Data centres have a major role in the Virtual Observatory (VO), as they are the primary source of astronomical data. The VO cannot (and does not) dictate how a data centre handles its own archive. However, ‘VO-layer’ is needed to ‘translate’ any locally defined parameter to the standard (i.e., International Virtual Observatory Alliance compliant) ones. The longer term vision of the VO is also to hide away any observatory/telescope/instrument specific detail and work in astronomical units, for example, ‘wavelength range’ and not grism or filter name. Data providers are then advised to systematically collect metadata (‘data about data’) about the curation process, assign unique identifiers, describe the general content (e.g., physical coverage) of a collection, and provide interface and capability parameters of public services. Finally, the VO will work at its best with high-level (‘science-ready’) data, so that the VO user is spared as much as possible any complex and time consuming data reduction. Data centres should then make an effort to provide such data.

The closest neighbour of the Milky Way (MW) the Sagittarius dwarf Spheroidal Galaxy (Sgr dSph) is being tidally destroyed by the interaction with our Galaxy, losing its stellar content along a huge stream clearly detectable within the Halo. This makes the Sgr dSph an ideal laboratory to study at the same time the chemical evolution of dwarf galaxies and their role in building bigger structures such as the MW. Since some years we are studying the stellar populations of the Sgr main body and stream, with particular attention to their detailed chemical composition. We collected detailed abundances (up to 22 elements, O to Eu) for 27 stars in the Sgr dSph main body, 5 in the associated globular cluster Terzan 7, and 12 more in the trailing Sgr tidal arm (UVES@VLT and SARG@TNG data). We are also conducting a large FLAMES@VLT chemical and dynamical analysis aimed at obtaining metallicities, alpha-elements content and radial velocities from automated analysis of the spectra. Finally, we just completed the first large scale photometric and spectroscopic survey of the stellar populations across all the dSph main body extension with VIMOS@VLT, aimed at exploring the variations in stellar populations and at deriving radial velocity memberships for future high resolution spectroscopic analysis. The picture emerging from all these studies portraits a large and extremely complex object, with signs of a long and still unclear evolution. Metallicity varies across three orders of magnitude ([Fe/H] from −3 to 0), CMDs change surprisingly from the core to the outskirts of the galaxy, and the chemical composition of the most metal rich objects show a very characteristic signature, with underabundant alpha elements, deficient Na, underabundant Fe-peak Mn, Co, Ni, Cu and Zn, and strongly enhanced n-capture elements La and Nd. This highly peculiar signature can also be effectively used to recognized stripped populations lost by Sgr in favour of the MW system, as clearly showed by the globular Palomar 12, which shows the same chemical anomalies detected in Sgr dSph.

A CCD UBVRI survey of northern open clusters is being undertaken at San Pedro Mártir, México, and performed using always the same instrumental setup (telescope, CCD, filters), reduction methods, and system of standards of Landolt (1992). To date more than 300 clusters (mostly unstudied previously) have been observed, and about half the data reduced using aperture-photometry and PSF techniques. Our analysis procedures are being refined by studying in detail a small subset of these clusters. For example, the heavily reddened clusters Be80 and Be95 are being examined in the color-color diagrams: (B-V, U-B) and (B-V, R-I) to better understand the problems of curvature and variable reddening. For clusters for which our U data reaches the F-type stars, such as NGC2192 and NGC7296, techniques are being examined for estimating both the reddening E(B-V) and metallicity [Fe/H] via the use of the (U-B) excess. If the clusters also have “red clump” stars, such as NGC1798 and Do02, these procedures can be iterated between the clump and main sequence stars to establish even better the values of E(B-V) and [Fe/H]. Finally, color-magnitude diagrams, such as (B-V, V) and (V-I, V), are being employed together with the SchmidtKaler (1982) colors and Padova isochrones of Girardi et al. (2000) to obtain distances and ages for these clusters. A java-based computer program is being developed to help in the visualization and analysis of these photometric data. This system is capable of displaying each cluster simultaneously in different color-color and color-magnitude diagrams and has an interactive way to identify a star, or group of stars, in one diagram and to see were it falls in the other diagrams, facilitating the elimination of field stars and the apperception of cluster features. This program is capable of displaying up to 16 different diagrams for one cluster and processing up to 20 clusters at the same time. Our aims are the following: (1) a common UBVRI photometric scale for open clusters, (2) an atlas of color-color and color-magnitude diagrams for open clusters, (3) a homogeneous set of cluster reddenings, distances, and ages, (4) an increased number of old and distant open clusters, and (5) a selection of interesting clusters for further study.

One of the main goals of the Virtual Observatory activities right now is to provide the simple and powerful access to the large existing astronomical datasets in the VO compatible way. That is why we want present the results of the recent development of Sternberg Astronomical Institute Catalogue Access Services (SAI CAS) project – the first and the only project in Russia, which provides on-line access to the major astronomical catalogues and different services on top of them. It is developed by a group of astronomers in a framework of SAI Astronet project, funded by Russian Foundation for Basic Research. SAI CAS is an open-source implementation of the general Catalogue access service (influenced by SDSS CASjobs & OpenSkyQuery projects), based on original algorithms and open-source software. We decided to build our own system providing an effective access to the major astronomical catalogues and different services including cone-searches and cross-matching of user data with hosted catalogues.

The hot He-burning horizontal-branch (HB) stars and their progeny are most likely dominant ultraviolet (UV) sources in the old stellar population systems such as globular clusters (GCs). Integrated FUV flux can be an age indicator of GCs and allow us to investigate age distributions of GCs within a given galaxy or between galaxies. The unprecedented set of UV photometry for M31 by Galaxy Evolution Explorer (GALEX), coupled with most recent detailed population models enable to study detailed global UV properties of M31 GCs.

The Virtual Observatory provides a natural solution to the existence problem in communications: how can one ask a question of another unless you know the other exists? Many think e-mail from apparent strangers, e-blogs, etc., suggest there is no shortage of possible such solutions. In that context, is the Virtual Observatory in fact the necessary and desirable part of the solution? Specifically, does the VO necessarily play a critical role in delivering end-to-end facility science, from ideas, through proposals, resources/facilities, to distributed, reviewed, knowledge? If not, what else needs to be added?

The true nature of the faint radio population remains elusive despite the many observations of the “sub-mJy” bump over the last two decades. This lack of information is largely due to the faint magnitudes of the optical counterparts to the radio sources. There are strong theoretical reasons (and a few observational ones) to believe that this rise in the counts is due to the emergence of a rapidly evolving star-forming population. Now, for the first time, we are able to separate the AGN and star-forming populations below 1mJy using a combination of multi-wavelength data from Spitzer, GMRT, MERLIN, CFHT, Keck, UKIRT, Subaru, Chandra and XMM-Newton. The many discriminators between these emission mechanisms include MIR colours, MIR/radio flux ratios, X-ray luminosities/spectra, optical spectra, radio morphologies and radio spectra. We can now derive the source counts separately for AGN and star-forming galaxies confirming that the latter population rise sharply at faint flux densities.

ANCHORS is a web based archive of all the point sources observed during Chandra observations of regions of star formation. It is designed to aid both the X-ray astronomer with a desire to compare X-ray datasets and the star formation astronomer wishing to compare stars across the spectrum. For some 50 Chandra fields, yielding 10000+ sources, the database contains X-ray source properties including position, net count rates, flux, hardness ratios, lightcurve statistics and plots.

The Canadian Astronomy Data Centre manages a heterogeneous collection of data from the following ground and space-based telescopes: CFHT, DRAO, FUSE, Gemini, HST, JCMT, and MOST. The archive data models implemented for these data collections are ten years old and pre-date two important developments: the Virtual Observatory and the systematic generation and management of data products. Three years ago, we began the process of supporting access to processed data products through IVOA protocols such as SIA by building a layer over the archive data models. Today, we now realise that this approach of layering VO models on archive models is not sufficient and that every archive must be re-tooled to properly support the VO – from the storage model through to the query, processing and access models. The CADC has begun an ambitious software development effort to implement a new infrastructure to serve both telescope archive and Virtual Observatory needs.

Using photoionization models applied to the data from the Sloan Digital Sky Survey (SDSS) we propose a physically motivated dividing line in the [OIII]/Hβ vs [NII]/Hα (BPT) diagram between normal star forming (NSF) galaxies and AGN hosts. We also propose a new diagnostic diagram which can be used for optical spectra of galaxies with redshifts up to z= 1.3.

We select far-infrared (60 μm) and far-ultraviolet (1530Å) samples of nearby galaxies. We derived distributions of the bolometric luminosity of young stars in both samples: they are found to be consistent with each other for galaxies of intermediate luminosities but some differences are found for high (>5 × 1010L⊙) luminosities. The ratio of the total IR luminosity to the FUV one is found to increase with the bolometric luminosity in a similar way for both samples up to 5 × 1010L⊙. Brighter galaxies are found to have a different behavior according to their selection: the LTIR/LFUV ratio of the FUV selected galaxies brighter than 5 × 1010L⊙ reaches a plateau whereas LTIR/LFUV continues to increase with the luminosity of bright galaxies selected in FIR. The volume averaged specific star formation rate (SFR per unit galaxy stellar mass, SSFR) is found to decrease toward massive galaxies within each selection. The SSFR is found larger than that measured for optical and NIR selected sample for the whole mass range for the FIR selection and for masses larger than 1010M⊙ for the FUV selection. Luminous and massive galaxies selected in FIR appear as active as galaxies with similar characteristics detected at z ~ 0.7. Details are presented in Buat et al. (2006).

The Space Telescope Science Institute (STScI), in collaboration with the European Coordinating Facility (ECF), and the Canadian Astronomy Data Centre (CADC), is studying the development of an enhanced archive for the Hubble Space TelescopeHST), with the goal of improving the scientific value of the data. The primary enhancements would be:

Many fundamental problems in optical astronomy – from planetary science, galactic structure, optical transients, to large-scale structure and cosmology – could be addressed though the same data set with millions of exposures in superb seeing, in multiple passbands, to very faint magnitudes over a large area of sky. This capability is largely driven by technology. In a logical progression towards this scientific capability, several increasingly ambitious wide-field optical surveys are planned in the next few years. A uniform high quality database covering all these science areas would be an ideal match to the VO. The above utopian goal of simultaneous pursuit of parallel surveys is achievable, but it relies on the ability to image a wide field quickly and deeply, and it is a non-linear function of the camera+telescope étendue.

We present a spectrophotometric study of circumnuclear star forming regions (CNSFR) in the galaxies: NGC 2903, NGC 3351 and NGC 3504, all of them of over solar metallicity according to standard empirical calibrations. A detailed determination of their abundances is made after careful subtraction of the prominent underlying stellar absorption. It is found that most regions show the highest abundances in HII region-like objects. It is also shown that CNSFR, as a class, segregate from the disk HII region family, clustering around smaller η' values, and therefore higher ionizing temperatures.

From [Sii],λλ 6717,6731 Å lines, we have derived an electron density range from 180 to 650 −3, with average values of around 350 cm−3, higher than that found in Giant Extragalactic HII Regions (GEHR). The very low intensity of the [Oiii] lines (λλ 4959, 5007 Å implies high metallicity. Measurement of line temperature of [Oiii] (t[Oiii]) requires detection of auroral [Oiii]λ 4363 Å lines a few percent of [Oiii]λ 5007 Å which is impossible.

Therefore, abundances for most of the regions require the use of empirical methods. CNSFRs show values of O23 (=([Oii]3727+[Oiii]4959, 5007)/Hβ; Pagel et al., 1979. MNRAS.189.95) which indicate oversolar metallicities, but the actual values are difficult to estimate since O23 levels off. At times [Oiii] lines are very difficult to measure. The combined parameter S23/O23 (S23 = ([Sii]6717, 6731+[Siii]9069, 9532)/Hβ; Vílchez & Esteban, 1996. MNRAS.280.720) yields values of the oxygen abundances higher than twice solar. Also the N2 parameter (log([Nii]/Hβ; Denicoló, Terlevich & Terlevich, 2002. MNRAS.330.69) renders oversolar abundances. Furthermore, the CNSFRs of our sample show the highest values of the ratio N/O known for the HII region-like objects.

When we study the relation between the metallicity and the ionisation degree parametrized by the ratio [Sii]6717, 6731[Siii]9069, 9532 we find that the CNSFRs of our sample are among the HII region-like objects with the lowest ionisation parameter. Moreover, we estimate that the S23 parameter is, in this case, better than N2 to discriminate between different metallicities.

The temperature of the ionising stars can be parametrized by the “softness parameter” η' (=([Oii]3727/[Oiii]4959, 5007)/([Sii]6717, 6731/[Siii]9069, 9532); Vílchez & Pagel, 1988. MNRAS.231.257). This parameter can be used as an ionising temperature indicator. Analysing N2 vs. η' we find that the CNSFR of our sample have, in general, lower values of η' than those of the GEHRs, implying higher temperatures. In an Eta Prime Plot (log([Oii]3727/[Oiii]4959, 5007) vs. log([Sii]6717, 6731/[Siii]9069, 9532)) we can see that the CNSFRs follow the behaviour of HII galaxies rather than that of GEHR implying, again, higher temperatures.

Some general conclusions are: CNSFR spectra are difficult to analyse; they show prominent underlying stellar populations so a careful subtraction of the absorption spectrum can be critical; abundance determination mostly comes from empirical calibrations. Furthermore, some conclusions derived from line diagnostics are that CNSFR can show very high metal abundances and N/O overabundances too; they show indications of low ionization parameter; regarding the temperature of ionizing stars, CNSFRs seem to share more properties with HII galaxies than with disk GEHR, which is puzzling.

Observational astronomy is entering an exciting new era with large surveys delivering deep multi-wavelength data over a wide range of the electromagnetic spectrum. The last ten years has seen a growth in the study of high redshift galaxies discovered with the method pioneered by Steidel et al. (1995) used to identify galaxies above z>1. The technique is designed to take advantage of the multi-wavelength data now available for astronomers that can extend from X-rays to radio wavelength. The technique is fast becoming a useful way to study large samples of objects at these high redshifts and we are currently designing and implementing an automated technique to study these samples of objects. However, large surveys produce large data sets that have now reached terabytes (e.g. for the Sloan Digital Sky Survey, <http://www.sdss.org>) in size and petabytes over the next 10yr (e.g., LSST, <http://www.lsst.org>). The Virtual Observatory is now providing a means to deal with this issue and users are now able to access many data sets in a quicker more useful form.

Some preliminary results focused on the kinematics and dynamics of the ionized gas in the Local Group dwarf irregular galaxy IC10 are presented.

We are using NVO tools to obtain a large (N≃100), uniform (SDSS images, cross checked with HST images; analyzed using WESIX) database of super star clusters in nearby star-forming galaxies in order to address two fundamental astronomical questions: (i) Is the initial luminosity function of star clusters universal?; and (ii) What fraction of super star clusters is ‘missing’ in optical studies (i.e., are hidden by dust)?

We developped a 3D Monte Carlo Lyα radiation transfer code to understand the diversity of Lyα line profiles observed in star forming galaxies and related objects (Verhamme et al. 2006). Our code allows for prescribed arbitrary hydrogen density, ionisation, temperature structures, and dust distributions, and arbitrary velocity fields and UV photon sources.Here we present results from the first modelling of the Lyα line and of the UV spectrum with our code of a sample of z ~ 3 Lyman break galaxies observed by Steidel and collaborators (Pettini et al. 2002) and taken from the FORS Deep Field (Tapken et al. 2006). A simple model of an expanding neutral shell surrounding a starburst region can reproduce the whole variety of spectra ranging from double-peaked profiles to asymetric emission lines, P-Cygni profiles or broad absorption. The main determining parameters are the outflow velocity and the dust content. Other parameters such as the hydrogen column density, the intrinsic Lyα emission and hence SFR, and the intrinsic Lyα line widths can be determined consistently taking all radiation transfer effects into account.

I discuss current observational constraints on the star-formation and stellar-assembly histories of galaxies at high redshifts. The data on massive galaxies at z < 1 implies that their stellar populations formed at z>2, and that their morphological configuration was in place soon thereafter. Spitzer Space Telescope 24 μ observations indicate that a substantial fraction of massive galaxies at z ~ 1.5–3 have high IR luminosities, suggesting they are rapidly forming stars, accreting material onto supermassive black holes, or both. I compare how observations of these IR–active phases in the histories of massive galaxies constrain current galaxy–formation models.

The main goal of the Armenian Virtual Observatory is to develop efficient methods for science projects based on the digitized famous Markarian survey (Digitized First Byurakan Survey, DFBS) and other large astronomical databases, both Armenian and international. Two groups of projects are especially productive: search for new interesting objects of definite types by low-dispersion template spectra, and optical identifications of new gamma, X-ray, IR and radio sources. The first one is based on modeling of spectra for a number of types of objects: QSOs, Seyfert galaxies, white dwarfs, subdwarfs, cataclysmic variables, planetary nebulae, late-type stars (K-M, S, carbon), etc. Each kind of object appears in the DFBS with its typical SED and spectral lines (for objects having broad lines only, like white dwarfs and subdwarfs, quasars and Seyferts, etc.), however affected also by its brightness, so that each template works for definite range of magnitudes. The search criteria define how many objects will be found for further study, and may restrict these numbers leaving with the best candidates. Optical identifications have been proven to be rather efficient for IR sources from IRAS-psc and -fsc. Tests have been carried out for X-ray and radio sources as well. Special emphasis is put on search for bright QSOs missed by the Sloan Digital Sky Survey (SDSS), rather important for making up their complete sample, studies of the properties of the Local Universe, a comparison of their X-ray, IR, and radio properties and making up their multiwavelength SEDs, as well as for a refinement of the AGN classification. A project for search for new bright QSOs using the DFBS has been started in the region with δ>0° and |b|>20°. The Byurakan 2.6m telescope is being used for the spectral identification of the candidates. The first test resulted in 145 objects found, 81 being known QSOs/Sys, and 64 new candidates (including 23 NVSS and FIRST radio sources).