appreciable and varies over the very wide range of nearly 5 to 1.

scholarly journals Photospheric plasma and magnetic field dynamics during the formation of solar AR 11190

2019 ◽  
Vol 622 ◽  
pp. A168 ◽  
Author(s):  
J. I. Campos Rozo ◽  
D. Utz ◽  
S. Vargas Domínguez ◽  
A. Veronig ◽  
T. Van Doorsselaere
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Active Regions ◽  
Rayleigh Distribution ◽  
The Other ◽  
The Sun ◽  
Flux Emergence ◽  
Convective Flows ◽  
Magnetic Elements ◽  
The Continuum

Context. The Sun features on its surface typical flow patterns called the granulation, mesogranulation, and supergranulation. These patterns arise due to convective flows transporting energy from the interior of the Sun to its surface. The other well known elements structuring the solar photosphere are magnetic fields arranged from single, isolated, small-scale flux tubes to large and extended regions visible as sunspots and active regions. Aims. In this paper we will shed light on the interaction between the convective flows in large-scale cells as well as the large-scale magnetic fields in active regions, and investigate in detail the statistical distribution of flow velocities during the evolution and formation of National Oceanic and Atmospheric Administration active region 11190. Methods. To do so, we employed local correlation tracking methods on data obtained by the Solar Dynamics Observatory in the continuum as well as on processed line-of-sight magnetograms. Results. We find that the flow fields in an active region can be modelled by a two-component distribution. One component is very stable, follows a Rayleigh distribution, and can be assigned to the background flows, whilst the other component is variable in strength and velocity range and can be attributed to the flux emergence visible both in the continuum maps as well as magnetograms. Generally, the plasma flows, as seen by the distribution of the magnitude of the velocity, follow a Rayleigh distribution even through the time of formation of active regions. However, at certain moments of large-scale fast flux emergence, a second component featuring higher velocities is formed in the velocity magnitudes distribution. Conclusions. The plasma flows are generally highly correlated to the motion of magnetic elements and vice versa except during the times of fast magnetic flux emergence as observed by rising magnetic elements. At these times, the magnetic fields are found to move faster than the corresponding plasma.

scholarly journals Panoramic Analyzer of Radio Spectra — Instrument for Measurements of Coronal Magnetic Fields on the Sun

1993 ◽  
Vol 141 ◽  
pp. 306-309 ◽  
Author(s):  
V. M. Bogod ◽  
S. M. Vatrushin ◽  
V. E. Abramov-Maximov ◽  
S. V. Tsvetkov ◽  
V. N. Dikij
Keyword(s):  
Solar Activity ◽  
Magnetic Fields ◽  
Plasma Diagnostics ◽  
Solar Radio ◽  
High Spatial Resolution ◽  
Solar Radio Emission ◽  
The Sun ◽  
Wide Range ◽  
Coronal Magnetic Fields ◽  
Special Value

The study of solar radio emission in a wide (covering many octaves) wavelength range is of great importance for plasma diagnostics of all types of solar activity. Here we describe a new spectroanalyzer covering a wide range in frequency from 1 to 18 GHz, which is used at the RATAN-600 radio telescope beginning 1991 December 20. Coronal magnetic fields have been measured with the various radio astronomical methods presented in these proceedings by Gelfreikh et al. and Bogod et al.Of special value are collaborative spectral-polarization observations using the RATAN-600 and high-spatial resolution observations with the VLA and WSRT (Akhmedov et al. 1986; Bogod et al. 1992; Alissandrakis et al. 1992).

scholarly journals On the Spottedness and Magnetic Field of T Tau-Type Stars

1977 ◽  
Vol 4 (2) ◽  
pp. 407-407
Author(s):  
R. E. Gershberg
Keyword(s):  
Magnetic Fields ◽  
High Ratio ◽  
Convective Zone ◽  
Polarization Degree ◽  
Additional Energy ◽  
Field Range ◽  
Strong Magnetic Fields ◽  
T Tau Type Stars ◽  
Hydromagnetic Waves ◽  
T Tau

There are several observations that suggest the existence of surface heterogeneities on the T Tau-type stars. Firstly Dr. Ismailov from Shemakha has found strong variations of emission line profiles for 5-10 minutes: 2-component profiles become 3 or 1 component and vice-versa. The results were confirmed recently in the Sternberg Institute. Secondly, variations of polarization degree and relative intensities in the IR calcium triplet were found when the stellar brightness were being constant. Then, the relative intensities of the Ca triplet are not equal to what must be expected for both optically thin or thick but homogeneous emission regions. On the basis of the data Petrov and Sheberbakov from Crimean Observatory have proposed that T Tau stars have active regions with strong magnetic fields similar to stellar ones: they can give noticeable heterogeneities for calcium emission, for polarization effects in dust envelopes and local processes for profile variations. The existence of rather strong and local magnetic fields on T Tauri stars may give a key for explaining the mysteries of these variables. Small variations of strong magnetic fields on stars with a convective zone can give a new mechanism for stellar variability. As it is known, only a quarter of the energy flux that reaches the bottom of the convective zone, is emitted from a sunspot in form of light and the main part of the energy escapes in form of hydromagnetic waves. Then, the sunspot exists if the field is not less than 1 kilogauss. Therefore the field acts as a relay: if the field is low we have light, if the field is strong we have mainly hydromagnetic waves. The transition from low to high field may occupy only a small part of the whole field range. The field variations on T Tau stars can give strong brightness variations without additional energy sources but only by magnetic relay operation. I hope that this scheme gives a possibility to explain a set of features of T Tau stars (such as their high ratio of chromospheric to photospheric radiation, IR excesses, the nature of their flares) as well as main features of FU Ori-type flares.

scholarly journals Are Solar Wind Measurements of Different Spacecraft Consistent?

1980 ◽  
Vol 91 ◽  
pp. 151-154
Author(s):  
R. Steinitz ◽  
M. Eyni
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Boundary Conditions ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
The Other ◽  
The Sun ◽  
Spatial Gradients ◽  
Wind Measurements ◽  
The One

Results of solar wind measurements by different spacecraft are not always in full accord. Such measurements are in general not from one and the same distance r from the sun, nor are they taken at the same phase of the solar activity cycle. One would like to be able to discriminate between spacecraft calibration effects on the one hand, and solar wind variations which reflect true spatial gradients or changing boundary conditions at the sun on the other hand. Accordingly, we examine in this paper the possibility of reconciling the apparent discrepancies.

scholarly journals Revisiting the nature of dark sunspots: the sun as a heat engine

2021 ◽  
Vol 5 (1) ◽  
pp. 6-9
Author(s):  
Soika Alexander Kuzmich
Keyword(s):  
Solar Activity ◽  
Heat Sink ◽  
Optical Radiation ◽  
Heat Engine ◽  
Physical Nature ◽  
Second Law Of Thermodynamics ◽  
Dissipative Structures ◽  
Second Law ◽  
The Sun

This work is a continuation of the author's studies,1,2,3 related to the elucidation of the physical nature of dark sunspots. They showed that the appearance of cold sunspots, the temperature of which is below the temperature of the photosphere, is incompatible with the second law of thermodynamics. Sunspots in the Sun's photosphere can only be hot. This article provides a thermodynamic analysis of the work of the Sun as a heat engine. It is shown that sunspots are dissipative structures that spontaneously appear in the photosphere of the Sun and ensure its viability as a source of optical radiation. Sunspots play the role of a cooler for the sun's global heat engine, and without them its radiant glow would be impossible, just like the operation of any heat engine without a cold heat sink. In addition, it is shown that all the phenomena of solar activity are caused by the operation of the photospheric heat engine of the Sun, in which sunspots are the source of heat.

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