Soft X-ray fluorescent emission from the surfaces of asteroids and other atmosphereless solar-system objects is studied using ray-tracing techniques. X-ray observations allow the assessment of the elemental composition and structure of the surface. The model regolith is assumed to consist of close-packed uniformly distributed spherical particles of equal size. The surface is also assumed to be rough according to a fractional-Brownian-motion model. The fluorescent X-ray emission from regolith surfaces is simulated in order to better understand the contribution of viewing-geometry -related phenomena on the signal obtained from, e.g., orbiting platforms. The first results are presented and the applicability of the methods to the interpretation of future asteroid and Mercury mission X-ray data (e.g., BepiColombo) is discussed.

We present a new spectral library for old and intermediate-aged single-age, single-metallicity stellar populations for a wide metallicity range. The major ingredient of these models is a new empirical stellar library composed of 985 stars, whose main characteristic is its unprecedented stellar atmospheric parameters coverage. The model SEDs cover the spectral range 3540-7410A at 2.3A (FWHM). We present some advantages and applications of these models.

Among the longest known eclipse durations and binary periods is that of the star ϵ Aurigae, which exhibits 2-year long eclipses every 27.1 years. Oddly, the nature of the secondary in the system continues to elude ready identification. In 1965, Huang proposed a massive disk as the eclipsing body, and study of the 1984 eclipse led Lissauer and Backman to suggest an embedded B star binary in the disk to maintain it. A collaboration of observers allows me to present recent optical photometry and spectroscopy, near-IR spectroscopy and Spitzer space telescope IRS and MIPS observations of ϵ Aurigae as it approaches its next eclipse. These data argue for current detectability of the embedded binary, and precession of the disk axis, suggesting a radical change is possible for the next mid-eclipse brightening. An international monitoring campaign for the 2009-2011 is being organized, and participation invited via website http://www.du.edu/~rstencel/epsaur.htm.

The scientific program is presented as well a the abstracts of the contributions. An extended account is published in “The Ultraviolet Universe: stars from birth to death” (Ed. Gómez de Castro) published by the Editorial Complutense de Madrid (UCM), that can be accessed by electronic format through the website of the Network for UV Astronomy (www.ucm.es/info/nuva).

There are five telescopes currently in orbit that have a UV capability of some description. At the moment, only FUSE provides any medium- to high-resolution spectroscopic capability. GALEX, the XMM UV-Optical Telescope (UVOT) and the Swift. UVOT mainly delivers broad-band imaging, but with some low-resolution spectroscopy using grisms. The primary UV spectroscopic capability of HST was lost when the Space Telescope Imaging Spectrograph failed in 2004, but UV imaging is still available with the HST-WFPC2 and HST-ACS instruments.

With the expected limited lifetime of sl FUSE, UV spectroscopy will be effectively unavailable in the short-term future. Even if a servicing mission of HST does go ahead, to install COS and repair STIS, the availability of high-resolution spectroscopy well into the next decade will not have been addressed. Therefore, it is important to develop new missions to complement and follow on from the legacy of FUSE and HST, as well as the smaller imaging/low resolution spectroscopy facilities. This contribution presents an outline of the UV projects, some of which are already approved for flight, while others are still at the proposal/study stage of their development.

This contribution outlines the main results from Joint Discussion 04 held during the IAU General Assembly in Prague, August 2006, concerning the rationale behind the needs of the astronomical community, in particular the stellar astrophysics community, for new UV instrumentation. Recent results from UV observations were presented and future science goals were laid out. These goals will lay the framework for future mission planning.

We have developed a code for modeling 3-dimensional kinematical data (i.e., both radial velocity and proper motions) of individual tracers in stellar systems. The code relies on the Schwarzschild method of orbit superposition to find the distribution function (a function of energy, angular momentum, and third integral of motion) that best reproduces all the observations (the positions and velocities of the tracers as well as the overall light distribution) in a given potential. Previous implementations of this method have generally focused on fitting integrated light measurements, instead of data for individual tracers. However, the latter is the only data that are generally available in a large class of problems (e.g., kinematics of tracers in nearby globular clusters, kinematics of planetary nebulae or globular clusters in galaxy halos, etc.). We have performed extensive tests of the fitting process by making use of data generated by a well-tested N-body simulation of an axisymmetric galaxy, quantifying how well the code can recover the known input distribution function and potential.

New ground-based telescopes and instruments, the return of the NICMOS instrument on the Hubble Space Telescope (HST), and the recent launch of the Spitzer Space Telescope have provided new tools that are being utilized in the study of planetary nebulae. Multiwavelength, high spatial resolution ground-based and HST imaging have been used to probe the inner regions of young PNe to determine their structure and evaluate formation mechanisms. Spitzer/IRAC and MIPS have been used to image more evolved PNe to determine the spatial distribution of molecular hydrogen, ionized gas, and dust in the nebulae and halos.

We argue that millimeter continuum observations promise to be an important diagnostic of chromospheric dynamics and the appropriate wavelengths to look for dynamic signatures are in the range 0.8–5.0 mm. We have analyzed the millimeter intensity spectrum expected from the dynamic model of the solar non-magnetic atmosphere of Carlsson & Stein (1992, 1995, 1997, 2002, hereafter CS) together with the interferometric observations of the quiet Sun obtained at a wavelength of 3.5 mm with the Berkeley-Illinois-Maryland Array. Model radio emission at millimeter wavelengths is found to be extremely sensitive to dynamic processes in the chromosphere, if these are spatially and temporally resolved. The estimated millimeter brightness temperatures are time-dependent, following changes in the atmospheric parameters, and result in clear signatures of waves with a period of 180 s seen in the radio intensity as a function of time. At the same time, the interferometric observations of the internetwork regions reveal significant oscillations with amplitudes of 50–150 K in the frequency range 1.5–8 mHz. We give an estimate of the influence of the limited available spatial resolution of observations on the comparison with the predictions of dynamic models. We are able to establish a correspondence between the CS model predictions and the observational data if we assume that the horizontal coherence length of the oscillations is on the order of 1 arcsec.

This paper summarizes the present situation concerning astronomy in Iran. Shiraz University introduced astronomy in the mid-1960s and established the Biruni Observatory. Astronomy is also carried out at Tabriz University and in Meshed, Zanjan, Tehran, Babol and other places. The Astronomical Society of Iran is flourishing, and is about 30 years old. Site-testing is underway for a National Observatory of Iran, which will be equipped with a 2-m class optical telescope. Iran publishes Nojum, the only astronomical monthly magazine of the Middle East, which is presently in its fifteenth year.

Near-Earth objects (NEOs) are objects of a special interest from the point of view not only of cosmogonic problems of the Solar system, but of the applied problems as well (the problem of asteroid hazard, NEOs as the potential sources of raw materials, etc.). They are much smaller in sizes than main-belt asteroids (MBAs), very irregular in shape and covered with a great number of craters of different sizes. Most of NEOs are covered by regolith of low thermal inertia and different thickness. Objects with complex non-principal axis rotation (tumbling bodies) and with super-fast rotational periods have been detected among them. The new data, based on photometric and radar observations, evidence that about 15-20 %; of NEOs could be binary systems. Most of the classified NEOs fragments of differentiated assemblages of S-and Q-types. Analysis of physical properties of NEOs clearly indicates that the asteroid main-belt is the principal source of their origin and only about 10 % of NEOs have a cometary origin.

This article is a study of a family of nonlinear force-free magnetic fields (FFMFs), in Cartesian geometry under assumption of translational symmetry, as simple models of the magnetic fields in the solar corona. For this configuration all the physical quantities are invariant under translations in a fixed direction to be the direction Oz of a Cartesian coordinate system. Two classes of exact analytic solutions for the steady state are obtained. These solutions may be helpful in understanding the physics involved in the transition from the low-confinement to the high-confinement mode in tokamaks. In particular, they can be employed for stability investigations, which would be of relevance to magnetic confinement systems. Further, the obtained solutions may have several applications in the study of solar photosphere, the solar corona, as well as astrophysical plasmas.

The fundamental properties of detached eclipsing binary stars can be measured very accurately, which could make them important objects for constraining the treatment of convection in theoretical stellar models. However, only four or five pieces of information can be found for the average system, which is not enough. We discuss studies of more interesting and useful objects: eclipsing binaries in clusters and eclipsing binaries with pulsating components.

The final phase of a star's life is crucial for the understanding of the chemical evolution of our Galaxy. The planetary nebula phase offers an excellent opportunity to study the nucleosynthesis history of low– and intermediate-mass stars, and to study the evolution of dust in evolved objects. For these purposes, infrared spectroscopy has been an ideal method to both determine accurate abundances and characterize the dust features that are seen in their spectra. This contribution briefly summarizes some of the main infrared spectroscopic advances in the field during the last few years, with emphasis on the recent results/projects from the Spitzer Space Telescope on galactic and extra–galactic planetary nebulae.

The goal of this Joint Discussion is to bring together theorists and observers from the stellar and extragalactic communities to discuss the properties of the most massive stars and the implications for cosmological studies. We will focus on a set of themes that follow from fundamental stellar astronomy, such as mass determinations in binary stars, to recent modeling of atmospheres and evolution, to the significance of massive stars for the ecology of the host galaxy, and finally to a critical assessment of the properties of the first generation of stars in the universe.

A statistical population is always associated with the distribution of a random variable. If the distribution is too complex, it is useful to think about a superposition of simpler components. For the stellar velocities, the distribution is generally assumed as a mixture of gaussian distributions, since these are particular solutions of Chandrasekhar equations for statistical equilibrium, easy to interprete dynamically. In any case, the nature of the phase space density function might be explained from the dynamics of large stellar groups, sharing a common potential, through integrals like the energy, the angular momentum, or more general quadratic integrals, rather than from the kinematics of particular groups of stars, such as those producing streaming motions. Another fact to point out is that a well defined population must be adult, that is, well described from some constant and consistent statistics. Otherwise, if a sample estimate varies depending on an external parameter, for example the mean age of a sample, then, either the type of distribution might be exchanged, or the population might be divided into an adequate number of subpopulations.

In this context, the MEMPHIS algorithm (Alcobé & Cubarsi 2005) has demonstrated to be useful in order to identify nearby stellar populations, by using the full space motions of a stellar sample obtained from the Hipparcos catalog (Cubarsi & Alcobé 2004). A sampling parameter, the modulus of the velocity |V|max, produces a hierarchical set of nested samples allowing to detect significant population components of their velocity distribution. Although the method was designed to identify normal distributions, it also provides, as a less prior information pattern, a good approach to segregate non-gaussian populations. The entropy variations of the mixture probability allow us to estimate the number of populations without any prior assumption about such a number, according to the parameters of the Table below (sampling parameter, velocity dispersions, means –in Km s−1– and vertex deviation are displayed in the UVW-cartesian heliocentric coordinates system). The main disk structure is supported by two gaussian populations, thin and thick disk. Two subcomponents were found within the thin disk, which have a high deviation from gaussianity in the radial direction, as a consequence of a non-random behaviour (Cubarsi & Alcobé 2006), but not in the other directions. Old disk stars were obtained as a broad wing of the young-thin disk. All together, with the early-thin population, they make up the thin disk component. In total 2+2 populations, since halo stars were not included in the sample.

(1) 52 photographic and 651 electronic spectra were disentangled using the program KOREL. This led to the detection of a number of weak absorption lines originating in the atmosphere of the accretion disk. So far, the detection of this disk spectrum was only reported for the Si 6347 and 6371 Å doublet. (2) The basic spectrophotometric quantities of 15 absorption lines of the primary were measured and corrected for the orbital light changes in order to eliminate the contribution of the secondary light to the observed continuum level. After the correction, a significant phase dependency of the spectral-line characteristics near the primary eclipse was detected. In all probability, another so far unknown absorption-line spectrum was thus found. This spectrum may be due to additional absorption of light of the primary in one of the jet-like structures and in the spherical gas envelope surrounding the accretion disk. Both these structures are seen projected against the primary during its eclipse.

We report a 3-dimensional numerical study of the accretion of stellar winds onto Sgr A*, the super-massive black hole at the centre of our Galaxy. Compared with previous investigations, we allow the stars to be on realistic orbits, include the recently discovered slow wind sources, and allow for optically thin radiative cooling. We first show the strong influence of the stellar dynamics on the accretion onto the central black hole. We then present more realistic simulations of Sgr A* accretion and find that the slow winds shock and rapidly cool, forming cold gas clumps and filaments that coexist with the hot X-ray emitting gas. The accretion rate in this case is highly variable on time-scales of tens to hundreds of years. Such variability can in principle lead to a strongly non-linear response through accretion flow physics not resolved here, making Sgr A* an important energy source for the Galactic centre.

In the last years, observations made by large international consortia made available hundreds of thousands of high-resolution spectra of galaxies in the local and distant Universe. The interpretation of these spectra in terms of stellar ages and metallicities is the key to reconstructing the star formation and chemical enrichment histories of the Universe. However, current spectral models rely on libraries of observed stars in the solar neighborhood, hampering our hability in interpreting populations that had undergone different star formation histories. Although it is available in the literature Lick/IDS model indices with variable chemical mixtures, we were still lacking high resolution spectral energy distribution models. Those models are required if we want to exploit the total amount of information contained in observed galaxy spectra. We present here our work aiming at the development of such models, constructed with a consistent set of synthetic stellar library and new stellar evolution models.

During the immediate post-Soviet period, the main infrastructure of astronomy over the territory of the former Soviet Union (FSU) was saved, in spite of dramatic decreases in financial support. Overall the situation for FSU astronomy is now stable. In Latvia, the 32-m radio-dish is in working order. This allows it to participate in VLBI programmes. In Russia, all three 32-metre radio dishes of the QUASAR VLBI system are operational, as well as the 2-m telescope with a high-resolution spectrograph (up to resolution R≃ 500 000) and the horizontal solar telescope (R= 320 000) of the Russian-Ukrainian Observatory on Peak Terskol (Caucasus, altitude 3100 m). However the situation with the observatory itself is worrying, because of the regional authorities' attempt to privatize its infrastructure.

The process of equipping a number of Commonwealth of Independent States (CIS) (including Russian) observatories with CCD-cameras is in progress. To solve staff problems, Kazakhstan, Tajikistan and Uzbekistan have begun to prepare national specialists in astronomy, and the Baltic States, Armenia, Azerbaijan, Georgia, Russia, and Ukraine continue to prepare astronomers.

Teaching of astronomy at schools is obligatory only in the Ukraine and partially in the Baltic states. To maintain a “common astronomical area”, the Eurasian Astronomical Society (EAAS) continues its programme of reduced-price subscription to Russian-language astronomical journals and magazines in the territory of FSU, the organization of international conferences and Olympiads for school students, and lectures for school teachers and planetarium lecturers, etc.

Telescopes in Russia and other CIS territories permit to monitor an object more then 12 hours and can be used in global monitoring programmes. The Central Asian sites have some of the very best astro-climates in the world. They are similar to (or a little better than) the well known Chilean sites (median seeing 0.7′′, very high fraction of clear nights, no light pollution and no high wind). It is imperative that these sites be protected and intensively used by the international astronomical community.

Winds and outflows powered by the release of gravitational potential energy of infalling matter have been invoked as the triggering agent for further star-formation on scales from dwarf galaxies to individual, low-mass stars. This brief review will touch upon the circumstances under which outflows can serve as star-formation triggers, from specific observations of present-day, nearby protostellar flows.

The theoretical results obtained in Uzbekistan in the field of relativistic astrophysics and cosmology are presented. In particular electrostatic plasma modes along the open field lines of a rotating neutron star and Goldreich-Julian charge density in general relativity are analyzed for the rotating and oscillating magnetized neutron stars. The impact that stellar oscillations of different type (radial, toroidal and spheroidal ones) have on electric and magnetic fields external to a relativistic magnetized star has been investigated. A study of the dynamical evolution and the number of stellar encounters in globular clusters with a central black hole is presented. Perturbation features and instabilities of the large-scale oscillations on the background of the non-linearly pulsating isotropic and isotropic Ω-models are studied. The non-stationary dispersion equation of the sectorial perturbations for the general case and the results of certain oscillation mode analysis are given. The model composed as the linear superposition of two other models was constructed and the stability of this model is studied. In a cosmological setting the theory of macroscopic gravity as a large-distance scale generalization of general relativity has been developed. Exact cosmological solutions to the equations of macroscopic gravity for a flat spatially homogeneous, isotropic space-time are found. The gravitational correlation terms in the averaged Einstein equations have the form of spatial curvature, dark matter and dark energy (cosmological constant) with particular equations of state for each correlation regime. Interpretation of these cosmological models to explain the observed large-scale structure of the accelerating Universe with a significant amount of the nonluminous (dark) matter is discussed.