scholarly journals Coronal mass ejections as a new indicator of the active Sun

2018 ◽  
Vol 13 (S340) ◽  
pp. 95-100
Author(s):  
Nat Gopalswamy
Keyword(s):  
Solar Activity ◽  
Coronal Mass Ejections ◽  
Rotation Period ◽  
The Sun ◽  
Solar Cycles ◽  
The North ◽  
Transient Events ◽  
Key Indicators ◽  
Quiescent Filament ◽  
Activity Indices

AbstractCoronal mass ejections (CMEs) have become one of the key indicators of solar activity, especially in terms of the consequences of the transient events in the heliosphere. Although CMEs are closely related to the sunspot number (SSN), they are also related to other closed magnetic regions on the Sun such as quiescent filament regions. This makes CMEs a better indicator of solar activity. While sunspots mainly represent the toroidal component of solar magnetism, quiescent filaments (and hence CMEs associated with them) connect the toroidal and poloidal components via the rush-to-the-pole (RTTP) phenomenon. Taking the end of RTTP in each hemisphere as an indicator of solar polarity reversal, it is shown that the north-south reversal asymmetry has a quasi-periodicity of 3-5 solar cycles. Focusing on the geospace consequences of CMEs, it is shown that the maximum CME speeds averaged over Carrington rotation period show good correlation with geomagnetic activity indices such as Dst and aa.

scholarly journals Complexes of activity on the Sun in solar cycle 21

2021 ◽  
pp. 3-9
Author(s):  
Sergey Yazev ◽  
Maria Ulianova ◽  
Elena Isaeva
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Natural Environment ◽  
Statistical Data ◽  
Sunspot Activity ◽  
The Sun ◽  
Solar Cycles ◽  
The North ◽  
South Asymmetry

The paper provides statistical data on solar activity complexes (ACs) observed in solar cycle 21. From the synoptic charts for the 1976–1986 sunspot activity, we have detected the regions where the sunspot generation was observed at least through three Carrington Rotations (CRs). These regions were identified as AC cores. We have compiled an AC catalogue. ACs are shown to evolve quasi-periodically, in pulses that are 15–20 rotations long. We have analyzed the North-South asymmetry in the AC location. In cycle 21, 90 % of the proton flares that affected the natural environment are shown to have occurred in ACs. We note a tendency for AC activity to decrease, as well as the manifestation of the Gnevyshev—Ohl rule in AC properties, in solar cycles 21–24.

Periodic Variation of the North-South Asymmetry of Solar Activity Phenomena

2000 ◽  
Vol 179 ◽  
pp. 173-176
Author(s):  
V. K. Verma
Keyword(s):  
Solar Activity ◽  
Periodic Variation ◽  
The Sun ◽  
Solar Cycles ◽  
The North ◽  
Sunspot Data ◽  
Flare Index ◽  
North And South ◽  
South Asymmetry

AbstractWe report here a study of various solar activity phenomena occurring in both north and south hemispheres of the Sun during solar cycles 8–23. In the study we have used sunspot data for the period 1832–1976, flare index data for the period 1936–1993, Hα flare data 1993–1998 and solar active prominences data for the period 1957–1998. Earlier Verma reported long-term cyclic period in N-S asymmetry and also that the N-S asymmetry of solar activity phenomena during solar cycles 21, 22, 23 and 24 will be south dominated and the N-S asymmetry will shift to north hemisphere in solar cycle 25. The present study shows that the N-S asymmetry during solar cycles 22 and 23 are southern dominated as suggested by Verma.

scholarly journals Complexes of activity on the Sun in solar cycle 21

2021 ◽  
Vol 7 (4) ◽  
pp. 3-9
Author(s):  
Sergey Yazev ◽  
Maria Ulianova ◽  
Elena Isaeva
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Natural Environment ◽  
Statistical Data ◽  
Sunspot Activity ◽  
The Sun ◽  
Solar Cycles ◽  
The North ◽  
South Asymmetry

The paper provides statistical data on solar activity complexes (ACs) observed in solar cycle 21. From the synoptic charts for the 1976–1986 sunspot activity, we have detected the regions where the sunspot generation was observed at least through three Carrington Rotations (CRs). These regions were identified as AC cores. We have compiled an AC catalogue. ACs are shown to evolve quasi-periodically, in pulses that are 15–20 rotations long. We have analyzed the North-South asymmetry in the AC location. In cycle 21, 90 % of the proton flares that affected the natural environment are shown to have occurred in ACs. We note a tendency for AC activity to decrease, as well as the manifestation of the Gnevyshev—Ohl rule in AC properties, in solar cycles 21–24.

ESTABLISHING SOLAR ACTIVITY TREND FOR SOLAR CYCLES 21 – 24

2021 ◽  
Vol 44 ◽  
pp. 100-106
Author(s):  
A.K. Singh ◽  
◽  
A. Bhargawa ◽  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Sunspot Number ◽  
Cosmic Ray ◽  
Occurrence Rate ◽  
The Sun ◽  
Solar Cycles ◽  
Lyman Alpha ◽  
Rate Versus ◽  
Alpha Index

Solar-terrestrial environment is manifested primarily by the physical conditions of solar interior, solar atmosphere and eruptive solar plasma. Each parameter gives unique information about the Sun and its activity according to its defined characteristics. Hence the variability of solar parameters is of interest from the point of view of plasma dynamics on the Sun and in the interplanetary space as well as for the solar-terrestrial physics. In this study, we have analysed various solar transients and parameters to establish the recent trends of solar activity during solar cycles 21, 22, 23 and 24. The correlation coefficients of linear regression of F10.7 cm index, Lyman alpha index, Mg II index, cosmic ray intensity, number of M & X class flares and coronal mass ejections (CMEs) occurrence rate versus sunspot number was examined for last four solar cycles. A running cross-correlation method has been used to study the momentary relationship among the above mentioned solar activity parameters. Solar cycle 21 witnessed the highest value of correlation for F10.7 cm index, Lyman alpha index and number of M-class and X-class flares versus sunspot number among all the considered solar cycles which were 0.979, 0.935 and 0.964 respectively. Solar cycle 22 recorded the highest correlation in case of Mg II index, Ap index and CMEs occurrence rate versus sunspot number among all the considered solar cycles (0.964, 0.384 and 0.972 respectively). Solar cycle 23 and 24 did not witness any highest correlation compared to solar cycle 21 and 22. Further the record values (highest value compared to other solar three cycles) of each solar activity parameters for each of the four solar cycles have been studied. Here solar cycle 24 has no record text at all, this simply indicating that this cycle was a weakest cycle compared to the three previous ones. We have concluded that in every domain solar 24 was weaker to its three predecessors.

scholarly journals Photospheric activity of the Sun with VIRGO and GOLF

2017 ◽  
Vol 608 ◽  
pp. A87 ◽  
Author(s):  
D. Salabert ◽  
R. A. García ◽  
A. Jiménez ◽  
L. Bertello ◽  
E. Corsaro ◽  
...  
Keyword(s):  
Solar Activity ◽  
Radial Velocity ◽  
Wavelength Dependence ◽  
Solar Photosphere ◽  
The Sun ◽  
Solar Cycles ◽  
Quasi Biennial Oscillation ◽  
Photometric Observations ◽  
Cycle 24 ◽  
Biennial Oscillation

We study the variability of solar activity using new photospheric proxies originally developed for the analysis of stellar magnetism with the CoRoT and Kepler photometric observations. These proxies were obtained by tracking the temporal modulations in the observations associated with the spots and magnetic features as the Sun rotates. We analyzed 21 yr of observations, spanning solar cycles 23 and 24, collected by the space-based photometric VIRGO and radial velocity GOLF instruments on board the SoHO satellite. We then calculated the photospheric activity proxy Sph is for each of the three VIRGO photometers and the associated Svel proxy from the radial velocity GOLF observations. Comparisons with several standard solar activity proxies sensitive to different layers of the Sun demonstrate that these new activity proxies, Sph and Svel, provide a new manner to monitor solar activity. We show that both the long- and short-term magnetic variabilities respectively associated with the 11-yr cycle and the quasi-biennial oscillation are well monitored, and that the magnetic field interaction between the subsurface, photosphere, and chromosphere of the Sun was modified between Cycle 24 and Cycle 23. Furthermore, the photometric proxies show a wavelength dependence of the response function of the solar photosphere among the three channels of the VIRGO photometers, providing inputs for the study of the stellar magnetism of Sun-like stars.

scholarly journals Temporal variations of different solar activity indices through the solar cycles 21-23

2017 ◽  
pp. 59-70 ◽  
Author(s):  
Ü.D. Gäoker ◽  
J. Singh ◽  
F. Nutku ◽  
M. Priyal
Keyword(s):  
Solar Activity ◽  
Detailed Comparison ◽  
Temporal Variations ◽  
Total Solar Irradiance ◽  
Magnetic Activity ◽  
Unexpected Finding ◽  
Solar Cycles ◽  
Percentage Decrease ◽  
Solar Activity Indices ◽  
Activity Indices

Here, we compare the sunspot counts and the number of sunspot groups (SGs) with variations of total solar irradiance (TSI), magnetic activity, Ca II K-flux, faculae and plage areas. We applied a time series method for extracting the data over the descending phases of solar activity cycles (SACs) 21, 22 and 23, and the ascending phases 22 and 23. Our results suggest that there is a strong correlation between solar activity indices and the changes in small (A, B, C and H-modified Zurich Classification) and large (D, E and F) SGs. This somewhat unexpected finding suggests that plage regions substantially decreased in spite of the higher number of large SGs in SAC 23 while the Ca II K-flux did not decrease by a large amount nor was it comparable with SAC 22 and relates with C and DEF type SGs. In addition to this, the increase of facular areas which are influenced by large SGs, caused a small percentage decrease in TSI while the decrement of plage areas triggered a higher decrease in the magnetic field flux. Our results thus reveal the potential of such a detailed comparison of the SG analysis with solar activity indices for better understanding and predicting future trends in the SACs.

scholarly journals Studies of synoptic solar activity using Kodaikanal Ca K data

2016 ◽  
Vol 12 (S328) ◽  
pp. 110-112
Author(s):  
K. P. Raju
Keyword(s):  
Solar Activity ◽  
Archival Data ◽  
Solar Cycles ◽  
Chromospheric Network ◽  
Uv Irradiance ◽  
Network Boundary ◽  
Good Proxy ◽  
Boundary Width ◽  
Bright Emission ◽  
Activity Indices

AbstractThe chromospheric network, the bright emission network seen in the chromospheric lines such as Ca ii K and Hα, outline the supergranulation cells. The Ca images are dominated by the chromospheric network and plages which are good indicators of solar activity. Further, the Ca line is a good proxy to the UV irradiance which is particularly useful in the pre-satellite era where UV measurements are not available. The Ca spectroheliograms of the Sun from Kodaikanal have a data span of about 100 years and covers over 9 solar cycles. The archival data is now available in the digitized form. Programs have been developed to obtain the activity indices and the length scales of the chromospheric network from the data. The preliminary results from the analysis are reported here. It is shown that the Ca ii K intensity and the network boundary width are dependent on the solar cycle.

scholarly journals The east-west asymmetry in Coronal Mass Ejections: evidence for active longitudes

2005 ◽  
Vol 23 (9) ◽  
pp. 3139-3147 ◽  
Author(s):  
M. Skirgiello
Keyword(s):  
Solar Activity ◽  
Southern Hemisphere ◽  
Coronal Mass Ejections ◽  
Solar Rotation ◽  
Occurrence Rate ◽  
The Sun ◽  
The Earth ◽  
Orbital Revolution ◽  
Time Periods ◽  
East West

Abstract. Various manifestations of solar activity are not uniformly distributed with heliographic longitude. By using east-west asymmetry in the occurrence rate of CMEs (coronal mass ejections), the longitudinal dependence in SOHO LASCO 1996-2004 data has been studied in this work. The solar rotation periodicity has been found, indicating the presence of active longitudes, whose phase is reversed twice during the studied period. It is more prominent in the Southern Hemisphere. The east-west asymmetry is also present when calculated for longer time periods. Sometimes (particularly during low solar activity), there is an alternation of the eastern and western domination every six months. Taking into account the orbital revolution of the Earth about the Sun, this indicates the existence of enhanced activity, fixed in space (not undergoing Carrington rotation). Moreover, there is about a 3.7% overall excess of western events, lasting for the entire reported time, suggesting some bias in the observations. A hypothesis to explain this phenomenon is proposed.

scholarly journals Influence of Coronal Mass Ejections from the Red Dwarf Component on the Accretion Pattern in CVs and LMXBs

1995 ◽  
Vol 151 ◽  
pp. 195-196
Author(s):  
Roberto Minarini ◽  
Grigory Beskin
Keyword(s):  
Mass Loss ◽  
Coronal Mass Ejections ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Magnetic Activity ◽  
The Sun ◽  
Surface Mass ◽  
Red Dwarfs ◽  
Low Mass ◽  
Transient Events

Low-mass main sequence stars show a magnetic activity similar to the Sun and as a consequence they lose mass in the form of a variable stellar wind. In the latest spectral types (red dwarfs) the activity and the mass loss rate appear to increase by a large factor of ∼ 103 with respect to the solar case, reaching Ṁ ∼ 2 · 10−11 M⊙/yr (Badalyan & Livshits 1992, Katsova 1993). The same happens for coronal mass ejections (CMEs), which are the most relevant transient events of mass loss in these objects. In the Sun, these appear as bubbles of coronal material, with dimensions of some fraction of the solar surface, mass M ≃ 2 · 1014 - 2 · 1016 g and ejection velocity v ≃ 3 · 107 - 2 · 108 cm/s, with an instantaneous mass loss rate Ṁ ∽ 10−13 - 10−11 M⊙/yr (Wagner 1984). In red dwarfs, as recently observed, the ejection velocities are higher, up to v ≃ 3 · 108 cm/s and the mass loss rate can reach the value Ṁ ≃ 10−8 M⊙/yr (Mullan et al. 1989, Houdebine et al. 1990). In both cases, the observations suggest that a bubble expands, once ejected, with a velocity of several hundreds of km/s.

scholarly journals Gradual onset of the Maunder Minimum revealed by high-precision carbon-14 analyses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiroko Miyahara ◽  
Fuyuki Tokanai ◽  
Toru Moriya ◽  
Mirei Takeyama ◽  
Hirohisa Sakurai ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
High Precision ◽  
Crop Yields ◽  
Maunder Minimum ◽  
The Sun ◽  
Solar Cycles ◽  
Precision Data ◽  
Carbon 14 ◽  
Grand Minimum

AbstractThe Sun exhibits centennial-scale activity variations and sometimes encounters grand solar minimum when solar activity becomes extremely weak and sunspots disappear for several decades. Such an extreme weakening of solar activity could cause severe climate, causing massive reductions in crop yields in some regions. During the past decade, the Sun’s activity has tended to decline, raising concerns that the Sun might be heading for the next grand minimum. However, we still have an underdeveloped understanding of solar dynamo mechanisms and hence precise prediction of near-future solar activity is not attained. Here we show that the 11-year solar cycles were significantly lengthened before the onset of the Maunder Minimum (1645–1715 CE) based on unprecedentedly high-precision data of carbon-14 content in tree rings. It implies that flow speed in the convection zone is an essential parameter to determine long-term solar activity variations. We find that a 16 year-long cycle had occurred three solar cycles before the onset of prolonged sunspot disappearance, suggesting a longer-than-expected preparatory period for the grand minimum. As the Sun has shown a tendency of cycle lengthening since Solar Cycle 23 (1996–2008 CE), the behavior of Solar Cycle 25 can be critically important to the later solar activity.

Sign in / Sign up

Export Citation Format

Share Document