Modern planetaria achieved in 1923 a synthesis between planetaries and stellariums. In 2009, there are nearly 3000 planetariums all over the world, mainly in developed countries. We present here a brief historical and statistical analysis of this development.

The Australia Telescope Large Area Survey (ATLAS; Norris et al. 2006) is the widest deep radio survey to date, covering approximately 7 square degrees over two fields, with extensive complementary data. We are investigating all possible discriminants between active galactic nuclei (AGN) and star-forming galaxies (SFG) in ATLAS, to determine a robust formula for distinguishing the two.

Until recently, the mechanism of the light variability of chemically peculiar (CP) stars was unclear. To improve this situation, we started a theoretical and observational campaign aimed at the nature of the light variability of these stars. We use the TLUSTY model atmospheres calculated for the appropriate surface chemical composition to obtain the emergent flux and to predict the rotationally modulated light curves. We show on example of several well-studied CP stars that their light variations can be explained as a result of i) the uneven surface distribution of the elements (creating overabundant regions), ii) the flux redistribution from the ultraviolet to the visible part of the spectrum (in the overabundant regions), and iii) rotation of the star. We show that the silicon and helium bound-free transitions and iron bound-bound transitions provide the main contribution to the flux redistribution. This result is also a very precise test of modern stellar model atmospheres. We conclude that the mentioned mechanism is a very promising explanation for the light variations in CP stars of earlier spectral types.

We present flux-calibrated integrated spectra in the optical spectral range of Galactic open clusters (GOCs) and Magellanic Cloud (MC) stellar clusters (SCs) obtained at CASLEO (Argentina). The SC parameters were derived using the equivalent-width (EW) method and the template-matching procedure by comparing the line strengths and continuum distribution of the cluster spectra with those of template spectra with known parameters. MC cluster reddening values were also estimated by interpolation between the available extinction maps. The derived ages for the GOCs range from 3 Myr to 4 Gyr, while those of the MC SCs vary from 3 Myr to 7 Gyr. E(B−V) colour-excess values in the MCs appear to be all lower than 0.17 mag, while those of the GOCs range from 0.00 to 2.40 mag. The present data led us to upgrade the spectral libraries of reference spectra or templates of solar and MC metallicities.

We discuss using high solar cycle atmospheric conditions as sensors for observing meteors and their properties. High altitude meteor trails (HAMTs) have sometimes been observed with HPLA (High Power Large Aperture) radars. At other times they are not seen. In the absence of systematic studies on this topic, we surmise that the reason might be differing atmospheric conditions during the observations. At EISCAT HAMTs were observed in 1990 and 1991. Very high meteor trails were observed with Israeli L-band radars in 1998, 1999 and 2001. Through the Leonid activity, around the latest perihelion passage of comet Tempel-Tuttle, optical meteors as high as 200 km were reported. This was partly due to new and better observing methods. However, all the reported periods of high altitude meteors seem to correlate with solar cycle maximum. The enhanced atmospheric and ionospheric densities extend the meteoroid interaction range with the atmosphere along its path, offering a better possibility to distinguish differential ablation of the various meteoric constituents. This should be studied during the next solar maximum, due within a few years.

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.

Ground-based optical interferometers can perform astrometric measurements with a precision approaching 10μas between pairs of stars separated by ~10″ on the sky. These narrow-angle measurements can be used to search for extrasolar planets and to determine their orbital parameters, to characterize microlensing events, and to measure the orbits of stars around the black hole at the center of our Galaxy.

We have obtained several hundred very deep spectra with DEIMOS/Keck in order to estimate the galactic mass flux density at intermediate redshifts (0.6 < z < 0.9) from the "blue cloud" to the red sequence across the so-called “green valley”, the intermediate region in the color-magnitude plot between those two populations. We use spectral indices (specifically Dn(4000) and Hδ, A) to determine star formation histories. Together with an independent measurement of number density of galaxies in each bin of the color-magnitude plot, one can infer the rate at which galaxies from a given sample are transiting through that bin. Measuring this value for all magnitude values, studies at lower redshift determined that the mass flux density in the green valley is comparable to both the mass build-up rate of the red sequence and the mass loss rate from the blue cloud. We show preliminary results for our intermediate redshift sample.

Gaia will perform an unprecedented high quality survey of the Milky Way. Distances, 3D kinematics, ages and abundances will be obtained, giving access to the overall mass distribution and to the Galactic potential. Gaia data analysis will involve a high level of complexity requiring new and efficient multivariate data analysis methods, improved modelling of the stellar populations and dynamical approaches to the interpretation of the data in terms of the chemical and dynamical evolution of the Galaxy.

During the latest decades the number of papers on stellar chemical abundances has increased dramatically. This is basically reflecting the very great achievements in telescope- and spectrometer-construction technology. The analysis of the resulting stellar spectra, however, is still not up to the standard that is offered by the observational methods. Recent significant advances in the analysis methods (i.e., in constructing model atmospheres and model spectra to compare with the observed ones) is reviewed with the emphasis on the application to abundance analysis of late-type stars. It is found that the very considerable progress that have been made beyond mixing-length convection and LTE is a major break-through for physically consistent modeling. Still, however, further steps must be taken, in particular for the cooler stars, before the situation is fully satisifactory.

The large burst of complex type which occurred at the metric, decimetric and microwave wavelengths from 0203 to 0304 UT on 2004 November 10 is analyzed in this present article, some prominent features of this event are obtained from the correlative analysis of this event with the Hα flare and coronal mass ejection (CME) and the radiation process of this event is discussed based on these observational features.

NGC 7582 was identified as a starburst galaxy in the optical (Veron et al. 1981) but its X-ray emission is typical of a Seyfert 1 galaxy (Ward et al. 1978). We analyzed a datacube on this object obtained with the GMOS-IFU on the Gemini-South telescope. After a subtraction of the stellar component using the starlight code (Cid Fernandes et al. 2005), we looked for optical signatures of the AGN. We detected a broad Hα component (Figure 1) in the source where Bianchi et al. (2007) identified the AGN in an HST optical image. We also found a broad Hβ feature (Figure 2), but its emission reveals a extended source. We suggest that it is the light of the AGN scattered in the ionization cone. We propose that NGC 7582 is a Seyfert 1 galaxy. A number of other “hot-spots” and Wolf–Rayet features were also identified.

The structure and dynamics of the Galaxy contain information about both its current workings and its assembly history. I review our understanding of the dynamics of the disk and stellar halo, and sketch how these may be used to unravel how our Galaxy formed.

In the last few years a variety of lithium and beryllium surveys have been carried out among Pop. I stars in the field and open clusters, with the goal to trace the dependence of these element abundances on stellar mass, age, metallicity, and to understand the physical processes that lead to their depletion. I summarize here the most recent results, focusing on stars with temperatures similar to the Sun. In particular, I will discuss Li measurements in solar-type members of old open clusters, which definitively show that the low solar lithium is not the standard for a star of that age and mass.

The Antikythera Mechanism is the most sophisticated extant ancient astronomical instrument and analogue computer known and was assembled sometime between 150 and 100 BCE, almost a century after the death of Archimedes. The mechanism has a great educational potential as it appeals to inquiring minds as an astonishing artefact of science and technology. The latest research findings reveal significant cultural and social functions in its operations. This astonishing astronomical instrument has a clear interdisciplinary valueand it has that it may be used as an educational medium, to engage the general public, and especially to attract students both to/from exact sciences and to/from the humanities. The astronomical and technical knowledge embedded in the mechanism can also be used to introduce some aspects of modern science through the unknown technological achievements of Hellenic antiquity.

We present a review on relativistic effects and best estimates of the relativistic PPN parameter γ obtained by analysis of data from the International VLBI Service for Geodesy and Astrometry (IVS). Relativistic implications are also considered in view of the upcoming new generation VLBI System: VLBI2010.

Non-local thermodynamic equilibrium (NLTE) line formation for neutral and singly-ionized iron is considered through a range of stellar parameters characteristic of cool stars. A comprehensive model atom for Fe I and Fe II is presented. Our NLTE calculations support the earlier conclusions that the statistical equilibrium (SE) of Fe I shows an underpopulation of Fe I terms. However, the inclusion of the predicted high-excitation levels of Fe I in our model atom leads to a substantial decrease in the departures from LTE. As a test and first application of the Fe I/II model atom, iron abundances are determined for the Sun and four selected stars with well determined stellar parameters and high-quality observed spectra. Within the error bars, lines of Fe I and Fe II give consistent abundances for the Sun and two metal-poor stars when inelastic collisions with hydrogen atoms are taken into account in the SE calculations. For the close-to-solar metallicity stars Procyon and β Vir, the difference (Fe II - Fe I) is about 0.1 dex independent of the line formation model, either NLTE or LTE. We evaluate the influence of departures from LTE on Fe abundance and surface gravity determination for cool stars.

The Dark Energy Survey (DES) will cover 5000 sq. deg. in grizY filters. Although its main goals are related to cosmology, it will yield photometric measurements of over 108 stars, most of them belonging to the Galaxy. DES will increase the sampling depth of very low-luminosity stellar and sub-stellar species, such as white, red, and brown dwarfs, by a factor of several as compared to SDSS. The structure of the Galactic halo, including its complex sub-structures caused by accretion remnants and globular cluster tidal tails, will also be probed and analyzed. DES will also allow comparison of star counts between Northern and Southern Galactic hemispheres to unprecedented detail. Finally, a significant sample of stars in the outskirts of the Large Magellanic Cloud (LMC) will be studied, providing new light into the debate about the existence of an LMC spheroidal component. These, among other important research goals attainable with the DES stellar data, are discussed in this contribution.

We have tested the reliability of various meteoroid streams identification methods. We used a numerically generated set of meteoroid orbits (a stream component and a sporadic background) that were searched for streams using several methods.

Globular clusters (GCs) are stellar systems (~106 M⊙) with very regular symmetry, single age, and single metallicity. Spectroscopic studies have revealed very old ages, suggesting that GCs were formed in the earliest stages of galaxy formation and assembly. The aim of this work is to find out how far we can measure the GC luminosity function, specific frequency, and radial distribution, applying the surface-brightness-fluctuations (SBF) technique to deep ACS images. To this end, we apply the effects caused by higher redshift to HST/ACS images (in two optical bands, F606W and F814W) of M87, an elliptical galaxy with a very well-studied GC system. The effects involved are: (i) evolution, (ii) inverse k correction, (iii) binning of the image to smaller angular size, (iv) cosmological dimming of surface brightness, and (v) noise addition to account for different exposure times. After processing the images we detect the brightest GCs through direct photometry (e.g., with SExtractor), whereas the unresolved clusters are measured through SBFs. The above treatment is repeated for z=0.05, 0.1, 0.14, and 0.18, and the results are compared to the measurements at z=0 to estimate biases and incompleteness.