On the periodicities of sunspots and solar strong hard X-ray bursts

Verma, V. K.; Joshi, G. C.

doi:10.1007/bf00167358

Cited by 43 publications

(17 citation statements)

References 5 publications

(3 reference statements)

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“…In addition to the 154 day periodicity, Pap, Tobsika, & Bouwer (1990) discovered a 51 day periodicity in active sunspot areas (areas of growing sunspot groups) of cycle 21. Results of periodicity analyses of sunspot numbers generally agree with the results of sunspot area analyses (Lean & Brueckner 1989;Krivova & Solanki 2002), but Verma & Joshi (1987), for some reason, did not detect the 154 day periodicity from sunspot numbers of cycle 21.…”

Section: Introductionsupporting

confidence: 63%

“…First of all, regardless of selection criteria, flare occurrence rates of solar cycle 21 all exhibited the 153 day periodicity: soft X-ray peak flux , hard X-ray peak rate (Dennis 1985;Bai & Sturrock 1987;Verma & Joshi 1987), H importance , H flare index (Ozguc & Atac 1989), 10 cm radio peak flux (Kile & Cliver 1991), production of solar energetic protons (Bai & Cliver 1990;Gabriel, Evans, & Feynman 1990), and production of energetic electrons in interplanetary space (Drö ge et al 1990). …”

Section: Introductionmentioning

confidence: 99%

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Periodicities in Solar Flare Occurrence: Analysis of Cycles 19–23

Bai

2003

ApJ

128

100

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Midrange periodicities in solar flare occurrence have been analyzed with new methods for cycles 19-23. During cycle 23, periodicities of 129 and 33.5 days were in operation. Five episodes of high activity occurred periodically with the 129 day period. The 33.5 day periodicity mainly operated for energetic flares. Results for cycles 19-21 are generally in agreement with previous analyses. For cycle 19, the 51 day periodicity is confirmed to be statistically significant. In the spectrum for cycle 20, two peaks are found at 84 and 129 days. The 129 day periodicity was in operation for eight cycles of 129 days. The 153 day periodicity, which operated during cycle 21, was more effective for modulating occurrence rates of energetic flares than for those of less energetic flares. No statistically significant periodicities are found from occurrence rates of energetic flares (!M1.0) of cycle 22. In the power spectra of major flare occurrence times for the time intervals analyzed by Ozguc and Atac and by Bai, the strongest peaks are found at 73, 76, and 51 days, in agreement with their results, but these periodicities are not statistically significant. It is interesting that the periods of 51, 129, and 153 days are very close to integral multiples of 25.5 days.

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Section: Introductionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Periodicities in Solar Flare Occurrence: Analysis of Cycles 19–23

Bai

2003

ApJ

128

100

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“…Asymmetries between the northern and the southern hemisphere were previously found in various solar indices, for instance in the distribution of flares (Reid 1968;Roy 1977;Ichimoto et al 1985;Verma 1987;Bai 1990;Garcia 1990;Atac & Ozguc 1996;Li et al 1998;Temmer et al 2001;Bai 2003b;Joshi & Joshi 2004) and filaments (Hansen & Hansen 1975;Vizoso & Ballester 1987;Duchlev & Dermendjiev 1996;Duchlev 2001), in the photospheric magnetic flux (Howard 1974;Mouradian & Soru-Escaut 1991;Knaack et al 2004), in the rotation velocities of photospheric magnetic fields (Antonucci et al 1990;Javaraiah & Gokhale 1997), and in the relative sunspot numbers and sunspot areas (Newton & Milsom 1955;Waldmeier 1971;Swinson et al 1986;Vizoso & Ballester 1989Carbonell et al 1993;Oliver & Ballester 1994;Verma 2000;Li et al 2002;Temmer et al 2002;Vernova et al 2002;Knaack et al 2004). North-south asymmetries may be due to phase differences between the magnetic activity in both hemispheres (Waldmeier 1971;Swinson et al 1986).…”

Section: Fig 1 A)mentioning

confidence: 60%

Evolution and rotation of large-scale photospheric magnetic fields of the Sun during cycles 21–23

Knaack¹,

Stenflo

Berdyugina

2005

A&A

121

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Abstract. We present the results of an extensive time series analysis of longitudinally-averaged synoptic maps, recorded at the National Solar Observatory (NSO/Kitt Peak) from 1975 to 2003, and provide evidence for a multitude of quasi-periodic oscillations in the photospheric magnetic field of the Sun. In the low frequency range, we have located the sources of the 3.6 yr, 1.8 yr, and 1.5 yr periodicities that were previously detected in the north-south asymmetry of the unsigned photospheric flux (Knaack et al. 2004, A&A, 418, L17). In addition, quasi-periodicities around 2.6 yr and 1.3 yr have been found. The 1.3 yr period is most likely related to large-scale magnetic surges toward the poles and appeared in both hemispheres at intermediate latitudes ∼30• -55• during the maxima of all three cycles 21-23, being particularly pronounced during cycle 22. Periods near

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“…), flares, prominences, radio bursts, hard X-ray bursts, gamma-ray bursts and coronal mass ejections. Investigations of the N-S asymmetry of solar flares have been carried out by Ružičková-Topolová (1974), Roy (1977), Knoška (1984), Verma (1987), Garcia (1990), Viktorinová & Antalová (1991), Joshi (1995), Ataç &Özgüç (1996, Li et al (1998) and Ataç &Özgüç (2001). All papers reveal the existence of a N-S asymmetry; however, there are different outcomes if the evolution of the N-S asymmetry is correlated with the solar cycle or not.…”

Section: North-south Asymmetrymentioning

confidence: 99%

Statistical analysis of solar H$\mathsf{\alpha}$ flares

Temmer

Veronig

Hanslmeier

et al. 2001

A&A

101

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Abstract.A statistical analysis of a large data set of Hα flares comprising almost 100 000 single events that occurred during the period January 1975 to December 1999 is presented. We analyzed the flares evolution steps, i.e. duration, rise times, decay times and event asymmetries. Moreover, these parameters characterizing the temporal behavior of flares, as well as the spatial distribution on the solar disk, i.e. N-S and E-W asymmetries, are analyzed in terms of their dependency on the solar cycle. The main results are: 1) The duration, rise and decay times increase with increasing importance class. The increase is more pronounced for the decay times than for the rise times. The same relation is valid with regard to the brightness classes but in a weaker manner.2) The event asymmetry indices, which characterize the proportion of the decay to the rise time of an event, are predominantly positive (≈90%). For about 50% of the events the decay time is even more than 4 times as long as the rise time.3) The event asymmetries increase with the importance class. 4) The flare duration and decay times vary in phase with the solar cycle; the rise times do not. 5) The event asymmetries do not reveal a distinct correlation with the solar cycle. However, they drop during times of solar minima, which can be explained by the shorter decay times found during minimum activity. 6) There exists a significant N-S asymmetry over longer periods, and the dominance of one hemisphere over the other can persist for more than one cycle. 7) For certain cycles there may be evidence that the N-S asymmetry evolves with the solar cycle, but in general this is not the case. 8) There exists a slight but significant E-W asymmetry with a prolonged eastern excess.

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On the periodicities of sunspots and solar strong hard X-ray bursts

Cited by 43 publications

References 5 publications

Periodicities in Solar Flare Occurrence: Analysis of Cycles 19–23

Periodicities in Solar Flare Occurrence: Analysis of Cycles 19–23

Evolution and rotation of large-scale photospheric magnetic fields of the Sun during cycles 21–23

Statistical analysis of solar H$\mathsf{\alpha}$ flares

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