scholarly journals STELLAR ACTIVITY CYCLES: WHY DO WE NEED IN THE LONG-TERM MEASUREMENTS OF THE MAGNETIC FIELD?

2017 ◽  
Vol 30 (0) ◽  
pp. 124-125
Author(s):  
S. I. Plachinda ◽  
V. V. Butkovskaya
Keyword(s):  
Magnetic Field ◽  
Stellar Activity ◽  
Activity Cycles ◽  
The Magnetic Field

Long-term stellar magnetic field study at the Crimean Astrophysical Observatory

2018 ◽  
Vol 13 (S340) ◽  
pp. 35-38
Author(s):  
Varvara Butkovskaya ◽  
Sergei Plachinda ◽  
Dilyara Baklanova
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Study ◽  
Crimean Astrophysical Observatory ◽  
Activity Cycles ◽  
Magnetic Cycles ◽  
Long Term Monitoring ◽  
The Magnetic Field ◽  
Term Monitoring

AbstractThe long-term monitoring of magnetic cycles is a key diagnostic in understanding how dynamo generation and amplification of magnetic fields occur in solar-like stars. One of the current key problems is the establishment of the magnetic field behavior during the activity cycles for stars of different ages and evolutionary statuses. We present the experience of using own long-term datasets for study of activity cycles in selected stars at the Crimean Astrophysical Observatory.

scholarly journals About long term modulation of cosmic rays in the 23-24 solar activity cycles

2021 ◽  
pp. 23-29
Author(s):  
Anatoly V. Belov ◽  
Raisa T. Gushchina ◽  
Victor Yanke
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Cosmic Rays ◽  
Solar Magnetic Field ◽  
The Sun ◽  
Model Calculations ◽  
Activity Cycles ◽  
The Magnetic Field ◽  
Solar Activity Cycles

Recently, there has been a significant trend in magnetic fields on the Sun. The total magnetic field of the Sun from the end of the 22nd cycle of solar activity (SA) has more than halved and this decrease continues. Chan- ges in the magnetic field are the key to all the active phenomena occurring on the Sun and in the heliosphere and, accordingly, to processes in cosmic rays. In long-term CR variations in 23-24 cycles of SA the attenuation of the solar magnetic field is displayed and these variations turned out to be the smallest for the entire time of CR observations. Model calculations of CR modulation for 21-22 and 23-24 cycles of SA showed: with a slight difference in the regression characteristics obtained, the distribution of contributions to the generated CR modulation from the effects of various SA indices is strongly varies in the analyzed periods. Possible reasons for the features of the last two CA cycles are discussed.

scholarly journals Joint Discussion 8 Solar and stellar activity cycles

2006 ◽  
Vol 2 (14) ◽  
pp. 271-272
Author(s):  
Alexander G. Kosovichev ◽  
Klaus G. Strassmeier
Keyword(s):  
Magnetic Field ◽  
Time Scales ◽  
Tree Ring ◽  
Solar Magnetic Field ◽  
Sunspot Cycle ◽  
Magnetic Cycle ◽  
Stellar Activity ◽  
Tree Ring Data ◽  
Activity Cycles

The solar magnetic field and its associated atmospheric activity exhibits periodic variations on a number of time scales. The 11-year sunspot cycle and its underlying 22-year magnetic cycle are, besides the 5-minute oscillation, the most widely known. Amplitudes and periods range from a few parts per million (ppm) and 2–3 minutes for p-modes in sunspots, a few 10 ppm and 10 minutes for the granulation turn around, a few 100 ppm and weeks for the lifetime of plages and faculae, 1000 ppm and 27 days for the rotational signal from spots, to the long-term cycles of 90 yr (Gleissberg cycle), 200 - 300 yr (Wolf, Spörer, Maunder minima), 2,400 yr from 14C tree-ring data, and possibly in excess of 100,000 yr.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

scholarly journals Practice and perspectives of using ultrasensitive magnetometers in biomedical research.

2021 ◽  
Author(s):  
Yu.V. Maslennikov ◽  
◽  
◽  
Keyword(s):  
Magnetic Field ◽  
Biomedical Research ◽  
Magnetic Measurements ◽  
Signal To Noise Ratio ◽  
Frequency Range ◽  
Optically Pumped ◽  
Technical Solutions ◽  
Further Development ◽  
The Magnetic Field

There are a large number of sensors for measuring the magnetic field of biological objects. They are characterized by the type of the measured physical parameter (magnetic field strength, magnetic flux, etc.), the level of intrinsic sensitivity, and the frequency range of the recorded signals. The long-term practice of studying biomagnetic signals shows that only SQUID-based magnetometers and optically pumped magnetometers have sensitivity levels sufficient for recording biomagnetic signals with the required signal-to-noise ratio. This chapter reflects the main directions of using such magnetometers and methods of magnetic measurements in biomedical research, gives examples of existing technical solutions, and shows possible ways of their further development.

EFFECT OF ATTENUATED MAGNETIC FIELD ON DEVELOPMENT OF THE LIVER AND SPLEEN IN EMBRYONIC JAPANESE QUAIL

2021 ◽  
Vol 55 (6) ◽  
pp. 50-55
Author(s):  
S.A. Pineguin ◽  
◽  
O.A. Dadasheva ◽  
E.I. Mednikova ◽  
O.A. Grushina ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Japanese Quail ◽  
First Generation ◽  
Space Missions ◽  
The Moon ◽  
Living Organisms ◽  
The Magnetic Field

Expectation of remote space missions and long-term stay and work on the Moon with the magnetic field 1,000 times weaker than on Earth sets the researchers the formidable task to investigate effects of the hypomagnetic environment on living organisms. The paper reports data about the liver and spleen development in Japanese quail embryos of various age exposed in a modeled lunar magnetic field. Retardation of hemopoiesis was observed as in the first generation embryos (F1), so in sequential embryo generations developed in the ordinary magnetic environment (F2).

scholarly journals Correcting the geomagnetic IHV index of the Eskdalemuir observatory

2006 ◽  
Vol 24 (12) ◽  
pp. 3411-3419 ◽  
Author(s):  
D. Martini ◽  
K. Mursula
Keyword(s):  
Magnetic Field ◽  
Data Center ◽  
Early Years ◽  
Correction Factors ◽  
Hourly Data ◽  
The World ◽  
Variability Index ◽  
The Magnetic Field ◽  
Long Term Studies

Abstract. We study here the recently proposed measure of local geomagnetic activity called the IHV (Inter-Hour Variability) index calculated for the Eskdalemuir (ESK) station. It was found earlier that the ESK IHV index depicts an artificial, step-like increase from 1931 to 1932. We show here that this increase is due to the fact that the values of the magnetic field components of the ESK observatory stored at the World Data Center are two-hour running averages of hourly data stored in ESK yearbooks. Two-hour averaging greatly reduces the variability of the data which leads to artificially small values of the IHV index in 1911–1931. We also study the effect of two-hour averaging upon hourly mean and spot values using 1-minute data available for recent years, and calculate the correction factors for the early years, taking into account the weak dependence of correction factors on solar activity. Using these correction factors, we correct the ESK IHV indices in 1912–1931, and revise the estimate of the centennial change based on them. The effect of correction is very significant: the centennial increase in the ESK IHV-raw (IHV-cor) index in 1912–2000 changes from 73.9% (134.4%) before correction to 10.3% (25.3%) thereafter, making the centennial increase at ESK quite similar to other mid-latitude stations. Obviously, earlier long-term studies based on ESK IHV values are affected by the correction and need to be revised. These results also strongly suggest that the ESK yearbook data should be digitized and the hourly ESK data at WDC should be replaced by them.

The long-term behavior of the magnetic field of beta CrB.

1973 ◽  
Vol 186 ◽  
pp. 211 ◽  
Author(s):  
E. F. Borra ◽  
M. M. Dworetsky
Keyword(s):  
Magnetic Field ◽  
Long Term Behavior ◽  
The Magnetic Field

scholarly journals A short and sudden increase of the magnetic field strength and the accompanying spectral variability in the O9.7 V star HD 54879

2019 ◽  
Vol 484 (4) ◽  
pp. 4495-4506 ◽  
Author(s):  
S Hubrig ◽  
M Küker ◽  
S P Järvinen ◽  
A F Kholtygin ◽  
M Schöller ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Longitudinal Magnetic Field ◽  
Sudden Increase ◽  
Spectral Variability ◽  
Dipole Strength ◽  
Large Program ◽  
Short And Long Term ◽  
The Magnetic Field

Abstract Only 11 O-type stars have been confirmed to possess large-scale organized magnetic fields. The presence of a −600 G longitudinal magnetic field in the O9.7 V star HD 54879 with a lower limit of the dipole strength of ∼2 kG was discovered a few years ago in the framework of the ESO large program ‘B-fields in OB stars’. Our FORS 2 spectropolarimetric observations from 2017 October 4 to 2018 February 21 reveal the presence of short- and long-term spectral variability and a gradual magnetic field decrease from about −300 G down to about −90 G. Different scenarios are discussed in an attempt to interpret our observations. Our FORS 2 radial velocity measurements indicate that HD 54879 is a member of a long-period binary.

The long-term optical activity of the propellers AE Aquarii and AR Scorpii

2020 ◽  
Vol 72 (2) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Magnetic Field ◽  
Real Time ◽  
Optical Activity ◽  
White Dwarf ◽  
Transient Decrease ◽  
Mass Outflow ◽  
Orbital Modulation ◽  
The Magnetic Field

Abstract This analysis of the long-term optical activity of the propellers AE Aqr and AR Sco uses data from the Catalina Real-time Transient Survey, DASCH, and AAVSO. The site and character of the emissions from the phenomena caused by the magnetic field of the white dwarf (WD) vary from system to system. The histogram of intensities of the ensemble of flares of AE Aqr suggests that the long-term activity consists of a large variety of the peak magnitudes of the flares, with the probability of their detection gradually decreasing with increasing intensity. Any increase of activity only leads to an increase of the number of blobs of the transferring matter. We also detected a season with a transient decrease or even a cessation of the mass outflow from the donor to the lobe of the WD. The very strong orbital modulation of AR Sco is most stable in the phases of the extrema of brightness for about a century; its minor changes suggest that the trailing side of the synchrotron-emitting region is more unstable than the leading side.

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