Chandra observations of early-type galaxies have resolved large populations of low-mass X-ray binaries (LMXBs) in early-type galaxies. The majority of these observations have been snapshots on the order of a day or less. In our own Galaxy, LMXBs are known to exhibit a range of luminosity and spectral variability. Multi-epoch observations of early-type galaxies are just beginning to explore the regime of variability on timescales of days to years. We present results for NGC 4365 and NGC 4697, and compare them to the Milky Way.

Before the discovery of the first member of the Kuiper belt in 1992, the trans-Neptunian population was supposed to lie on a flat disk and each member would follow a barely eccentric orbit. While less conventional orbits for the trans-Neptunian objects were being discovered, our understanding of its orbital structure and origin was continually changed. A basic classification of the trans-Neptunian population as to their orbits identifies a classical low inclination Kuiper belt population, a resonant population, a high inclination Kuiper belt population, a scattered population and an extended population. Several mechanisms have been proposed to explain the orbital architecture of the Kuiper belt population. Presently, the most plausible scenarios are unequivocally related with the primordial planetary migration induced by a planetesimal disk. Low inclination orbits in the Kuiper belt may have been moderately pushed out from a dynamically cold primordial disk by the resonance sweeping mechanism. The origin of high inclination objects in the classical Kuiper belt is however to be found in a primordial Neptune scattered population, through a perihelion increasing mechanism based on secular resonances. Another push-out mechanism based on the sweeping of the 1:2 resonance with Neptune has also been invoked to explain the low inclination orbits in the classical Kuiper belt. Assuming these last two mechanisms, Kuiper belt objects do not need to have been formed in situ. This kind of formation process would demand a quite large original mass in the Kuiper belt region, which would have brought Neptune beyond its present position at 30 AU. Thus with the exception of the low inclination classical Kuiper belt objects and a few resonant ones, all other trans-Neptunian objects are present or past scattered objects. This notion also includes the case for Sedna, so far the only certain member of the extended population. In its most plausible formation scenario, it was a primordial scattered object by Neptune whose perihelion was increased by the close passage of a star.

We present optical observations of an ultraluminous X-ray source (ULX) in Holmberg IX, a dwarf galaxy near M81. The ULX has an average X-ray luminosity of some $10^{40}$ erg/s. It is located in a huge (400pc$\,{\times}\,$300pc) ionized nebula being much larger than normal supernova remnants. From the observed emission lines (widths and ratios) we find that the structure is due to collisional excitation by shocks, rather than by photoionization.

We identify the optical counterpart to be a 22.8 mag blue star ($M_V=-5.0$) belonging to a small stellar cluster. From isochrone fitting of our multi-colour photometry we determine a cluster age of some 60 Myr. We also discovered strong stellar HeII$\lambda$4686 emission (equivalent width of $\mbox{10 \AA}$) which proves the identification with the X-ray source, and which suggests the presence of an X-ray heated accretion disc around the putative black hole.

With the detection of relativistic broad emission lines in MCG 6-30-15 (Tanaka 1995) X-ray observations have become an important tool to test the direct environment of black holes.

XMM-Newton observations were the basis of remarkable progress in different directions in recent years. On the one side the birth and the growth of black holes could be addressed in detail. On the other side several observations allowed the study of the strong gravitational field in the vicinity of black holes.

The talk provides an overview of XMM-Newton observations of black holes: starting from the creation of stellar-mass black holes, through mass growth via accretion disks and occasional tidal disruption events, up to intermediate and supermassive black holes in the centre of active and non-active galaxies. Special attention will be given to the achieved status in the determination of the measurable quantities of black holes, i.e. mass and spin.

Molecular cloud cores—whether stellar, non-stellar, proto-stellar, or pre-proto-stellar—have come to be recognized as key elements in the study of star formation. For both high-and low-mass stars, these cores hold key information for the final make-up of the stellar cluster and the physical processes by which the cluster and/or the individual stars form. In the case of massive stars, the chemical effects extend even beyond the molecular core, reaching into the photo-dissociated region produced by the harder spectrum of the massive stars. We discuss the directions in which these studies are taking us, with special attention given to those aspects which are unique to high-mass star-forming regions.

Polarimetry in gamma-rays has the capability to enhance our understanding of compact object emission in our galaxy. In particular this diagnostic method could provide useful insight into the geometrical arrangement of these emitting objects and the roles that magnetic fields play in their emisson mechanisms. Gamma Ray Bursts have been studied in this way but the results, perhaps indicating a high degree of polarisation, remain unverified [Coburn & Boggs (2003), Wigger et al. (2004), Willis et al. (2005)]. The nature of GRBs solve many instrumental problems in polarimetry, however their true nature is less well defined and so a study of a better understood object such as the Crab Pulsar, for now, may reveal more as to the physics of the system.

We present the detection of molecular oxygen with Odin toward the dense molecular core pOph A, which is part of a region of active star formation. The observed spectral line is the $(N_J=1_1-1_0)$ ground state transition of O2 at 119GHz ($\lambda$=2.5 mm). The line center is at the LSR velocity of a number of optically thin lines from other species in the region. The O2 line also has a very similar, narrow, line width. Within the $10^{\prime}$ beam, the line intensity is $\int\!T_{\rm A}\,{\rm d}v = 28$mK kms−1, which corresponds to $5\,\sigma$ of the rms noise. A standard LTE analysis results in an O2 abundance of $5 \times 10^{-8}$, with an uncertainty of at least a factor of two. We show that standard methods, however, do not apply in this case, as the coupling of the Odin beam to the source structure needs to be accounted for. Preliminary model results indicate O2 abundances to be higher by one order of magnitude than suggested by the standard case. This model predicts the 487GHz line of O2 to be easily detectable by the future Herschel-HIFI facility, but to be out of reach for observations on a shorter time scale with the Odin space observatory.

Classically, comets from the outer solar system (beyond the orbit of Neptune), are expected to be icy, and thus active near the Sun, while asteroids in the inner solar system (interior to the orbit of Jupiter) are expected to be relatively ice-deficient, and thus inert. Studies of anomalous objects, most recently 133P/Elst-Pizarro, challenge this classical picture, however, and suggest that either (1) subsurface ice can in fact be preserved over billions of years in small bodies in the inner solar system but still be close enough to the surface to be excavated by an impact by another body, or (2) non-gravitational dynamical evolution (primarily driven by asymmetrical outgassing) of icy bodies from the outer solar system can drive these cometary bodies onto thoroughly asteroid-like orbits, erasing all dynamical signs of their trans-Neptunian origins in the process. The question thus boils down to whether occasionally sublimating icy bodies on stable asteroid-like orbits in the inner solar system, particularly in the main asteroid belt, may in fact be native to the region or whether they must necessarily be recent arrivals.

Accumulating evidence indicates that some of ultra-luminous X-ray sources (ULXs) are intermediate mass black holes (IMBHs), but the formation process of IMBHs is unknown. One possibility is that they were formed as remnants of population III (Pop III) stars, but it has been thought that the probability of being an ULX is too low for IMBHs distributed in galactic haloes to account for the observed number of ULXs. Here we show that the number of ULXs can be explained by such halo IMBHs passing through a dense molecular cloud, if Pop III star formation is very efficient as recently suggested by the excess of the cosmic near-infrared background radiation that cannot be accounted for by normal galaxy populations. We calculate the luminosity function of X-ray sources in our scenario and find that it is consistent with observed data. Our scenario can explain that ULXs are preferentially found at outskirts of large gas concentrations in star forming regions. A few important physical effects are pointed out and discussed, including gas dynamical friction, radiative efficiency of accretion flow, and radiative feedback to ambient medium. ULXs could last for ${\sim}10^{5-6}$ yr to emit a total energy of ${\sim}10^{53}$ erg, which is sufficient to power the ionized expanding nebulae found by optical observations.

The supernova explosion of 1054 AD, which originated the Crab Nebula and Pulsar, is probably the astronomical event which has been most deeply studied by means of historical sources. However, many mysteries and inconsistencies, both among the different sources and between what is deduced by the historical records and the present day astronomical data, are demanding extraordinary efforts by theoretical astrophysicists in order to put all the data in a meaningful framework. An accurate analysis of the historical sources, like the one we are presenting here, may contribute to solve some of these problems.

A review of the current knowledge of physical properties and chemical composition of meteoroids entering the Earth's atmosphere is presented. Meteoroid penetration ability, ablation coefficients, beginning heights, light curves, fragmentation, and spectra are considered. The inferred bulk densities, mechanical strengths, rotation, and atomic elemental abundances are discussed. Cometary meteoroids are effectively grain aggregates with low bulk density (100–1000 kg m$^{-3}$), high porosity and low cohesivity. A volatile matrix holding the grains together may be present. Presence of large amounts of organic material is not firmly established. Small chunks ($\sim $mm) of denser material are sometimes contained in cometary meteoroids. Chemically, cometary grains are similar to CI chondrites but there is a hint of enhancement of Na, Si, and Mg and depletion of Fe, Cr, and Mg. Larger chemical diversity is observed among small meteoroids on cometary orbits not belonging to meteoroid streams. The relatively frequent Na-free meteoroids are probably fragments of cometary irradiation crust. Asteroidal meteoroids exhibit much lower mechanical strengths than stony meteorites, clearly due to the presence of large scale cracks. Iron meteoroids dominate among asteroidal meteoroids smaller than 1 cm.

This talk reviews the observations of the high-energy emission of young supernovae, providing an update from previous reviews in 1995 and 2003. A summary plot shows the number distribution of X-ray luminosities, currently totalling 25 supernovae, from which it is clear that SN IIP are weak X-ray sources, SN IIn are very luminous sources, and SN Ib/c cover a broad range in luminosity.

The field of ground based gamma-ray astronomy has seen rapid growth over the past thirty years with the development of the Imaging Atmospheric Cherenkov Technique to search for Very High Energy (VHE; E > 100 GeV) gamma radiation. This growth continues with the construction of four third generation telescope systems in Namibia, Australia, La Palma and the USA. These systems will search for VHE gamma radiation from such objects as AGN, SNRs, microquasars, dark matter and the galactic centre.

We report the results of a deep Chandra survey of the Sculptor dwarf spheroidal galaxy. We find five X-ray sources with $L_X$ of at least $6\times10^{33}$ ergs/sec with optical counterparts establishing them as members of Sculptor. These X-ray luminosities indicate that these sources are X-ray binaries, as no other known class of Galactic point sources can reach 0.5-8 keV luminosities this high. Finding these systems proves definitively that such objects can exist in an old stellar population without stellar collisions. Three of these objects have highly evolved optical counterparts (giants or horizontal branch stars), as do three other sources whose X-ray luminosities are in the range which includes both quiescent low mass X-ray binaries and the brightest magnetic cataclysmic variables. We predict that large area surveys of the Milky Way should also turn up large numbers of quiescent X-ray binaries.

We report on our first results from a mid-infrared spectroscopic study of ISM features in a sample of deeply obscured ULIRG nuclei using the InfraRed Spectrograph (IRS) on the Spitzer Space Telescope. The spectra are extremely rich and complex, revealing absorption features of both amorphous and crystalline silicates, aliphatic hydrocarbons, water ice and gas-phase bands of hot CO and warm C2H2, HCN and CO2. PAH emission bands were found to be generally weak and in some cases absent. The features probe a dense and warm environment, in which crystalline silicates and water ice are able to survive but volatile ices, commonly detected in Galactic dense molecular clouds, cannot. If powered largely by star formation, the stellar density and conditions of the gas and dust have to be extreme not to give rise to the commonly detected emission features associated with starbursts.

The Submillimeter Wave Astronomy Satellite (SWAS) has recently completed 5.5 years of successful operation. Among the legacies of the mission has been a greater understanding of the abundance and spatial distribution of H2O and O2 within molecular clouds. We summarize SWAS results and discuss how the measured low abundance of water vapor and non-detections of molecular oxygen are suggestive of a general lack of atomic oxygen in the dense centers of molecular clouds. We also present a new more comprehensive model for the oxygen chemistry in the interstellar medium.

We review the recent progress in the exploration of the interrelations between primitive small bodies of the solar system which are preserved the pristine material in their interior: cometary nuclei, Transneptunian Objects, Centaurs, and primitive asteroids, and they are considered as primordial objects. In addition, we discuss the properties of the asteroid-comet transition objects which have really enigmatic behavior. The comets have most primitive, accessible material in the solar system but we do not know what is hidden below the evolved surface layers. Comets must become dormant but we do not know whether the ice is exhausted or sublimation is inhibited (blocked by quenching mechanisms). There must be many dormant comets masquerading as asteroids but we do not know to identify these bodies unless via serendipitous discovery observations. Indeed, there are some asteroids which temporarily show comet-like activity. These are among the Damocloids (C/2001 OG108 (LONEOS)), main belt asteroids (7968 Elst-Pizarro = 133P/E-P) and Near-Earth objects (4015 Wilson-Harrington = 107P/W-H). The important questions are: where is the pristine material in the cometary nuclei and in the asteroid-comet transition objects, do comets lose their ice or seal it in? Both the large survey projects and in-situ space missions will help to answer these questions in the near future.

Very massive stars (${\gtrsim} 20$ M$_{\odot}$) are rare but important components of galaxies. Products of core nucleosynthesis from these stars are distributed into the circumstellar environment via wind-driven mass loss. Explosive nucleosynthesis after core collapse further enriches the galactic medium. Clusters of such stars can produce galactic chimneys which can pierce the galactic disk and chemically enrich intergalactic space. Such processes are vitally important to the chemical evolution of the early Universe, when the stellar mass function was much more weighted to massive stars.

Very massive stars are difficult to study, since they are formed in distant clusters which yield problems of sensitivity and source crowding. A relatively new tool for studying these systems is via high spatial, spectral and temporal resolution observations in the X-ray band. In this note we describe some recent progress in studying mechanisms by which very massive stars produce X-ray emission.

Within the near-Earth object population, one finds asteroids, comets, and meteorites thereby placing the NEO population at the center of the ACM conference. The longstanding gulf between the spectral properties of S-type asteroids and ordinary chondrite meteorites appears to be bridged, where the observational data are consistent with a space weathering type process. As much as 30% of the entire NEO population may reside in orbits having a Jovian Tisserand parameter <30, and among these roughly half are observed to have comet-like physical properties in terms of their albedos and spectra (taxonomy). Thus 15±5% of the entire NEO population may be comprised by extinct or dormant comets.

The recurrence time $T_{\rm C}$ of outbursts of the remarkable and unique system, the Rapid Burster (MXB 1730–335), observed by ASM/RXTE, is analyzed by the method of the O–C residuals. The variations of $T_{\rm C}$ are large and occur all the time, but generally they are not chaotic; the mean value of $T_{\rm C}$ is 160 days between the years 1996–2005 but a large shortening of $T_{\rm C}$, accompanied by a large decrease of the maximum intensity $I_{\rm max}$ and the relative energy RE (energy output) of most outbursts, occurred in this interval. The outbursts are found to display a correlation between RE and $I_{\rm max}$, but no correlation with the outburst duration. The observed behaviour is discussed in terms of the thermal instability of the accretion disk. A comparison of this prototype with other neutron star soft X-ray transients, like Aql X-1 and 4U 1608–52, helps us find the common links in the disk behaviour in such systems.