We report an ultra-high-resolution simulation that follows evolution from the earliest stages of galaxy formation through the period of dynamical relaxation. The bubble structures of gas revealed in our simulation (<3×108 years) resemble closely the high-redshift Lyman α emitters (LAEs). After 109 years these bodies are dominated by stellar continuum radiation and look like the Lyman break galaxies (LBGs) known as the high-redshift star-forming galaxies at which point the abundance of elements appears to be solar. After 1.3×1010 years, these galaxies resemble present-day ellipticals. The comparisons of simulation results with the observations of elliptical galaxies allow us to conclude that LAEs and LBGs are infants of elliptical galaxies or bulge systems in the nearby universe.

This paper reports the development of an experiment (TEPEE/GReAT) to test the Equivalence Principle (EP) at a level of accuracy equal to 5 × 10-15, by means of a differential accelerometer free falling in a cryogenic vacuum capsule released from a stratospheric balloon. Such an accuracy requires resolving a very small signal out of the instrument's intrinsic noise and the noise associated with the instrument's motion. Imperfections in the construction of the detector introduce gravity gradient noise that it is possible to separate from the violation signal spinning the detector around an horizontal axis in order to have the EP violation signal and the gravity gradients one modulated at two different frequencies. Experimental results on prototype instruments showing high sensitivity and common mode rejection factor are shown.

Betelgeuse, the bright red supergiant (RSG) in Orion, is a runaway star. Its supersonic motion through the interstellar medium has resulted in the formation of a bow shock, a cometary structure pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse’s bow shock. We show that the bow shock morphology depends substantially on the growth timescale for Rayleigh-Taylor versus Kelvin-Helmholtz instabilities. We discuss our models in light of the recent Herschel, GALEX and VLA observations. If the mass in the bow shock shell is low (~few  × 10-3M⊙), as seems to be implied by the AKARI and Herschel observations, then Betelgeuse’s bow shock is very young and is unlikely to have reached a steady state. The circular, smooth bow shock shell is consistent with this conclusion. We further discuss the implications of our results, in particular, the possibility that Betelgeuse may have only recently entered the RSG phase.

This paper gives an overview of the potential of and developments on Transition Edge Sensors for astronomical research from Space. This type of sensor is under development for imaging X-ray spectrometers as well as for very sensitive InfraRed and sub-mm imaging detectors. This paper describes developments in Europe for the International X-ray Observatory IXO (ESA, JAXA, NASA) and for the SAFARI instrument on the Japanese IR-mission SPICA. 
The micro-calorimeter array for the IXO-mission will have an imaging array of at least 1024 pixels with high quantum efficiency in the 0.1–10 keV energy range and an energy resolution as small as 2 eV for each detected photon. The SAFARI instrument requires three imaging arrays with an optical Noise Equivalent Power (NEP) as low as ≤ 5 × 10-19 W/√Hz with a total amount of 5940 pixels to read a Fourier Transform Spectrometer. The paper is written to be read together with the presentation given at the Astrophysics Detector Workshop 2008, Nice 17–20 November 2008, France.

We studied the stellar populations of Fornax dwarf spheroidal galaxy using HST/WFPC2 imaging of 7 galaxy fields. Our observations reach the oldest main-sequence turn-off, revealing distinct stars formation episodes and allowing us to address the evolution of this prototype dwarf spheroidal galaxy known to have experienced an extended history of star formation. From our HST data, spatial gradients in the stellar content of Fornax emerge with greater clarity. The outermost fields show only stars with ages between 7–12Gyr, while the intermediate region hosts a stellar population between 4–10Gyr, and stars younger of 2 Gyr are found in the innermost fields. A clearly visible gap in the subgiant branch points to bimodality in the main star formation episode. Our observations also indicate that the inner clump detected by Coleman et al. (2004) is characterized by the presence of young stars with age about 1.8 Gyr.

We have chosen the name of GYES, one of the mythological giants with one hundred arms,offspring of Gaia and Uranus, for our instrument study of a multifibre spectrograph forthe prime focus of the Canada-France-Hawaii Telescope. Such an instrument could provide anexcellent ground-based complement for the Gaia mission and a northern complement to theHERMES project on the AAT. The CFHT is well known for providing a stable prime focusenvironment, with a large field of view, which has hosted several imaging instruments, buthas never hosted a multifibre spectrograph. Building upon the experience gained at GÉPIwith FLAMES-Giraffe and X-Shooter, we are investigating the feasibility of a highmultiplex spectrograph (about 500 fibres) over a field of view one degree in diameter. Weare investigating an instrument with resolution in the range 15 000 to 30 000, whichshould provide accurate chemical abundances for stars down to 16th magnitude and radialvelocities, accurate to 1 km s-1 for fainter stars. The study is led byGÉPI-Observatoire de Paris with a contribution from Oxford for the study of thepositioner. The financing for the study comes from INSU CSAA and Observatoire de Paris.The conceptual study will be delivered to CFHT for review by October 1st 2010.

We summarize the current discussions towards astronomical time-series observations at Dome C and emphasize some near-future projects. We define time-series as the continuous process of data taking that takes advantage of the unique time windows and observing conditions at Dome C. We emphasize that most of the current approaches to time-series astrophysics require a dedicated flux collector. In addition, some specific scientific topics may proceed with significant fractions of time on multi-purpose facilities. We consider only on those ideas and projects that were presented at least once during the various ARENA workshops and conferences. Topics of solar science are not considered in detail here.

The wealth of data in the past decades, and especially in the past 15 years has transformed our picture of the gas around the Milky Way and other spiral galaxies. There is good evidence for extraplanar gas that is a few kpc in height and is seen in all gaseous phases: neutral; warm atomic; and hot, X-ray emitting gas. This medium is seen not only around the Milky Way, but other spiral galaxies and it is related to the star formation rate, so it is likely produced by the activity in the disk through a galactic fountain. More extended examples of halo gas are seen, such as the HVC around the Milky Way and around M 31. This gas is typically 10–20 kpc from the galaxy and is not seen beyond 50 kpc. This gas is most likely being accreted. A hot dilute halo (106 K) is present with a similar size, although its size is poorly determined.

An ongoing controversy surrounds the relative amounts of outflow from the disk and accretion onto galaxies such as the Milky Way. There is good evidence for accretion of cold material onto the Milky Way and other galaxies, but it is not clear if there is enough to modify the gas content and star formation properties in the disk. The reservoir of accretion material is as yet unidentified. Some of these findings may be related to the issue that galaxies are baryon-poor: their baryon to dark matter ratio is well below the cosmological value. The absence of baryons may be due to extremely violent outflow events in the early stages of galaxy formation. We may be able to understand this stage of galaxy evolution by applying our deepening understanding of our local disk-halo environment.

Rapidly rotating solar type stars display varying amounts ofchromospheric emission in their Balmer lines. The profiles of theselines often display rapid variability. Since the mid-1980s,high-cadence echelle spectroscopy of numerous such stars has revealedthat some of the variability is caused by concentrations of neutralhydrogen, trapped in the stellar coronal magnetic field at distancesup to a few stellar radii from the rotation axis. In this paper wereview the observations and the tomographic techniques that can beapplied to mapping these "slingshot prominence" systems. We discussthe possible mechanisms for formation and mechanical support of thesecondensations, in the light of recent efforts to map 3-dimensionalstellar coronal magnetic fields and X-ray emission measuredistributions, with the help of Zeeman-Doppler imaging.

This paper reviews the overall principles of astronomical spectrographs and the design rules that cover low, medium, and high spectral resolution instruments. Several examples of spectrograph designs are described that are easy to build and are optimised for amateur telescopes. Results are given for each of these instruments. Despite the modest size of amateur telescopes, we show that high performance spectrographs in the hands of amateur astronomers provide access to some specialised areas where the amateur could contribute to useful astrophysical work.

Thick layers of warm, low density ionized hydrogen (i.e., the warm ionized medium or WIM) in spiral galaxies provide direct evidence for an interaction between the disk and halo. The wide-spread ionization implies that a significant fraction of the Lyman continuum photons from O stars, produced primarily in isolated star forming regions near the midplane and often surrounded by opaque clouds of neutral hydrogen, is somehow able to propagate large distances through the disk and into the halo. Moreover, even though O stars are the source of the ionization, the temperature and ionization state of the WIM differ significantly from what is observed in the classical O star H ii regions. Therefore, the existence of the WIM and observations of its properties provide information about the structure of the interstellar medium and the transport of energy away from the midplane as well as place significant constraints on models.

Recent ultra-high precision observations of eclipsing binaries, especially data acquired by the Kepler satellite, have made accurate light curve modelling increasingly challenging but also more rewarding. In this contribution, we discuss low-amplitude signals in light curves that can now be used to derive physical information about eclipsing binaries but that were unaccessible before the Kepler era. A notable example is the detection of Doppler beaming, which leads to an increase in flux when a star moves towards the satellite and a decrease in flux when it moves away. Similarly, Rømer delays, or light travel time effects, also have to taken into account when modelling the supreme quality data that is now available. The detection of offsets between primary and secondary eclipse phases in binaries with extreme mass ratios, and the observation of Rømer delays in the signals of pulsators in binary stars, have allowed us to determine the orbits of several binaries without the need for spectroscopy. A third example of a small-scale effect that has to be taken into account when modelling specific binary systems, are lensing effects. A new binary light curve modelling code, PHOEBE 2.0, that takes all these effect into account is currently being developed.

In this brief review we discuss how some of our basic understanding of chemical processes in interstellar medium has received a boost from the Herschel Space Observatory. With Herschel in operations for over 1 year, it is still early to discuss the full impact of new results and instead I demonstrate the new science enabled by near-complete spectroscopic access to sub-millimeter to far-infrared wavelengths.

Irradiation by cosmic ions plays a relevant role in the “space weathering” of solid materials in the airless bodies (rocky and/or icy objects) in the Solar System. Here, I discuss about some of the effects that have been studied in “simulation” experiments with a view to their astrophysical relevance. In particular I review some experimental results obtained so far after irradiation of relevant materials, namely: sputtering, ion implantation, and chemical synthesis of molecular species different from the original ones. All of those effects are accomplished by changes in the optical properties of irradiated layers and then of the color of the surfaces of the airless bodies. Some specific examples of the application of the experimental results to the physics and chemistry of planetary surfaces are discussed as well.

The mid-infrared emission of Polycyclic Aromatic Hydrocarbons is found in many phases ofthe interstellar medium. Towards cold dense clouds,however,the emission is heavilyquenched. In these regions molecules are found to efficiently freeze-out on interstellargrains forming thin layers of ices. PAHs are highly non-volatile molecules and are alsoexpected to freeze-out. PAHs trapped in interstellar ices are likely to participate in theoverall chemistry,leading to the formation of cations and complex molecules in thesolid-state. The work presented here aims to experimentally study the chemical reactionsthat PAHs undergo upon vacuum ultraviolet irradiation when trapped in interstellarH2O ice.

The dust in protoplanetary disks is influenced by many different processes. Among others, heating processes are the most important ones: they change not only the physical and chemical properties of dust particles, but also their emission spectra. In order to compare observed infrared spectra of young stellar systems with laboratory data of hot (up to 655°C) circumstellar dust analogues, we investigate materials, which are important constituents of dust in protoplanetary disks. We calculated the optical constants by means of a simple Lorentzian oscillator fit and applied them to simulations of small-particle emission spectra in order to compare our results with real astronomical spectra of AGB-stars and protoplanetary disks.

Multi-epoch, high-resolution (R ∼ 50 000) optical spectrosco-py of the O-type (O9 III – IV) star HD 152246 suggests that it is a triple system where a close inner pair (Aa–Ab) with a circular orbit and a period of 6 days is in a 53–d eccentric orbit (e = 0.68) with a third component Ac. The mass ratios for the inner and outer system are 0.10 and 0.96, respectively. The strengths of various He lines classify Aa and Ac as late O-type stars while Ab is invisible in our spectra.

In-depth analysis of eclipsing binary (EB) observational data collected for several decades can inform us about a lot of astrophysically interesting processes taking place in the systems. We have developed a wide-ranging method for the phenomenological modelling of eclipsing binary phase curves that enables us to combine even very disparate sources of phase information. This approach is appropriate for the processing of both standard photometric series of eclipses and data from photometric surveys of all kind. We conclude that mid-eclipse times, determined using the latest version of our “hi-fi” phenomenological light curve models, as well as their accuracy, are nearly the same as the values obtained using much more complex standard physical EB models.

In this paper we examine the effects introduced in the luminosityfunction of white dwarf stars by a change of the gravitationalconstant during the life of the Universe. A decrease of G inducesthe expansion of the star and accelerates its cooling. This effecthas noticeable effects on the luminosity function and can be used toset upper bounds on the rate of change of G. Preliminary resultsindicate that Ġ/G ≤ 10-13 yr-1. These values are thebest ever obtained and will improve as the white dwarf luminosityfunction will improve.