The orbital parameters of extra-solar planets have a significant impact on the probability that the planet will transit the host star. This was recently demonstrated by the transit detection of HD 17156b whose favourable eccentricity and argument of periastron dramatically increased its transit likelihood. We present a study which provides a quantitative analysis of how these two orbital parameters affect the geometric transit probability as a function of period. Further, we apply these results to known radial velocity planets and show that there are unexpectedly high transit probabilities for planets at relatively long periods. For a photometric monitoring campaign which aims to determine if the planet indeed transits, we calculate the significance of a null result and the subsequent constraints that may be applied to orbital parameters.

A method for the localization of the radio burst sources associated with the flare accelerated electron beams and coronal mass ejection (CME) shocks is presented. This method involves the computations of the ray trajectories, time delays, and optical depths in the refracting solar atmosphere. The coordinates of the radiating source can be obtained by comparing the time delays and intensity ratios of the bursts observed by widely separated spacecraft with the computed group delays and intensity ratios at exit points of the rays from the solar atmosphere. This method is applied to a type III radio burst observed by the STEREO spacecraft.

Asteroseismology is a powerful tool to derive stellar ages, masses, gravities, radii, etc. Precise determinations of these parameters need deep analyses for each individual stars. Approximate theories are not efficient enough. Here I present results for two stars, μ Arae and ι Hor, which have both been observed during eight nights with the HARPS spectrograph in La Silla. I also show that important constraints can be obtained on core overshooting using the same techniques.

We investigate the global photometric scaling relations traced by early-type galaxies in different environments, ranging from dwarf spheroidals, over dwarf elliptical galaxies, up to giant ellipticals (−8 mag ≳ MV ≳ −24 mag). These results are based in part on our new HST/ACS F555W and F814W imagery of dwarf spheroidal galaxies in the Perseus Cluster. We show that at MV ~ −14 mag, the slopes of the photometric scaling relations involving the Sérsic parameters change significantly. We argue that these changes in slope reflect the different physical processes that dominate the evolution of early-type galaxies in different mass regimes. We present N-body/SPH simulations of the formation and evolution of dwarf spheroidals that reproduce these slope changes and discuss the underlying physics. As such, these scaling relations contain a wealth of information that can be used to test models for the formation of early-type galaxies.

Through the techniques of millimeter-wave and infrared spectroscopy, over 60 species of gas-phase molecules and a variety of inorganic and organic solids have been detected in the short phase of stellar evolution between the asymptotic giant branch and planetary nebulae. The chemical pathways that lead to the synthesis of complex organic compounds in such low-density environments are therefore important topics of astrochemistry. In this review, we summarize the observational evidence for the existence of complex aliphatic and aromatic compounds in these circumstellar environments, and discuss the nature of their possible carriers. Also discussed are a number of unidentified emission features which may also have an organic origin. The possible relations between these circumstellar organic matter with Solar System organic matter are explored.

We have analysed spectra obtained with the Gemini Multi Object Spectrograph (GMOS) for more than 50 stars in the ionising cluster of 30 Doradus during a seven epochs observing campaign at Gemini South. We derive a binary candidate rate of about 50%, which is however consistent with an intrinsic 100% binary rate among massive stars. After decontaminating the sample from the stars that show binary orbital motions, we were able to calculate the “true” cluster velocity dispersion and found it to be about 8 km s−1. This value implies a virial mass of about 4.5 × 105 M⊙ which is consistent with previous photometric mass determinations therefore suggesting that NGC 2070 is a firm candidate for a future globular cluster.

Division VII gathers astronomers studying the diffuse matter in space between stars, ranging from primordial intergalactic clouds, via dust and neutral and ionized gas in galaxies, to the densest molecular clouds and the processes by which stars are formed.

Applications of the Hanle effect have revealed the existence of vast amounts of “hidden“ magnetic flux in the solar photosphere, which remains invisible to the Zeeman effect due to cancellations inside each spatial resolution element of the opposite-polarity contributions from this small-scale, tangled field. The Hanle effect is a coherency phenomenon that represents the magnetic modification of the linearly polarized spectrum of the Sun that is formed by coherent scattering processes. This so-called “Second Solar Spectrum” is as richly structured as the ordinary intensity spectrum, but the spectral structures look completely different and have different physical origins. One of the new diagnostic uses of this novel spectrum is to explore the magnetic field in previously inaccessible parameter domains. The earlier view that most of the magnetic flux in the photosphere is in the form of intermittent kG flux tubes with tiny filling factors has thereby been shattered. The whole photospheric volume instead appears to be seething with intermediately strong fields, of order 100G, of significance for the overall energy balance of the solar atmosphere. According to the new paradigm the field behaves like a fractal with a high degree of self-similarity between the different scales. The magnetic structuring is expected to continue down to the 10m scale, 4 orders of magnitude below the current spatial resolution limit.

We present calculations of 7Li evolution in halo dwarfs during pre-MS and MS. The combination of tachocline mixing, nuclear destruction and microscopic diffusion is investigated. We briefly touch on the question of 6Li.

The chemical enrichment by the first sources of light in the universe ultimately set the stage for the subsequent evolution of the Milky Way system. The oldest and, usually, the most-metal poor stars are our ‘near-field’ link to this ancient epoch as they, apart from tracing the chemical enrichment itself, also indirectly hold information on, e.g., the conditions for star formation and feed-back effects in the early universe. In particular, I will discuss the possible origins of the relatively large number of carbon enhanced metal-poor stars in the Galactic halo. Furthermore, I will argue that the apparent absence of the chemical signature of so-called pair-instability supernovae (PISNe), which are a natural consequence of current theoretical models for primordial star formation at the highest masses, may arise from a subtle observational selection effect. Whereas most surveys traditionally focus on the most metal-poor stars, early PISN enrichment is predicted to ‘overshoot’, reaching enrichment levels of [Ca/H] ~ −2.5 that would be missed by current searches.

Massive spectroscopic surveys of stars in the thick disk and halo populations of the Galaxy hold the potential to provide strong constraints on the processes involved in (and the timing of) the assembly history of the primary structural components of the Galaxy. In this talk, we explore what has been learned from one of the first such dedicated surveys, SDSS/SEGUE. Over the course of the past three years, SEGUE has obtained spectra for over 200,000 stars, while another hundred thousand stars been added from the calibration star observations of the (primarily extragalactic) SDSS, and other directed programs. A total of well over 10,000 stars with [Fe/H] < −2.0 have been discovered, including several hundred with [Fe/H] < −3.0. Their kinematics have revealed a inner/outer halo structure of the Galaxy.

New determinations of the alpha element ratios for tens of thousands of these stars are reported. Correlations of the alpha-element ratios with kinematics and orbital parameters can be used to test models of the likely formation of the thick-disk and halo components. These new data will (eventually) be considered in connection with possible associations with the present dwarf satellite galaxies of the Milky Way.

The initial surface abundances of Population II stars have been altered by the interplay between convection, rotational mixing and diffusion. In particular the shallower the outer convection zone the stronger the diffusion impact. We present preliminary results on constraining the extension of the convection zones of Population II stars thanks to 3D hydrodynamical simulations.

From NLTE computations of the magnesium abundance in a sample of extremely metal-poor giants we derive [Mg/Fe]=+0.7, leading to [Al/Mg]=−0.80 and [Na/Mg]=−0.85 in the early Galaxy. The ratio [O/Mg] should be near to the solar value. Measurements of nitrogen abundances derived from the analysis of the NH band in eight more stars confirm the large scatter of the ratios [N/Fe] and [N/O] in the early Galaxy.

One of the key questions of infrared astronomy is how the characteristics of dust depend on the physical properties of the surrounding medium. To address this question, we present results from the Spitzer Space Telescope on two projects designed to study the dust properties of a sample of 25 Planetary Nebulae (PNe) in the Magellanic Clouds, and three well-known Giant Hii regions (NGC 3603, 30 Doradus and N 66/NGC 346). Most PNe show emission from polycyclic aromatic hydrocarbons (PAHs) and only two of them show amorphous silicates. Eleven PNe display a strong broad feature around 11 μm which is attributed to silicon carbide and 8 of them show magnesium sulfide. One PNe, SMP LMC 11, shows spectacular absorption bands due to molecules which are the precursors from which more complex hydrocarbons are formed. The Spitzer spectra of the Hii regions, NGC 3603, 30 Doradus, and NGC 346 are very rich, displaying a wealth of spectral features within each region. This not only allows us to compare the dust at different metallicities but also to study the spatial variations of many features across a given region and correlate it with the distance to the ionizing cluster(s) and other parameters.

Interplanetary radio observations provide important information on particle acceleration processes at the Sun and propagation of the accelerated particles in the solar wind. Cane et al. (2002) have drawn attention to a class of prominent radio bursts that accompany >20 MeV solar proton events. They call these bursts ‘type III-L’ because: they are fast drifting (like normal type III bursts associated with electrons accelerated at impulsive solar flares); they are Long-lasting compared to normal type III bursts; they occur Late compared to the onset of the related solar event; and, they commence at Lower frequencies (~100 MHz) than normal type III bursts, suggesting that they originate higher in the corona at ~0.5 Rs above the Sun. We report on an analysis of the correlated radio and SEP events during 1996-2006 using the Wind Waves and near-Earth SEP data sets, and discuss whether the characteristics of the complex type III bursts (at less than 14 MHz) will permit them to serve as proxies for SEP event occurrence and intensity.

Commission 33 provides a forum for astronomers studying the structure and dynamics of the Milky Way Galaxy, a unique laboratory for exploring the stellar and gaseous components of galaxies and the processes by which they form and evolve.

We have developed a new method to improve the transit detection of Earth-sized planets in front of solar-like stars by fitting stellar microvariability by means of a spot model. A large Monte Carlo numerical experiment has been designed to test the performance of our approach in comparison with other variability filters and fitting techniques for stars of different magnitudes and planets of different radius and orbital period, as observed by the space missions CoRoT and Kepler. Here we report on the results of this experiment.

Mini-filaments are a small-scale phenomenon of the solar chromosphere, which frequently occur across the entire disk (see e.g. Wang, Li, Denker, et al. 2000). They share a variety of characteristics with their larger-scale cousins and may serve as a proxy for more complex systems. They play an important role in the energy and mass supply to the corona. In the case of small-scale eruptive filaments, only a single, small-scale loop system is involved. Furthermore, they are supported by simple magnetic field configurations (see Livi, Wang & Martin 1985), either magnetic bipoles or well-defined multipoles, easing their theoretical description. Since mini-filaments are small (just a few tens of seconds of arc) but highly dynamic (eruptions can occur within just a few minutes), they are an ideal target for high-resolution two-dimensional spectroscopy. We present a preliminary analysis of two-dimensional Hα spectroscopic data accompanied by broad-band speckle-restored images to demonstrate that chromospheric small-scale phenomena can serve as building blocks for our understanding of solar eruptive events such as filament/prominence eruptions and even coronal mass ejections (CMEs).

We present HE 1523-0901, a metal-poor star in which the radioactive elements Th and U could be detected. Only three stars have measured U abundances, of which HE 1523-0901 has the most confidently determined value. From comparing the stable Eu, Os, and Ir abundances with measurements of Th and U, stellar ages can be derived. Based on seven such chronometer abundance ratios, the age of HE 1523-0901 was found to be ~13 Gyr. Only an upper limit for Pb could be measured so far. Knowing all three abundances of Th, U, and Pb would provide a self-consistent test for r-process calculations. Pb is the beta- plus alpha-decay end-product of all decay chains in the mass region between Pb and the onset of dominant spontaneous fission above Th and U. Hence, in addition to Th/U also Th, U/Pb should be used to obtain a consistent picture for actinide chronometry. From recent r-process calculations within the classical “waiting-point” model, for a 13 Gyr old star we predict the respective abundance ratios of logϵ(Th/U) = 0.84, logϵ(Th/Pb) = −1.32 and logϵ(U/Pb) = −2.16. We compare these values with the measured abundance ratios in HE 1523-0901 of logϵ(Th/U) = 0.86, logϵ(Th/Pb) > −1.0 and logϵ(U/Pb) > −1.9. With this good level of agreement, HE 1523-0901 is already a vital probe for observational “near-field” cosmology by providing an independent lower limit for the age of the Universe.

The past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field, including evidence for reduced mass-loss rates and faster stellar rotational velocities in the Clouds, and their present-day compositions. I also discuss the stellar temperature scale, emphasizing its dependence on metallicity across the entire upper-part of the Hertzsprung-Russell diagram.