Ivan Zolotukhin

Analytical approximations of K‐corrections in optical and near‐infrared bands

To compare photometric properties of galaxies at different redshifts, the fluxes need to be corrected for the changes of effective rest-frame wavelengths of filter bandpasses, called K-corrections. Usual approaches to compute them are based on the template fitting of observed spectral energy distributions (SED) and, thus, require multicolour photometry. Here, we demonstrate that, in cases of widely used optical and near-infrared (NIR) filters, K-corrections can be precisely approximated as two-dimensional low-order polynomials of only two parameters: redshift and one observed colour. With this minimalist approach, we present the polynomial fitting functions for K-corrections in Sloan Digital Sky Survey (SDSS) ugriz, United Kingdom Infrared Telescope (UKIRT) Wide Field Camera YJHK, Johnson-Cousins U BV R c I c and Two Micron All Sky Survey J H K s bands for galaxies at redshifts Z < 0.5 based on empirically computed values obtained by fitting combined optical-NIR SEDs of a set of 10 5 galaxies constructed from SDSS Data Release 7 (DR7) and UKIRT Infrared Deep Sky Survey DR5 photometry using the Virtual Observatory. For luminous red galaxies we provide K-corrections as functions of their redshifts only. In two filters, g and r, we validate our solutions by computing K-corrections directly from SDSS DR7 spectra. We also present a K-corrections calculator, a web-based service for computing K-corrections online.

Period–luminosity relation for persistent low-mass X-ray binaries in the near-infrared

We study relations between the X-ray luminosity, orbital period and absolute near-infrared magnitude of persistent low-mass X-ray binaries (LMXBs). We show that often optical and near-infrared spectral energy distribution of LMXBs can be adequately described by a simple model of an accretion disc and a secondary star reprocessing X-ray emission of a central compact object. This gives us an evidence that using an X-ray luminosity and an absolute infrared magnitude of a persistent LMXB one can make reliable estimate of its orbital period. Using a sample of well-known LMXBs, we have constructed a correlation of L_X, P_orb and M_K values which can be approximated by a straight line with the RMS scatter at the level of ~0.3 mag. Such a correlation, being to some extent an analogous to the correlation, found by van Paradijs & McClintock 1994, might be helpful for future population studies especially in the light of forthcoming surveys of the Galaxy in X-ray and infrared spectral domains.

Sample of LMXBs in the Galactic bulge – I. Optical and near‐infrared constraints from the Virtual Observatory

We report on the archival optical and near-infrared observations of six low-mass X-ray binaries situated in the Galactic bulge. We process several recent Chandra and XMM-Newton as well as Einstein data sets of binary systems suspected to be ultracompact, which give us arcsec-scale positional uncertainty estimates. We then undertake a comprehensive search in existing archives and other Virtual Observatory resources in order to discover unpublished optical/near-infrared data on these objects. We find and analyse data from European Southern Observatory Archive and UKIRT Infrared Deep Sky Survey on SLX 1735-269, 3A 1742-294, SLX 1744-299, SLX 1744-300, GX 3+1 and IGR J17505-2644 systems and publish their finding charts and optical flux constraints in this paper, as well as simple estimates of the physical parameters of these objects.

Virtual Observatory based identification of AX J194939+2631 as a new cataclysmic variable

We report the discovery of a new cataclysmic variable (CV) among unidentified objects from the ASCA Galactic Plane Survey made using the Virtual Observatory data mining. First, we identified AX J194939+2631 with IPHAS J194938.39+263149.2, the only prominent H-alpha emitter among 400 sources in a 1 arcmin field of the IPHAS survey, then secured as a single faint X-ray source found in an archival Chandra dataset. Spectroscopic follow-up with the 3.5-m Calar Alto telescope confirmed its classification as a CV, possibly of magnetic nature. Our analysis suggests that AX J194939+2631 is a medium distance system (d ~ 0.6 kpc) containing a late-K or early-M type dwarf as a secondary component and a partially disrupted accretion disc revealed by the double-peaked H-alpha line. However, additional deep observations are needed to confirm our tentative classification of this object as an intermediate polar.

Infrared identification of 4U1323‐619 revisited

We re-examine the infrared counterpart of the dipping low-mass X-ray binary 4U1323-619. New X-ray data available from the XMM and Chandra observatories combined with archival infrared observations from the European Southern Observatory 3.6-m New Technology Telescope allow us to define a new possible counterpart. We present here its photometric properties and compare them with a simple analytical model of an accretion disc illuminated by a hot central corona.

Search for and investigation of new stellar clusters using the data from huge stellar catalogues

We present new automatic methods of search for star clusters using the data available in new huge stellar catalogues. Using 2MASS catalogue we have discovered over ten new open clusters in the region of Galaxy anticenter and determined their physical parameters.G01 New evidence for a connection between massive black holes and ULX G02 Long-Term Evolution of Massive Black Hole Binaries G03 NBODY Meets Stellar Population Synthesis G04 N-body modelling of real globular star clusters G05 Fokker-Planck rotating models of globular clusters with black hole G06 Observational Manifestation of chaos in spiral galaxies: quantitative analysis and qualitative explanation G07 GRAPE Clusters: Beyond the Million-Body Problem G08 Orbital decay of star clusters and Massive Black Holes in cuspy galactic nuclei G09 An Edge-on Disk Galaxy Catalog G10 Complexes of open clusters in the Solar neighborhood G11 Search for and investigation of new stellar clusters using the data from huge stellar catalogues G12 Computing 2D images of 3D galactic disk models G13 Outer Pseudoring in the Galaxy G14 Where are tidal-dwarf galaxies? G15 Ultra compact dwarf galaxies in nearby clusters G16 Impact of an Accretion Disk on the Structure of a stellar cluster in active galactic nuclei G17 Order and Chaos in the edge-on profiles of disk galaxies G18 On the stability of OB-star configurations in the Orion Nebula cluster G19 Older stars captured in young star clusters by cloud collapse G20 General features of the population of open clusters within 1 kpc from the Sun G21 Unstable modes in thin stellar disks G22 From Newton to Einstein – Dynamics of N-body systems G23 On the relation between the maximum stellar mass and the star cluster mass

RCSED—A Value-added Reference Catalog of Spectral Energy Distributions of 800,299 Galaxies in 11 Ultraviolet, Optical, and Near-infrared Bands: Morphologies, Colors, Ionized Gas, and Stellar Population Properties*

We present RCSED, the value-added Reference Catalog of Spectral Energy Distributions of galaxies, which contains homogenized spectrophotometric data for 800,299 low and intermediate redshift galaxies (0.007 < z < 0.6) selected from the Sloan Digital Sky Survey spectroscopic sample. Accessible from the Virtual Observatory (VO) and complemented with detailed information on galaxy properties obtained with the state-of-the-art data analysis, RCSED enables direct studies of galaxy formation and evolution during the last 5 Gyr. We provide tabulated color transformations for galaxies of different morphologies and luminosities and analytic expressions for the red sequence shape in different colors. RCSED comprises integrated k-corrected photometry in up-to 11 ultraviolet, optical, and near-infrared bands published by the GALEX, SDSS, and UKIDSS wide-field imaging surveys; results of the stellar population fitting of SDSS spectra including best-fitting templates, velocity dispersions, parameterized star formation histories, and stellar metallicities computed for instantaneous starburst and exponentially declining star formation models; parametric and non-parametric emission line fluxes and profiles; and gas phase metallicities. We link RCSED to the Galaxy Zoo morphological classification and galaxy bulge+disk decomposition results by Simard et al. We construct the color–magnitude, Faber–Jackson, mass–metallicity relations, compare them with the literature and discuss systematic errors of galaxy properties presented in our catalog. RCSED is accessible from the project web-site and via VO simple spectrum access and table access services using VO compliant applications. We describe several SQL query examples against the database. Finally, we briefly discuss existing and future scientific applications of RCSED and prospectives for the catalog extension to higher redshifts and different wavelengths.

Open Clusters Science in the Virtual Observatory Era

We present http://ocl.sai.msu.ru, a modern web application with an integrated rich set of third-party analysis tools aimed at facilitating astrophysical research with the Open Cluster Catalog of the Sternberg Astronomical Institute (Koposov et al. Astron. Astrophys. 486:771, 2008; Glushkova et al. Astron. Lett. 36:75, 2010). Discovered using Virtual Observatory (VO) technologies, almost 200 new open clusters are presented in a way that allows further exploitation of the multiple VO-compatible datasets through the single web site serving as an entry point. As more datasets become available (e.g. UCAC3 with proper motions Zacharias et al. Astron. J., 139:2184, 2010), new research perspectives arise with this set of open clusters making it possible to do quick-look science online, which have successfully been demonstrated during several VO-Science tutorials. If populated with a more comprehensive set of open clusters, this tool may become a new WEBDA prototype in the VO era. In this manuscript we also briefly describe steps of a demonstration shown as a contributed talk at JENAM-2010 conference to give an overlook of what kind of original research studies it is now possible to do online.

Properties of Star Clusters Found and Investigated by Data from Large Surveys

An automated method capable of searching for star clusters in large surveys has been applied to J, H, K s data from 2MASS catalog. Totally, we found and verified 168 new clusters; for 142 of them, we evaluated ages, distances and color excesses using photometric data from the 2MASS and UKIDSS surveys. Most of new clusters are older than 100 Myr and have distances within the range 1–4 kpc. 26 newly discovered objects are embedded clusters. An independent check against UBVI photometric data obtained at a 104-cm Sampurnanad telescope demonstrated a very good agreement of our results with these observational data. Some known, but doubted or poorly studied clusters were also investigated using the 2MASS catalog.