Polarization of radio emission on the solar disk was studied according to of Nobeyama radio heliograph observations during 1992-2003. The latitude-time diagrams of polarization circular radio emission were constructed. For a decrease of the noises we used several solar images for a day. We found polarization drifts of radio emission in the high-latitudes activity and at latitude band of the sunspots. Process of the magnetic field reversal of the large-scale magnetic field in polarization of radio emission of the Sun was found during 22-23 cycles. An analysis of polarization for the structures various brightness temperatures has been carried.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

After a careful study of Mars observations obtained by Tycho Brahé (1546-1601), Kepler (1571-1630) discovered the now-called Kepler's third law. In 1627 he published his famous Tabulae Rudolphinae, a homage to his protector Rudolph II (1552-1612), tables (Kepler 1609, 1627) from which he predicted Mercury and Venus transits over the Sun. In 1629 Kepler published his Admonitio ad Astronomos… Advertisement to Astronomers (Kepler 1630), Avertissement aux Astronomes in French Au sujet de phénomènes rares et étonnants de l'an 1631: l'incursion de Vénus et de Mercure sur le Soleil. This was the beginning of the interest of French astronomers, among many others, in such transits, mostly for Venus, the subject of this paper in which dates are given in the Gregorian calendar.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

A major goal in solar physics has during the last five decades been to find how energy flux generated in the solar convection zone is transported and dissipated in the outer solar layers. Progress in this field has been slow and painstaking. However, advances in computer hardware and numerical methods, vastly increased observational capababilities and growing physical insight seem finally to be leading towards understanding. Here we present exploratory numerical MHD models that span the entire solar atmosphere from the upper convection zone to the lower corona. These models include non-grey, non-lte radiative transport in the photosphere and chromosphere, optically thin radiative losses as well as magnetic field-aligned heat conduction in the transition region and corona.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

The paper is devoted to the coronal bright points. We carried out the analysis of the simultaneous observations in IR He $\lambda$10830 Å and microwaves at 5.2 and 1.76 cm. It was obtained that microwave sources correspond to the dark points in IR He $\lambda$10830 Å with line-of-sight velocities directed from a observer. The possible mechanism of the energy transport within the bright points are suggested.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The comparison of the polarization presence in Ellerman bombs or moustaches and the active region arch structure was carried out. In the most cases of the polarization, interpreted as impact polarization, were detected in that regions where the bright small loops were observed. On the contrary, when a significant polarization wasn't detected the scanning during observation was carried out nearby the large loops.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

To obtain the wave characteristics of hot magnetized plasma, requires investigating a complete dispersion equation describing the oscillations of magnetized plasma, of the form \begin{equation} a+(\omega ^2/k^2c^2)b+(\omega ^4/k^4c^4)c_0=0. \end{equation} Here, \begin{center} $a=(k_{\bot }^2/k^2)\varepsilon _{xx}+(k_z^2/k^2)\varepsilon_{zz}+2(k_{\bot }k_z/k^2)\varepsilon _{xz}$, \end{center} \begin{center} $b=-\varepsilon _{xx}\varepsilon _{zz}+\varepsilon_{xx}^2-(k_z^2/k_{}^2) (\varepsilon _{yy}\varepsilon_{zz}+\varepsilon _{yz}^2)-(k_{\bot }^2/k^2) (\varepsilon_{xx}\varepsilon _{yy}+\varepsilon _{xy}^2)\nonumber +2(k_{\bot}k_z/k^2)(\varepsilon _{xy}\varepsilon _{yz}-\varepsilon_{xz}\varepsilon _{zy})$,\end{center}\begin{center}$c_0=\varepsilon _{zz}(\varepsilon _{xx}\varepsilon_{yy}+\varepsilon _{xy}^2)+\varepsilon _{xx}\varepsilon_{yz}^2-\varepsilon _{yy}\varepsilon _{xz}^2+2\varepsilon_{yz}^{}\varepsilon _{xz}\varepsilon _{xy}$,\vspace*{4pt}\end{center} ω is the complex frequency of the wave, k is the wave number, c is the velocity of light in a vacuum, $k_z$ is the longitudinal (with respect to the magnetic field) wave vector component, $k_{\bot}$ is the transverse wave vector component, and $\varepsilon_{ij}$ stands for the components of the dielectric tensor.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

There are dozen instruments successfully operating aboard the solar satellite CORONAS-F, which was launched in the summer of 2001. Among them are two (Polish-led) Bragg crystal spectrometers – RESIK and Diogeness – recording solar flare and active region spectra. A short description of the CORONAS-F satellite operation is presented together with that of the two Polish spectrometers, stressing their unique characteristics. The average spectra have been derived and shown here, covering the wavelength range between 3 Å and 7 Å. Future steps in the analysis of the large database collected are outlined.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Multi-wavelength imaging of the solar corona is a powerful observational method to study CME-related dynamics of structures in spectral bands related to the solar corona and transition region. We analyze large-scale eruptive events caused by halo-type CMEs observed at the solar disk with the CORONAS-F/SPIRIT (175, 304, and 284 Å) and SOHO/EIT telescopes on November 4, 2001 and October–November, 2003. For most events, CME-associated dimmings coincide in different bands, but the 304 Å dimming in November 4, 2001 event was delayed by $>1/2$ hours. In October–November events, coronal waves were observed in 195 Å and some in 175 Å channel. In a CME event associated with a filament eruption on November 18, the SPIRIT images display a propagating disturbance seen as a darkening in 304 Å channel only. This phenomenon was not described earlier.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

We present the outline and current status of the nano-JASMINE project. Nano-JASMINE is a nano size astrometry satellite (the total payload mass is between 1 kg and 10 kg), which is expected to be launched in 2006. The main purpose of the project is to prove and demonstrate the key technologies required for JASMINE (Japanese Astrometry Satellite Mission for Infrared Exploration) in a real space environment Gouda et. al. (2002). Nano-JASMINE will measure annual parallaxes of bright stars (7 mag) with an accuracy greater than 1 milliarcsecond after two years of operation. This is comparable to the accuracy of the Hipparcos catalog. Currently, the subject of major research and development of the project is to build optical and telescope structures using new material, and to establish a data acquisition and control system.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The renew non-hydrostatic model of electron density, temperature and velocity distribution with height in coronal hole (CH) is build. The presented model is based on the measurements of magnetic field in CH with RATAN-600 observations and on the assumption about equality of magnetic and kinetic energy of upward plasma flows in CH at heights of generation of radio emission in wavelength range 20–30 cm. To construct this model the observational spectrum of brightness temperatures of CH in wavelength range 2–30 cm is used. The first results of modeling are presented.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A preflare situation in a loop structure for stability to the development of plasma waves at the chromosphere part of a current circuit of a loop is investigated. We consider the situation when plasma has the spatial gradients of the density and temperature. In accordance with Heyvarts-Priest-Rust theory such a preflare situation would typically exist when the amplitude of weak electric field in the circuit of an “old” loop in an active region begins to increase as “new” magnetic flux emerges from under the photosphere (Heyvaerts, Priest & Rust (1977)).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have investigated the optical design for the Japan astrometry satellite mission (JASMINE). In order to accomplish measurements of astrometric parameters with high accuracy, optics with a long focal length and a wide focal plane for astrometry are required. In 1977 Korsch proposed a three mirror system with a long focal length and a wide focal plane. The Korsch system is one of the convincing models. However, the center of the field is totally vignetted because of the fold mirror. Therefore we consider an improved Korsch system in which the center of the field is not vignetted. Finally, we obtain the diffraction limited optical design with small distortion. Our project needs a common astrometric technique to obtain precise positions of star images on solid state detectors to accomplish its objectives. In order to determine the centers of stars, an image of the point source must be focused onto the CCD array with a spread of a few pixels. The distribution of photons (photoelectrons) over a set of pixels enables us to estimate positions of stars with sub-pixel accuracy. We modify the algorithm to estimate the real positions of stars from the photon weighted mean, which was originally developed by the FAME (Full-Sky Astrometric Mapping Explorer) group. Finally, we obtain the results from the experiment that the accuracy of estimation of distance between two stars has a variance of about 1/300 pixel; that is, the error for one measurement is about 1/300 pixel, which is almost an ideal result given by Poisson photon noise. We also investigate the accuracy of estimation of positions with a different size of PSF. In this case also, we find that the accuracy of estimation has a variance of about 1/300 pixel.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A sufficiently thick and dense flaring magnetic loop is shown to be able to support global sausage magnetoacoustic modes. The oscillation period of this mode, calculated in the straight cylinder approximation, is determined by the length of the loop, not by its diameter, as it has previously been assumed. For the existence of this mode, the ratio of the loop length to its diameter is to be less than about a half of the square root of the density contrast ratio. This mode has a maximum of the magnetic field perturbation at the loop apex and nodes at the footpoints. We demonstrate that the 14-17 sec quasi-periodical pulsations of microwave emission, oscillating in phase at a loop apex and at its legs, as observed with the Nobeyama Radioheliograph, are interpreted in terms of the global sausage mode.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present observations of the dynamic evolution of photospheric magnetic elements in the G-band, magnetograms and Dopplergrams. The observations were obtained with the Swedish 1m Solar Telescope on La Palma at close to the diffraction limit of $0{\hbox{.\!\!^{\prime\prime}}}1$. In the most quiet regions we observe individual bright points in the G-band with corresponding magnetic signal in the magnetograms. Where the filling factor of the magnetic field is larger, the bright points interact when advected by the granular and super-granular flow-fields, flux sheets form and fragment. The plage region of the decaying active region is filled with more complex topologies like ribbon structures with darker interior and bright, knotted edges. These change into flower-like shape when small in extent and into micro-pores when the flux region is larger in extent. The magnetic elements in the plage region are associated with upflows with strong downflows in the immediate vicinity in the low-field region.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

One of the main characteristics of Mercury is its 3:2 spin-orbit resonance, combined with a 1:1 resonance between the orbital node of its orbit and the angle describing the precession of the rotation axis, both measured on the ecliptic plane. We build an analytical model, using Hamiltonian formalism, that takes into account this phenomenon thanks to the introduction of three resonant variables and conjugated momenta. We calculate the equilibria corresponding to four different configurations, which means four completely different values of the (ecliptic) obliquity; in particular, we focus on the present (stable) situation of Mercury, and thanks to several canonical transformations, we obtain, near the equilibrium, three pairs of angle-action variables, and consequently, three basic frequencies. Let us note that the model is as simple as possible: the gravitational potential is limited to the second degree terms (the only ones for which a value can be presently given), and the orbit of Mercury is Keplerian. The numerical values obtained by our simplified model are validated by the coherence with existing complete numerical models.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A revolution is taking place in the research of extra-solar planets with the discovery of the first exoplanets only a decade ago to the more than 100 systems known to date. Almost all of these extrasolar planets have been discovered using the radial velocity technique. Unfortunately, this limits the amount of information which can be obtain from these systems, with a $\sin i$ ambiguity in the planet's mass, and no further measurements of fundamental parameters as long as these planets can not be detected directly. This situation is very different in the rare case that the orbit of a planet has an inclination such that it occults its host star, as in the case of HD 209458b. Not only can the mass and radius of the planet be accurately determined, but it makes the system also suitable for many detailed follow-up studies, in particular atmospheric transmission spectroscopy. This has resulted in the detection of the atmosphere of HD 209458b in Sodium, and the discovery of an evaporating exosphere in Hydrogen, Carbon and Oxygen using the Hubble Space Telescope. In this paper I briefly review transiting exoplanets and methods to probe their atmospheres, with the emphasis on a new method of transmission spectroscopy making use of the Rossiter effect, which may be more suitable for the large ground-based telescopes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This paper is devoted to the investigation of the synchronous enhancements of the solar source fluxes according to the RATAN-600 Southern Sector observations at the 1.92 cm, 2.24 cm, 2.74 cm, and 3.21 cm radio waves. The observations were carried out on 11.09.01 from 8:30 UT to 10:30 UT every 8 min. We use the term “synchronous bursts” or “synchronous brightenings” instead of the “sympathetic bursts” as the time resolution of the RATAN - 600 is not high. The solar source brightenings are synchronous if they are registered in 2 - 2.5 min time lag, i.e. in the time interval of passage of the Sun through the central part of the main lobe of the antenna power pattern. The high flux sensitivity of the radio telescope - radiometer system was 0.005 s.f.u. The solar sources were identified with the active regions: AR 9610, AR 9608, AR 9606, AR 9616, AR 9617, which widely separated from each other (up to $10^{6}$ km). According to our observations, the synchronous enhancements were observed at the moments of the soft X ray brightenings and X ray bursts (Figure 1a). The temporal variations of the relative fluxes of the solar sources $F/F_{0}$ were compared to the $X$-ray (GOES 8,10; $H_{\alpha}$ - flares and to the radio bursts at 9100 MHz, $F_{0}$ - the radio emission flux from the “quiet” Sun, $F$ - the radio emission flux from the solar source). It turned out that the interrelationships of the active regions AR 9610, AR 9608, AR 9606 were the most interesting. It was registered 4 synchronous brightenings of solar sources AR 9610, AR 9608 at the moment of the observations: 8:38 UT, 9:02 UT, 9:50 UT, 10:30 UT. We recorded synchronous brightenings of solar sources at 1.92 cm, 2.24 cm, 2.74 cm, and 3.21 cm radio waves: at $\lambda=2.24 cm$ – $\Delta(F)=(0.24 \div 0.88)$ s.f.u. and at $\lambda=3.21$ cm – $\Delta(F)=(0.21 \div 0.94)$ s.f.u. The detailed halo solar source is the magnetosphere, which was identified with all extensive AR 9608 region excepting the primary the most strong solar source of the active region radio emission. The angular size of halo is closed to the angular size of AR 9608 ($7.7 \arcmin$). The comparison of the brightening onset of the AR 9610, AR 9608 interacting active regions in the time interval (9:26 - 9:58 UT) and the discovered forestalling of the halo flux quick intensification at $\lambda=2.24$ cm and $\lambda=3.21$ cm pointed to the active process start in the AR 9608 solar source at $\lambda=3.21$ cm. As it was shown, the dynamics of the time intensity variation of solar sources at $\lambda=3.21$ cm, $\lambda$=2.74 cm is more complicated. It is demonstrated by against of the synchronous of the moments of the AR 9610 relative flux maxima with the $\lambda$ increase (Figure 1b).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html