We examine the processes responsible for the large scatter in the X-ray/optical luminosity scaling relation of early-type galaxies.

I present a review of the main phenomenological properties at high energies related to massive gamma-ray binaries and I discuss some aspects of pulsar models for these objects.

The combination of classical models of chemical evolution with radial mixing and dynamics of the Galactic disc has opened alternative methods of understanding the detailed structure of the solar neighbourhood. I will show how radial mixing alters the views on chemical evolution as demonstrated by Schönrich & Binney (2009). I will explain how the model gives rise to a very natural division of the Galactic disc into a thick and a thin component, which can be examined in the light of detailed observational studies combining information on kinematics, chemistry and stellar ages.

This was a very pleasant and interesting meeting on star formation. The debate run on freely and contributions were of a very high level, including the oral contributions of four exceptional graduate students.

My aim is to show how the abundance ratios of the light elements (6 to 11) are related to the properties of the strong nuclear interaction and, in particular, to the major influence of closed shells of neutrons and protons, (the magic numbers : 2, 8, etc) on the binding energies of the nuclei.

ω Centauri is a massive stellar system which is currently going through the Galactic Halo. Its compact aspect and spheroidal shape have for a long time led to it being classified as a Globular Cluster. However the fact that its stars cover a wide metallicity range (−0.6 < [Fe/H] < −2.1), points to this object as an external galaxy, satellite of the Milky Way. Lithium among warm metal-poor stars shows a roughly constant abundance, the “Spite Plateau”. This has been interpreted as evidence for a primordial origin of the lithium nucleus, at the time of nucleosynthesis. After the physical conditions under which nucleosynthesis occurred, have been constrained by the observations of the fluctuations of the Cosmic Microwave Background, we are facing a “cosmological lithium problem”, namely the primordial lithium was a factor of three to four higher than what observed in the Spite plateau. Several avenues may be taken to solve this conundrum, either relying on fundamental physics or on stellar physics, however the realm of possibilities may be considerably narrowed by observing stellar populations in different galaxies, which have experienced different evolutionary histories. Some of the proposed “solutions” may be clearly ruled out, depending on the observation of lithium in the metal-poor populations of external galaxies. ω Centauri is the only external galaxy amenable to such an investigation in the era of 8m telescopes. We have pushed to its limits FLAMES at the ESO 8.2m telescope to obtain high resolution spectra of the Li i doublet in 91 Turn-Off and Sub-Giant stars at V ~ 18 in ω Centauri. We present our preliminary results on this data which suggest that the Li content in ω Centauri warm stars is comparable to that observed in Galactic Halo field stars of similar metallicities and temperatures. This may effectively rule out a whole class of models which invoke a severe Li depletion through processing of material in an early generation of massive stars.

The passively evolving stellar population in elliptical galaxies (Es) provides a continuous source of fuel for accretion on the central supermassive black hole (SMBH), which is 1) extended over the entire galaxy life (but declining with cosmic time), 2) linearly proportional to the stellar mass of the host spheroid, 3) summing up to a total gas mass that is > 100 times larger than the currently observed SMBH masses, 4) available independently of merging events. The main results of numerical simulations of Es with central SMBH, in which a physically based implementation of radiative and mechanical feedback effects is considered, are presented.

A magnetic field embedded in a perfectly conducting fluid preserves its topology for all times. Although ionized astrophysical objects, like stars and galactic disks, are almost perfectly conducting, they show indications of changes in topology, magnetic reconnection, on dynamical time scales. Reconnection can be observed directly in the solar corona, but can also be inferred from the existence of large scale dynamo activity inside stellar interiors. Solar flares and gamma ray busts are usually associated with magnetic reconnection. Previous work has concentrated on showing how reconnection can be rapid in plasmas with very small collision rates. Here we present numerical evidence, based on three dimensional simulations, that reconnection in a turbulent fluid occurs at a speed comparable to the rms velocity of the turbulence, regardless of the value of the resistivity. In particular, this is true for turbulent pressures much weaker than the magnetic field pressure so that the magnetic field lines are only slightly bent by the turbulence. These results are consistent with the proposal by Lazarian & Vishniac (1999) that reconnection is controlled by the stochastic diffusion of magnetic field lines, which produces a broad outflow of plasma from the reconnection zone. This work implies that reconnection in a turbulent fluid typically takes place in approximately a single eddy turnover time, with broad implications for dynamo activity and particle acceleration throughout the universe. In contrast, the reconnection in 2D configurations in the presence of turbulence depends on resistivity, i.e. is slow.

Star formation is such a huge problem, covering such a large range of physical scales and involving so many physical processes, that the results of simulations should always be taken with care.

The model of Schönrich & Binney (2009) offers new ways to understand the chemo-kinematic structure of the solar neighbourhood in the light of radial mixing. The combination of chemical information with rich kinematic data reveals a still hardly explored abundance of interconnections and structures from which we can learn about both the physics and history of our Galaxy. Large upcoming datasets can be used to improve estimates of central parameters, to shed light on the Galaxy's history and to explore the unexpected way of understanding the well-known division of the Galactic disc yielded by the new model.

The atmospheres of chemically peculiar stars can be highly structured in both the horizontal and vertical dimensions. While most prevalent in the magnetic stars, these structures can also exist in non-magnetic stars. In addition to providing an important window to understanding the physical processes at play in these complex atmospheres, they can also be exploited to study stellar pulsations. This article reviews contributions to the session “A 3D look into the atmosphere” of the Joint Discussion “Progress in understanding the physics of Ap and related stars”. It is divided into 3 sections: “Magnetic field and surface structures”, “Pulsations in the atmospheres of roAp stars/inversions”, and “Spectral synthesis/atmospheric models”.

Our recent study of solar-type stars from the HARPS GTO sample provides highly accurate information with regard to Lithium abundances in stars with and without detected planets (Israelian et al. 2009). When the Li abundances of planet bearing stars are compared with the “single” stars, we find an excess of Li depletion in planet hosts with effective temperatures in the range 5700-5850 K. We also found that small amounts of Li have survived in the atmospheres of some planet-host solar analogs. Enhanced Li depletion in planet host stars puts constraints on mixing processes responsible for this phenomenon. We show that neither age nor metallicity are responsible for this observational fact.

In this paper I briefly summarize a number of robust results derived from observational and theoretical studies of roAp stars over the past three decades.

We have undertaken a campaign to expand the census of WRs throughout the Galaxy using the 2MASS and Spitzer/GLIMPSE surveys. Free-free emission generated within the ion-dense winds of WRs generates a significant infrared excess which forms the basis of an excellent criterion for photometrically selecting WRs from the stellar field.

Molecular transitions recently discovered at redshift zabs=2.059 toward the bright background quasar J2123-0050 are analysed to limit cosmological variation in the proton-to-electron mass ratio, μ ≡ mp/me. Observed with the Keck telescope, the optical spectrum has the highest resolving power and largest number (86) of H2 transitions in such analyses so far. Also, (7) HD transitions are used for the first time to constrain μ-variation. These factors, and an analysis employing the fewest possible free parameters, strongly constrain μ's relative deviation from the current laboratory value: Δμ/μ =(+5.6±5.5stat±2.7sys)×10−6. This is the first Keck result to complement recent constraints from three systems at zabs>2.5 observed with the Very Large Telescope.

In July 2008 the IAU became a union member of the ICSU body SCAR—the Scientific Committee on Antarctic Research. At the same time, SCAR initiated a Planning Group to establish a Scientific Research Program in Astronomy and Astrophysics from Antarctica. Broadly stated, the objectives of Astronomy and Astrophysics from Antarctica are to coordinate astronomical activities in Antarctica in a way that ensures the best possible outcomes from international investment in Antarctic astronomy, and maximizes the opportunities for productive interaction with other disciplines.

The uncertainties which still plague our understanding of the evolution of the light nuclides D, 3He and 4He in the Galaxy are described. Measurements of the local abundance of deuterium range over a factor of 3. The observed dispersion can be reconciled with the predictions on deuterium evolution from standard Galactic chemical evolution models, if the true local abundance of deuterium proves to be high, but not too high, and lower observed values are due to depletion onto dust grains. The nearly constancy of the 3He abundance with both time and position within the Galaxy implies a negligible production of this element in stars, at variance with predictions from standard stellar models which, however, do agree with the (few) measurements of 3He in planetary nebulae. Thermohaline mixing, inhibited by magnetic fields in a small fraction of low-mass stars, could in principle explain the complexity of the overall scenario. However, complete grids of stellar yields taking this mechanism into account are not available for use in chemical evolution models yet. Much effort has been devoted to unravel the origin of the extreme helium-rich stars which seem to inhabit the most massive Galactic globular clusters. Yet, the issue of 4He evolution is far from being fully settled even in the disc of the Milky Way.

Monitoring the Earth rotation is essential in various domains linked to reference frames firstly with applications in orbit determination, space geodesy or Astronomy. Secondly for geophysical studies where are involved mass motions within the different external fluid layers, atmosphere, hydrosphere, core and mantle of the earth, this on time scales ranging from a few hours to decades. The Earth Orientation Centre of the IERS is continuously monitoring the earth orientation variations from results derived from the various astro-geodetic techniques. It has in particular the task of deriving an optimal combined series of UT1 which is now based mainly on Very Long Baseline Interferometry (VLBI) with some contribution of LOD derived from GPS. We give here a brief summary concerning the contribution of the various techniques to UT1 and in aprticular how the use of LOD derived from GPS can improve the combination. More details are available in Gambis (2004) and Bizouard and Gambis (2009) and the website http://hpiers.obspm.fr/eop-pc/

The growth of a forming star takes place by accretion from the surrounding dense medium, facilitated by a circumstellar disk. But at the same time the forming system produces collimated outflows of gas that remove excess angular momentum and magnetic flux. A key question in the field is whether we can extend the disk/jet model to stars of the largest masses or if other ingredients are present. In this note, I review recent observations from the Very Large Array and the Submillimeter Array, of IRAS 16547-4247, a massive young stellar object that exhibits evidence for both a disk and an outflow.

As the 7th brightest star and the most luminous star in the solar neighborhood, Rigel (β Orionis) is a very intriguing object. This blue supergiant (B8 Iab; V-mag = +0.05–0.18-mag; B–V = -0.03), at a distance (from Hipparcos) of ~240±35 pc has a 〈MV〉 = -6.7 mag. The following physical properties were determined via spectroscopic, photometric, and interferometric studies: L/L⊙ ≈ 66,000 K; Teff ≈ 12,000 K; M/M⊙ ≈ 17±3; R/R⊙ ≈ 70; τ ≈ 3–10 Myr. Interestingly Rigel has similar physical properties with the 12th mag blue supergiant progenitor of SN 1987A: Sanduleak -69° 202a. Thus Rigel (along with its co-asterism Betelgeuse) are likely to be the nearest progenitors of a Type II supernova. Such a nearby explosion would be V ≈ -11th mag (similar to a quarter moon).