Geomagnetic activity variations are closely related to the global magnetic field of the Sun and could serve as useful proxies to reconstruct the solar wind history and evolution of the inner heliosphere. Historical geomagnetic records reveal trends in the solar wind and interplanetary magnetic field variability resulting from topological changes of the heliospheric current sheet and solar corona viewed from the Earth. Predictions of the solar cycle based on geomagnetic trends are presented.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We compare the enhanced temperature regions (ETRs) in the millimeter radio emission of the Sun with other manifestation of solar activity during 10 days in 1997, 1998, 2000 and 2003. The radio observations at 37 GHz and 87 GHz were done with the Metsahovi Radio Telescope (Finland). We concentrate on the weak ETRs with no discernible connection to sunspots, and in some case compare their properties with those which do have a clear connection to sunspots. Extended observations at 37 GHz in July 2003 enable us to measure the lifetimes of some weak ETRs and also their brightness temperature variations. The 37/87 GHz full-disk radio intensity contours are superposed on $CaII (k_{3})$ and $H_{\alpha}$ images observed with the Meudon Spectroheliograph (France) for comparing the optical positions and the brightness characteristics of these regions. A similar comparison is also made with the SOHO/MDI full-disk magnetograms and SOHO/EIT images. There appear to be two different classes of weak ETRs. One class is connected with local brightness features seen in $CaII (k_{3})$, $H_{\alpha}$ images and magnetograms. The other class is connected with so-called minor brightness features.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Solar sporadic radio emission takes place in a wide range of time scales; from milliseconds to days. Researches have been conduced mainly to explain the behavior of radio emission in specific time scales and lately to millisecond spikes research has been devoted a lot of papers.

In this work we pay attention to the characteristics of millisecond spikes in relation to the general activity in which they are included, processes with very different time scales.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We show that the latitudinal distribution of the coronal bright points (BPs) changes between the solar minimum and the rising phase of solar cycle 23. In 1996, the number of BPs peaks near the disk center. In 1998, the distribution shows bands of increased BPs' number at the ARs' latitudes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the preliminary results of study of the coronal bright points (BPs) using the SoHO/EIT data. We show that the number of BPs in quiet Sun areas does not vary between 1996 and 1997. In 1998 the BPs number (full disk) increases by about 20%.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The purpose of this investigation is a comparison of long-wave radiobursts, registered in the range of frequencies 100-1500 kHz with multi-channel radiometer AKR-X installed on INTERBALL-1, and hard X-ray fluxes in energy range 14-93 keV observed by YOHKOH/HXT during solar flares. We selected several events with flares of importance X and M, for which there were simultaneous observations in the hard X-ray and radio ranges during the impulsive phase of a flare. The temporal profiles of radiobursts are characterized by the rapid frequency drift, typical to the radiobursts of III type, caused by the motion of energetic electrons accelerated in the flare and which are spreading at the corona and interplanetary medium, up to the Earth orbit.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Preliminary analysis of spectra collected with the RESIK Bragg bent crystal X-ray spectrometer aboard CORONAS-F indicates the presence of many spectral features which until recently were unidentified. We present RESIK spectra in which the H-like Cl XVII Ly$\alpha$ line at 4.182 Å and He-like Cl XVI triplet components in the range 4.43 Å-4.45 Å are identified.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Results of detailed investigations of the whole variety of solar activity events are widely used in studies of relevant stellar activity manifestations. On the other hand, investigations of a plenty of active stars which differ in mass and age lead to determination of the decisive factor of the solar activity evolution and give ideas on the past and the future of this activity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

AE Aquarii is a star with unique flaring activity. It is a close binary system, which contains a K3V-K5V red dwarf (secondary) and a magnetized white dwarf rotating with the period of 33 s (primary). It is traditionally classified as a peculiar nova-like star and assigned to the DQ Her subclass of magnetic Cataclysmic Variables (CVs).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

From long-term multicolour photometric observations of strongly spotted stars, one concludes usually on a presence of active longitudes. We argue the latitudinal effects in distribution spots over the surface and noticeable equatorward drift of the low-latitude boundary of the spotted region during the rising phase of activity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The results of photometric investigations of the eclipsing binary CM Dra are presented. The observations of CM Dra were taken with the 70-cm telescope and two-star photometer of the Ural State University Astronomical Observatory in 1996–1997 (the total duration was 155 hours). The solution of the composite lightcurve yielded some fundamental physical parameters of CM Dra components. Four flares were observed, the calculated flare rate was 0.026. The Flares power was about handred times larger than solar ones. The CM Dra composite lightcurve shows the outside-eclipse low-amplitude (0.024mag) brightness variations which appeared to be shifted by 120 degrees in phase over a 20-years period. It may be explained supposing an appearance of the star spots on another longitude.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Some properties of General Magnetic Fields (GMF) of the Sun as a star and of two solar-like stars (an active young $\xi$ Boo A with no cyclicity of activity, and 61 Cyg A – an old star with a moderate level of cyclic activity) are represented.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We computed chromospheric models of the Sun as a star and of nine solar analogues. The stars have a wide variety of magnetic activity levels, which allows us to study the differences in atmospheric structures induced by activity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

To begin with, I would like to say a few words about the CORONAS-F mission, about what observations are carried out onboard and what is the present state of the obtained scientific data. Then, we shall briefly discuss the proposals on coordinated observations with other projects and on collaboration in data analysis.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Many records of climatic and environmental changes based on various proxy data exhibit distinct cyclicities that have been attributed to extraterrestrial forcing such as changes in solar activity. To study the long-term changes of solar activity, different data sets of solar activity, both indirect data (the Schove series) and proxy data (cosmogenic isotopes) were analyzed. Both sets of solar activity clearly show centennial and millennial changes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We summarize the recent results and prospective work in two parallel studies (Komitov; Bonev, Penev and Sello) of the long-term trends in solar variability that can be deduced from both indirect data and optical records. Analysis of data from $^{14}C$ measurements (Stuiver et al. 1998), aurorae (Schove series: Shove 1983), and direct astronomical records (group sunspot number) (Hoyt & Schatten 1998) focus on the stability and changes in amplitude of the cycles with duration near one and two centuries. Although these two projects have been carried independently and different methods have been used. We present them in a joint fashion in order to emphasize the common direction of their work.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The time series of geophysical data are chaotic and, on the other hand, extremely noisy. Thus, though there are a number of advanced methods of chaotic time series prediction, the improvement of geophysical data is crucial to succeed. Mainly, it is connected with low determinism of such time series. The improvement procedure, we are about to represent, does not directly enhance deterministic component, but regularity properties of a signal, and, therefore, causes the increase of a deterministic portion in data. The main advantage consists in the fact that the method preserves the initial structure (information) of a time series, while effectively reduces noises, even knowing nothing about its actual nature.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The average sunspot activity level for the last millennium is reconstructed. There is a good agreement between the reconstructions, independently built by different proxiesThe full version of this paper can be found at http://www.gao.spb.ru/personal/ivanov/papers/mil-iva-iaus2004.pdf.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This paper utilizes a searchable Solar Feature Catalogue (SFC) for sunspots created from the SOHO/MDI whitelight images and magnetograms in 2001-2003 using the automated pattern recognition techniques described at http://www.cyber.brad.ac.uk/egso/. Comparison of sunspot areas taklen from the SFC with the daily sunspot numbers published in the Sunspot Index Data Centre (SIDC) shows very good correlation of 78–86%. The total magnetic flux from sunspot areas, measured from a single solar image, is shown to have a strong northern-southern asymmetry revealing magnetic flux decrease in the northern hemisphere and an increase in the southern one with the solar cycle descendence towards the period end (year 2003). The resulting, or excess, flux has also demonstrated very significant asymmetry being negative in the southern hemisphere and positive in the northern at the beginning of the period (solar maximum, 2001)with its amplitude descreasing towards the the period end (2003), or the solar minimum. Also, in 2003 there are signs of change in the excess flux polarity between the northern and southern hemispheres.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

There are many reasons to study the Sun: it is of great scientific interest in its own right; it has profound influences on the Earth; and it is of crucial importance for astronomy, since it is the only star where we can observe fundamental cosmic processes in great detail. However, many of the basic properties of the Sun are still a mystery and so the Sun is one of the liveliest branches of astronomy to which many students are currently being attracted.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html