We present lithium abundances for ∼50 late-type members of the ∼30 — 50 Myr old open clusters IC 2602 and IC 2391 derived from high-resolution spectra obtained at ESO and CTIO. These data enlarge and extend to cooler temperatures previous Li surveys of these clusters by Stauffer et al. (1989) and Randich et al. (1997). We discuss the lithium vs. temperature distribution in the two clusters and we compare our results with those obtained for the Pleiades (∼120 Myr). The results are discussed in the general framework of lithium depletion in young clusters, from the pre-main sequence to the age of the Pleiades.

In the last several years the manually operated fish-eye cameras in the Czech part of the European fireball Network (EN) have been gradually replaced with new generation cameras, the modern and sophisticated completely autonomous fireball observatories (AFO), which were recently developed in the Czech Republic. The main motivation for construction of this new observing system was to continue in regular fireball observations and to make these observations more complex and efficient. In this paper we briefly describe basic design and work of this new instrument and its deployment at the Czech stations of the EN. The current dislocation of the individual stations and their equipment is also discussed. Along with this new modern instrument we developed also new software for measurement of photographic negatives which makes this time consuming work more efficient and easier. The AFOs provide us with data on fireballs far richer and more interesting than those we were able to get in the past. This is illustrated by the cases of two recently observed fireballs which were recorded by the AFOs. We describe the high precision of all the measureded values as well as the very detailed information about light curves in both cases.

As a major component of the LAMOST Galactic surveys, the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC) will survey a significant volume of the Galactic thin/thick disks and halo in a contiguous sky area of ~3,400 sq.deg., centered on the Galactic anti-center (|b| ≤ 30°, 150 ≤ l ≤ 210°), and obtain λλ3800–9000 low resolution (R ~1,800) spectra for a statistically complete sample of ≳ 3 M stars of all colors, uniformly and randomly selected from (r, g - r) and (r, r - i) Hess diagrams obtained from a CCD imaging photometric survey of ~5,400 sq.deg. with the Xuyi 1.04/1.20 m Schmidt Telescope, ranging from r = 14.0 to a limiting magnitude of r = 17.8 (18.5 for limited fields). The survey will deliver spectral classification, radial velocity (Vr) and stellar parameters (effective temperature (Teff), surface gravity (log g) and metallicity [Fe/H]) for millions of Galactic stars. Together with Gaia which will provide accurate distances and tangential velocities for a billion stars, the LSS-GAC will yield a unique data set to study the stellar populations, chemical composition, kinematics and structure of the disks and their interface with the halo, identify streams of debris of tidally disrupted dwarf galaxies and clusters, probe the gravitational potential and dark matter distribution, map the 3D distribution of interstellar dust extinction, search for rare objects (e.g. extremely metal-poor or hyper-velocity stars), and ultimately advance our understanding of the assemblage of the Milky Way and other galaxies and the origin of regularity and diversity of their properties.

The survey was initiated in the fall of 2012 and expected to complete in the spring of 2017. Hitherto, about 0.4 M spectra of S/N(λ7450) ≥ 10 per pixel have been accumulated. In addition, bright nights have been used to target stars brighter than 14 mag and have so far generated over 0.4 M spectra, yielding an excellent sample of local stars to probe the solar neighborhood. LSP3, a set of pipelines tailored to the need of LSS-GAC, for spectral flux-calibration, and radial velocity and stellar parameter determinations, have been developed at Peking University, based on packages developed for the SDSS and those at the National Astronomical Observatories of Chinese Academy of Sciences. Comparisons of multi-epoch observations, with the SDSS results, as well as applying the pipelines to open and globular clusters show that LSP3 has achieved a precision of 5 km s−1, 110 K, 0.15 dex and 0.15 dex for Vr, Teff, log g and [Fe/H], respectively. The data are publicly available, subject to regulations of the LAMOST data policy, and begin to yield scientific results. The potential of LSS-GAC and power of existing data are illustrated with examples of selected problems.

Theoretical models for the interaction of stellar winds and the interstellar medium are described. Stellar wind energy sources are listed, and observations of expanding shells around stars and star clusters are reviewed. Giant expanding shells, or “superbubbles,” with radius > 100 pc, are formed by the combined action of stellar winds and supernovae from clusters of OB stars. Smaller expanding shells around Wolf-Rayet stars are probably formed by the interaction of the WR stellar wind with matter ejected in a previous red supergiant phase of stellar evolution. Stellar wind activity is evident in regions of star formation in dense molecular clouds.

The constitution of stationary single sunspots of circular shape is considered. Account is taken of the mechanical effects of the magnetic field, including those which arise from the curvature of the lines of force. To make the system of magneto-hydrostatic equations manageable, it is assumed that the relative distribution of the vertical component of the magnetic field is the same across the flux-tube of the spot in all depths. Preliminary results indicate that suppression of convective energy transport by the magnetic field in those depths in which ionization of hydrogen takes place, will give the essential observable properties of sunspots, relatively independent on the asumptions about the physical processes in greater depths. There the physical properties of matter can deviate but very little from those of the indisturbed hydrogen convection zone.

The large-scale surveys such as PTF, CRTS and Pan-STARRS-1 that have emerged within the past 5 years or so employ digital databases and modern analysis tools to accentuate research into Time Domain Astronomy (TDA). Preparations are underway for LSST which, in another 6 years, will usher in the second decade of modern TDA. By that time the Digital Access to a Sky Century @ Harvard (DASCH) project will have made available to the community the full sky Historical TDA database and digitized images for a century (1890–1990) of coverage. We describe the current DASCH development and some initial results, and outline plans for the “production scanning” phase and data distribution which is to begin in 2012. That will open a 100-year window into temporal astrophysics, revealing rare transients and (especially) astrophysical phenomena that vary on time-scales of a decade. It will also provide context and archival comparisons for the deeper modern surveys.

Observations prompted by Sheeley's discovery of outflowing CN bright points from sunspots have established that there occur small moving magnetic features (MMF's) near sunspots. These MMF's exhibit a highly ordered pattern of movement directly related to the associated sunspot. The observations are consistent with the concept of magnetic flux outflow (MFO), a process whereby net magnetic flux of the same polarity as the sunspot is transferred from a decaying sunspot to the surrounding magnetic network. Small magnetic flux concentrations are apparently convected outward by a velocity cell centered on the sunspot. Doppler spectroheliograms have provided evidence for such systematic outward velocities extending as far as 10000 to 20000 km beyond the outer edge of the penumbra of some sunspots, which is comparable to the extent of MFO. While MFO is best observed by means of time-lapse movies of the magnetic fields, it is also manifested morphologically on individual magnetograms by features that resemble moats (or bays) and wreaths around only those sunspots where MFO is present. Two examples of magnetic features streaming toward and into rapidly forming sunspots are described, providing evidence for the occurrence of magnetic flux inflow (MFI) associated with the growth phase of sunspot development. It is, therefore, likely that MFI and MFO are basic aspects of the evolutionary development of sunspots. Observational and instrumental aspects relevant to the investigation of MMF's are described in the Appendix.

I present evolutionary tracks and curves of constant central hydrogen abundance in diagrams based on frequencies of high-order, low-degree p modes. For stars with masses between 0.7 and 1.5 M⊙, a clean separation is obtained between the effects of varying mass and varying evolutionary state.

We review the role of rotation in massive close binary systems. Rotation has been advocated as an essential ingredient in massive single star models. However, rotation clearly is most important in massive binaries where one star accretes matter from a close companion, as the resulting spin-up drives the accretor towards critical rotation. Here, we explore our understanding of this process, and its observable consequences. When accounting for these consequences, the question remains whether rotational effects in massive single stars are still needed to explain the observations.

The world biggest decameter wavelength radio telescope UTR-2 and VLBI system URAN, as well as main observational programs carried out with the above mentioned instruments, are described.

Since the last IAU symposium on planetary nebulae (PNe), several deep spectroscopic surveys of the relatively faint optical recombination lines (ORLs) emitted by heavy element ions in PNe and H II regions have been completed. New diagnostic tools have been developed thanks to progress in the calculations of basic atomic data. Together, they have led to a better understanding of the physical conditions under which the various types of emission lines arise. The studies have strengthened the previous conjecture that nebulae contain another component of cold, high metallicity gas, which is too cool to excite any significant optical or UV CELs and is thus invisible via such lines. The existence of such a plasma component in PNe and possibly also in H II regions provides a natural solution to the long-standing problem in nebular astrophysics, i.e. the dichotomy of nebular plasma diagnostics and abundance determinations using ORLs and continua on the one hand and collisionally excited lines (CELs) on the other.

A review of observational data on interstellar polarization is given. The degree of fluctuation in the direction of the galactic magnetic field is discussed. An empirical formula is given which fits all the observations of the wavelength dependence of interstellar polarization when they are normalized with the wavelength λmax of maximum polarization. Well-defined regions on the sky with values of λmax deviating from an average are found. Values of λmax are correlated with the ratio of total to selective interstellar extinction. A unified wavelength dependence of interstellar extinction is obtained by normalizing the observations with the wavelength λmax of maximum interstellar polarization.

As demonstrated by de Vaucouleurs (1956, 1975a, b, 1976), Abell (1961), Karachentsev (1966), Kiang and Saslaw (1969) and others, clusters of galaxies as well as groups of galaxies have a tendency to form second-order clusters of galaxies, often called superclusters. Recent statistical studies by the Princeton group (Davis, Groth and Peebles 1977, Seldner and Peebles 1977a) have confirmed this result. Statistical studies, however, give little information about the internal structure of second-order clusters.

Diffuse radio sources in clusters remain a poorly understood phenomenon. They are very extended sources (0.4-0.6 Mpc), of low surface brightness and steep spectrum, which cannot be identified with any active radio galaxy. They are a rare phenomenon, as they have been found so far in few clusters of galaxies. This paper reviews the current findings about this kind of sources, and the suggestions about their formation and evolution.

Be star binaries with neutron star companions are shown to constitute a major class of X-ray sources. Some general observational and interpretive techniques of X-ray astronomy are reviewed. Data for 12 Be/X-ray binary systems are summarized. The Be/X-ray binaries are found to be systematically wider systems, with lower-mass primaries, and with significantly more transient behavior than the “standard” massive X-ray binaries such as Cen X-3 and SMC X-1. The difference between the two types of X-ray binaries is explained in the context of slightly different evolutionary scenarios for the progenitor binaries. The “standard” massive X-ray binaries result from wind-mass-loss dominated evolution of very massive close binaries, while Be/X-ray binaries probably result from mass-transfer dominated evolution of systems with primary masses ≲ 20 M⊙. The implications of the X-ray observations of Be/X-ray binaries for Be stars in general are discussed.

In his book Plurality of Worlds, Steven J. Dick (1984) has chronicled the millennia of discourse about other inhabited worlds, based upon deeply held religious or philosophical belief systems. The popularity of the idea of extraterrestrial life has waxed and waned and, at its nadir, put proponents at mortal risk. The several generations of scientists now attending this General Assembly of the International Astronomical Union at the beginning of the 21st century have a marvelous opportunity to shed light on this old question of habitable worlds through observation, experimentation, and interpretation, without recourse to belief systems and without risking their lives (though some may experience rather bumpy career paths). The newly-named and funded, multi-disciplinary field of astrobiology is extremely broad in its scope and is encouraging IAU members to learn and speak the languages of previously disparate disciplines in an attempt to answer the big picture questions: ‘Where did we come from?’, ‘Where are we going?’, and ‘Are we alone?’ These are questions that the general public understand and support, and these are questions that are attracting students of all ages to science and engineering programs. These questions also push the limits of modern instrumentation to explore the cosmos remotely across space and time, as well as to examine samples of interplanetary space returned to the laboratory and samples of distant time teased out of our own Earth.

Within my personal event horizon, the other planetary systems long-predicted by theorists have been uncovered, along with many whose structures were not predicted. The ‘just-so’ conditions requisite for the comfort of astronomers have been understood to be only a very narrow subset of the conditions that nurture extremophilic, microbial life. Thus the potentially habitable real estate beyond Earth has been greatly expanded and within the next few decades it may be possible to detect the biosignatures or technosignatures of inhabitants on distant worlds, should there be any.

Preliminary results are given for a systematic survey of K-dwarf stars in the solar vicinity. Nine companions to the G and K dwarfs have very low M2 sin i, less than 0.08 M⊙. These detections from a sample of 540 G and K primary stars support the reality of the existence of companions with mass below 0.08 M⊙: brown dwarfs exist.

A comparison of the relative mass function distribution f(m)/M1 between low-mass (M1 < 1.3 M⊙) and intermediate-mass (2 < M1 < 5 M⊙) binaries suggests a dependence of the mass-ratio distribution on the mass of the primary: f(q, M1).

By combining the photometric information with orbital elements constraints, we have derived the mass-ratio distribution for intermediate-mass stars. As is the case for low-mass stars, this distribution does not have any maximum close to M2/M1 = 1.

Interstellar masers are unique probes of the environments in which they arise. In studies of high-mass star formation their primary function has been as signposts of these regions and they have been used as probes of the kinematics and physical conditions in only a few sources. With a few notable exceptions, we know relatively little about the evolutionary phase the different maser species trace, nor their location with respect to other star formation tracers. While detailed studies of a small number of maser regions can reveal much about them, other information can only be obtained through large, systematic searches. In particular, such surveys are vital in efforts to determine an evolutionary sequence for the common maser species, and there is growing evidence that methanol masers may trace an earlier phase than the other common maser species of OH and water.

We examine the question of planetary classification, making recommendations both for the criteria by which planethood should be evaluated, as well as for more detailed physical and dynamical subtype classification schemes.

We have made detailed comparisons of coronal structure, as photographed at λ5303 Å, with magnetic lines of force, as computed from measurements of the longitudinal component of the underlying photospheric magnetic fields. Coronal fields were computed under the assumption that the space above the active regions is current-free. Out of 36 regions for which there exist both magnetic and coronal data at the Sacramento Peak Observatory, we found only four suitable for analysis. Using a light-pen attachment to a digital computer, we were able to choose lines of force whose footpoints in the photosphere best matched those of the lines of force which were suggested by local intensity variations in the corona. The lines of force thus computed give excellent agreement with the apparent height and shape of coronal fieldlines. In particular the magnetic field in the loop structures of 2 November 1969 and 18–19 November 1968 falls from several hundred gauss at 10000–20000 km above the photosphere to 2–20 G at heights of 100000–150000 km. These computed values are in general agreement with other measurements. Spectra of the loops reveal that the direction of the line-of-sight component of the motion agrees with that anticipated from a comparison of the computed fieldline orientation and the observed motion in the plane of observation. We conclude that coronal magnetic fields above slowly changing active regions are nearly the same as the vacuum potential fields derived from underlying photospheric field sources (principally the larger sunspots in a region) and that calculations of this type may be relied upon to give the magnetic fields for studies of coronal dynamics.