Surface brightness measurements of the diffuse intracluster light (ICL) in centrally concentrated, relaxed clusters have demonstrated that stars bound only to the cluster potential can contain anywhere from 5 to 50% of the total cluster flux. These stars are a by-product of the evolution of galaxies in clusters, and can be used to constrain models for the structure and evolution of clusters and their member galaxies. The ICL will be an important test of cosmological models as it is a baryonic component of clusters that is likely to evolve with redshift. To learn about these processes we are undertaking a program to measure the characteristics of the ICL (total flux, color, and substructure) as a function of cluster mass, morphology, and redshift. We have obtained data for a sample of 10 clusters at low and moderate redshifts. We discuss here our preliminary results for one cluster in that sample, A3888. With 4-5 hour integration times on-source per filter (V & gunn-r), we reach a 1 sigma surface brightness limit of 29.9 mag/arcsec$^{2}$ in the V band. We have identified an intracluster light component that is $\sim10\%$ of total cluster light, extends to 600 kpc from the center of the cluster, and is redder in color than the cluster galaxies ($V-r = 0.4$ near the center, increasing to $V-r = 0.8$ at r = 500 kpc). In addition we find 3 low surface brightness features which are blue ($V-r \simeq 0$), and in total are equivalent to one $m_V = 20.8$ mag galaxy.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

LLAGN that include low-ionization nuclear emission-line regions (LINERs), and transition-type objects (TOs) represent the most common type of nuclear activity. Here, a study of the central stellar population of LLAGN is presented. Our goal is to search for spectroscopic signatures of young and intermediate age stars, and to investigate their relationship with the ionization mechanism in LLAGN. The method used is based on the stellar population synthesis of the UV-optical continuum of the innermost (20-100 pc) regions in these galaxies. Half of the LINERs and TOs of the Palomar catalogue are analysed. It is found that weak-[OI] ([OI]/Hα≤0.25) LLAGN have an intermediate age stellar population that dominates the optical light. But young stellar clusters dominate the UV continuum in these objects. These clusters can co-exist with a black-hole in spatial scales of a few pc. Most of the strong-[OI] LLAGN have a predominantly old stellar population. These results suggest that young and intermediate age stars do not play a significant role in the ionization of LLAGN with strong [OI].To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The paper emphasizes the connection between observations and theory in the Lower Instability Strip. It is argued that the $\delta$ Scuti and $\gamma$ Doradus pulsators are very close relatives in the sense that the $\gamma$ Doradus phenomenon can also be seen in the slightly hotter $\delta$ Scuti variables.

New developments and recent progress are reviewed. Arguments are given why all (or almost all) stars in the Lower Instability Strip are pulsators. Furthermore, the question of the so-called missing modes is answered as very extensive photometry campaigns have revealed a large number of pulsation modes with amplitudes less than one millimag. Arguments are given that the 500+ $\ell$ = 0 to 2 modes predicted for $\delta$ Scuti stars are actually present.

The progress made in developing reliable methods of pulsation mode identification is briefly discussed. The discovery of many close modes with small amplitudes sets severe requirements concerning the length of future studies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In the framework of the restricted three body problem, the resonant periodic orbits associated with the Kuiper belt dynamics are studied. Particularly, all the first, second and third order exterior mean motion resonances with Neptune located up to 50A.U. and the asymmetric resonances (beyond the 48 A.U.) are considered. We present the bifurcation points of families of periodic orbits of the planar circular problem from which families of periodic orbits are generated in the planar elliptic and in the 3D circular problem. Similarities and differences between the various resonant cases are noticed. The relation between the distribution of the bifurcation points and the population of small bodies at the particular resonances is discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this paper we report on our recent results connected with the direct environment of the super massive black hole of the Milky Way. The data are obtained using the VLT facilities (ISAAC and NAOS/CONICA instruments) in the near- and mid-infrared wavelength ranges. We provide a calibration of the foreground and local differential (in wavelength and spatially) extinction of the Galactic Center and report on the discovery of a new complex of infrared excess sources (possibly young stars) located at the northern part of the IRS 13 cluster. Finally, we discuss the origin of filamentary structures observed in the L-band images.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We investigate the broadband optical emission of diffuse intergalactic stars in galaxy clusters at $z\sim0.25$ by means of an image stacking technique. The images of 654 clusters, selected with the max-BCG algorithm from a subsample of the SDSS-Data Release 1 (DR1), have been stacked after masking all the sources detected down to very low S/N. The resulting images in the g, r and i bands provide reliable photometric data at the level of $\gtrsim30$ mag$/\square$” (r band), out to $\gtrsim 600$ kpc from the Brightest Cluster Galaxy (BCG). Our analysis shows that: i) the IntraCluster Light (ICL) is much more concentrated than the galaxy light, contributing $\sim$30% of the total cluster optical emission at $R=100$ kpc, but less than 10% at $R > 500$ kpc; ii) the ICL contributes between 15 and 20% of the total cluster optical luminosity between the optical radius ($\mu_r=25$ mag$/\square$”) of the BCG and 500 kpc; iii) the colours of the ICL are consistent with the global colours of the cluster galaxies, with little evidence for redder g$-$r.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

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

The origin of stony meteorites landing on Earth today is directly linked to the history of the main belt, which evolved both through collisional evolution and dynamical evolution/depletion. In this paper, we focus our attention on the main belt dynamical evolution scenario discussed in Petit et al. (2001). According to Petit et al., during the planet formation epoch, the primordial main belt contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales.

After a few My, the accretion of planetary embryos in the main belt zone dynamically stirred the remaining planetesimals to high enough velocities to initiate fragmentation. After a short interval, perhaps as long as 10 My, the primordial main belt was dynamically depleted of $>99$% of its material via the combined perturbations of the planetary embryos and a newly-formed Jupiter. The small percentage of objects that survived in the main belt zone became the asteroid belt. It has been shown that the wavy-shaped size-frequency distribution of the main belt is a “fossil” left over from this violent period (Bottke et al. 2004).

Using a collisional/dynamical model of this scenario, we tracked the evolution of stony meteoroids produced by catastrophic disruption events over the last several Gy. We show that most stony meteoroids are a byproduct of a collisional cascade derived from large and ancient asteroid families or smaller, more recent breakup events. The meteoroids are then delivered to Earth by drifting in semimajor axis via Yarkovsky thermal drag forces until they reach a resonance powerful enough to place them on an Earth-crossing orbit.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The internal magnetic field structure of CMEs and the field structure of the solar source regions were systematically investigated during different phases of the solar cycle in cycles 19-23 based on plasma and magnetic field measurements sampled by various satellites and through multi-wavelength remote sensing observations. It is found that: 1. To first order, the internal magnetic structure of CMEs varies systematically from one solar cycle to the next with respect to the prevailing hemispheric magnetic patterns of bipolar regions following the law of hemispheric helicity dependence. 2. To second order, the field structure in CMEs varies with respect to the complex spatial evolution of the magnetic flux in the photosphere in both hemispheres over the course of the cycle itself. The two effects can naturally explain the cyclic behavior of the SN, NS variations of the internal magnetic fields in CMEs in the solar wind as well as intermittent periods of mixed distributions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Research in roAp stars is being vigorously pursued, both theoretically and observationally by many groups. We report the discovery of a 21-min period, luminous roAp star, HD 116114. Longer periods for more luminous stars have been predicted theoretically and this is the first discovery of such a star. We discuss a model for the blue-to-red line profile variability observed in some roAp stars involving a shock wave high in the atmosphere of roAp stars, yet show that the H$\alpha$ line in 33 Lib has the blue-to-red-to-blue line profile variability expected for subsonic dipolar pulsation concentrated towards the pulsation pole. Further we report for 33 Lib unprecedented observations of the amplitudes and phases of its principal mode at 2.015 mHz and its first harmonic of that at 4.030 mHz.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We review in this paper the main results recently obtained on the identification and study of very high-z galaxies using lensing clusters as natural gravitational telescopes. We present in detail our pilot survey with ISAAC/VLT, aimed at the detection of z$>7$ sources. Evolutionary synthesis models for extremely metal-poor and PopIII starbursts have been used to derive the observational properties expected for these high-$z$ galaxies, such as expected magnitudes and colors, line fluxes for the main emission lines, etc. These models have allowed to define fairly robust selection criteria to find z$\sim 7-10$ galaxies based on broad-band near-IR photometry in combination with the traditional Lyman drop-out technique. The first results issued from our photometric and spectroscopic survey are discussed, in particular the preliminary confirmation rate, and the global properties of our high-z candidates, including the latest results on the possible z=10.0 candidate A1835-1916. The search efficiency should be significantly improved by the future near-IR multi-object ground-based and space facilities. However, strong lensing clusters remain a factor of $\sim$ 5-10 more efficient than blank fields in the z $\sim$ 7-11 domain, within the FOV of a few arcminutes around the cluster core, for the typical depth required for this survey project.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

We investigated variations of the radio emission of the whole Sun at 1.76 cm obtained and archived at the Nobeyama radio heliograph in 1992–2003. For this purpose the daily data of the intensity and also right/left circular polarization of the radio emission with one-second average were processed. It was found that 3 minutes oscillations are present at the different phases of solar activity, including the minimum of activity. Especially conspicuous these oscillations present in a difference between the right and the left circular polarization. Intensity of the oscillations changes with a level of the solar activity. As we register fluctuations from the full Sun that their source can be not only sunspots but also and chromosphere of the Sun. Spectral analysis of the presence of 3-minute oscillations in polarization of the solar radio emission shows that there exist modulation with the periods of 27 and 157 days.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

New pulsating pre-main sequence (PMS) stars have been discovered in the young open clusters IC 4996 and NGC 6383 using CCD time series photometry in Johnson B and V filters. As the cluster ages are both smaller than 10 million years, all members later than spectral type A0 are still contracting towards the ZAMS, hence providing ideal candidates for searches of pulsation. A dozen stars in NGC 6383 and 35 stars in IC 4996 lie within the boundaries of the classical instability region in the Hertzsprung-Russell (HR) diagram, but pulsation was detected for only two of them in each cluster.

For the well-studied cluster NGC 2264, the two already known PMS pulsating members, V 588 Mon and V 589 Mon, have been analysed using new data from a multi-site campaign. All data collected since their discovery in 1972 build the basis for the first measurements of period changes in PMS pulsators.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present results from an SED analysis of two lensed high-$z$ objects, the $z=6.56$ galaxy HCM6A behind the cluster Abell 370 discovered by Hu et al. (2002) and the triple arc at $z \sim 7$ behind Abell 2218 found by Kneib et al. (2004). For HCM 6A we find indications for the presence of dust in this galaxy, and we estimate the properties of its stellar populations (SFR, age, etc.), and the intrinsic ly$\alpha$ emission. From the “best fit” reddening ($E(B-V) \sim 0.25$) its estimated luminosity is $L \sim (1-4) \times 10^{11} \lsun$, in the range of luminous infrared galaxies. For the arc behind Abell 2218 we find a most likely redshift of $z \sim$ 6.0–7.2 taking into account both our photometric determination and lensing considerations. SED fits indicate generally a low extinction but do not strongly constrain the SF history. Best fits have typical ages of $\sim$ 3 to 400 Myr. The apparent 4000 Å break observed recently by Egami et al. (2004) from combination of IRAC/Spitzer and HST observations can also well be reproduced with templates of young populations ($\sim$ 15 Myr or even younger) and does not necessarily imply old ages. Finally, we briefly examine the detectability of dusty lensed high-z galaxies with Herschel and ALMA.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

VLBI – Very Long Baseline Interferometry – is a radio interferometry technique which provides the highest spatial resolution observations to human kind. But at the present, the accuracy of the astrometry observations is limited by the atmospheric light path variations and instrumental phase errors, and only group delay measurements are used. To overcome these error factors, we have developed the VERA system, which has the first dual beam system. VERA is the first VLBI array to be free from the atmospheric phase fluctuations. It has four VLBI stations with 2300-km maximum baseline length in Japan. To compensate phase fluctuations of interferometer visibilities, which are mainly caused by the atmosphere, the VERA antenna observes two objects simultaneously. In order to do such observations, VERA has a two-receiver system, which tracks a focal plane according to a separation angle between observing objects. By comparing the visibility phase between two beams, simultaneous phase referencing VLBI will be achieved. The goal accuracy of astrometry observations is 10 micro-arcseconds, which makes annual parallax and proper motion measurements of galactic maser objects possible. 10 micro-arcsecond accuracy is equivalent to 10% distance accuracy for the galactic centre. This becomes 20% accuracy at the opposite side of the galaxy. The main scientific targets of VERA are to make a 3-dimensional maser object map of the galaxy and reveal the velocity field of the galaxy. This will show the mass distribution of the galaxy. Currently, construction of four stations is complete, and test observations are underway. We show the scientific goal, current results and instrumental accuracy of VERA.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Meteor streams that form as a result of cometary activity around perihelion consist of both structured and background components. The former are often referred to as trails. A trail is created at each perihelion passage as a result of the meteoroids' range of orbital periods. Trail locations can be precisely calculated by numerical integrations, allowing predictions of meteor outbursts and storms. The initial distribution of meteoroids, which relates to the meteor shower profile, depends on the meteoroid production rate and ejection velocity distribution as functions of heliocentric distance and on solar radiation pressure. The profile can gradually evolve owing to other radiative forces. This paper reviews such work on these aspects of shower predictions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the analysis of Hubble Space Telescope blue spectra at intermediate spectral resolution for the nuclei of 23 nearby disk galaxies. These objects were selected to have nebular emission in their nuclei, and span a range of emission-line classifications as well as Hubble types. Here we focus on the stellar population as revealed by the continuum spectral energy distribution measured within the central 0.″13 (∼8 pc) of these galaxies. The data were modeled with linear combinations of single-age stellar population synthesis models. The large majority (∼80%) of the surveyed nuclei have spectra whose features are consistent with a predominantly old ($\gtrsim 5 \times 10^9$ yr) stellar population. Approximately 25% of these nuclei show evidence of a component with age younger than 1 Gyr, with the incidence of these stars related to the nebular classification. Successful model fits imply an average reddening corresponding to AV∼0.4 mag and stellar metallicity of (1–2.5)$Z_\odot$. Our findings reinforce the picture wherein Seyfert nuclei and the majority of low-ionization nuclear emission-line regions (LINERs) are predominantly accretion-powered, and suggest that much of the central star formation in HII nuclei is actually circumnuclear.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

By means of multiwavelength data, we study the eruptions of two filaments and the relationship between the first filament eruption and a subsequent CME. The main results are: (1) The disturbances of the two filaments showed different features, indicating that their eruptive mechanisms were possibly different. (2) A subsequent CME was well correlated with the first eruption in both time and space.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the ability of weak lensing surveys to locate massive clusters. We use both analytic models of dark matter halos and mock weak lensing surveys generated from a large cosmological $N$-body simulation. We find that, for a weak lensing survey with a galaxy number density of $n_g=30$ arcmin$^{-2}$ with a mean redshift $z=1$, the mean number of galaxy clusters which are expected to be identified is $N({\rm S/N}>4)=7$ per 1 deg$^2$. Weak lensing surveys thus provide a reasonably efficient way to search for massive clusters. We also describe our project on the weak lensing cluster survey exploiting Suprime-Cam (the wide-field prime focus camera on the 8m Subaru telescope), called Suprime-33 and present current status. We also present results from its pilot survey in the Suprime-Cam 2.1 deg$^2$ field.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html