In this paper, we present a first comparison of different Adaptive Optics (AO) concepts to reach a given scientific specification for 3D spectroscopy on Extremely Large Telescope (ELT). We consider that a range of 30%–50% of Ensquarred Energy (EE) in H band (1.65$\mu$m) and in an aperture size from 25 to 100mas is representative of the scientific requirements. From these preliminary choices, different kinds of AO concepts are investigated: Ground Layer Adaptive Optics (GLAO), Multi-Object AO (MOAO) and Laser Guide Stars AO (LGS). Using Fourier based simulations we study the performance of these AO systems depending on the telescope diameter.

AMS (Alpha Magnetic Spectrometer) is a particle detector designed to operate at the International Space Station. Starting in 2008, its purpose is to perform accurate, high statistics, long duration measurements of energetic (0.1 GeV to $\sim$TeV) charged cosmic ray spectra in space, providing fundamental information about key ingredients in the spallation reactions taking place in the interstellar medium. We present here the characteristics of this experiment and the extense collaboration supporting the project.

Outer satellites of the planets have distant, eccentric orbits that can be highly inclined or even retrograde relative to the equatorial planes of their planets. These irregular orbits cannot have formed by circumplanetary accretion and are likely products of early capture from heliocentric orbit. The irregular satellites may be the only small bodies remaining which are still relatively near their formation locations within the giant planet region. The study of the irregular satellites provides a unique window on processes operating in the young solar system and allows us to probe possible planet formation mechanisms and the composition of the solar nebula between the rocky objects in the main asteroid belt and the very volatile rich objects in the Kuiper Belt. The gas and ice giant planets all appear to have very similar irregular satellite systems irrespective of their mass or formation timescales and mechanisms. Water ice has been detected on some of the outer satellites of Saturn and Neptune whereas none has been observed on Jupiter's outer satellites.

As high contrast imaging surveys are being designed and carried out to directly detect extrasolar planets around young, nearby stars it is important to carefully evaluate the criteria for selection of target stars, as well as the predicted success of such a survey based on the sensitivity of the AO system used. We have developed a routine to simulate a large number of planets around each potential target star, and determine what fraction can be reliably (5$\sigma$) detected using an AO system's predicted or observed sensitivity curve (the maximum flux ratio between the parent star and a detectable planet as a function of projected radius). Each planet has a randomly assigned semi-major axis, mass, and eccentricity (following extrapolations of detected radial velocity planet power laws), as well as random viewing angles and orbital phase. The orbital parameters give a projected separation for each planet, while the mass is converted into a flux ratio in the appropriate bandpass of the detector using the models of Burrows et al. (2003); this allows the simulated planets to be directly evaluated against the system's sensitivity curve. Since this method requires basic parameters (age, distance, spectral type, apparent magnitude) for each target star, a target list can be constructed that maximizes the likelihood of detecting planets, or competing instrument designs can be evaluated with respect to their predicted success for a given survey. We are already employing this method to select targets for our Simultaneous Differential Imaging (SDI) surveys (Biller et al. 2004), now underway at telescopes in the northern (MMT) and southern hemispheres (VLT).

The benefits of placing ultraviolet (UV) spectrographs in space were first pointed out by Spitzer (1946) and Spitzer & Zabriskie (1959), with much of the emphasis on absorption-line measurements of interstellar atoms and molecules. The first UV observations of the diffuse interstellar medium took place in the early 1970s, using sounding rockets, which were followed by a series of orbital instruments starting in the later 1970s and extending almost to the present time. Many of these observations have provided information on the chemistry of the diffuse ISM, and will be emphasized here. The most abundant molecule in space, H$_2$, is not readily observed in other wavelength bands and was first detected by a UV sounding rocket experiment (Carruthers 1970). Thereafter a series of orbital instruments, starting with the Copernicus satellite in 1972 and culminating with the launch of FUSE in 1999, carried out broad surveys of molecular hydrogen in a variety of ISM environments (e.g., Spitzer et al. 1973; Snow et al. 2000; Shull et al. 2000; see also the review by Shull & Beckwith 1982). The UV observations of electronic transitions of H$_2$, including lines arising from excited rotational levels of the ground state, have provided a wealth of information on not only the chemistry of the diffuse ISM, but also the composition and physical conditions. The second most abundant molecule in the diffuse ISM, CO, also has numerous electronic transitions in the UV, and has been widely observed by many different instruments, most usefully the Hubble Space Telescope (HST) (e.g., Lambert et al. 1994; Sheffer et al. 2002). Valuable information on diffuse ISM chemistry, isotopic composition, and physical conditions has been provided by these observations. A few additional molecules, all of them diatomics such as OH and N$_2$, have been detected through UV absorption-line observations, and many others have been sought unsuccessfully. The Cosmic Origins Spectrograph, expected to be installed aboard the HST in 2007, will have enhanced UV sensitivity and will provide information on molecular abundances in denser clouds than previously studied. One of the high priorities will be the search for electronic transitions of complex organic molecules such as PAHs.

We present time-resolved spectroscopy from the January 2005 outburst of the X-ray nova XTE J1118+480. X-ray observations show this outburst to be about half as bright as the previous outburst in 2000. This suggests that the accretion rate was lower than that in the 2000 outburst. Our spectroscopic analysis shows that the emission from the H$\alpha$ line occurs at a higher velocity in the recent outburst compared with the 2000 outburst, more consistent with quiescence/near-quiescence values. This is surprising, considering the $\sim$5 magnitude brightening of the accretion disk relative to its quiescent state.

We present first studies of dE galaxies by means of 3D spectroscopy, and address questions concerning data processing and analysis techniques used to extract internal kinematics and stellar population properties from integrated light spectra.

Massive stars begin their lives in cold, dense cores which are much more massive than the stars which form in them. We summarise the results of a program to find the earliest examples of massive star formation, and to examine the evolutionary sequence of events that occurs as such a star begins to form and heat its surroundings. Methanol maser emission has proved to be a particularly potent tool to locate such cores, though there are also clearly many massive cores which do not exhibit such maser emission. Our program began with a survey for 6.6 GHz methanol maser emission, but expanded to include dust continuum surveys in the mm and sub–mm, a survey for hot molecular cores associated with ‘isolated’ masers through mm-line CH3CN emission, and follow-up probing of some cores through sub-arcsecond, diffraction limited observations in the mid–IR. This program is outlined below.

Commission 21, one of IAU's smallest commissions, consists of some hundred members and consultants working to understand and describe the light of the night sky with emphasis on the diffuse components. Many more work on these topics without being members of the commission. Light is here defined in its broader sense of electromagnetic radiation of any frequency. The diffuse components of the light of the night sky encompass a variety of physical phenomena over the full range of cosmic distance scales and include scattered light, thermal emission, line emission, and any other emission phenomena producing a diffuse light source. These attract interest not only as scientific topics of study in their own right but also as an unwanted foreground or background against which all other sky phenomena are observed. Commission 21 has for mandate to promote research and availability of results on issues related to the diffuse light of the night sky. This document is a report on activities in this field and is not confined to the activities of its members, no distinction is made between work carried out by commission members and non commission members. The report is organized starting with a summary of the state of broad surveys that provide most of the observations. The report on developments in the various disciplines start with the sources closest to the observer known as airglow and progresses by way of the interplanetary and interstellar mediums to the increasingly distant integrated starlight, diffuse galactic light and diffuse emission in other galaxies ending with the extragalactic background radiation.

We study the physical conditions in damped Lyman-$\alpha$ systems (DLAs), using a sample of 33 systems toward 26 QSOs acquired for a recently completed survey of H$_2$ by Ledoux et al. (2003). H$_2$ is detected in 13-20% of the DLAs in our sample. Using the rotation level populations of H$_2$ and fine-structure excitations of C I we show the mean kinetic temperature of H$_2$ components is 153$\pm$78 K, $n_{\rm H}$ = 10$-$250 cm$^{-3}$, and the ambient radiation field is similar to or slightly higher than the mean diffuse UV field of the Galaxy. Combining this with the success rate of detecting H$_2$ in DLAs we conclude that at least 13$-$20% of DLAs at $z_{\rm abs}\ge1.9$ show the presence of CNM and substantial star-formation activity. C II$^*$ absorption is detected in all the components where H$_2$ absorption is seen. The level populations of C II in these systems is consistent with the physical parameters derived from the excitation of H$_2$ and C I. We detect C II$^*$ in about 50% of the DLAs and therefore in a considerable fraction of DLAs that do not show H$_2$. The absence of C I absorption, the measured N(C II$^*$)/N(C II) and N(Al III)/N(Al II) ratios in these systems are consistent with the gas having lower density (n$_{\rm H} = 0.3-6 cm^{-3}$) than that seen in the H$_2$ components. 50% of the DLAs that do not show C II$^*$ are consistent with them originating from a low density warm neutral medium.

We use Monte Carlo techniques to estimate the results and character of the early TPF-C mission. Using 108 samples to represent the planets of interest, we compute the completeness of the first search observations of prioritized target stars with optimized exposure times that sum to one year total. Assuming simple observing protocols and decision rules for searching, verifying, and characterizing observations, and taking into account ranges of probabilities for confusion sources ($P_\mathrm{confusion}$) and the occurrence of planets of interest ($\eta$), we compute 105 samples of the TPF-C schedule and observational outcomes for the first year of exposure time. For example, for Earth-like planets on habitable-zone orbits, assuming no observing overheads or pointing restrictions, and for the values $P_\mathrm{confusion}=0.5$ and $\eta=0.1$, we find that a median 2.2 planets are found, verified, and characterized in one year of exposure time, with the 68 highest priority stars searched.

Since Pietrowsky's first analytical study of collisional systems of asteroids (1953), through Dohnanyi's comprehensive theory (1969), to the analytical and numerical studies of the last two decades, the collisional evolution of populations of asteroids — and to a less extent, of Trojans and TNOs— has been investigated by many researchers.

The study of such systems is an intrinsically delicate mathematical problem, as their evolution in time is properly described in terms of systems of first–order, non–linear differential equations. Physically, the limited knowledge of some of the collisional properties, rotations and internal structure of bodies, and the complex interplay with dust, non–gravitational effects and dynamical interactions with planets, make the study of the collisional evolution a hard multi–parametric problem. Nevertheless, the task is worth the effort, in fact the understanding of evolutionary processes in the solar system's small body belts provides the main tools to discriminate between the many different theoretical scenarios proposed to explain the formation of the solar system itself.

This review tries to give an updated overall view of the research done in this field, and to show the connections between apparently independent phenomena that may affect the evolution of collisional systems of asteroids and TNOs.

Millimeter-wave (mm-wave) absorption profiles toward extragalactic sources consistently find just diffuse (occasionally perhaps translucent) neutral gas—low/moderate density and extinction—along even some very long, dark lines of sight. CO, often heavily fractionated and mimicking the appearance of dark gas in emission, occasionally absent in emission even when present in absorption, is not the dominant form of carbon in these regions (presumably it is C+) yet the abundances of many other molecules resemble those seen in TMC-1. Some species (OH, HCO+, C2H and C3H2) turn on with high abundances just when H2 does; others (HCN, HNC, CN) require slightly higher $N$(H2) and yet others (CS and other sulfur-bearing species,NH3 and H2CO) even higher $N$(H2). The systematics and implications of these recent discoveries are discussed here.

I present a large sample of precise ($\pm2$ km/s) stellar radial velocities obtained to serve as kinematic tracers in Milky Way dwarf spheroidal (dSph) satellite galaxies. This includes velocities for $\sim$750 member stars spanning several core radii in the Sculptor dSph, and $\sim$400 member stars extending out to the nominal tidal radius of the Fornax dSph. The resulting radial velocity dispersion profiles are flat, with no evidence for a sharp decrease in the velocity dispersion at large galactocentric radius in either Sculptor of Fornax. Application of a non-parametric method for estimating the radial mass distributions gives results consistent with mass determinations from classical analyses, with lower limits of $[M/L]_V \,{\sim} 7$ for Fornax and $[M/L]_V\,{\sim}4$ for Sculptor.

The amount and spatial distribution of dark matter in elliptical galaxies are poorly known, despite extensive observations with multi-object spectrographs on 4-10m-class telescopes. We examine the prospects for measuring the structure of dark matter halos in elliptical galaxies — and the orbital properties of their planetary nebula and globular cluster systems — from radial velocity measurements made with WFOS, a wide-field optical spectrograph operating on the Thirty Meter Telescope (TMT).

Using the method of spectral synthesis we derived the abundances of Li in the atmospheres of 100 stars in the range of metallicities −3${<}$[Fe/H]${<}$0.2. The investigated spectra are part of the library collected at the Haute Provence Observatory, they were obtained with the 193 cm telescope equipped with ELODIE spectrometer (R=42000). For the metal-poor dwarfs, in the “Spite plateau” region ([Fe/H]${<}$−1.7, $T_{\rm {eff}}{>}$5700 K) we obtain logA(Li)${=}$2.30${\pm}$0.05, which is in a good agreement with the results of other authors. Our values of Li abundances do not indicate any trends either with $T_{\rm {eff}}$ or with [Fe/H]. The “plateau” is also traced in the metallicity range −0.7${<}$[Fe/H]${<}$−0.3. The behavior of the lithium abundance for stars with [Fe/H]${>}$−1.7, $T_{\rm {eff}}{<}$5700 K shows a depleting mechanism in these stars, the growth of its efficiency with an increase of the metallicity. The “lithium plateau” was also found for thick disk dwarfs with $T_{\rm {eff}}{>}$5800 K.

There have been three international meetings where the subject area of the meeting was to significant extent within the area of interest of commission 22. These were: The Meteoroids 2004 Conference was held at the University of Western Ontario in London, Canada from August 15 to 21, 2004. This conference was the fifth in a series of meteoroid meetings which have been held approximately every three years since 1992, the previous one being in Kiruna, Sweden in 2001. Ingrid Mann chaired a scientific organizing committee which set the program for the conference. The meeting brought together scientists from more than twenty countries, to deliver 84 oral and 38 poster presentations. The papers represented the research contributions of more than 150 different scientists. The conference provided a comprehensive overview of leading edge research on topics ranging from the dynamics, sources and distribution of meteoroids, their chemistry and their physical processes in the interplanetary medium and the Earthõs atmosphere, and space and laboratory studies of meteorites, micrometeorites and interplanetary dust were also well represented. It was clear from the conference that the coordinated international campaigns for the Leonid showers provided a rich observational dataset and lead to the development of new observational and analysis techniques. Another trend obvious at the conference was the increasing use of sophisticated large aperture radars for meteor studies. High performance computing facilitates both dynamical model calculations and sophisticated ablation models. Significant progress was reported on ablation models for meteoroids ranging from dust to those producing bright fireballs. Study of solid particles entering the solar system from interstellar space and improved dust measuring capabilities on interplanetary spacecraft are an important research area which links astrophysical dust with solar system dust. The majority of papers presented at the conference (a total of 69 papers) are being published as a special issue of the journal Earth, Moon, and Planets (Vol. 95, Nos. 1–4) and also in the form of an associated book published by Springer: Modern Meteor Science: An Interdisciplinary View which was edited by R.Hawkes, I. Mann and P. Brown (ISBN 1-4020-4374-0). The book will be accompanied by a CD-ROM which includes a selection of conference photographs and the complete abstracts of all papers from the conference. As is reflected in the title of the spin-off book, this field is becoming increasingly interdisciplinary in nature, with researchers from astronomy, astrophysics, space science, space engineering, cosmochemistry, atmospheric science and geophysics, as well as others, now contributing to research in the field.

The ESA observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory) is dedicated to fine imaging and spectroscopy in the energy range 15 keV to 10 Mev with concurrent X-ray (3-35 keV) and optical monitoring. It was launched on October 17, 2002 and has been succesfully operating ever since. Its two main instruments the spectrometer SPI – optimized for high resolution spectroscopy – and the imager IBIS – optimized for for high resolution imaging – are complemented by the X-ray monitor JEM-X and the optical monitor OMC. All the high energy instruments use coded mask techniques, allowing imaging in the gamma-ray range and combining wide fields of view with high spatial resolution. The presentation gives an overview of the unique properties of INTEGRAL.

To date, half a dozen DLAs have been detected in GRB afterglows, but most have modest signal-to-noise ratios. Our detection of a DLA in the afterglow of GRB 030323 is unambiguous: its neutral hydrogen column density is log N(HI)=21.90$\pm$0.07, higher than any (GRB- or QSO-) DLA HI column density inferred directly from Ly$\alpha$ in absorption. We discuss several other properties such as the metallicity, the detection of fine-structure lines of SiII, and our strong upper limit on the H$_2$ content. The GRB afterglow allows us to infer all these quantities, even with the host being as faint as V=28. The successful launch of the Swift satellite (November 2004) has made high-resolution spectroscopy of a large sample of GRB afterglows possible. This will offer a unique way to study in detail the interstellar medium inside GRB host galaxies as a function of redshift.

A large body of theoretical and computational work shows that jets - modelled as magnetized disk winds - exert an external torque on their underlying disks that can efficiently remove angular momentum and act as major drivers of disk accretion. These predictions have recently been confirmed in direct HST measurements of the jet rotation and angular momentum transport in low mass protostellar systems. We review the theory of disc winds and show that their physics is universal and scales to jets from both low and high mass star forming regions. This explains the observed properties of outflows in massive star forming regions, before the central massive star generates an ultracompact HII region. We also discuss the recent numerical studies on the formation of massive accretion disks and outflows through gravitational collapse, including our own work on 3D Adaptive Mesh simulations (using the FLASH code) of the hydromagnetic collapse of an initial rotating, and cooling Bonner-Ebert sphere. Magnetized collapse gives rise to outflows. Our own simulations show that both a jet-like disk wind on sub AU scales, and a larger scale molecular outflow occur (Banerjee & Pudritz 2005).