Angular positions of the brightest coronal streamers observed during the total solar eclipses (TSEs) in 1870-2001 are compared with calculated tilts of the heliospheric current sheet (HCS) in 1976-2001 and with reconstructed ones in 1870-1976.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The gravitational microlensing experiments in the direction of Large Magellanic Cloud (LMC) predict a large amount of white dwarfs ($\sim$ 20%) filling the galactic halo. However, the predicted white dwarfs have not been observed at the galactic halo. To interpret the microlensing results and resolving the mentioned problems, we use the hypothesis of spatially varying mass function of MACHOs, proposed by Kerins & Evans (1998) (hereafter KE). However the KE model is not compatible with the duration distribution of events (Rahvar 2004a). Here we use more realistic power-law model of MF, $dn/dm\propto m^{\alpha}$ for the MACHOs of halo. The index of MF in this model changes from $-2.7$ for stars with $m>1 M_{\bigodot}$ at the central part of galactic halo to the substellar regime with an upper limit of $-1$ at the edge of halo. We show that in contrast to the abundant brown dwarfs of galactic halo, heavy MACHOs can be responsible for the microlensing events in the direction of LMC.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

JASMINE (Japan Astrometry Satellite Mission for INfrared Exploration) is a mission to determine positions and parallaxes accurate to $\sim 10$$\mu$arcsec, with proper motion errors $\sim 10$$\mu$arcsec yr$^{-1}$ for Galactic stars observed in the z-band (0.9 $\mu$m). In this article, we report some technical investigations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We perform a statistical analysis to study the infall of galaxies onto groups and clusters in the nearby Universe. The study is based on the UZC/SSRS2 group catalogs and galaxy peculiar velocity data. We find a clear signature of infall of galaxies onto groups in a large range of scales 5 Mpc h$^{-1} < r < 30$ Mpc h$^{-1}$. We obtain a significant increase of the infall amplitude with group mass derived from virial equilibrium and from the luminosity of the member galaxies. We compare the observational results with mock catalogs derived from numerical simulations of semi-analytical models where we obtain a behavior similar to observations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The source of long-period comets can be numerically modeled by means of Monte Carlo simulation of the Oort cloud dynamics. Tracing a comet motion under the galactic perturbations over a long time interval requires taking into account of planetary perturbations. A method for the approximate treating of the planetary perturbations in such simulations is described. Some peculiarities found in planetary action on long-period simulated cometary sample are also discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The role of stars and starbursts in AGN has been a recurring issue for nearly as long as AGN have been recognized as hosts of interesting phenomena. The heated “starburst versus monster” controversy of the 80's and 90's was gradually replaced by “starburst plus monster” studies, as observational work in the past decade has firmly established that accretion onto a super-massive black-hole and star-formation coexist in many galactic nuclei. Whereas the physical link between starbursts and AGN remains unclear, there remains no doubt that starbursts affect a number of properties traditionally associated to the AGN alone, such as the so called “featureless continuum”, emission line ratios and luminosities. This contribution glosses over some of the techniques used to diagnose stellar populations in AGN, focusing on recent results and how this type of work can lead us well beyond what became known as the starburst-AGN connection.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In a recent study Andrews found that approximately 40% of M-class flares between 1996 and 1999, classified according to GOES X-ray flux, are not associated with Coronal Mass Ejections (CMEs). Using 133 events from his dataset for which suitable photospheric magnetograms and coronal images were available, we studied the pre-flare coronal helicity of the active regions that produced big flares. The coronal magnetic field of 78 active regions was modeled under the “constant $\alpha$” linear force-free field assumption. We find that in a statistical sense the pre-flare value of $\alpha$ and coronal helicity of the active regions producing big flares that do not have associated CMEs is smaller than the coronal helicity of those producing CME-associated big flares. A further argument supporting this conclusion is that for the active regions whose coronal magnetic field deviates from the force-free model, the change of the coronal sign of $\alpha$ within an active region is twice more likely to occur when the active region is about to produce a confined flare than a CME-associated flare. Our study indicates that the amount of the stored pre-flare coronal helicity may determine whether a big flare will be eruptive or confined.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

BALEGA: Is there any sense in performing a speckle interferometric survey to search for secondaries among the Ap stars? As a rule, the secondary companion will be always fainter and cooler than the primary star. Therefore, its input into the common spectrum will be negligible. A good example is 53Cam with a magnitude difference between the components of 1.2.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A review of recent work on pulsating A stars is presented. The types of pulsating stars are the roAp, $\delta$ Scuti, $\lambda$ Bootis, Am stars, pre-Main Sequence pulsating A stars and $\alpha$ Cygni stars (pulsating A supergiants). Population II pulsating A stars such as SX Phe (blue stragglers) and RR Lyraes are also discussed. The emphasis is on the physics that can be derived from the study of stellar pulsations and suggestions for further progress.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using the observations of LASCO aboard SOHO in the interval from Mar. 1997 to Dec. 2003, 301 earth-directed halo CMEs are selected and the source regions are located in MDI synoptic charts. A statistical analysis has been made with the emphasis on the CMEs' large-scale source regions as well as the correlation between CMEs and solar surface activity. The statistics show that CMEs are intrinsically related to surface activity. Four groups of CMEs' large-scale source structures are identified on the photosphere. They are: I, Extended bipole regions (EBRs) with long magnetic neutral line; II, Closely packed active regions (ARs); III, Large-scale magnetic flux of the same polarity runs through the opposite hemisphere, along the boundary there appears transequatorial filaments; IV, Between two EBRs with long filament. The result shows that CME-associated source activity is closely related to the types of large-scale magnetic structures.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using adaptive optics on Keck and the VLT in the H- and K-bands, we have begun a project to probe the dynamics and star formation around AGN on scales of 0.1″. The stellar content of the nucleus is traced through the 2.29 µm CO 2-0 and 1.62 µm CO 6-3 absorption bandheads. These features are directly spatially resolved, allowing us to measure the extent and distribution of the nuclear star forming region. The dynamics are traced through the 2.12 µm H2 1-0 S(1) and 1.64 µm [FeII] emission lines, as well as stellar absorption features. Matching disk models to the rotation curves at various position angles allows us to determine the mass of the stellar and gas components, and constrain the mass of the central black hole. In this contribution we summarise results for the two type 1 AGN Mkn 231 and NGC 7469.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A multi-object spectroscopy follow-up survey of galaxy clusters selected from the Red-sequence Cluster Survey (RCS) is being completed. About forty clusters were chosen with redshifts from 0.15 to 0.6, and in a wide range of richnesses. One of the main science drivers of this survey is a study of internal dynamics of clusters. We present some preliminary results for a subset of the clusters, including the correlation of optical richness with mass, and the mass-to-light ratio as a function of cluster mass.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

2003 VB$_{12}$ (Sedna) is as much distinguished by its considerable size as by its extremely unusual orbit, which has perihelion at about $q=76$ AU with semi-major axis $a=533$ AU (Brown et al. 2004, JPL Horizons). Thus it is effectively decoupled from both Neptune and the Galactic tide (Fernandez 1997). Brown et al. (2004) and Morbidelli & Levison (2004) maintain that only scattering by a so-far-unobserved “Planet X” or by an errant star could produce such a high-perihelion orbit for a scattered-disk KBO. While a close encounter is plausible, given the Sun's likely birth in an open cluster, such an interaction would profoundly disturb the Oort cloud and would require fundamental revision to the present theories of its formation.

Although the planets cannot significantly affect VB$_{12}$'s orbit through close approaches, resonant perturbations could conceivably produce secular effects on it. To explore this possibility, we have numerically integrated test particles with $480 < a < 580$ AU and a fixed $q=76$ AU. Including the four giant planets, but ignoring the Kuiper Belt and the inner Oort Cloud, as well as the Galactic tide, we find multiple resonances, some of which perturb significantly the test particles' eccentricity more strongly than the leading secular terms. We identify these resonances as variants of the very high-order ($n_N > 60 \n$) mean-motion commensurabilities between Neptune and VB$_{12}$. Although unprecedented, these extremely high-order resonances can be significant due to VB$_{12}$'s very high eccentricity ($e=0.86$). Even powers of eccentricity beyond sixty are still on the order of $10^{-4}$, which is comparable to the strength of low-order resonances involving near-circular orbits. We extrapolate the possible long-term drift rate and estimate the likelihood of such resonances producing an “inner Oort cloud” population consistent with VB$_{12}$ over the age of the Solar System. Finally we discuss how planetary migration and the Kuiper-Belt's depletion might have affected VB$_{12}$'s putative resonance.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A new technique of nonlinear interrelations between time series developed by Marwan & Kurths, (2002) has been applied to the sunspot data. By using this tools we have investigated synchronization and phase difference in annual sunspot areas — time series available for Northern and Southern Hemispheres of the Sun.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the first results from our next-generation microlensing survey, the SuperMACHO project. We are using the CTIO 4m Blanco telescope and the MOSAIC imager to carry out a search for microlensing toward the Large Magellanic Cloud (LMC). We plan to ascertain the nature of the population responsible for the excess microlensing rate seen by the MACHO project. Our observing strategy is optimized to measure the differential microlensing rate across the face of the LMC. We find this derivative to be relatively insensitive to the details of the LMC's internal structure but a strong discriminant between Galactic halo and LMC self lensing. In December 2003 we completed our third year of survey operations. 2003 also marked the first year of real-time microlensing alerts and photometric and spectroscopic followup. We have extracted several dozen microlensing candidates, and we present some preliminary light curves and related information. Similar to the MACHO project, we find SNe behind the LMC to be a significant contaminant - this background has not been completely removed from our current single-color candidate sample. Our follow-up strategy is optimized to discriminate between SNe and true microlensing.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Traditionally the $\alpha - \omega$-dynamo is regarded as a basic theory of solar activity (SA) cycle. Here the model of solar magnetic cycle based on the new MHD-solutions for the mean large-scale magnetic field is presented. The hypothesis of gyrotropic plasma turbulence and cyclic restoring of the poloidal magnetic field from the rising toroidal magnetic flux tubes due to the $\alpha$-effect is not used (see Solov'ev and Kiritchek (2004)).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We explain simulation tools in the JASMINE project (JASMINE simulator). The JASMINE project stands at the stage where its basic design will be determined in a few years. Therefore it is very important to simulate the data stream generated by astrometric fields at JASMINE in order to support investigations of error budgets, sampling strategy, data compression, data analysis, scientific performances, etc. We find that new software technologies, such as Object Oriented (OO) methodologies, are ideal tools for the simulation system of JASMINE (the JASMINE simulator). In this article, we explain the framework of the JASMINE simulator.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The methods of radioastronomy are in important observational tool to explore magnetic energy releases in the solar corona. When combined with the useful diagnostics provided by observations in other wavelengths, namely with data from space missions such as Yohkoh, SOHO, and more recently RHESSI, these datasets allow us to track the progression of solar eruptive events from the low corona into the interplanetary medium. One of the most dramatic forms of solar activity, coronal mass ejections (CMEs) encompass a large range of spatial scales in a question of a few minutes. These go from the very small like current sheets, to small like active regions, to the very big like trans-equatorial loops and the transient seen in white light images (with angular extents in excess of 100 degrees for some events). Hence, in order to understand the CME phenomenon, its origin, and early development, we need a set of observations able to image the whole Sun with time cadences of the order of the second. Radio observations can do that presently. Multifrequency radio observations of the solar corona in the metric domain provide diagnostics of a wide variety of phenomena that occur in association CMEs. Radio imaging instruments can follow the processes leading to CME initiation, follow the expansion of the CME in the low corona, both on disk, and above the solar limb, and as such make the link with coronagraphic data. The characteristic signatures of the many CME related phenomena go from thermal emission of the eruptive cavity in the low corona, to direct imaging of the CME loops from synchrotron emission, to radio continua and shock associated emissions, recent progress on the understanding of the early development of CMEs, and on the coronal restructuring in the aftermath of the mass ejection, based on solar radio imaging from the Nancay Radioheliograph, is reviewed here.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We consider a contribution of microlensing to the X-ray variability of high-redshifted QSOs. Cosmologically distributed gravitational microlenses could be localized in galaxies (or even in bulge or halo of gravitational macrolenses) or could be distributed in a uniform way. We have analyzed both cases of such distributions. We found that the optical depth for gravitational microlensing caused by cosmologically distributed deflectors could be significant and could reach $10^{-2} - 0.1$ at $z\sim 2$. This means that cosmologically distributed deflectors may contribute significantlly to the X-ray variability of high-redshifted QSOs ($z>2$). Considering that the upper limit of the optical depth ($\tau\sim 0.1$) corresponds to the case where dark matter forms cosmologically distributed deflectors, observations of the X-ray variations of unlensed QSOs can be used for the estimation of the dark matter fraction of microlenses.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html