The hypothesis that polyaromatic molecules are the carriers of the infrared interstellaremission bands has spurred the laboratory spectroscopy of this class of molecules. Here wewill give an overview of the infrared spectroscopic methods that have been applied overthe past two decades to investigate the IR spectra of PAHs, their ions and relatedspecies.

The origin and types of spiral arms are reviewed with an emphasis on the connections between these arms and star formation. Flocculent spiral arms are most likely the result of transient instabilities in the gas that promote dense cloud formation, star formation, and generate turbulence. Long irregular spiral arms are usually initiated by gravitational instabilities in the stars, with the gas contributing to and following these instabilities, and star formation in the gas. Global spiral arms triggered by global perturbations, such as a galaxy interaction, can be wavemodes with wave reflection in the inner regions. They might grow and dominate the disk for several rotations before degenerating into higher-order modes by non-linear effects. Interstellar gas flows through these global arms, and through the more transient stellar spiral arms as well, where it can reach a high density and low shear, thereby promoting self-gravitational instabilities. The result is the formation of giant spiral arm cloud complexes, in which dense molecular clouds form and turn into stars. The molecular envelops and debris from these clouds appear to survive and drift through the interarm regions for a long time, possibly 100 Myr or more, with lingering spontaneous star formation and triggered star formation in the pieces that are still at high-pressure edges near older HII regions.


Observations of far-infrared (FIR) and submillimeter (SMM) polarizedemission are used to study magnetic fields and dust grains in denseregions on the interstellar medium (ISM). These observations placeconstraints on models of molecular clouds, star-formation, grainalignment mechanisms, and grain size, shape, and composition.
The FIR/SMM polarization is strongly dependent onwavelength. We have attributed this wavelength dependence to samplingdifferent grain populations at different temperatures. To date, mostobservations of polarized emission have been inthe densest regions of the ISM. Extending these observations toregions of the diffuse ISM, and to microwave frequencies, will provideadditional tests of grain and alignment models.
An understanding of polarized microwave emission from dust is key toan accurate measurement of the polarization of the cosmic microwavebackground. The microwave polarization spectrum will put limits on thecontributions to polarized emission from spinning dust and vibratingmagnetic dust.


The T-REX project aims at developing novel readout techniques for Time Projection Chambers in experiments searching for rare events. The enhanced performance of the latest Micromegas readouts in issues like energy resolution, gain stability, homogeneity, material budget, combined with low background techniques, is opening new windows of opportunity for their application in this field. Here we review the latest results regarding the use and prospects of Micromegas readouts in axion physics (CAST and the future helioscope), as well as the R&D carried out within NEXT, to search for the neutrinoless double-beta decay.

Magnetic fields have been detected on stars across the H-R diagram and substellar objects either directly by their effect on the formation of spectral lines, or through the activity phenomena they power which can be observed across a large part of the electromagnetic spectrum. Stars show a very wide variety of magnetic properties in terms of strength, geometry or variability. Cool stars generate their magnetic fields by dynamo effect, and their properties appear to correlate – to some extent – with stellar parameters such as mass, rotation, and age. With the improvements of instrumentation and data analysis techniques, magnetic fields can now be detected and studied down to the domain of very-low-mass stars and brown dwarfs, triggering new theoretical works aimed, in particular, at modelling dynamo action in these objects. After a brief discussion on the importance of magnetic field in stellar physics, the basics of dynamo theory and magnetic field measurements are presented. The main results stemming from observational and theoretical studies of magnetism are then detailed in two parts: the fully-convective transition, and the very-low mass stars and brown dwarfs domain.

After a brief introduction, this contribution will discuss practical strategies to exploit the unique science potential of closure phases in optical interferometry, especially in the case of only three telescopes when direct imaging is near-impossible. Prototype source morphologies will be investigated in detail (binary and "dust shell + star"), and will illustrate how closure phase measurements can be used both for "Precision Interferometry" as well as qualitatively new probes of circumstellar environments. During this meeting, the notion of a "Closure Differential Phase" came to light, and some interesting properties of this quantity are here introduced.

Gaia is an ESA mission to build a census of our Milky Way Galaxy. This is done with a suite of three instruments combining two fields of view into a single focal plane. On-board detection of all sources will ensure a bias free survey down to the 20th magnitude. In addition to astrometry also photometry is done down to the 20th magnitude. The third, spectroscopic instrument will provide radial velocities down to the 17th magnitude of the Galactic stellar population. Currently the scientific requirements on Gaia are largely met except for bright stars for which in astrometry additional efforts are needed to squeeze the remaining μarcsecs out of the positional information error budgets. In the mid-magnitude range (15 mag) the end of mission parallax errors are from 10 to 25 μarcsec and photometry errors are between 5 and 16 mmag. Radial velocities are better than 1 km s-1 for the bright stars with errors increasing to 15 km s-1 for the faintest ones. At the moment there are no unsolvable technical challenges on the table and Gaia is progressing toward the launch in 2012.

Angular momentum is one of the most fundamental properties of matter in our universe, which has deep consequences on its evolution. In particular, the formation and the physical characteristics of cosmic structures such as galaxies, stars and planets are intimately linked to the amount of angular momentum they carry, to the way it is redistributed within the system and exchanged with the surrounding environment. Considerable efforts have been undertaken during the last decades to identify and quantify the various physical mechanisms responsible for the transport of angular momentum in these objects. While some of them are relatively well understood, in many circumstances the underlying mechanism turns out to be extremely complex and very challenging. In this introductory chapter, we first introduce some general considerations on the angular momentum impact and transport. We then derive the MHD equations both in the ideal and non-ideal limit. Finally, after deriving the conservative form of the angular momentum equation, we discuss in more details some of the mechanisms that can contribute to the transport of angular momentum in various astrophysical contexts.


The Hessian of the entropy function can be thought of as a metrictensor on state space. In the context of thermodynamicalfluctuation theory Ruppeiner has argued that the Riemannian geometryof this metric gives insight into the underlying statisticalmechanical system; the claim is supported by numerous examples. Westudy these geometries for some families of black holes and find thatthe Ruppeiner geometry is flat for Reissner–Nordström black holesin any dimension, while curvature singularities occur for the Kerrblack holes. Kerr black holes have instead flat Weinhold curvature.

Recent radio polarization observations have revealed a plethora ofunexpected features in the polarized Galactic radio background thatarise from propagation effects in the random (turbulent) interstellarmedium. The canals are especially striking among them, a random networkof very dark, narrow regions clearly visible in many directions againsta bright polarized Galactic synchrotron background. There are no obviousphysical structures in the ISM that may have caused the canals, and sothey have been called Faraday ghosts. They evidently carry informationabout interstellar turbulence but only now is it becoming clear how thisinformation can be extracted. Two theories for the origin of the canalshave been proposed; both attribute the canals to Faraday rotation, butone invokes strong gradients in Faraday rotation in the sky plane(specifically, in a foreground Faraday screen) and the other only relieson line-of-sight effects (differential Faraday rotation). In this reviewwe discuss the physical nature of the canals and how they can be used toexplore statistical properties of interstellar turbulence. This opensstudies of magnetized interstellar turbulence to new methods ofanalysis, such as contour statistics and related techniques ofcomputational geometry and topology. In particular, we can hope tomeasure such elusive quantities as the Taylor microscale and theeffective magnetic Reynolds number of interstellar MHD turbulence.

We first review the results of the tidal stirring model for the transformation of gas-rich dwarf irregulars into dwarf spheroidals, which turns rotationally supported stellar systems into pressure supported ones. We emphasize the importance of the combined effect of ram pressure stripping and heating from the cosmic ultraviolet background in removing the gas and converting the object into a gas poor system as dSphs. We discuss how the timing of infall of dwarfs into the primary halo determines the final mass-to-light ratio and star formation history. Secondly we review the results of recent cosmological simulations of the formation of gas-rich dwarfs. These simulations are finally capable to produce a realistic object with no bulge, an exponential profile and a slowly rising rotation curve. The result owes to the inclusion of an inhomogeneous ISM and a star formation scheme based on regions having the typical density of molecular cloud complexes. Supernovae-driven winds become more effective in such mode, driving low angular momentum baryons outside the virial radius at high redshift and turning the dark matter cusp into a core. Finally we show the first tidal stirring experiments adopting dwarfs formed in cosmological simulations as initial conditions. The latter are gas dominated and have turbulent thick gaseous and stellar disks that cannot develop strong bars, yet they are efficiently heated into spheroids by tidal shocks.

A classical nova outburst arises from a thermonuclear runaway in the hydrogen-richmaterial accreted onto the surface of a white dwarf in a binary system. These explosionscan produce copious amounts of heavy element enriched material that are ejected violentlyinto the surrounding interstellar medium. In some novae, conditions in the ejecta aresuitable for the formation of dust of various compositions, including silicates, amorphouscarbon, silicon carbide, and hydrocarbons. Multiple dust grain types are sometimesproduced in the same system. CO formation in novae may not reach saturation, thusinvalidating the usual paradigm in which the C:O ratio determines the dust species. A fewnovae, such as V705 Cas and DZ Cru, have exhibited emission features near 6, 8, and 11μmthat are similar to “Unidentified Infrared” (UIR) features, but withsignificant differences in position and band structure. Here, we present SpitzerIRS spectra of two recent dusty novae, V2361 Cyg and V2362 Cyg, that harborsimilar peculiar emission structures superimposed on features arising from carbonaceousgrains. In other astronomical objects, such as star forming regions and young stellarobjects, emission peaks at 6.2, 7.7, and 11.3 μmhave been associated withpolycyclic aromatic hydrocarbon (PAH) complexes. We suggest that hydrogenated amorphouscarbon (HAC) may be the source of these features in novae based upon the spectral behaviorof the emission features and the conditions under which the dust formed.

We review the presupernova evolution, the explosion and the explosive nucleosynthesis of massive stars in the range 11–120 M๏. We mainly focus on the advanced evolutionary phases prior to the explosion, i.e. from the core He exhaustion up to the onset of the iron core collapse.

A widely held view is that a “mini halo” with much less than 108 M⊙ in dark matter is unlikely to retain any baryons because even a single SN event is expected to sweep out all of the gas. But we show that a clumpy medium is much less susceptible to SN sweeping (particularly if it is off-centred) because the coupling efficiency of the explosive energy is much lower than for a diffuse interstellar medium. With the aid of the sophisticated 3D hydro code Fyris, we show that baryons are retained and stars are formed in dark matter haloes down to 3 × 106 M⊙. The gas survives the SN explosion and is enriched with specific abundance yields of the discrete events. The smallest galaxies may not contribute a large fraction of baryons and dark matter to the formation of galaxies. But they are likely to carry important chemical signatures that were laid down in the earliest epochs of star formation, as we show. We discuss the results in light of the newly discovered, very metal poor, damped Lyα systems and ultra-faint dwarf galaxies.

Observations of magnetic fields in molecular clouds are essential for understanding their role in the evolution of dense clouds and in the star formation process. The two extreme-case models of star formation are the weak magnetic field scenario, in which turbulence drives molecular cloud evolution and therefore star formation, and the strong magnetic field scenario, with magnetic fields governing molecular cloud formation and ambipolar diffusion ultimately driving star formation. Continuum and spectral line polarization observations make it possible to infer magnetic field strengths and morphologies, and therefore to test which of the two star formation scenarios dominates. The observational techniques available for such observations – the Zeeman effect, mapping of polarized dust emission, and mapping of linearly polarized line emission – are briefly described, together with how these observations can test star formation theory. Examples of the existing observations and the current state of the testing of magnetically controlled star formation are presented. Finally, the prospects for the future of study of magnetic fields in molecular clouds and their role in the star formation process is discussed.

Stars can be seen as modern physics laboratory from which fundamental processes as diverse as atomic physics or turbulence can be studied and understood. Being able to model accurately their structure, dynamic and evolution is thus of fundamental importance and is the subject of intense research. In this short review we will present some of the numerical simulations in three dimensions performed in recent years to model such complex and nonlinear objects, focussing mostly our discussion on results obtained with the anelastic spherical harmonic (ASH) code. Using the Sun as a reference star, we wish to gain insight and to constrain magnetohydrodynamical processes (such as Reynolds and Maxwell stresses, meridional circulations, differential rotation (i.e. ω-effect), thermal wind, α-effect) at the origin of the solar small and large scale dynamics and magnetism. We will then extend our study to other stars, such as young Suns, massive stars or evolved RGB stars in order to identify which processes are at the origin of their significantly different dynamics.

Polar ring galaxies, where matter is in equilibrium in perpendicularorbits around spiral galaxies, are ideal objects to probe the 3D shapesof dark matter halos. The conditions to constrain the halos are that theperpendicular system does not strongly perturb the host galaxy, or thatit is possible to derive back its initial shape, knowing the formationscenario of the polar ring. The formation mechanisms are reviewed:mergers, tidal accretion, or gas accretion from cosmic filaments.The Tully-Fisher diagram for polar rings reveals that the velocityin the polar plane is higher than in the host plane, which can only be explained if the dark matter is oblate and flattened along the polar plane. Only a few individual systems havebeen studied in details, and 3D shapes of their haloes determinedby several methods. The high frequency of warps could be explainedby spontaneous bending instability, if the disks are sufficientlyself-gravitating, which can put constraints on the dark matter flattening.

SPIRE, the Spectral and Photometric Imaging Receiver, is Herschel's submillimetre camera and spectrometer. It comprises a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier Transform Spectrometer (FTS) covering 194–672 μm. The design of SPIRE is described, and the expected scientific performance is summarised, based on modelling and flight instrument test results.

In this lecture I review the theory of magnetized accretion discs driving jets, with a focus on Young Stellar Objects (YSOs). I first introduce observational and theoretical arguments in favor ofthe "disc wind" paradigm. There, accretion and ejection are interdependent, requiring therefore to revisit the standard picture of accretion discs. A simple magnetostatic approach is shown to already provide some insights into the basic phenomena. The magnetohydrodynamic equations as well as all usual assumptions are then clearly listed. The relevant physical mechanisms of steady-state accretion and ejection fromdiscs are explained in a model independent way. The results of self-similar calculations are shown and criticallydiscussed, for both cold and warm jet configurations. I finally provide observational predictions and the physical conditions required in YSOs discs. The need for introducing a magnetospheric interaction between the disc and the protostar is briefly discussed.