Effects of activity complexes and active longitudes on variations in total solar irradiance

A numerical technique of time-longitude analysis has been developed by studying the fine structure of temporal variations in total solar irradiance (TSI). This analysis produces maps of large-scale thermal inhomogeneities on the Sun and reveals corresponding patterns of radiative excess and deficit relative to the unperturbed solar photosphere. These patterns are organized in two-and four-sector structures and exhibit the effects of both activity complexes and the active longitudes. Large-scale patterns with radiative excess show a facular macrostructure caused by the relaxation of large-scale thermo-magnetic perturbations and/or energy output due to very large-scale solar convection. These thermal patterns are related to long-lived magnetic fields that are characterized by rigid rotation. The patterns with radiative excess tend to concentrate around the active longitudes and are centered at 103° and 277° in the Carrington system when averaged over the time-longitude distribution of thermal inhomogeneities during activity cycles 21–23.     

The sector structure of the active longitudes in solar cycles

The longitudinal distributions of the polar faculae, bright K Ca⁺ points, and sunspot areas have been investigated in three-year intervals at the minima and maxima of the last five solar cycles in the rotation system which corresponds to the background magnetic field:T = 27.23 days (Mikhailutsa, 1994b). It has been shown that there were three specific features of the polar faculae and bright K Ca⁺ point longitudinal distributions: (1) The longitudes of maxima and minima of the distributions were approximately the same in the last five solar cycles. (2) There were predominantly two opposite longitudinal maxima and two opposite longitudinal minima in the distributions of each hemisphere. (3) The distributions of the northern and southern hemispheres were in opposite phase. The extremes of the sunspot area longitudinal distributions were preferentially between the longitudes of the polar facular extremes. The period of the sector structure rotation was defined more precisely:T = 27.227 ± 0.003 days. The results found can serve as an indication that there is a global foursector structure seated in the solar interior which plays a visible role in the polar facular and sunspot distributions.     

‘Bartels' active longitudes’, sector boundaries and flare activity

The flare activity and especially the proton-flare activity is concentrated in the zones of Bartels' active longitudes and in the neighbourhood closest to the sector boundaries of the interplanetary magnetic field. This concentration seems to be greater if the importance of the event increases.On leave from the Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, Academy of Sciences, U.S.S.R.     

Observation of solar particle fluxes over extended solar longitudes

Detailed particle observations from various Pioneer Spacecrafts located at different heliolongitudes during the complex solar flare events of March 30–April 10, 1969 have been utilised to investigate the energy dependence of azimuthal gradients of cosmic ray particles and its effect on the decay of the flare intensity. For an observer located to the east of the centroid of the population, the azimuthal corotation term and the convection term will be additive, resulting in a short decay time constant. An observer located to the west of the centroid of the population will experience a much longer decay time constant, the corotation term partially or completely compensating the loss of particles due to convection. At very low energies, the azimuthal corotation term may even be more than the convection term, thus resulting in a rise in intensity instead of decay during late in the event. Using the relationship showing the dependence of the spectral exponent of the cosmic ray flux late in a flare event on the azimuth from the centroid of the population given by McCracken et al., the energy dependence of the decay time constant and the cross-over energy at which the azimuthal gradient term equals the convection term are investigated. The experimental observations are shown to be generally consistent with the theoretical picture, confirming the importance of convection and the azimuthal gradient in determining the decay profile of flare events.On leave from Physical Research Laboratory, Ahmedabad, India.Now at CSIRO, G.P.O. Box 136, North Ryde, N.S.W., Australia.     

On the problem of active longitudes of sunspots and flares

The active longitudes of indices for sunspot activity and solar flares were detected and investigated by the method of isoline for the period July 1, 1957 to December 31, 1962. In the most active hemisphere of the sun the active longitudes of sunspot and flares appear to coincide. It is shown that the rate of concentration in the active longitudes is the highest for more important formations. Arguments for the reality of the active longitudes of sunspot areas are advanced. In conclusion the question of the influence of the uncertainty of the solar rotation period on the detection of active longitudes of flares is considered.     

Evidence for two maxima of activity in the 20th solar cycle

Analysis of the 5303 Å coronal line intensity and of the sunspot activity during the period 1962–1970 confirms the existence of two distinct maxima of solar activity, in accordance with the previous findings of Gnevyshev for the period 1954–1960.     

Persistent 22-year cycle in sunspot activity: Evidence for a relic solar magnetic field

We use the recently presented group sunspot number series to show that a persistent 22-year cyclicity exists in sunspot activity throughout the entire period of about 400 years of direct sunspot observations. The amplitude of this cyclicity is about 10% of the present sunspot activity level. A 22-year cyclicity in sunspot activity is naturally produced by the 22-year magnetic polarity cycle in the presence of a relic dipole magnetic field. Accordingly, a persistent 22-year cyclicity in sunspot activity gives an evidence for the existence of such a relic magnetic field in the Sun. The stable phase and the roughly constant amplitude of this cyclicity during times of very different sunspot activity level strongly support this interpretation.     

The fuzzy forecast of the activity of solar active regions

In this paper, the theory and method of fuzzy mathematics are applied to forecast the activity of solar active regions. According to the correlation between flares and several solar activity indices of active regions, the membership functions are constructed to comprehensively evaluate and predict the activity of solar active regions. By means of data reduction and analysis, some comparatively accurate results of prediction have been obtained. The accuracy of predicting the activity grades of active regions is higher than 97%. This implies that the method of fuzzy forecast is a good one for solar activity prediction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spots on FK Com: active longitudes and “flip‐flops”

We have earlier investigated the surface structures of a late‐type, single, giant FK Com for the years 1994–1998 using Doppler imaging. These surface temperature maps revealed long‐lived active regions at high latitudes. Long‐term photometric observations also show that these active regions tend to occur at two permanent active longitudes which are 180 degrees apart from each other, and that the activity switches the longitude with an average period of about 3 years (the “flip‐flop” phenomenon). In this work we present new Doppler maps of FK Com obtained 1998‐2003 and light‐curve maps obtained 2002–2003. These new maps are investigated together with the earlier temperature maps and light‐curve maps, with an aim of further studying the active longitudes, “flip‐flop” phenomenon and surface differential rotation on FK Com. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A forecast of solar activity for the 21st solar cycle

Predicted values of some main indices of solar activity for the 21st solar cycle are given. The epoch of maximum of solar activity has been placed in 1980.8±0.1. The predicted peak values of the relative sunspot numbers published by other authors are also given.     

Infrared photometry of solar active regions

Simultaneous time series of broad-band images of two active regions close to the disk center were acquired at the maximum (0.80Μm) and minimum (1.55Μm) continuum opacities. Dark faculae are detected in images obtained as weighted intensity differences between both wave-length bands. The elements of quiet regions can be clearly distinguished from those of faculae and pores in scatter plots of brightness temperatures. There is a smooth transition between faculae and pores in the scatter plots. These facts are interpreted in terms of the balance between the inhibition of convective energy transport and the lateral radiative heating.     

Soft solar X-rays and solar activity

Soft solar X-rays in the wavelength interval 8–12 Å were observed from OSO III. The totality of the observations that were made between 9 March, 1967, and 18 May, 1968, is summarized graphically and compared to the course of solar activity as observed at other wavelengths, with particular emphasis upon visible activity.     

Soft solar X-rays and solar activity

Soft X-radiation between 8–12 Å was found to be emitted from the Sun at the time of four optically-identified major systems of loop prominences. The peak emission rates and time-integrated X-ray energies are very similar for three of the events while the fourth appeared to emit X-rays only weakly. The data are not consistent with a compression-condensation model for the loops, and support the fast-proton injection model. Proton injection may take place on a long time scale.     

The basic cycle of solar activity and the global magnetic field and active phenomena distribution

We have compared the latitudinal distributions of polar faculae, green coronal emission maxima, prominences and of a new index of enhanced geomagnetic recurrence with the distribution of magnetic fields during the cycles Nos. 20 and 21.We did not find a distinct high-latitude initial stage of an extended cycle in the corona, prominences and polar faculae distribution. On the contrary, it seems that the polar faculae and their following polarity magnetic fields represent the last evolutionary phase of a magnetic activity cycle lasting 15–17 years. The enhanced recurrent geomagnetic activity seems to be related to the old cycle fields.All studied phenomena clearly display two types of latitudinal distribution: the polar belts, into which the old following polarity fields have been transported from the equatorial belt where both the polarities developin situ simultaneously, but in which the leading polarity fields only remain, crossing the equator during the minimum of activity, to play the same role on the opposite hemispheres in the new cycle.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Evidence for solar neutrino flux variability and its implications

Although KamLAND apparently rules out resonant-spin-flavor-precession (RSFP) as an explanation of the solar neutrino deficit, the solar neutrino fluxes in the Cl and Ga experiments appear to vary with solar rotation. Added to this evidence, summarized here, a power spectrum analysis of the Super-Kamiokande data reveals significant variation in the flux matching a dominant rotation rate observed in the solar magnetic field in the same time period. Three frequency peaks, all related to this rotation rate, can be explained quantitatively. A Super-Kamiokande paper reported no time variation of the flux, but showed the same peaks, there interpreted as statistically insignificant, due to an inappropriate analysis. This modulation is small (7%) in the Super-Kamiokande energy region (and below the sensitivity of the Super-Kamiokande analysis) and is consistent with RSFP as a subdominant neutrino process in the convection zone. The data display effects that correspond to solar-cycle changes in the magnetic field, typical of the convection zone. This subdominant process requires new physics: a large neutrino transition magnetic moment and a light sterile neutrino, since an effect of this amplitude occurring in the convection zone cannot be achieved with the three known neutrinos. It does, however, resolve current problems in providing fits to all experimental estimates of the mean neutrino flux, and is compatible with the extensive evidence for solar neutrino flux variability.     

Evidence for solar neutrino flux variability and its implications

Although KamLAND apparently rules out resonant-spin-flavor-precession (RSFP) as an explanation of the solar neutrino deficit, the solar neutrino fluxes in the Cl and Ga experiments appear to vary with solar rotation. Added to this evidence, summarized here, a power spectrum analysis of the Super-Kamiokande data reveals significant variation in the flux matching a dominant rotation rate observed in the solar magnetic field in the same time period. Three frequency peaks, all related to this rotation rate, can be explained quantitatively. A Super-Kamiokande paper reported no time variation of the flux, but showed the same peaks, there interpreted as statistically insignificant, due to an inappropriate analysis. This modulation is small (7%) in the Super-Kamiokande energy region (and below the sensitivity of the Super-Kamiokande analysis) and is consistent with RSFP as a subdominant neutrino process in the convection zone. The data display effects that correspond to solar-cycle changes in the magnetic field, typical of the convection zone. This subdominant process requires new physics: a large neutrino transition magnetic moment and a light sterile neutrino, since an effect of this amplitude occurring in the convection zone cannot be achieved with the three known neutrinos. It does, however, resolve current problems in providing fits to all experimental estimates of the mean neutrino flux, and is compatible with the extensive evidence for solar neutrino flux variability.     

Evidence for opposed currents in active region loops

EUV and X-ray images of the Sun are used as tracers of the magnetic field structure in the Solar atmosphere in order to study the existence of currents in active regions. Criteria are suggested for comparing the data with theoretical extrapolations of magnetic field lines above the level of magnetograph observations. Analysis of the data presented in conjunction with force-free field calculations suggests the existence of currents flowing in opposite directions in nearby sets of loops in the active regions shown. Some simple qualitative implications of opposed current structures are suggested.     

Stability of the solar system: Evidence from the asteroids

An analysis of the distribution of the orbital periods of the asteroids has shown that there is a preference for these periods to be near-commensurate with that of Mars. We suggest that this preference is associated with a formation process and implies that the orbital period of Mars has not changed greatly since the time of asteroid formation. We deduce from this that the solar system is highly stable and long-period gravitational perturbations have probably had little influence on the gross evolution of the solar system.Paper presented to the NATO Advanced Study Institute on Lunar Studies, Patras, Greece, September 1971.     

QSO pairsacross active galaxies: Evidence of blueshifts?

Several QSO pairs have been reported and their redshifts determined, where the two objects in each pair are locatedacross an active galaxy. The usually accepted explanation of such occurrences is that the pair is ejected from the parent galaxy. Currently interpreted redshifted spectra for both the QSOs imply that both the objects are receding from the observer. However, ejection can occur towards and away from the observer with equal probability. We argue that for a system with two QSOs lyingacross the parent galaxy, ejection should have occurred in opposite directions, whereby one object will be approaching us and the other will be receding from us. The former would exhibit a blueshifted spectrum. We analyse here a sample of four such pairs and show that the observed spectrum of one QSO in each pair can be interpreted as blueshifted. The other exhibits the usual redshifted spectrum. A scenario based on the ‘sling-shot’ mechanism of ejection is presented to explain the occurrences of the pairs in opposite sides of the active galaxies moving in opposite directions.