The structure and chemistry of protoplanetary disks depends strongly on the nature of the central star around which it has formed. The dust temperature is mainly set by the stellar luminosity, while the chemistry of the upper disk layers depends on the amount of intercepted UV and X-ray flux. We discuss here the differences in chemistry, thermal structure and line emission around Herbig Ae/Be, T Tauri stars and low-mass M dwarfs. Predictions will be made for future observations with SOFIA and Herschel.

Observations of CO can provide constraints on the density and temperature of the dense star-forming gas in galaxies, while observations of [CI] trace photon-dominated regions and provide information on the amount of atomic carbon in molecular clouds. In this paper, I review CO and [CI] observations of nearby galaxies, with an emphasis on galaxies for which high-resolution observations of multiple transitions and isotopologues are available. I also briefly discuss upper limits on water emission from nearby starburst galaxies and on O2 emission in the SMC obtained with the Odin satellite.

First, the X-ray source populations of M31 and M33 as known from Einstein and ROSAT observations are presented. Then, chandra results on the galaxies are shortly summarized which not only spatially resolved the centre areas but also supernova remnants (SNRs) in both galaxies, and led to source catalogues of restricted areas with high astrometric accuracy. Also luminosity function studies and studies of individual sources based on chandra and XMM-Newton observations led to a better knowledge of the X-ray source populations. After that I will concentrate on XMM-Newton surveys, in which more than 850 and 400 X-ray sources were detected in M31 and M33, respectively, down to a 0.2–4.5 keV luminosity of less than 1035 erg s−1. EPIC hardness ratios as well as informations from earlier X-ray, optical, and radio catalogues were used to distinguish between different source classes (SNRs, supersoft sources (SSSs), X-ray binaries (XRBs), globular cluster sources within the galaxies, and foreground stars, and objects in the background). However, many sources could only be classified as hard.They may either be XRBs or Crab-like SNRs in the galaxies or background sources. Within M31, two globular cluster sources could be identified as low mass XRBs as they showed type I X-ray bursts. Many of the SSSs in both galaxies were identified as optical novae. Due to the high frequency of outbursts in the bulge area of M31 many novae can be monitored at the same time which makes the investigation of class properties much easier compared to novae in the Milky Way or the Magellanic Clouds.

We examine the origin of water in the terrestrial planets. We list various geochemical measurements that may be used to discriminate between different endogenous and exogenous sources of water. Late stage delivery of significant quantities of water from asteroidal and cometary sources appears to be ruled out by isotopic and molecular ratio considerations, unless either comets and asteroids currently sampled spectroscopically and by meteorites are unlike those falling to Earth 4.5 Ga ago or our measurements are not representative of those bodies. The dust in the accretion disk from which terrestrial planets formed was bathed in a gas of H, He and O. The dominant gas phase species were H2O, He, H2O, and CO. Thus grains in the accretion disk must have been exposed to and adsorbed H2 and water. We examine the efficacy of nebular gas adsorption as a mechanism by which the terrestrial planets accreted “wet”. A simple model suggests that grains accreted to Earth could have adsorbed 1 - 3 Earth oceans of water. The fraction of this water retained during accretion is unknown, but these results suggest that at least some of the water in the terrestrial planets may have originated by adsorption.

Until recently hot cores were the first indirect manifestation of a young massive star, but recent observational successes are now providing us with the first candidates for the very early phases of massive star formation, probably the precursors of hot cores. The characteristic hot core chemistry is believed to arise from the evaporation of the icy mantles that accumulate on the dust grains during the collapse the leads to the formation of the massive star. The duration over which the grains are warmed is determined by the time taken for a pre-stellar core to evolve to the Main Sequence. Hence, hot cores and their precursors contain an integrated record of the physics and chemistry occurring during the collapse that led to the star. In this article I will review recent advances in the chemical modelling of hot cores and their precursors in light of the recent TPD experiments on a variety of ices and I will briefly discuss the implications of such studies for the interpretation of high mass protostellar objects.

The SMC is now known to contain many more transient X-ray pulsars than would be expected based on a simple scaling of the number of such sources in the Galaxy by the relative mass of the SMC. We have been conducting regular monitoring observations of the SMC with the Proportional Counter Array on the Rossi X-ray Timing Explorer since 1997. This has resulted in the discovery of many of these X-ray pulsars and also provided orbital period measurements from detections of regular outbursts. We can now investigate the differences and similarities of the Galactic and SMC X-ray pulsar populations and consider the origin of the huge SMC X-ray pulsar over-abundance.

In a subset of the most luminous of the so-called “ultra-luminous” X-ray sources in nearby galaxies, there is evidence for black holes with masses considerably higher than found in Galactic binaries. Apart from extremely high X-ray luminosities, cool disks found in the X-ray spectra of these sources and X-ray timing measurements form the basis for present evidence for intermediate-mass black holes in these sources. New optical and radio measurements appear to support the X-ray evidence. I will review recent X-ray, optical, and radio observations of these ULXs, and discuss the strengths of the intermediate-mass black hole interpretation, arguments against this interpretation, and future prospects for revealing the nature of these ULXS more clearly.

We detail a model we have created to describe the optical emission from a ULX in terms of an irradiated companion star and disk. We apply this model to optical observations of ULX X-7 in NGC 4559. We revise the parameters of the companion star in this system to be older, less massive and of a later spectral type than previously reported. We find the black hole to be of a few hundred solar masses at most.

In the local Universe most massive black holes at the centers of galaxies are not luminous quasars. Is this because (1) they are starved of gas, (2) they accrete without emitting radiation, (3) they refuse to eat, ejecting the incoming material, or (4) they are storing up matter in an accretion disk to feast later?

With Chandra ACIS we have imaged a pilot sample of 6 nearby (D $<$ 30 Mpc) elliptical galaxies chosen to be especially quiescent based on the careful optical spectroscopy of Ho, measured black hole masses (Mbh$\,{>}\,$10(7)Msol), and with existing X-ray upper limits (Lx$\,{<}\,$10(40)erg/s) implying far sub-Eddington accretion. In these galaxies we can measure, or limit, the diffuse hot interstellar medium, and so constrain the Bondi accretion rate.

Faint X-ray emission is detected at or around the nucleus in each galaxy. The morphology of these weak X-ray sources is complex. The X-ray colors of the sources can be determined, and a moderate quality spectrum for one was obtained. We discuss these results against the possible explanations of black hole quiescence.

On the other hand, a few percent of all galaxies shows evidence for nuclear activity and a brief review of the high energy emission from Active Galactic Nuclei is given.

We present optical observations of the newly discovered accretion powered millisecond pulsar IGR J00291+5934, undertaken in the weeks following its outburst on 2$^{nd}$ December 2004. The decay to quiescence is seen to be highly variable with no indication of a modulation on the $\sim$2.46 hr orbital period apparent in the data, consistent with a system at low inclination. We also have a single Keck LRIS spectrum of the companion to IGR J00291+5934 taken 10 days after outburst. Strong hydrogen and helium emission lines are observed confirming the identity of the counterpart.

Instruments will be briefly introduced and the main mission results to date will be described.

We present results from the hard X-ray sky survey being performed with INTEGRAL observatory. During two years of operation the significant sky area was covered with moderate sensitivity which now allows us to estimate surface number density of Active Galactic Nuclei (AGN) in hard (17-60 keV) energy band. Our catalog of detected sources comprises $>60$ AGN with wide range of intrinsic absorption. We used $24000 deg^{2}$ sky coverage (high Galactic latitude observations) with total exposure $>2$ Msec to derive source number-flux relation. The estimated surface density of extragalactic hard X-ray sources with flux $>10^{-11}$ erg s$^{-1}$ cm$^{-2}$ is $(1.0 \pm 0.5) 10^{-2} deg^{-2}$.

Over the past 25 years the number of reliably determined rotation rates of asteroids has increased by an order of magnitude, from 157 in 1979 to 1686 in 2005. As the numbers have increased, various special classes and features have emerged. Asteroids larger than $\sim 50 \,\rm{km}$ diameter have a dispersion of spin rates that is well represented by a single Maxwellian distribution. Smaller asteroids have a more dispersed distribution, with both slow and fast spinning populations. We see a “spin rate barrier” in the size range of 1–10 km diameter that suggests that even rather small asteroids are “rubble piles”. Among the very slow rotators are some (but not all) that are “tumbling” in non-principal axis rotation states. Among the smallest asteroids (less than a few hundred m diameter) are some that spin dramatically faster than the “spin barrier”, indicating that they must have some tensile strength rather than consisting of loose regolith. In the last few years it has been recognized that the spins of asteroids smaller than a few tens of km diameter are affected by radiation pressure torques that tend to either speed up or slow down asteroid spin rates, thus providing an explanation for the dispersion of small asteroid spins, and also their non-random axis orientations. Lightcurves have also revealed the presence of binary asteroids among both Near-Earth and Main-Belt populations. Automated robotic observatories and next-generation survey instruments promise to increase the rate of production of asteroid lightcurves so that we may soon have tens of thousands of lightcurve results, extending down to even smaller sizes. In contrast, there are only about 20 rotation rates known for comets, and 15 for TNOs. Very little can be said from such meager statistics; the mean spin rate of TNOs appears to be comparable to that of asteroids, without extremes of fast or slow rotation; the mean spin rate of comets appears to be a bit slower than asteroids, perhaps due to lower mean density, and there may be an excess of slow rotators, probably due to gas jetting effects. The future is promising for studies of these objects as larger telescopes become available to do photometry to fainter magnitudes, so that comet nuclei can be studied at greater heliocentric distance with less coma interference, and more TNOs can be observed.

We refer on analysis of the ESA INTEGRAL satellite data for blazars, promising sources to be observed during their active states. We further refer on searches for and analysis of supermassive binary black holes requiring very long time intervals (50 years and more) provided by digitised astronomical plates.

Pathways leading to the formation of complex organic molecules are described. Gas-phase processes that may build large carbon-chain species in cold molecular clouds are summarised. Catalytic reactions on grain surfaces can lead to a large variety of organic species, and model calculations of mantle formation by atom additions to multiply-bonded molecules are presented. The subsequent desorption of these mixed molecular ices can initiate a distinctive organic chemistry via ion-molecule pathways. The predictions of this theory are briefly compared with observations to show how possible organic formation pathways in the interstellar medium may be constrained.

Recent observations have suggested that the true energy release of GRBs is potentially far less than previously thought. This is due to beaming, a signature of which is a broadband break in the power-law decay of the afterglow emission. Taking these results we have constructed a basic distance estimator, which may be useful as a diagnostic tool for the large amount of GRBs without a spectroscopically measured redshift.

Over the last few years, we have applied the CRESU (Reaction Kinetics in Uniform Supersonic Flow) technique to the study of neutral-neutral reactions and energy transfer processes in the gas phase. This has enabled the rates of a wide range of reactions between electrically neutral species to be measured down to temperatures as low as $\sim $10 K. These results have generated significant interest amongst theoretical chemists, and especially amongst astrochemists. Our measurements of low-temperature rate coefficients have had a significant impact on the models used to simulate the chemistry of dense interstellar clouds. In this article the motivations for the experimental study of reaction kinetics at low temperatures are described, and a detailed description of the CRESU technique is given, followed by a brief overview of the results obtained in Rennes and Birmingham. Four recent low-temperature kinetic studies are then described: the reaction O + OH and the interstellar oxygen problem, reactions of the C$_2$ radical, energy transfer in collisions of C($^3{\rm P}_J$) with He and H$_2$, and preliminary results on the reaction kinetics of the C$_4$H radical.

Although it is presently not possible to extract the true composition of a comet nucleus from its coma composition, the distribution of physical and chemical coma properties among comets may be expedient to establish a comet classification scheme that reflects their origin and/or evolution. Most of the coma species visible in the optical were extensively observed in the past. The analysis of these gas coma constituents, mainly daughter products produced for the most part by photolytic destruction of their parent species, is therefore of major importance, if we want to draw conclusions on diversities and similarities of comets in terms of coma composition on a statistically relevant basis. Hundreds of gas and dust production rates are published, but have never been combined into a single database that would allow identifying whether and how the abundances of coma species differ from comet to comet and how they vary with heliocentric distance and with the number of apparitions. A common database can however only be established if the production rates are re-calculated with a common model and set of parameters.

Dust particles in the solar system are produced from the small bodies: asteroids, comets, meteoroids and Kuiper belt objects. A further source of dust is provided by the warm interstellar medium that the Sun is currently embedded in and that streams into the solar system. We review the physical properties of solar system dust and trace back its interrelation with the small solar system bodies. Comets contain relatively pristine material that they transport to the inner solar system. The alteration of dust in the vicinity of comets is complex and connected to the gas evolution, but a significant part of the organic dust material survives these alterations. The optical properties of cometary dust are best described with a mixture of silicate and carbon bearing materials. As far as the darkness of the cometary material is concerned, according to recent models, this is not a result of the porosity, but rather of the darkness of the carbon bearing component. This does not contradict the observation of silicate features in the thermal emission brightness of cometary dust, since porous mixtures of silicate and carbon bearing dust can produce the observed polarization and albedo characteristics, as well as the silicate features. The carbon-bearing component is most likely an organic refactory component. The relative contributions of different sources change within the solar system dust cloud and depend as well on the measurement technique considered. In particular, the dust from asteroids, which provides a large component of the dust near Earth orbit, is also preferably seen with most of the detection methods. The majority of dust inward from 1 AU is produced from cometary dust and meteoroids. Dust material evaporation induced by collisions inward from 1 AU produces a minor heavy ion component in the solar wind plasma known as inner source pick-up ions.

In this paper I describe some of the recent advances made in the modelling of chemistry of protoplanetary disks, and in particular, of the inner regions where $r<100$ AU. These advances include the treatment of mass-transport processes, the interaction of radiation with chemistry, the augmentation of chemical networks to include isotopic species and their fractionation, and the attempt to connect disk chemistry with solar system bodies like comets. In the spirit of the title of this volume, I also briefly describe what in my opinion are the current challenges facing models of disk chemistry. These include the unification of chemistry, radiation and dynamics, the treatment of gas-grain interaction and the usefulness of observations to discriminate the different models in the literature.