INFLUENCE OF THE SOLAR GLOBAL MAGNETIC FIELD DECREASE ON THE FORMATION AND PARAMETERS OF CORONAL MASS EJECTIONS IN CYCLE 24

AbstractWe investigated the prominence eruptions and disappearances observed with the Nobeyama Radioheliograph during over 20 years for studying the anomaly of the recent solar cycle. Although the sunspot number of Cycle 24 is smaller than the previous one dramatically, the occurrence rate, size and radial velocity of the prominence activities are not changed significantly. We also found that the occurrence of the prominence activities in the northern hemisphere is normal from the duration of the cycle and the migration of the producing region of the prominence activities. On the other hand, the migration in the southern hemisphere significantly differs from that in the northern hemisphere and the previous cycles. Our results suggest that the anomalies of the global magnetic field distribution started at the solar maximum of Cycle 23.

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On the origin of variable structures in the winds of hot luminous stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stt2102 ◽

2013 ◽

Vol 440 (1) ◽

pp. 2-9 ◽

Cited By ~ 9

Author(s):

Yannick J. L. Michaux ◽

Anthony F. J. Moffat ◽

André-Nicolas Chené ◽

Nicole St-Louis

Keyword(s):

Magnetic Field ◽

Empirical Evidence ◽

Temporal Variability ◽

Large Scale ◽

Small Scale ◽

Ionization Zone ◽

Corotating Interaction Regions ◽

Wind Variability ◽

Global Magnetic Field ◽

Interaction Regions

Abstract Examination of the temporal variability properties of several strong optical recombination lines in a large sample of Galactic Wolf–Rayet (WR) stars reveals possible trends, especially in the more homogeneous WC than the diverse WN subtypes, of increasing wind variability with cooler subtypes. This could imply that a serious contender for the driver of the variations is stochastic, magnetic subsurface convection associated with the 170 kK partial-ionization zone of iron, which should occupy a deeper and larger zone of greater mass in cooler WR subtypes. This empirical evidence suggests that the heretofore proposed ubiquitous driver of wind variability, radiative instabilities, may not be the only mechanism playing a role in the stochastic multiple small-scaled structures seen in the winds of hot luminous stars. In addition to small-scale stochastic behaviour, subsurface convection guided by a global magnetic field with localized emerging loops may also be at the origin of the large-scale corotating interaction regions as seen frequently in O stars and occasionally in the winds of their descendant WR stars.

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Magnetic field changes preceding filament eruptions and coronal mass ejections

10.1063/1.2993658 ◽

2008 ◽

Cited By ~ 2

Author(s):

B. Schmieder ◽

T. Török ◽

G. Aulanier ◽

Vasile Mioc ◽

Cristiana Dumitrache ◽

...

Keyword(s):

Magnetic Field ◽

Coronal Mass Ejections

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A multi-wavelength analysis of the WASP-12 planetary system

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311020126 ◽

2010 ◽

Vol 6 (S276) ◽

pp. 163-166 ◽

Cited By ~ 1

Author(s):

Luca Fossati ◽

Carole A. Haswell ◽

Cynthia S. Froning

Keyword(s):

Magnetic Field ◽

Atmospheric Pollution ◽

Planetary System ◽

Light Curves ◽

Absorption Lines ◽

Transiting Planets ◽

Multi Wavelength ◽

Global Magnetic Field ◽

Solar Type ◽

Solar Type Star

AbstractWASP-12 is a 2 Gyr old solar type star, hosting WASP-12b, one of the most irradiated transiting planets currently known. We observed WASP-12 in the UV with the Cosmic Origins Spectrograph (COS) on HST. The light curves we obtained in the three covered UV wavelength ranges, all of which contain many photospheric absorption lines, imply effective radii of 2.69±0.24 RJ, 2.18±0.18 RJ, and 2.66±0.22 RJ, suggesting that the planet is surrounded by an absorbing cloud which overfills the Roche lobe. We clearly detected enhanced transit depths at the wavelengths of the MgII h&k resonance lines. Spectropolarimetric analysis of the host star was also performed. We found no global magnetic field, but there were hints of atmospheric pollution, which might be connected to the very unusual activity of the host star.

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Dynamics of the circumpolar magnetic field of the Sun at a maximum of cycle 24

Kinematics and Physics of Celestial Bodies ◽

10.3103/s0884591316020069 ◽

2016 ◽

Vol 32 (2) ◽

pp. 78-85 ◽

Cited By ~ 2

Author(s):

M. I. Pishkalo ◽

U. M. Leiko

Keyword(s):

Magnetic Field ◽

The Sun ◽

Cycle 24

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Modulation Effectiveness of Coronal Mass Ejections with Different Structure of the Magnetic Field

Bulletin of the Russian Academy of Sciences Physics ◽

10.3103/s1062873821100075 ◽

2021 ◽

Vol 85 (10) ◽

pp. 1183-1186

Author(s):

A. V. Belov ◽

M. A. Abunina ◽

E. A. Eroshenko ◽

A. A. Abunin ◽

A. Papaioannou ◽

...

Keyword(s):

Magnetic Field ◽

Coronal Mass Ejections ◽

The Magnetic Field

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Source-region characteristics of anemone active regions in the ascending phase of solar cycle 24

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038927 ◽

2020 ◽

Vol 642 ◽

pp. A233

Author(s):

R. Sharma ◽

C. Cid

Keyword(s):

Magnetic Field ◽

Solar Cycle ◽

Minimum Distance ◽

Source Region ◽

Coronal Holes ◽

Active Regions ◽

Yearly Average ◽

Solar Cycle 24 ◽

Cycle 24 ◽

Rise Phase

Context. Active regions in close proximity to coronal holes, also known as anemone regions, are the best candidates for studying the interaction between closed and open magnetic field topologies at the Sun. Statistical investigation of their source-region characteristics can provide vital clues regarding their possible association with energetic events, relevant from space weather perspectives. Aims. The main goal of our study is to understand the distinct properties of flaring and non-flaring anemone active regions and their host coronal holes, by examining spatial and magnetic field distributions during the rise phase of the solar cycle, in the years 2011–2014. Methods. Anemone regions were identified from the minimum-distance threshold, estimated using the data available in the online catalogs for on-disk active regions and coronal holes. Along with the source-region area and magnetic field characteristics, associated filament and flare cases were also located. Regions with and without flare events were further selected for a detailed statistical examination to understand the major properties of the energetic events, both eruptive and confined, at the anemone-type active regions. Results. Identified anemone regions showed weak asymmetry in their spatial distribution over the solar disk, with yearly average independent from mean sunspot number trend, during the rise phase of solar cycle 24. With the progression in solar cycle, the area and minimum-distance parameters indicated a decreasing trend in their magnitudes, while the magnetic field characteristics indicated an increase in their estimated magnitudes. More than half of the regions in our database had an association with a filament structure, and nearly a third were linked with a magnetic reconnection (flare) event. Anemone regions with and without flares had clear distinctions in their source-region characteristics evident from the distribution of their properties and density analysis. The key differences included larger area and magnetic field magnitudes for flaring anemone regions, along with smaller distances between the centers of the active region and its host coronal hole.

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Influence of the magnetic field of stellar wind on hot jupiter’s envelopes

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320000083 ◽

2019 ◽

Vol 15 (S354) ◽

pp. 268-279

Author(s):

Dmitry V. Bisikalo ◽

Andrey G. Zhilkin

Keyword(s):

Magnetic Field ◽

Plasma Flow ◽

Coronal Mass Ejections ◽

Stellar Wind ◽

Roche Lobe ◽

Bow Shock ◽

Hot Jupiters ◽

The Magnetic Field ◽

Alfven Velocity ◽

Hot Jupiter

AbstractHot Jupiters have extended gaseous (ionospheric) envelopes, which extend far beyond the Roche lobe. The envelopes are loosely bound to the planet and, therefore, are strongly influenced by fluctuations of the stellar wind. We show that, since hot Jupiters are close to the parent stars, magnetic field of the stellar wind is an important factor defining the structure of their magnetospheres. For a typical hot Jupiter, velocity of the stellar wind plasma flow around the atmosphere is close to the Alfvén velocity. As a result stellar wind fluctuations, such as coronal mass ejections, can affect the conditions for the formation of a bow shock around a hot Jupiter. This effect can affect observational manifestations of hot Jupiters.

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