We perform a 3D-MHD simulation of a self-gravitating isothermal gas layer that is initially penetrated by a uniform magnetic field. The strength of the initial magnetic field is such that the cloud is slightly subcritical. In this system, we input random supersonic turbulence initially. Ion-neutral friction is also introduced in the magnetized gas so that the magnetic diffusion allows gas to go across the magnetic field and form self-gravitating cores. We found that self-gravitating cores are formed in the dense region enhanced by the shock waves if ion-neutral friction is introduced. The time scale of core formation is on the order of the 106 years, which is faster than the usual magnetic diffusion time (107 years) estimated from the initial condition. Our result is consistent with the results of 2D-MHD simulations by Li & Nakamura (2004).

Galactic clusters have well organized directions of their velocities at the instant of birth measured with respect to the local circular velocity. Preferential directions survive more than 100 Myrs. This can only be explained by star formation triggered by spiral arms.

The extreme carbon star, AFGL 3068, is losing mass at a rate in excess of 10$^{-4}$ M$_{\odot}$ yr$^{-1}$, and has so far been detected only in the infrared because it is hidden by a thick dust photosphere having a color temperature of $\sim$300K. Using the ACS camera on HST, we have imaged AFGL 3068 with broad-band filters at 0.6 and 0.8 $\mu$m and find a thin, apparently continuous spiral arc winding 4 or 5 times around the location of the star, from angular radii of 2 to 10 arcsec. We interpret this as the projection of nested spiral shells such as were predicted to occur when the mass-losing star is a member of a binary system. In this case, the illumination is presumably provided by ambient galactic starlight. Subsequent near-IR observations with the NIRC2 camera on the Keck II telescope using adaptive optics reveal that AFGL 3068 has two components separated by 0.11 arcsec, or 109 AU at a distance of 1 kpc. One very red component is presumably the mass-losing carbon star, while the other component is apparently a much bluer companion. Assuming each component has mass M(M$_{\odot}$), and ignoring the projection of the separation vector, we find the binary period to be 810 M$^{-0.5}$ yrs, strikingly comparable to the 710-yr separation of the shells obtained from the known outflow velocity of 14.7 km s$^{-1}$.

Globular clusters have been long predicted to host intermediate-mass black holes (IMBHs) in their centres. The growing evidence that some/all Galactic globular clusters (GCs) could harbour middle range (102 – 104M⊙) black holes, just as galaxies do, stimulates the searches and the development of new methods for proving their existence. Here we propose another method of detection – the microlensing of the cluster stars by the central BH.

With the first discovery of surviving pre-solar minerals in primitive meteorites in 1987 a new kind of astronomy emerged, based on the study of stellar condensates with all the detailed methods available to modern analytical laboratories. The pre-solar origin of the grains is indicated by considerable isotopic ratio variations compared with Solar System materials, characteristic of nuclear processes in different types of stars.

We analyze the periodicities for 294 solar flares observed by Nobeyama Radioheliograph over 6 discrete frequencies of 1, 2, 3.75, 9.4, 17 and 35 GHz during the solar cycle 23 between 1998 and 2004. Using Fourier analysis, we pick up the shortest period ($T_{\rm{s}}$) for each event at each frequency channel. We find that $T_{\rm{s}}$ varies in the range of 0.25–0.62 s over 6 frequency channels.

Multi-object spectrographs available on 8-m class telescopes provide the unique opportunity to directly investigate the kinematical and chemical properties of significant samples of resolved stars in galaxies of the Local Group. We present here the first results concerning an extensive study of stellar populations of the Carina dSph galaxy, based on data collected with the multi-object spectrographs FORS2 and FLAMES, both available at VLT. Preliminary estimates concerning the radial velocity distributions of the different samples are presented.

We report the discovery of two peculiar galaxies infalling into the lensing clusters of galaxies Abell 1689 (z~ 0.18) and 2667 (z~ 0.23). Hubble Space Telescope images show extraordinary trails composed by blue bright knots and stellar streams associated with both these systems, an ~L* and ~0.1L* galaxy. Under the combined action of tidal interaction with the cluster potential and of ram pressure by the intra-cluster medium the morphologies and star formation histories of these two galaxies are strongly perturbed. While in the massive system tidal interactions are the dominant effect and are able to produce a sinking of gas towards the galaxy center triggering a strong burst of star formation and changing galaxy's morphology, in the smaller galaxy the effects of gravitation are reduced by ram pressure stripping which blows away the neutral hydrogen from the galactic disk, quenching the star formation activity and transforming a gas rich late type spiral into quiescent disk dominated early type system. This result is a new additional evidence that galaxy mass represents the main driver of galaxy evolution, even during their dive into the harsh cluster environment and can give additional insights on the origin of S0s and dwarf cluster galaxies.

High-resolution echelle spectroscopic observations taken with the FEROS spectrograph at the ESO 2.2-m telescope confirm the binary nature of the dMe stars EUVE J0825−16.3 and EUVE J1501−43.6, previously reported by Christian & Mathioudakis (2002). In these binary systems, emission of similar intensity from both components is detected in the Na i D1 & D2, He i D3, Ca II H&K, Ca II IRT and Balmer lines. We have determined precise radial velocities by cross-correlation with radial velocity standard stars, which have allowed us to obtain for the first time the orbital solution of these systems. Both binaries consist of two nearly equal M0V components with an orbital period shorter than 3.5 days. We have analyzed the behaviour of the chromospheric activity indicators (variability and possible flares). In addition, we have determined its rotational velocity and kinematics.

Millimeter and submillimeter interferometry allows to probe the environment around evolved massive stars, where optical and NIR studies might be severely limited by large extinctions due to dusty environments. We present here the morphology and kinematics of the molecular envelope around the red supergiant star VY CMa. We have used the Submillimeter Array (SMA) to map the $^{12}$CO(J=2–1) line and 1.3 mm continuum emissions with an unprecedent resolution of $<$ 2″ or 3000 AU. While the line emission presents a roughly circular shape with a radius of $\sim$ 6000 AU, the velocity structure is markedly different from that of a simple spherically expanding shell. In particular, there is a significant velocity gradient in the East-West direction, confirming the presence of a bipolar outflow.

Episodic activity in super-massive black holes is shown by radio galaxies exhibiting ‘double-double’ radio morphologies (Subrahmanyan et al. 1996, Schoenmakers et al. 2000). Spectacular examples showing a renewal of beam activity in the form of new beams emerging within relic radio lobes of previous activity have placed the phenomenon of recurrence in AGN outflows on a firm footing.

By using the SUMSS and WENSS GRG samples, we infer that on timescales of order a few million years, low luminosity radio sources are more likely to exhibit episodic behaviour in the accretion on to their supermassive black holes as compared to the more powerful radio galaxies.

Small amounts of pre-solar grains have survived in the matrices of primitive meteorites and interplanetary dust particles. Their detailed study in the laboratory with modern analytical tools provides highly accurate and detailed information with regard to stellar nucleosynthesis and evolution, grain formation in stellar atmospheres, and Galactic Chemical Evolution. Their survival puts constraints on conditions they were exposed to in the interstellar medium and in the Early Solar System.

Most of the galaxies in the local universe are located in groups, in particular in small groups, and most of the transformations suffered by galaxies located in today's clusters are likely to have occurred in groups at higher redshifts. Understanding the formation and evolution of groups is essential to understand the whole picture of structures and galaxy build-up. Using multi-band photometry we studied the intragroup light component (IGL) observed in compact groups of galaxies in a subsample of Hickson's catalogue, an efficient tool for determining its stage of dynamical evolution and for mapping its gravitational potential. Applying the OV_WAV package, a wavelet based technique, we can identify the IGL independently of the main contaminating effects. The fractions of IGL detected range from 11% to 46%, with one group with no IGL detected. The colors are consistent with those for old stellar populations and the mean surface brightnesses range from 24.8 to 28.4 B mag arcsec−2. Using the IGL, along with other dynamical evolution indicators, we could establish an evolutionary sequence for our sample.

A comprehensive study of clustered star formation in the Rosette Molecular Complex was carried out based on archived data from the 2 Micron All Sky Survey. We presented strong evidence that triggered formation of embedded clusters and stellar aggregates took place in the working shells of the Rosette Nebula, a spectacular HII region excavated by the dozens of OB stars of the emerging massive cluster NGC 2244. Surprisingly, we have identified, within the confines of NGC 2244, a distinct congregation of young stellar objects showing prominent NIR excess that forms an arc like structure in appearance. Its location right to the south-east of the center of the main cluster and its strange morphology indicate most likely an origin from a former working shell of the HII region. This relic arc and the large, fragmented working surface layer of Rosette with the ambient cloud roughly show a concentric origin in morphology. This implies also a common origin of the clusters or stellar aggregates in association. The formation of massive star clusters was evidenced further into the heart of the molecular complex, and structured clustering star formation seemed to have taken place toward the south-east edge of the complex.

In the frame of the collaboration of several Southern European observatories, we are examining a number of eclipsing binary systems in search for evidence of pulsating phenomena. We hope our candidate systems will be suitable for subsequent astroseismological studies. As a first step towards this end, we are analyzing spectroscopic observations of several such binary stars; these observations have been made at the National Astronomical Observatory Rozhen, Bulgaria, in the period from 2002 to 2005, and the reduction was done at the Astronomical Observatory of Belgrade, Serbia. The measurements of radial velocities and RV curve analysis are in preparation.

Based on the concept that the CMEs are the results of coronal magnetic restructuring or reconfiguring, we analyze the December 18, 2000 event by using Nançay Radioheliograph (NRH) images and combining the multi-spatial scale observations. We investigated the onset, duration and position of the radio emissions in relation to EUV dimming and the inferred CME onset, with the purpose to estimate the spatial and temporal scales of the coronal restructuring, thus, to understand the physics of the initiation and development of the CME.

During Cycle 14 a total of 113 HST orbits were secured to observe five isolated dwarf galaxies, namely Tucana, LGS3, LeoA, IC1613, and Cetus. The aim of the project is a full characterization of the stellar content of these galaxies, in term of their SFH, radial distributions, halo populations and variable stars. Deep (V≈29) F475W, F814W data allowed us to fully sample all the evolutionary phases from the tip of the Red Giant Branch (RGB) to well below the old Main Sequence Turnoff (MSTO). Here we describe the observational design, and the reduction and calibration strategy adopted. A comparison of the results obtained using two different packages, ALLFRAME and Dolphot, is presented.

In the last years we started a long-term project devoted to obtain a complete photometric and spectroscopic screening of the stellar populations of the LMC globular cluster system and surrounding fields. The ultimate goals of this project are as follows:

• • The definition of reliable and homogeneous cluster metallicity and age scales from high quality, high resolution spectra and color-magnitude diagrams.

• • The detailed study of the chemical abundance patterns of iron-peak, alpha-, s- and r-process elements, in order to constrain the star formation and chemical enrichment timescales of both the cluster and field populations and check for possible self-enrichment in the clusters.

Infrared dark clouds (IRDCs) are generally assumed to be a promising hunting ground for tracing very early stages of massive star formation. Observations with Spitzer are a viable tool to probe their interiors that are still dominated by strong dust extinction even at 8 μm. With Spitzer/MIPS, we have observed several IRDCs at 24 and 70 micron. We generally find weak 24 micron sources within the IRDCs. However, at 70 micron these sources remain weak and thus indicate lower luminosities at the current state of evolution. Indications for internal substructures exist, separating regions with compact IR sources from even more dark regions.

The solar magnetism, its origin, and its impact on the earth are of primary interest for solar physicists. The understanding of the solar dynamo in the convection zone and the coupling of the magnetic fields up to the corona and the heliosphere calls for synoptic as well as for high spatial resolution observations of the Sun. Understanding the interactions between radiative and magneto-convective processes at the interface between the solar interior and the atmosphere requires spectro-polarimetric observations at high spatial and spectral resolution with high polarimetric accuracy. Thus large-aperture telescopes are needed to resolve the small scales and to collect enough photons to study the evolution of the magnetic processes. For assembling the mosaic of the solar dynamo and its magnetic coupling out to the heliosphere, large scale properties and hence synoptic observations play a crucial role. I present my personal perspective of the prospects in ground-based solar physics, and comment on the planned and upcoming new facilities including SOLIS, GREGOR, NST, SUNRISE, and ATST, as well as ALMA and FASR, but also mention the upcoming space missions HMI@SDO and SOLAR-B.