Archival full disk observations of the central depth of Mn 539.467, a photospheric line, have been found to correlate with chromospheric Ca K intensity. In this paper we present spectroheliograms taken in Mn I 539.467 and 542.32 nm lines and other nearby lines to see if the other photospheric lines show chromospheric structures. We see both Mn images and also Si I 542.118 mimic magnetograms the similar way, while strong Fe and Ti lines only faintly reveal magnetic features, and weak Fe lines of comparable strength to Mn show nothing.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the review of temporal variations of the solar neutrino flux, including our original results of investigations of the solar neutrino flux variations in 1970–1997.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Gaia is a mission to map the positions and determine the velocities of 1 billion stars in the Galaxy, in order to determine how it was formed and how it has evolved. Spectroscopy provides one component of the space velocities for 200 million objects, and, in addition, astrophysical information such as temperature and metallicity for the brighter 40 million stars in a large unbiased Galactic sample. Together the instruments on Gaia will transform our knowledge of the Galaxy. We describe here a sample of the science that will be done with Gaia concentrating on aspects in which the spectroscopy plays a central role.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We studied the line-of-sight (LOS) velocity field at the photospheric and chromospheric levels in the $H_{\alpha}$-loops in the course of the development of the bright flare. The spectra and filtergrams were acquired with the solar telescope ATsU-26 at the Terskol Peak Observatory. Time variations of the LOS velocities at loop tops and bases were compared to the $H_{\alpha}$ and hard X-ray fluctuations. The intensity variations and $H_{\alpha}$-filtergrams are evidence that elementary X-ray spikes are associated with consecutive disturbances of $H_{\alpha}$-loops in the arcade. The $H_{\alpha}$ intensities and velocities at the loop bases are much higher than at the tops. Different mechanisms can be efficient at the early stages of elementary X-ray spikes and at their maxima: ascent of photospheric matter at loop bases was recorded only when the $H_{\alpha}$ and hard X-ray intensities were minimum, and the intensity maxima were accompanied by descending motions of the photospheric plasma.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The solar results from CORONAS-F satellite have been reviewed. The observations with the DIFOS multi-channel photometer in a broad spectral range from 350 to 1500 nm have allowed to determine the dependence of the relative amplitudes of p-modes of the global solar oscillations on the wavelength. The EUV observations in SPIRIT experiment have enabled the study of various manifestations of solar activity and high-temperature events on the Sun. The data from the flare instruments-gamma spectrometer HELICON, flare spectrometer IRIS, amplitude-time spectrometer AVS-F, and X-ray spectrometer RPS-1 have been used to analyze the hard emission from solar flares and to carry out the diagnostics of the solar flare plasma. The Solar Cosmic Ray Complex has investigated the solar flare effects in the Earth's environment. The UV emission variations during solar flares in the vicinity of the 120-nm wavelengh have been recorded and the relative variation amplitude has been determined.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

An erupting prominence seen by SOHO/EIT was tracked into the field of view of the LASCO C2 and C3 coronagraphs where it developed into the core of a structured CME. The erupting prominence was deflected by an angle of $\sim 20^{\circ}$ towards the north pole whereas the consequent core of the CME and it's leading edge propagated in the outer corona at constant position angle. The prominence material underwent a constant acceleration phase until a height of $\sim$1.5 solar radii before it started to decelerate up to a distance of 5.0 solar radii. An inflow of plasma with a speed of about 70-80 km/s was discovered in the EIT observations at a height of 1.5-1.2 solar radii in the course of the prominence eruption, matching in time the prominence deceleration phase. The downflowing material followed a curved path, suggestive of the apex of a contracting magnetic loop sliding down along other field lines.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Results of modern multi-wavelength observations of large solar non-stationary events are briefly summarized. Such events consist of a puls, an eruption (surge or CME) and a long-living system of giant arches.

Observations demonstrate often that the pulse arises as a result of “avalanche” of interaction of small-scale magnetic elements, while the dynamic system transforms into a state of self-organizing criticality (SOC) on the post-eruptive phase. We developed new code for the avalanche model where it is possible to consider a transition of the active region as a dynamic system in a state of SOC. Derived solutions show, firstly, that the avalanche is naturally developed nearby spots during the pulse. Secondly, during long-duration events, occuring along the neutral line of the longitudinal magnetic field, behaviour of the large-scale coronal magnetic field is characterized by a state of SOC.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We represent results of experiments on investigation of solar wind plasma by the method of radio sounding, when the signal from the radio source paths through the solar wind plasma and then it's received at ground-based radiointerferometer.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

We present results of an investigation into the coupling between solar-like magnetoconvection and coronal structures using self-consistent numerical simulations of compressible fluids. The model consists of a stratified MHD fluid spanning multiple scale heights, encompassing the transition of the plasma beta from high to low values. The lower portion of the domain, where the beta is high, is convectively unstable while the upper portion is stabilized by the presence of a strong magnetic field and energy losses. As a result, the dynamics associated with evolving magnetic features in the solar atmosphere can be modelled in a manner that is self-consistent with the convective motions that provide the driving. We present simulations of arcade-like reconnection in the presence of supergranular-scale flows.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

According to daily observation SOHO/MDI during 1996-2003 and NSO/KP Vacuum Telescope during 1978-2003 magnetic elements with intensity of the magnetic field above background have been allocated. The knots were then identified that allowed to trace their displacement comparatively of heliographic grid. Thus, fields of speeds for the period with 1978 on 2003 have been constructed. Variations of speed meridional circulation are found out. The basic direction of speed meridional drift is directed to poles. At the same time it is shown, that during a maximum of activity at latitude less than $20^o$ arise currents in the direction of equator. Streams in the direction to equator arise and during a minimum of activity at latitude about $40-60^o$. Fields of speeds on various phases of solar cycle are constructed.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

The Fraunhofer spectra were used to study the physical condition variations in the photospheric layers in the course of a bright solar flare. The observations involve both the impulsive and main phases of the flare. The spectral lines are formed in the photosphere at the interval 12–500 km. The modelling was made by fitting the observed and calculated line profiles using the SIR program. The models represent the distributions of temperature, gas density, line-of-sight velocities, etc. on the height. They show some inhomogeneities of these physical parameters at various photospheric levels. Their significant deviations from the VAL-F model may be seen in the course of the flare. The largest heating of the high and middle photospheric levels take place close to two X-ray maxima. At the final flare stage the photosphere is disturbed appreciably while the spectral data testify to the flaring process fading in the chromosphere. This may be an evidence of a disturbance propagation from the upper atmospheric levels to the low ones in the impulsive and main phases.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report on a novel investigation of the complex magnetism of the quiet Sun which is based on a realistic three-dimensional modeling of the Hanle effect.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

On the base of the interferometric observations during the total solar eclipse on 11 August 1999 magnetic field strength in a coronal volume at the height of 10$^5$ km above the solar limb has been evaluated using an indirect method. A cold coronal emission (CCE), seen in the lines of $H_{\alpha}$ and K CaII, existed there. The conclusion is made that the magnetic field strength in this bulk, before the investigated CCE-region formed, was about 100-200 G.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In Eselevich V. and M. Solar Phys. 195, 319, 2000 is shown that in brightness rays of the streamer belt from time to time there exist additional plasma streams of enhanced density moves antisunward and occupies a separate ray. The duration of additional streams can range from a few hours to several days. For that reason, some of them may be categorized as sporadic SW streams and the others as quasi-stationary SW streams. Preliminary investigations showed that the leading edge of such streams can be extremely small in width. The purpose of this paper is to verify the conclusions about the existence of additional plasma streams with steep fronts in streamer belt rays, based on analyzing the calibrated data from LASCO/SOHO C2 and C3.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The spectra of the MnI 539.47 nm spectral line were observed in three different sunspots of the NOAA 0431 active region. Perpendicularly to the dispersion axis, the spectra were divided into several strips that covers the quiet photosphere, penumbra and the umbra of the appropriate sunspot. The manganese spectral line parameters variation along the spectrograph slit were determined and analyzed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The data from the Greenwich Observatory for 1879–2003 (cycles 12–23) have been used to plot a time (Carrington rotations) vs. Carrington longitude diagram of distribution of the rotation–summed daily areas for each sunspot group. It has been revealed that most of the sunspots appear as clusters having common sources (Sunspot Formation Zones) that lie on a surface rotating with a period close to the Carrington rotation period $T=27.2753$ days. At the same time both the active longitudes and medium-size spots shift in the Carrington heliolongitude and rotate at an angular velocity corresponding to the rotation period $T\sim26.8-26.9$ days. An attempt is made to explain contradictory data on the character of rotation of sunspots and active longitudes.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

During the 25 years that the author has been involved in astrometry, the quality of ground-based parallaxes has increased by about a factor of 10 (from 3 mas to 0.3 mas), but the quantity has increased by only a few hundred. When asked, the average astronomer will cite the $H^2$ space missions (Hubble and Hipparcos) as the great advances in astrometry even thought the ground-based work has played a critical role in the understanding classes of stars such as the L- and T-dwarfs. The next decade promises stunning advances in both the quality and quantity of parallax measurements, and both ground- and space-based projects will play significant roles. The Gaia space mission and the various ground-based telescopes with large etendue (DMT, LSST, Pan-STARRS, etc.) will improve the quality or quantity (or both) by factors of a thousand or more. The situation will be discussed, and the author will express his hope that he might live long enough to see the fruits of these labors.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html