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Sample records for rosat galex 2mass

  1. Panchromatic Properties of 99,000 Galaxies Detected by SDSS, and (some by) ROSAT, GALEX, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS Surveys

    CERN Document Server

    Obric, M; Best, P N; Lupton, R H; Tremonti, C A; Brinchmann, J; Agüeros, M A; Knapp, G R; Gunn, J E; Rockosi, C M; Schlegel, D J; Finkbeiner, D; Gacesa, M; Smolcic, V; Anderson, S F; Voges, W; Juric, M; Siverd, R J; Steinhardt, W; Jagoda, A S; Blanton, M R; Schneider, D P

    2006-01-01

    We discuss the panchromatic properties of 99,088 galaxies selected from the SDSS Data Release 1 spectroscopic sample (a flux-limited sample for 1360 deg^2). These galaxies are positionally matched to sources detected by ROSAT, GALEX, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS. We find strong correlations between the detection fraction at other wavelengths and optical properties such as flux, colors, and emission-line strengths. Using GALEX, SDSS, and 2MASS data, we construct the UV-IR broad-band spectral energy distributions for various types of galaxies, and find that they form a nearly one-parameter family. For example, based on SDSS u- and r-band data, supplemented with redshift, the K-band 2MASS magnitudes can be "predicted" with an rms scatter of only 0.2 mag. When a dust content estimate determined from SDSS data by Kauffmann et al. (2003) is also utilized, this scatter decreases to 0.1 mag. We demonstrate that this dust content is indeed higher for galaxies detected by IRAS and that it can be used to "pre...

  2. Panchromatic properties of 99 000 galaxies detected by SDSS, and (some by) ROSAT, GALEX, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS surveys

    NARCIS (Netherlands)

    Obric, M.; Ivezic, Z.; Best, P. N.; Lupton, R. H.; Tremonti, C.; Brinchmann, J.; Agueeros, M. A.; Knapp, G. R.; Gunn, J. E.; Rockosi, C. M.; Schlegel, D.; Finkbeiner, D.; Gacesa, M.; Smolcic, V.; Anderson, S. F.; Voges, W.; Juric, M.; Siverd, R. J.; Steinhardt, W.; Jagoda, A. S.; Blanton, M. R.; Schneider, D. P.

    2006-01-01

    We discuss the panchromatic properties of 99 088 galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 1 'main' spectroscopic sample ( a flux-limited sample for 1360 deg(2)). These galaxies are positionally matched to sources detected by ROSAT, Galaxy Evolution Explorer (GALEX), tw

  3. Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands

    OpenAIRE

    2013-01-01

    Using the "standard pair" technique of paring stars of almost nil and high extinction but otherwise of almost identical stellar parameters from the SDSS, and combing the SDSS, GALEX, 2MASS and WISE photometry ranging from the far UV to the mid-IR, we have measured dust reddening in the FUV-NUV, NUV-u, u-g, g-r, r-i, i-z, z-J, J-H, H-Ks, Ks-W1 and W1-W2 colors for thousands of Galactic stars. The measurements, together with the E(B-V) values given by Schlegel et al. (1998), allow us to derive ...

  4. Properties of Near-Infrared Selected AGN Candidates with 2MASS/ROSAT Catalogues

    CERN Document Server

    Kouzuma, Shinjirou

    2010-01-01

    We report on the near-infrared selected AGN candidates extracted from 2MASS/ROSAT catalogues and discuss their properties. First, near-infrared counterparts of a X-ray source in ROSAT catalogues (namely, Bright Source Catalogue (BSC) and Faint Source Catalogue (FSC)) were extracted by positional cross-identification of <=30''. Because these counterparts would contain many mis-identifications, we further imposed near-infrared colour selection criteria and extracted reliable AGN candidates (BSC: 5,273, FSC: 10,071). Of 5,273 (10,071) candidates in the BSC (FSC), 2,053 (1,008) are known AGNs. Near-infrared and X-ray properties of candidates show similar properties with known AGNs and are consistent with previous studies. We also searched for counterparts in other wavelengths (that is, optical, near-infrared, and radio), and investigated properties in multiwavelength. No significant difference between known AGNs and unclassified sources could be seen. However, some unclassified sources in the FSC showed slight...

  5. Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands

    CERN Document Server

    Yuan, Hai-Bo; Xiang, Mao-Sheng

    2013-01-01

    Using the "standard pair" technique of paring stars of almost nil and high extinction but otherwise of almost identical stellar parameters from the SDSS, and combing the SDSS, GALEX, 2MASS and WISE photometry ranging from the far UV to the mid-IR, we have measured dust reddening in the FUV-NUV, NUV-u, u-g, g-r, r-i, i-z, z-J, J-H, H-Ks, Ks-W1 and W1-W2 colors for thousands of Galactic stars. The measurements, together with the E(B-V) values given by Schlegel et al. (1998), allow us to derive the observed, model-free reddening coefficients for those colors. The results are compared with previous measurements and the predictions of a variety of Galactic reddening laws. We find that 1) The dust reddening map of Schlegel et al. (1998) over-estimates E(B-V) by about 14 per cent, consistent with the recent work of Schlafly et al. (2010) and Schlafly & Finkbeiner (2011); 2) All the new reddening coefficients, except those for NUV-u and u-g, prefer the R(V) = 3.1 Fitzpatrick reddening law rather than the R(V) = 3...

  6. Searching for Young M Dwarfs with GALEX

    CERN Document Server

    Shkolnik, Evgenya L; Reid, Iain Neill; Dupuy, Trent; Weinberger, Alycia

    2010-01-01

    The census of young moving groups in the solar neighborhood is significantly incomplete in the low-mass regime. We have developed a new selection process to find these missing members based on the GALEX All-Sky Imaging Survey (AIS). For stars with spectral types later than K5 (R - J >= 1.5) and younger than ~300 Myr, we show that near-UV (NUV) and far-UV (FUV) emission is greatly enhanced above the quiescent photosphere, analogous to the enhanced X-ray emission of young low-mass stars seen by ROSAT but detectable to much larger distances with GALEX. By combining GALEX data with optical (HST Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 sq. deg. region around the 10-Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had H_alpha in emission, which were then followed-up at high resolution to search for spectroscopic evidence of youth and to measure their radial velocities. Four objects have low s...

  7. XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources

    CERN Document Server

    Haakonsen, Christian Bernt; 10.1088/0067-0049/184/1/138

    2009-01-01

    The 18806 ROSAT All Sky Survey Bright Source Catalog (RASS/BSC) X-ray sources are quantitatively cross-associated with near-infrared (NIR) sources from the Two Micron All Sky Survey Point Source Catalog (2MASS/PSC). An association catalog is presented, listing the most likely counterpart for each RASS/BSC source, the probability Pid that the NIR source and X-ray source are uniquely associated, and the probability Pnoid that none of the 2MASS/PSC sources are associated with the X-ray source. The catalog includes 3853 high quality (Pid>0.98) X-ray--NIR matches, 2280 medium quality (0.98>Pid>0.9) matches, and 4153 low quality (0.9>Pid>0.5) matches. Of the high quality matches, 1418 are associations that are not listed in the SIMBAD database, and for which no high quality match with a USNO-A2 optical source was presented for the RASS/BSC source in previous work. The present work offers a significant number of new associations with RASS/BSC objects that will require optical/NIR spectroscopy for classification. For...

  8. XRT -- ROSAT XRT Data Reduction

    Science.gov (United States)

    Davenhall, A. C.; Platon, R. T.

    XRT is a package for reducing data acquired with the ROSAT XRT instruments. The XRT (X-Ray Telescope) was the principal scientific payload of the ROSAT X-ray astronomy satellite. The XRT had two instruments: the PSPC (Position Sensitive Proportional Counter) and the HRI (High Resolution Imager). The XRT package operates on data produced by these instruments and can be used to transform them into calibrated images, spectra, time-series etc. XRT was created by taking the ROSAT XRT-specific functions in the ASTERIX general X-ray astronomy data reduction system and re-packaging them as stand-alone applications.

  9. New GALEX UV Data Products At MAST For Stellar Astrophysics

    Science.gov (United States)

    Shiao, Bernie; Fleming, S. W.; Million, C.; Seibert, M.; Bianchi, L.; Thompson, R.; Tseng, S.; Adler, W. J.; Hubbard, M.; Levay, K.; Madore, B. F.; Martin, C. D.; Nieto-Santisteban, M. A.; Sahai, R.; Schiminovich, D.; White, R. L.; Wyder, T. K.

    2014-01-01

    The Galaxy Evolution Explorer (GALEX) mission ended in June 2013 after ten years in orbit. Its FUV and NUV microchannel plate detectors were used to conduct a variety of direct imaging and spectroscopic astronomical surveys with various depths and sky coverage, recording individual photon events with a time resolution of five thousandths of a second. Although the mission has ended, MAST is continuing to provide new data products as the mission transitions to a legacy archive. One product is the GCAT (Seibert et al., in prep), a catalog of GALEX sources across the entire GR6 data release that removes duplicate objects found in the GALEX MCAT. The GCAT defines "primary" NUV and FUV fluxes within the AIS and MIS surveys 40 million and 22 million sources, respectively), accounting for tile overlaps, and with visual inspection of every tile to flag artifacts and conduct other quality control checks. Another catalog of unique sources is that of Bianchi et al. (2013). Similar to the GCAT, their catalog produces a list of distinct GALEX sources in both the FUV and NUV from the AIS and MIS surveys, and includes data from GR7 (through the end of 2012). They have also cross-matched their sources with SDSS DR9, GSC-II, PanSTARRS, and 2MASS. We review access options for these catalogs, including updated matches between the GCAT and SDSS / Kepler available at MAST. In addition to these unique GALEX source catalogs, MAST will provide a database and software package that archives each of the ~1.5 trillion photon events detected over the lifetime of the mission. For the first time, users will be able to create calibrated lightcurves, intensity maps, and animated movies from any set of photons selected across any tile, and with specified aperture sizes, coordinates, and time steps. Users can access the data using either a python-based command-line software package, through a web interface at MAST, or (eventually) through CasJobs using direct SQL queries. We present some example

  10. An Updated Ultraviolet Catalog of GALEX Nearby Galaxies

    CERN Document Server

    Bai, Yu; Liu, JiFeng; Wang, Song

    2015-01-01

    The ultraviolet catalog of nearby galaxies made by \\citet{Gil07} presents the integrated photometry and surface brightness profiles for 1034 nearby galaxies observed by \\textit{Galaxy Evolution Explorer} (\\textit{GALEX}). We provide an updated catalog of 4138 nearby galaxies based on the latest Genral Release (GR6/GR7) of \\textit{GALEX}. These galaxies are selected from HyperLeda with apparent diameter larger than 1{\\arcmin}. From the surface brightness profiles accurately measured with the deep NUV and FUV images, we have calculated asymptotic magnitudes, aperture (D25) magnitudes, colors, structural parameters (effective radii and concentration indices), luminosities, and effective surface brightness. Archival optical and infrared photometry from HyperLeda, 2MASS, and IRAS are also integrated into the catalog. Our parameter measurements and some analyses are consistent with those of \\citet{Gil07}. The (FUV $- K$) color provides a good criterion to distinguish early and late-type galaxies, which can be impro...

  11. Colors of Ellipticals from GALEX to Spitzer

    CERN Document Server

    Schombert, J

    2016-01-01

    Multi-color photometry is presented for a large sample of local ellipticals selected by morphology and isolation. The sample uses data from GALEX, SDSS, 2MASS and Spitzer to cover the filters NUV, ugri, JHK and 3.6mum. Various two-color diagrams, using the half-light aperture defined in the 2MASS J filter, are very coherent from color to color, meaning that galaxies defined to be red in one color are always red in other colors. Comparison to globular cluster colors demonstrates that ellipticals are *not* composed of a single age, single metallicity (e.g., [Fe/H]) stellar population, but require a multi-metallicity model using a chemical enrichment scenario. Such a model is sufficient to explain two-color diagrams and the color-magnitude relations for all colors using only metallicity as a variable on a solely 12 Gyrs stellar population with no evidence of stars younger than 10 Gyrs. The [Fe/H] values that match galaxy colors range from -0.5 to +0.4, much higher (and older) than population characteristics dedu...

  12. Colors of Ellipticals from GALEX to Spitzer

    Science.gov (United States)

    Schombert, James M.

    2016-12-01

    Multi-color photometry is presented for a large sample of local ellipticals selected by morphology and isolation. The sample uses data from the Galaxy Evolution Explorer (GALEX), Sloan Digital Sky Survey (SDSS), Two Micron All-Sky Survey (2MASS), and Spitzer to cover the filters NUV, ugri, JHK and 3.6 μm. Various two-color diagrams, using the half-light aperture defined in the 2MASS J filter, are very coherent from color to color, meaning that galaxies defined to be red in one color are always red in other colors. Comparison to globular cluster colors demonstrates that ellipticals are not composed of a single age, single metallicity (e.g., [Fe/H]) stellar population, but require a multi-metallicity model using a chemical enrichment scenario. Such a model is sufficient to explain two-color diagrams and the color-magnitude relations for all colors using only metallicity as a variable on a solely 12 Gyr stellar population with no evidence of stars younger than 10 Gyr. The [Fe/H] values that match galaxy colors range from -0.5 to +0.4, much higher (and older) than population characteristics deduced from Lick/IDS line-strength system studies, indicating an inconsistency between galaxy colors and line indices values for reasons unknown. The NUV colors have unusual behavior, signaling the rise and fall of the UV upturn with elliptical luminosity. Models with blue horizontal branch tracks can reproduce this behavior, indicating the UV upturn is strictly a metallicity effect.

  13. AN UPDATED ULTRAVIOLET CATALOG OF GALEX NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yu; Zou, Hu; Liu, JiFeng; Wang, Song, E-mail: ybai@nao.cas.cn, E-mail: zouhu@nao.cas.cn, E-mail: jfliu@nao.cas.cn, E-mail: songw@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang Distict, 100012 Beijing (China)

    2015-09-15

    The ultraviolet (UV) catalog of nearby galaxies compiled by Gil de Paz et al. presents the integrated photometry and surface brightness profiles for 1034 nearby galaxies observed by GALEX. We provide an updated catalog of 4138 nearby galaxies based on the latest Genral Release (GR6/GR7) of GALEX. These galaxies are selected from HyperLeda with apparent diameters larger than 1′. From the surface brightness profiles accurately measured using the deep NUV and FUV images, we have calculated the asymptotic magnitudes, aperture (D25) magnitudes, colors, structural parameters (effective radii and concentration indices), luminosities, and effective surface brightness for these galaxies. Archival optical and infrared photometry from HyperLeda, 2MASS, and IRAS are also integrated into the catalog. Our parameter measurements and some analyses are consistent with those of Paz et al. The (FUV − K) color provides a good criterion to distinguish between early- and late-type galaxies, which can be improved further using the concentration indices. The IRX–β relation is reformulated with our UV-selected nearby galaxies.

  14. A GALEX based search for the sparse young stellar population in the Taurus-Aurigae star forming region

    CERN Document Server

    de Castro, Ana I Gomez; López-Martínez, Fátima; Sánchez, Néstor; Sestito, Paola; de Castro, Elisa; Cornide, Manuel; Gestoso, Javier Yañez

    2014-01-01

    In this work, we identify 63 bona fide new candidates to T Tauri stars (TTSs) in the Taurus-Auriga region using as baseline its ultraviolet excess. The initial data set has been defined from the GALEX all sky survey (AIS). The GALEX satellite obtained images in the near ultraviolet (NUV) and far ultraviolet (FUV) bands where the TTSs show a prominent excess, compared with main sequence or giants stars. GALEX AIS surveyed the Taurus-Auriga molecular complex, as well as, a fraction of the California Nebula and the Perseus complex; bright sources and the dark clouds themselves are avoided. The properties of the TTSs in the ultraviolet (GALEX), optical (UCAC4) and infrared (2MASS) have been defined using as qualification sample the TTSs observed with the International Ultraviolet Explorer. The candidates have been identified by means of a mixed ultraviolet-optical-infrared excess set of colors; it is found that the color-color diagram FUV-NUV versus J-K is ideally suited for this purpose. From an initial sample o...

  15. Two new hot subdwarf binaries in the GALEX survey

    CERN Document Server

    Kawka, A; Nemeth, P; Kraus, M; Kubat, J

    2010-01-01

    We report the discovery of two new hot, hydrogen-rich subdwarfs (sdB) in close binary systems. The hot subdwarfs, GALEX J0321+4727 and GALEX J2349+3844, were selected from a joint optical-ultraviolet catalogue of hot sub-luminous stars based on GSC2.3.2 and the Galaxy Evolution Explorer all-sky survey. Using high-dispersion spectra of the Halpha core obtained using the 2m telescope at Ondrejov Observatory we measured the radial velocities of the sdB primaries and determined orbital periods of 0.26584+/-0.00004 days and 0.46249+/-0.00007 days for GALEX J0321+4727 and GALEX J2349+3844, respectively. The time series obtained from the Northern Sky Variability Survey with an effective wavelength near the R band show that GALEX J0321+4727 is a variable star (Delta m=0.12 mag) while no significant variations are observed in GALEX J2349+3844. The period of variations in GALEX J0321+4727 coincides with the orbital period and the variability is probably caused by a reflection effect on a late-type secondary star. Lack ...

  16. A GALEX-BASED SEARCH FOR THE SPARSE YOUNG STELLAR POPULATION IN THE TAURUS-AURIGAE STAR FORMING REGION

    Energy Technology Data Exchange (ETDEWEB)

    Gómez de Castro, Ana I.; Lopez-Santiago, Javier; López-Martínez, Fatima; Sánchez, Néstor; Sestito, Paola; Gestoso, Javier Yañez [AEGORA Research Group, Universidad Complutense de Madrid, Plaza de Ciencias 3, E-28040 Madrid (Spain); De Castro, Elisa; Cornide, Manuel [Fac. de CC. Físicas, Universidad Complutense de Madrid, Plaza de Ciencias 1, E-28040 Madrid (Spain)

    2015-02-01

    In this work, we identify 63 bona fide new candidates to T Tauri stars (TTSs) in the Taurus-Auriga region, using its ultraviolet excess as our baseline. The initial data set was defined from the GALEX all sky survey (AIS). The GALEX satellite obtained images in the near-ultraviolet (NUV) and far-ultraviolet (FUV) bands where TTSs show a prominent excess compared with main-sequence or giants stars. GALEX AIS surveyed the Taurus-Auriga molecular complex, as well as a fraction of the California Nebula and the Perseus complex; bright sources and dark clouds were avoided. The properties of TTSs in the ultraviolet (GALEX), optical (UCAC4), and infrared (2MASS) have been defined using the TTSs observed with the International Ultraviolet Explorer reference sample. The candidates were identified by means of a mixed ultraviolet-optical-infrared excess set of colors; we found that the FUV-NUV versus J–K color-color diagram is ideally suited for this purpose. From an initial sample of 163,313 bona fide NUV sources, a final list of 63 new candidates to TTSs in the region was produced. The search procedure has been validated by its ability to detect all known TTSs in the area surveyed: 31 TTSs. Also, we show that the weak-lined TTSs are located in a well-defined stripe in the FUV-NUV versus J–K diagram. Moreover, in this work, we provide a list of TTSs photometric standards for future GALEX-based studies of the young stellar population in star forming regions.

  17. Binary properties of subdwarfs selected in the GALEX survey

    CERN Document Server

    Kawka, Adela; O'Toole, Simon; Vennes, Stephane; Nemeth, Peter; Williams, Andrew; Iliev, Lubomir; Kolaczkowski, Zbyszek; Steslicki, Marek

    2012-01-01

    We describe our programme to identify and analyse binary stars among the bright subdwarfs selected in the Galaxy Evolution Explorer (GALEX) survey. Radial velocity time-series helped us identify subdwarfs with low-mass or compact stellar companions: We describe work conducted on the bright binaries GALEX J0321+4727 and GALEX J2349+3844, and we present a radial velocity study of several objects that include three new likely binaries. We also carried out photometric observations that allowed us to detect long period pulsations in the subdwarf components in two of the close binaries.

  18. The Brera Multi-scale Wavelet ROSAT HRI source catalogue (BMW-HRI)

    CERN Document Server

    Panzera, M R; Covino, S; Lazzati, D; Mignani, R P; Moretti, A; Tagliaferri, G

    2003-01-01

    We present the Brera Multi-scale Wavelet ROSAT HRI source catalogue (BMW-HRI) derived from all ROSAT HRI pointed observations with exposure time longer than 100 s available in the ROSAT public archives. The data were analyzed automatically using a wavelet detection algorithm suited to the detection and characterization of both point-like and extended sources. This algorithm is able to detect and disentangle sources in very crowded fields and/or in presence of extended or bright sources. Images have been also visually inspected after the analysis to ensure verification. The final catalogue, derived from 4,303 observations, consists of 29,089 sources detected with a detection probability of greater or equal 4.2 sigma. For each source, the primary catalogue entries provide name, position, count rate, flux and extension along with the relative errors. In addition, results of cross-correlations with existing catalogues at different wavelengths (FIRST, IRAS, 2MASS and GSC2) are also reported. All these information ...

  19. Rosat observations of FK comae berenices

    Science.gov (United States)

    Welty, Alan D.; Ramsey, Lawrence W.

    1994-01-01

    We obtained ROSAT PSPC observations of FK Com over a period of 24.4 h, or 0.42 rotation. During the observations the x-ray flux increased by a factor of at least 5 before declining toward its previous level. A single temperature Raymond-Smith model is adequate to model the low signal-to-noise ratio spectrum from each observation interval. Initially the spectrum was that of a 8.5 x 10(exp 6) K plasma, with L9sub x)=0.66 x 10(exp 31) erg s(exp -1). When the x-ray flux was greatest, the model plasma temperature rose to 2.5 x 10(exp 7) K, and L(sub x)=3.46 x 10(exp 31) ergs(exp -1). During the post-maximum decline in luminosity the plasma temperature was approximately 12 x 10(exp 6) K. We conclude that the increase of x-ray flux recorded by ROSAT was due to an x-ray flare with a 1.5 h decline time scale.

  20. Rosat observations of FK comae berenices

    Science.gov (United States)

    Welty, Alan D.; Ramsey, Lawrence W.

    1994-01-01

    We obtained ROSAT PSPC observations of FK Com over a period of 24.4 h, or 0.42 rotation. During the observations the x-ray flux increased by a factor of at least 5 before declining toward its previous level. A single temperature Raymond-Smith model is adequate to model the low signal-to-noise ratio spectrum from each observation interval. Initially the spectrum was that of a 8.5 x 10(exp 6) K plasma, with L9sub x)=0.66 x 10(exp 31) erg s(exp -1). When the x-ray flux was greatest, the model plasma temperature rose to 2.5 x 10(exp 7) K, and L(sub x)=3.46 x 10(exp 31) ergs(exp -1). During the post-maximum decline in luminosity the plasma temperature was approximately 12 x 10(exp 6) K. We conclude that the increase of x-ray flux recorded by ROSAT was due to an x-ray flare with a 1.5 h decline time scale.

  1. A selection of hot subluminous stars in the GALEX survey II. Subdwarf atmospheric parameters

    CERN Document Server

    Németh, Péter; Vennes, Stéphane

    2012-01-01

    We present an update of our low-resolution spectroscopic follow-up and model atmosphere analysis of hot subdwarf stars from the Galaxy Evolution Explorer (GALEX) survey. Targets were selected on the basis of colour indices calculated from the GALEX GR6 N_UV, Guide Star Catalogue (GSC2.3.2) V and the Two Micron All Sky Survey (2MASS) J and H photometry. High signal-to-noise ratio spectra were obtained at the European Southern Observatory (ESO) and the Kitt Peak National Observatory (KPNO) over the course of three years. Detailed H, He and CNO abundance analysis helped us improve our T_eff, log g and He abundance determination and to constrain CNO abundances. We processed 191 observations of 180 targets and found 124 sdB and 42 sdO stars in this sample while some blue horizontal branch stars were also found in this programme. With quantitative binary decomposition of 29 composite spectra we investigated the incidence of A, F and G type companions. The incidence of late G and K type companions and their effects ...

  2. Galex Catalog And Atlas Of Our Local Group Of Galaxies

    Science.gov (United States)

    Madore, Barry

    The NASA Galaxy Evolution Explorer (GALEX) mission contains the most comprehensive collection of ultraviolet imaging of Local Group galaxies likely to exist for decades. Unfortunately, this impressive resource will be under-utilized because the standard GALEX pipeline and source catalogs are not designed to properly measure point sources in crowded fields. We propose to solve this problem and unlock this great wealth of data obtained by NASA by constructing the GALEX Catalog and Atlas of Our Local Group Galaxies which shall include 49 GALEX observed Local Group members within 1.5 Mpc including the Large and Small Magellanic Clouds in their entirety. The PSF- fitting photometry method has already been tested and increases the number of detected point sources by 300% over the standard GALEX pipeline. Our catalogs will provide approximately 5-6 million point source measurements. We have also developed a novel method for producing wide field background-balanced mosaics of GALEX data. This has already been implemented for the Magellanic Clouds and the method will be applied to the other largest Local Group Members (M31 and M33). The Atlas images we produce will combine imaging data from all GALEX surveys to achieve maximum depth. Quality assurance of the images and catalogs will be done by the proposers in the course of undertaking a number of science-driven projects that require cross-matching the ultraviolet point sources of the Magellanic Clouds to similar resolution optical (MCPS) and infrared (SAGE) source catalogs. The Catalogs and Atlas (including the Magellanic Clouds cross-matched catalogs) will be made available to the astronomical community by providing them to the Mikulski Archive for Space Telescopes (MAST, the official GALEX archive) as a High Level Science Product as well as assimilated on an object-by- object basis into the NASA/IPAC Extragalactic Database (NED) and thereby made immediately accessible in VO-compatible format. This program will enhance

  3. Nitrogen Production in Starburst Galaxies Detected by GALEX

    CERN Document Server

    Mallery, Ryan P; Rich, R Michael; Salim, Samir; Charlot, Stephane; Tremonti, Christy; Seibert, Mark; Small, Todd; Wyder, Ted; Barlow, Tom A; Forster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Neff, Susan G; Schiminovich, David; Bianchi, Luciana; Donas, Jose; Heckman, Timothy; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Szalay, Alexander S; Welsh, Barry Y; Yi, Suk Young

    2007-01-01

    We investigate the production of nitrogen in star forming galaxies with ultraviolet (UV) radiation detected by the Galaxy Evolution Explorer Satellite (GALEX). We use a sample of 8,745 GALEX emission line galaxies matched to the Sloan Digital Sky Survey (SDSS) spectroscopic sample. We derive both gas-phase oxygen and nitrogen abundances for the sample, and apply stellar population synthesis models to derive stellar masses and star formation histories of the galaxies. We compare oxygen abundances derived using three different diagnostics. We derive the specific star formation rates of the galaxies by modeling the 7-band GALEX+SDSS photometry. We find that galaxies that have log SFR/M$_*$ > -10.0 typically have values of log N/O ~0.05 dex less than galaxies with log SFR/M$_*$ < -10.0 and similar oxygen abundances.

  4. ROSAT Discovers Unique, Distant Cluster of Galaxies

    Science.gov (United States)

    1995-06-01

    Brightest X-ray Cluster Acts as Strong Gravitational Lens Based on exciting new data obtained with the ROSAT X-ray satellite and a ground-based telescope at the ESO La Silla Observatory, a team of European astronomers [2] has just discovered a very distant cluster of galaxies with unique properties. It emits the strongest X-ray emission of any cluster ever observed by ROSAT and is accompanied by two extraordinarily luminous arcs that represent the gravitationally deflected images of even more distant objects. The combination of these unusual characteristics makes this cluster, now known as RXJ1347.5-1145, a most interesting object for further cosmological studies. DISCOVERY AND FOLLOW-UP OBSERVATIONS This strange cluster of galaxies was discovered during the All Sky Survey with the ROSAT X-ray satellite as a moderately intense X-ray source in the constellation of Virgo. It could not be identified with any already known object and additional ground-based observations were therefore soon after performed with the Max-Planck-Society/ESO 2.2-metre telescope at the La Silla observatory in Chile. These observations took place within a large--scale redshift survey of X-ray clusters of galaxies detected by the ROSAT All Sky Survey, a so-called ``ESO Key Programme'' led by astronomers from the Max-Planck-Institut fur Extraterrestrische Physik and the Osservatorio Astronomico di Brera. The main aim of this programme is to identify cluster X-ray sources, to determine the distance to the X-ray emitting clusters and to investigate their overall properties. These observations permitted to measure the redshift of the RXJ1347.5-1145 cluster as z = 0.45, i.e. it moves away from us with a velocity (about 106,000 km/sec) equal to about one-third of the velocity of light. This is an effect of the general expansion of the universe and it allows to determine the distance as about 5,000 million light-years (assuming a Hubble constant of 75 km/sec/Mpc). In other words, we see these

  5. GALEX UV Color Relations for Nearby Early-Type Galaxies

    CERN Document Server

    Donas, J; Rich, R M; Yi, S K; Lee, Y W; Boselli, A; De Paz, A G; Boissier, S; Charlot, S; Salim, S; Bianchi, L; Barlow, T A; Forster, K; Friedman, P G; Heckman, T M; Madore, B F; Martin, D C; Milliard, B; Morrissey, P; Neff, S G; Schiminovich, D; Seibert, M; Small, T; Szalay, A S; Welsh, B Y; Wyder, T K; Donas, Jose; Deharveng, Jean-Michel; Yi, Sukyoung K.; Lee, Young-Wook; Boselli, Alessandro; Paz, Armando Gil de; Boissier, Samuel; Charlot, Stephane; Salim, Samir; Bianchi, Luciana; Barlow, Tom A.; Forster, Karl; Friedman, Peter G.; Heckman, Timothy M.; Madore, Barry F.; Milliard, Bruno; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Seibert, Mark; Small, Todd; Szalay, Alex S.; Welsh, Barry Y.; Wyder, Ted K.

    2006-01-01

    We use GALEX/optical photometry to construct color-color relationships for early-type galaxies sorted by morphological type. We have matched objects in the GALEX GR1 public release and the first IR1.1 internal release, with the RC3 early-type galaxies having a morphological type -5.5GALEX pipeline photometry in the far-UV and near-UV bands. This sample is divided into Ellipticals (-5.5GALEX NUV band. We suspect that the main source ...

  6. SSGSS : The Spitzer-SDSS-GALEX Spectroscopic Survey

    NARCIS (Netherlands)

    O'Dowd, Matthew J.; Schiminovich, David; Johnson, Benjamin D.; Treyer, Marie A.; Martin, Christopher D.; Wyder, Ted K.; Charlot, Stephane; Heckman, Timothy M.; Martins, Lucimara P.; Seibert, Mark; van der Hulst, J. M.

    2011-01-01

    The Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) provides a new sample of 101 star-forming galaxies at z <0.2 with unprecedented multi-wavelength coverage. New mid-to far-infrared spectroscopy from the Spitzer Space Telescope is added to a rich suite of previous imaging and spectroscopy, includin

  7. ROSAT observations of compact groups of galaxies

    CERN Document Server

    Saracco, P; Saracco, P; Ciliegi, P

    1994-01-01

    A search for X-ray emission from compact groups revealed detection from 8 out of the 12 HCG images extracted from the ROSAT public archive. For two of them the X-ray emission originates from galaxies in the group. On the contrary, three groups show an extended emission clearly caused by hot intracluster gas. A Raymond-Smith hot plasma model provides an excellent fit to the X-ray spectra. The estimated temperatures are distributed in a quite narrow range (from 0.73 to 0.92 keV) and are consistent, within the errors, with 0.9 keV. The luminosity ranging from 0.75 to 5.1\\cdot10^{42}erg s^{-1}. The most relevant result is the low metal abundance surely detected in two of them and likely in a third that characterizes the hot gas cloud responsible for the X-ray emission. The data concerning the remaining 3 detected compact groups are not sufficient to discriminate with certainty between diffuse and/or point-like X-ray emission. However the results of the spectral analysis point to the presence of a hot gas again wi...

  8. The particle background of the ROSAT PSPC

    Science.gov (United States)

    Snowden, S. L.; Plucinsky, P. P.; Briel, U.; Hasinger, G.; Pfeffermann, E.

    1992-07-01

    In order to permit quantitative studies of the diffuse cosmic X-ray background and of extended X-ray sources, the particle induced background of the Roentgen Satellite, Rosat, Position Sensitive Proportional Counter (PSPC) is parameterized. Data collected during 210,000 s of PSPC operation have been analyzed and the temporal, spectral, and spatial distributions investigated. About 77 percent of the residual events originate within the detector while the remainder enter through the counter window. During typical conditions, the count rate of the residual events is well correlated with the Master Veto (MV) count rate. The spectrum of these events is well described by a flat component plus a soft power law and an Al K-alpha line at 1.5 keV. Also during typical conditions, the ratio between the power law and flat components remains constant to +/- 4 while the relative Al K-alpha contribution increases with increasing MV count rate. The distribution of the counts over the field of view is uniform except for a slight radial dependence and shadowing caused by blockage of the externally produced component by the window support structure.

  9. Searching for flares in GALEX data with gPhoton

    Science.gov (United States)

    Million, Chase; Fleming, Scott W.; Brasseur, Clara; Osten, Rachel A.; Bianchi, Luciana; Shiao, Bernie

    2017-06-01

    The Galaxy Evolution Explorer (GALEX) spacecraft observed a large fraction of the sky in two ultraviolet bands using micro-channel plate detectors with time resolutions of less than ten milliseconds. The gPhoton database of calibrated GALEX photon events at MAST has recently enabled a thorough search of this legacy data set for astrophysical variability at cadences shorter than the orbital period of the spacecraft. (https://archive.stsci.edu/prepds/gphoton/) We explore techniques for mining photon-level data for variability on timescales of seconds to minutes with an emphasis on dwarf star flares, which can be probed at lower energies and shorter durations with gPhoton than prior surveys. We present the early results of a systematic search for such events.

  10. An Atlas of GALEX UV Images of Interacting Galaxies

    CERN Document Server

    Giroux, Mark L; Struck, Curtis; Hancock, Mark; Hurlock, Sabrina

    2009-01-01

    We present GALEX ultraviolet images from a survey of strongly interacting galaxy pairs, and compare with images at other wavelengths. The tidal features are particularly striking in the UV images. Numerous knots of star formation are visible throughout the disks and the tails and bridges. We also identify a possible `Taffy' galaxy in our sample, which may have been produced by a head-on collision between two disk galaxies.

  11. Properties of hot subdwarfs in the GALEX survey

    CERN Document Server

    Nemeth, Peter; Vennes, Stephane

    2012-01-01

    We have analyzed a sample of hot subdwarfs (sdB, sdO) selected from the GALEX ultraviolet sky survey. Applying a model atmosphere analysis we determined the temperature, surface gravity, and helium-to-hydrogen abundance ratio, and obtained preliminary constraints on the CNO abundance for a sample of 181 stars. Adopting colourimetric (ultraviolet-infrared) and quantitative spectral decomposition we also investigated the incidence of solar type or earlier (A, F, G) companions.

  12. QSOs in the combined SDSS/GALEX database

    CERN Document Server

    Hutchings, J B

    2008-01-01

    We discuss selection of QSO candidates from the combined SDSS and GALEX catalogues. We discuss properties of QSOs within the combined sample, and note uncertainties in number counts and completeness, compared with other SDSS-based samples. We discuss colour and other properties with redshift within the sample and the SEDs for subsets. We estimate the numbers of faint QSOs that are classified as extended objects in the SDSS, and consequent uncertainties that follow.

  13. VizieR Online Data Catalog: GALEX UV photometry of M31 Globular Clusters (Rey+, 2007)

    Science.gov (United States)

    Rey, S.-C.; Rich, R. M.; Sohn, S. T.; Yoon, S.-J.; Chung, C.; Yi, S. K.; Lee, Y.-W.; Rhee, J.; Bianchi, L.; Madore, B. F.; Lee, K.; Barlow, T. A.; Forster, K.; Friedman, P. G.; Martin, D. C.; Morrissey, P.; Neff, S. G.; Schiminovich, D.; Seibert, M.; Small, T.; Wyder, T. K.; Donas, J.; Heckman, T. M.; Milliard, B.; Szalay, A. S.; Welsh, B. Y.

    2009-05-01

    The M31 images were obtained as part of the Nearby Galaxy Survey (NGS) carried out by GALEX in two UV bands: FUV (135-175nm) and NUV (175-275nm). Details on the early observations of 14 fields released under the GALEX Release 1 (GR1) can be found in Thilker et al. (2005ApJ...619L..67T) and Paper I (Rey et al., 2005ApJ...619L.119R). We have observed an additional nine GALEX fields in 2004 September-November, which are included in the GALEX Release 2 (GR2). (1 data file).

  14. ROSAT observations of the RSCVn binary sigma Geminorum

    DEFF Research Database (Denmark)

    Yi, Z.; Elgaroy, O.; Engvold, O.

    1997-01-01

    X-ray observations of the RSCVn system sigma Geminorum have been undertaken with the ROSAT observatory. Several spectra of very good signal-to-noise ratio were obtained. Spectral fitting using metal abundances amounting to 50% of solar values reveal two temperature components at 2 MK and 12 MK. P...

  15. The ROSAT All-Sky Survey Bright Source Catalogue

    CERN Document Server

    Voges, W; Boller, T; Bräuninger, H; Briel, U G; Burkert, W K A; Dennerl, K; Englhauser, J; Gruber, R; Haberl, F; Hartner, G; Hasinger, G; Pfeffermann, E; Pietsch, W; Predehl, P; Rosso, C; Schmitt, J H M M; Trümper, J E; Zimmermann, H U; Voges, Wolfgang; Aschenbach, Bernd; Boller, Thomas; Braeuninger, Heinrich; Briel, Ulrich; Burkert, Wolfgang; Dennerl, Konrad; Englhauser, Jakob; Gruber, Rainer; Haberl, Frank; Hartner, Gisela; Hasinger, Guenther; Pfeffermann, Elmar; Pietsch, Wolfgang; Predehl, Peter; Rosso, Cristina; Schmitt, Juergen H.M.M.; Truemper, Joachim; Zimmermann, Hans-Ulrich

    1999-01-01

    We present the ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, revision 1RXS) derived from the all-sky survey performed during the first half year (1990/91) of the ROSAT mission. 18,811 sources are catalogued (i) down to a limiting ROSAT PSPC count-rate of 0.05 cts/s in the 0.1-2.4 keV energy band, (ii) with a detection likelihood of at least 15 and (iii) at least 15 source counts. The 18,811 sources underwent both an automatic validation and an interactive visual verification process in which for 94% of the sources the results of the standard processing were confirmed. The remaining 6% have been analyzed using interactive methods and these sources have been flagged. Flags are given for (i) nearby sources; (ii) sources with positional errors; (iii) extended sources; (iv) sources showing complex emission structures; and (v) sources which are missed by the standard analysis software. Broad band (0.1-2.4 keV) images are available for sources flagged by (ii), (iii) and (iv). For each source the ROSAT name...

  16. Two Cataclysmic Variables Identified from ROSAT Bright Sources

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents the results of optical spectroscopic observations of two ROSAT bright sources, 1RXS J020928.9+283243 and 1RXS J042332.8+745300. The low-dispersion spectra suggest the cataclysmic variable classification for the two objects. Further photometric observations are expected to reveal the variable features and to confirm the classifications.

  17. Measuring the Ultraviolet Variability of M Dwarfs with GALEX

    Science.gov (United States)

    Miles, Brittany E.; Shkolnik, Evgenya L.

    2016-01-01

    The likelihood of finding an Earth-like planet in the habitable zone of an M dwarf in the near future is very high. In order to characterize such a planet's habitability, we need to understand how much ultraviolet (UV) radiation the planet is receiving from its host star. UV light from the host star influences a planet's atmospheric photochemistry and will affect our interpretations of measured exoplanetary atmospheric compositions from future missions like JWST and the extremely large ground-based telescopes. Time resolved UV data for a large number of stars can provide more detailed boundary conditions for atmospheric modeling and information on the activity behavior of low-mass stars. The Galaxy Evolution Explorer (GALEX) provides time resolved data in the near- ultraviolet (NUV) band (1771 - 2831 Å). On average, there are 4 UV observations per M dwarf in our population of 436 M dwarfs within 25 pc of Earth. The GALEX mission has multiple surveys, which covered different sized areas of the sky. At the final data release, the All Sky Survey (AIS) covered 2/3 of the sky and accounts for 58% of our 2595 measurements. The Deep Imaging Survey (DIS), Medium Imaging Survey (MIS), Guest Investigator Survey (GII), and Nearby Galaxy Survey (NGS) contribute the remaining data. From the NUV GALEX data we find an increase in variability among later M dwarfs within the M0 - M4 range. M0 stars vary on average by 9% around their mean flux, while M4 stars vary by 31% around their mean flux.

  18. The ultraviolet, optical, and infrared properties of Sloan Digital Sky Survey sources detected by GALEX

    NARCIS (Netherlands)

    Agueros, MA; Ivezic, Z; Covey, KR; Obric, M; Hao, L; Walkowicz, LM; West, AA; Vanden Berk, DE; Lupton, RH; Knapp, GR; Gunn, JE; Richards, GT; Bochanski, J; Brooks, A; Claire, M; Haggard, D; Kaib, N; Kimball, A; Gogarten, SM; Seth, A; Solontoi, M

    2005-01-01

    We discuss the ultraviolet, optical, and infrared properties of the Sloan Digital Sky Survey (SDSS) sources detected by the Galaxy Evolution Explorer ( GALEX) as part of its All-sky Imaging Survey Early Release Observations. Virtually all (> 99%) the GALEX sources in the overlap region are detected

  19. The ultraviolet, optical, and infrared properties of Sloan Digital Sky Survey sources detected by GALEX

    NARCIS (Netherlands)

    Agueros, MA; Ivezic, Z; Covey, KR; Obric, M; Hao, L; Walkowicz, LM; West, AA; Vanden Berk, DE; Lupton, RH; Knapp, GR; Gunn, JE; Richards, GT; Bochanski, J; Brooks, A; Claire, M; Haggard, D; Kaib, N; Kimball, A; Gogarten, SM; Seth, A; Solontoi, M

    We discuss the ultraviolet, optical, and infrared properties of the Sloan Digital Sky Survey (SDSS) sources detected by the Galaxy Evolution Explorer ( GALEX) as part of its All-sky Imaging Survey Early Release Observations. Virtually all (> 99%) the GALEX sources in the overlap region are detected

  20. Luminosity dependent star-formation history of S0 galaxies: evidence from GALEX-SDSS-2MASS-WISE colours

    CERN Document Server

    Barway, Sudhanshu; Vaghmare, Kaustubh; Kembhavi, Ajit K

    2013-01-01

    We combine UV/Optical/near-IR/mid-IR data on a sample of ~240 S0 galaxies to examine various star formation related processes in them. We split the sample into bright and faint S0 galaxies based on their K band luminosity. Comparing the FUV-NUV versus NUV-K color-color diagram with a Simple Stellar Population (SSP) model shows that ellipticals and bright S0 galaxies are dominated by a stellar population of age > 10^9 years while faint S0 galaxies may contain stars as young as 10^8 years, providing evidence for relatively recent star formation activity. The strength of the 4000A break is also systematically higher in brighter S0 galaxies, again indicating the presence of an old stellar population. Their mid-IR colours indicate that bright S0 colours are like those of ellipticals while faint S0 colours are more like spirals. All these observations are consistent with a scenario in which low-luminosity S0 galaxies likely formed by the stripping of gas from the discs of late-type spiral galaxies, which in turn fo...

  1. Detecting Star Formation in Brightest Cluster Galaxies with GALEX

    CERN Document Server

    Hicks, Amalia; Donahue, Megan

    2010-01-01

    We present the results of GALEX observations of 17 cool core (CC) clusters of galaxies. We show that GALEX is easily capable of detecting star formation in brightest cluster galaxies (BCGs) out to $z\\ge 0.45$ and 50-100 kpc. In most of the CC clusters studied, we find significant UV luminosity excesses and colors that strongly suggest recent and/or current star formation. The BCGs are found to have blue UV colors in the center that become increasingly redder with radius, indicating that the UV signature of star formation is most easily detected in the central regions. Our findings show good agreement between UV star formation rates and estimates based on H$\\alpha$ observations. IR observations coupled with our data indicate moderate-to-high dust attenuation. Comparisons between our UV results and the X-ray properties of our sample suggest clear correlations between UV excess, cluster entropy, and central cooling time, confirming that the star formation is directly and incontrovertibly related to the cooling g...

  2. The Second Galex Ultraviolet Variability (GUVV-2) Catalog

    CERN Document Server

    Wheatley, Jonathan M; Browne, Stanley E

    2008-01-01

    We present the second Galaxy Evolution Explorer (GALEX) Ultraviolet Variability (GUVV-2) Catalog that contains information on 410 newly discovered time-variable sources gained through simultaneous near (NUV 1750-2750A) and far (FUV 1350-1750A) ultraviolet photometric observations. Source variability was determined by comparing the NUV and/or FUV fluxes derived from orbital exposures recorded during a series of multiple observational visits to 169 GALEX fields on the sky. These sources, which were contained within a sky-area of 161 square deg, varied on average by amplitudes of NUV = 0.6 mag and FUV = 0.9 mag during these observations. Of the 114 variable sources in the catalog with previously known identifications, 67 can be categorized as being active galaxies (QSO's, Seyfert 1 or BL Lac objects). The next largest groups of UV variables are RR Lyrae stars, X-ray sources and novae. By using a combination of UV and visible color-color plots we have been able to tentatively identify 36 possible RR Lyrae and/or ...

  3. Second ROSAT all-sky survey (2RXS) source catalogue

    CERN Document Server

    Boller, Th; Truemper, J; Haberl, F; Voges, W; Nandra, K

    2016-01-01

    We present the second ROSAT all-sky survey source catalogue, hereafter referred to as the 2RXS catalogue. This is the second publicly released ROSAT catalogue of point-like sources obtained from the ROSAT all-sky survey (RASS) observations performed with the PSPC between June 1990 and August 1991, and is an extended and revised version of the bright and faint source catalogues. We used the latest version of the RASS processing to produce overlapping X-ray images of 6.4x6.4 degrees sky regions. To create a source catalogue, a likelihood-based detection algorithm was applied to these, which accounts for the PSF across the PSPC field of view. Improvements in the background determination compared to 1RXS were also implemented. We obtained about 135,000 X-ray detections in the 0.1-2.4 keV energy band down to a likelihood threshold of 6.5. Our simulations show that the expected spurious content of the catalogue is a strong function of detection likelihood, and the full catalogue is expected to contain about 30% spu...

  4. The GALEX/S4G UV-IR color-color diagram: Catching spiral galaxies away from the Blue Sequence

    CERN Document Server

    Bouquin, Alexandre Y K; Boissier, Samuel; Muñoz-Mateos, Juan-Carlos; Sheth, Kartik; Zaritsky, Dennis; Laine, Jarkko; Gallego, Jesús; Peletier, Reynier F; Röck, Benjamin R; Knapen, Johan H

    2015-01-01

    We obtained GALEX FUV, NUV, and Spitzer/IRAC 3.6$\\mu$m photometry for > 2000 galaxies, available for 90% of the S4G sample. We find a very tight "GALEX Blue Sequence (GBS)" in the (FUV-NUV) versus (NUV-[3.6]) color-color diagram which is populated by irregular and spiral galaxies, and is mainly driven by changes in the formation timescale ($\\tau$) and a degeneracy between $\\tau$ and dust reddening. The tightness of the GBS provides an unprecedented way of identifying star-forming galaxies and objects that are just evolving to (or from) what we call the "GALEX Green Valley (GGV)". At the red end of the GBS, at (NUV-[3.6]) > 5, we find a wider "GALEX Red Sequence (GRS)" mostly populated by E/S0 galaxies that has a perpendicular slope to that of the GBS and of the optical red sequence. We find no such dichotomy in terms of stellar mass (measured by $\\rm{M}_{[3.6]}$), since both massive ($M_{\\star} > 10^{11} M_{\\odot}$) blue and red sequence galaxies are identified. The type that is proportionally more often foun...

  5. The Ultraviolet Sky: An Overview from the GALEX Surveys

    CERN Document Server

    Bianchi, Luciana; Shiao, Bernie

    2013-01-01

    The Galaxy Evolution Explorer (GALEX) has performed the first surveys of the sky in the Ultraviolet (UV). Its legacy is an unprecedented database with more than 200 million source measurements in far-UV (FUV) and near-UV (NUV), as well as wide-field imaging of extended objects, filling an important gap in our view of the sky across the electromagnetic spectrum. The UV surveys offer unique sensitivity for identifying and studying selected classes of astrophysical objects, both stellar and extra-galactic. We examine the overall content and distribution of UV sources over the sky, and with magnitude and color. For this purpose, we have constructed final catalogs of UV sources with homogeneous quality, eliminating duplicate measurements of the same source. Such catalogs can facilitate a variety of investigations on UV-selected samples, as well as planning of observations with future missions. We describe the criteria used to build the catalogs, their coverage and completeness. We included observations in which bo...

  6. gPhoton: The GALEX Photon Data Archive

    CERN Document Server

    Million, Chase; Shiao, Bernie; Seibert, Mark; Loyd, Parke; Tucker, Michael; Smith, Myron; Thompson, Randy; White, Richard L

    2016-01-01

    gPhoton is a new database product and software package that enables analysis of GALEX ultraviolet data at the photon level. The project's stand-alone, pure-Python calibration pipeline reproduces the functionality of the original mission pipeline to reduce raw spacecraft data to lists of time-tagged, sky-projected photons, which are then hosted in a publicly available database by the Mikulski Archive at Space Telescope (MAST). This database contains approximately 130 terabytes of data describing approximately 1.1 trillion sky-projected events with a timestamp resolution of five milliseconds. A handful of Python and command line modules serve as a front-end to interact with the database and to generate calibrated light curves and images from the photon-level data at user-defined temporal and spatial scales. The gPhoton software and source code are in active development and publicly available under a permissive license. We describe the motivation, design, and implementation of the calibration pipeline, database,...

  7. Statistical Properties of the GALEX/SDSS matched source catalogs, and classification of the UV sources

    CERN Document Server

    Bianchi, L; Viton, M; Laget, M; Efremova, B; Herald, J; Conti, A; Shiao, B; De Paz, A G; Salim, S; Thakar, A; Friedman, P G; Rey, S C; Thilker, D; Barlow, T A; Budavari, T; Donas, J; Forster, K; Heckman, T M; Lee, Y W; Madore, B F; Martin, D C; Milliard, B; Morrissey, P; Neff, S G; Rich, R M; Schiminovich, D; Seibert, M; Small, T; Szalay, A S; Wyder, T K; Welsh, B Y; Yi, S K; Bianchi, Luciana; Rodriguez-Merino, Lino; Viton, Maurice; Laget, Michel; Efremova, Boryana; Herald, James; Conti, Alberto; Shiao, Bernie; Paz, Armando Gil de; Salim, Samir; Friedman, Peter G.; Thilker, David; Barlow, Tom A.; Budavari, Tamas; Donas, Jose; Forster, Karl; Heckman, Timothy M.; Lee, Young-Wook; Madore, Barry F.; Milliard, Bruno; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Seibert, Mark; Small, Todd; Szalay, Alex S.; Wyder, Ted K.; Welsh, Barry Y.; Yi, Sukyoung K.

    2006-01-01

    We use the Galaxy Evolution Explorer (GALEX) Medium and All-Sky-Imaging Survey (MIS & AIS) data from the first public data release (GR1), matched to the Sloan Digital Sky Survey (SDSS) DR3 catalog, to perform source classification. The GALEX surveys provide photometry in far- and near-UV bands and the SDSS in five optical bands (u,g,r,i,z). The GR1/DR3 overlapping areas are 363[83]deg^2 for the GALEX AIS[MIS], for sources within the 0.5deg central area of the GALEX fields. Our sample covers mostly |b|>30deg galactic latitudes. We present statistical properties of the GALEX/SDSS matched sources catalog, containing >2x10^6 objects detected in at least one UV band. We classify the matched sources by comparing the seven-band photometry to model colors constructed for different classes of astrophysical objects. For sources with photometric errors <0.3 mag, the corresponding typical AB-magnitude limits are m_FUV~21.5, m_NUV~22.5 for AIS, and m_FUV~24, m_NUV~24.5 for MIS. At AIS depth, the number of Galactic ...

  8. Cluster science from ROSAT to eROSITA

    CERN Document Server

    Chon, Gayoung

    2012-01-01

    Galaxy clusters are one of the important cosmological probes to test the consistency of the observable structure and evolution of our Universe with the predictions of specific cosmological models. We use results from our analysis of the X-ray flux-limited REFLEX cluster sample from the ROSAT All-Sky Survey to illustrate the constraints on cosmological parameters that can be achieved with this approach. The upcoming eROSITA project of the Spektrum-Roentgen-Gamma mission will increase these capabilities by two orders of magnitude and importantly also increase the redshift range of such studies. We use the projected instrument performance to make predictions on the scope of the eROSITA survey and the potential of its exploitation.

  9. A ROSAT Bright Source Catalog Survey with the Swift Satellite

    CERN Document Server

    Fox, D B

    2004-01-01

    We consider the prospects for a complete survey of the 18,811 sources of the ROSAT All-Sky Survey Bright Source Catalog (BSC) with NASA's Swift gamma-ray burst (GRB) mission. By observing each BSC source for 500 s with the satellite's imaging X-ray and UV/optical telescopes, this "Swift Bright (Source) Catalog Survey" (Swift-BCS) would derive ~20 mCrab, 10-100 keV) with the wide-field Burst Alert Telescope (BAT); and a two-year all-sky BAT survey down to >~1 mCrab. The resulting expansion of the catalog of identified X-ray sources from 2000 to 18,000 will provide a greatly-enriched set of targets for observation by XMM-Newton, Chandra, and future high-energy observatories.

  10. Automated Classification of ROSAT Sources Using Heterogeneous Multiwavelength Source Catalogs

    Science.gov (United States)

    McGlynn, Thomas; Suchkov, A. A.; Winter, E. L.; Hanisch, R. J.; White, R. L.; Ochsenbein, F.; Derriere, S.; Voges, W.; Corcoran, M. F.

    2004-01-01

    We describe an on-line system for automated classification of X-ray sources, ClassX, and present preliminary results of classification of the three major catalogs of ROSAT sources, RASS BSC, RASS FSC, and WGACAT, into six class categories: stars, white dwarfs, X-ray binaries, galaxies, AGNs, and clusters of galaxies. ClassX is based on a machine learning technology. It represents a system of classifiers, each classifier consisting of a considerable number of oblique decision trees. These trees are built as the classifier is 'trained' to recognize various classes of objects using a training sample of sources of known object types. Each source is characterized by a preselected set of parameters, or attributes; the same set is then used as the classifier conducts classification of sources of unknown identity. The ClassX pipeline features an automatic search for X-ray source counterparts among heterogeneous data sets in on-line data archives using Virtual Observatory protocols; it retrieves from those archives all the attributes required by the selected classifier and inputs them to the classifier. The user input to ClassX is typically a file with target coordinates, optionally complemented with target IDs. The output contains the class name, attributes, and class probabilities for all classified targets. We discuss ways to characterize and assess the classifier quality and performance and present the respective validation procedures. Based on both internal and external validation, we conclude that the ClassX classifiers yield reasonable and reliable classifications for ROSAT sources and have the potential to broaden class representation significantly for rare object types.

  11. gPhoton: The GALEX Photon Data Archive

    Science.gov (United States)

    Million, Chase; Fleming, Scott W.; Shiao, Bernie; Seibert, Mark; Loyd, Parke; Tucker, Michael; Smith, Myron; Thompson, Randy; White, Richard L.

    2016-12-01

    gPhoton is a new database product and software package that enables analysis of GALEX ultraviolet data at the photon level. The project’s stand-alone, pure-Python calibration pipeline reproduces the functionality of the original mission pipeline to reduce raw spacecraft data to lists of time-tagged, sky-projected photons, which are then hosted in a publicly available database by the Mikulski Archive at Space Telescope. This database contains approximately 130 terabytes of data describing approximately 1.1 trillion sky-projected events with a timestamp resolution of five milliseconds. A handful of Python and command-line modules serve as a front end to interact with the database and to generate calibrated light curves and images from the photon-level data at user-defined temporal and spatial scales. The gPhoton software and source code are in active development and publicly available under a permissive license. We describe the motivation, design, and implementation of the calibration pipeline, database, and tools, with emphasis on divergence from prior work, as well as challenges created by the large data volume. We summarize the astrometric and photometric performance of gPhoton relative to the original mission pipeline. For a brief example of short time-domain science capabilities enabled by gPhoton, we show new flares from the known M-dwarf flare star CR Draconis. The gPhoton software has permanent object identifiers with the ASCL (ascl:1603.004) and DOI (doi:10.17909/T9CC7G). This paper describes the software as of version v1.27.2.

  12. A selection of hot subluminous stars in the GALEX survey I. Correlation with the Guide Star Catalog

    CERN Document Server

    Vennes, S; Nemeth, P

    2010-01-01

    We assembled a catalogue of bright, hot subdwarf and white dwarf stars extracted from a joint ultraviolet, optical, and infrared source list. The selection is secured using colour criteria that correlate well with effective temperatures T_eff ~> 12,000 K. We built a N_UV-V versus V-J diagram for more than 60,000 bright sources using the Galaxy Evolution Explorer (GALEX) N_UV magnitude (N_UV<14), and the associated Guide Star Catalog (GSC2.3.2) photographic quick-V magnitude and the Two Micron All Sky Survey (2MASS) J and H magnitudes. This distillation process delivered a catalogue of approximately 700 sources with N_UV-V<0.5 comprising ~160 known hot subdwarf stars and another ~60 known white dwarf stars. A reduced proper-motion diagram built using the proper-motion measurements extracted from the Naval Observatory Merged Astrometric Dataset allowed us to identify an additional ~120 new hot subdwarf candidates and ~10 hot white dwarf candidates. We present a spectroscopic study of a subset of 52 subdwa...

  13. The GALEX Arecibo SDSS Survey V: The Relation between the HI Content of Galaxies and Metal Enrichment at their Outskirts

    CERN Document Server

    Moran, Sean M; Kauffmann, Guinevere; Davé, Romeel; Catinella, Barbara; Brinchmann, Jarle; Wang, Jing; Schiminovich, David; Saintonge, Amélie; Gracia-Carpio, Javier; Tacconi, Linda; Giovanelli, Riccardo; Haynes, Martha; Fabello, Silvia; Hummels, Cameron; Lemonias, Jenna; Wu, Ronin

    2011-01-01

    We have obtained long-slit spectra of 174 star-forming galaxies with stellar masses greater than 10^10 M_\\odot from the GALEX Arecibo SDSS (GASS) survey. These galaxies have both HI and H_2 mass measurements. The average metallicity profile is strikingly flat out to R_90, the radius enclosing 90% of the r-band light. Metallicity profiles which decline steadily with radius are found primarily for galaxies in our sample with low stellar mass (Log(M_*)<10.2), concentration, and/or mean stellar mass density. Beyond ~R_90, however, around 10 percent of the galaxies in our sample exhibit a sharp downturn in metallicity. Remarkably, we find that the magnitude of the outer metallicity drop is well correlated with the total HI content of the galaxy (measured as f_HI=M_HI/M_*). We examine the radial profiles of stellar population ages and star formation rate densities, and conclude that the galaxies with largest outer metallicity drops are actively growing their stellar disks, with mass doubling times across the who...

  14. Asteroids in GALEX: Near-ultraviolet photometry of the major taxonomic groups

    CERN Document Server

    Waszczak, Adam; Kulkarni, Shrinivas R

    2015-01-01

    We present ultraviolet photometry (NUV band, 180--280 nm) of 405 asteroids observed serendipitously by the Galaxy Evolution Explorer (GALEX) from 2003--2012. All asteroids in this sample were detected by GALEX at least twice. Unambiguous visible-color-based taxonomic labels (C type versus S type) exist for 315 of these asteroids; of these, thermal-infrared-based diameters are available for 245. We derive NUV-V color using two independent models to predict the visual magnitude V at each NUV-detection epoch. Both V models produce NUV-V distributions in which the S types are redder than C types with more than 8-sigma confidence. This confirms that the S types' redder spectral slopes in the visible remain redder than the C types' into the NUV, this redness being consistent with absorption by silica-containing rocks. The GALEX asteroid data confirm earlier results from the International Ultraviolet Explorer, which two decades ago produced the only other sizeable set of UV asteroid photometry. The GALEX-derived NUV...

  15. The properties of diffuse interstellar dust clouds as determined from GALEX and infrared (IRAS, Herschel) observations

    Science.gov (United States)

    Armengot, M.; Gómez de Castro, A. I.

    2017-03-01

    Dust grain properties are known to vary in the interstellar medium depending on the density, the ultraviolet radiation field and the local abundances of metal elements. Though there are plenty of studies addressing the atomic and molecular gas component or the infrared radiation of dust grains, there are very few studies that address the spatial distribution of small large grains and large molecules such as the Polyaromathic Hydrocarbons (PAHs).In this work, we make use of the GALEX survey of the Galaxy to identify the absorption produced in the GALEX far UV (write in the spectral range) and new UV (write in the spectral range) by well know infrared cirrus and compare the absorption produced in the UV by the thin cirrus with the infrared dust emissivity in various bands; (describe the IRAS bands used and whether there is any Herschel band in this study). As the spatial resolution of GALEX images is significantly larger than that of IRAS images data handling has required mosaicking and and rescaling GALEX data as well as transforming the images form equinox 1950 to equinox 2000. We describe in this work the computational procedures used to generate the ultraviolet and infrared maps. Also we present our first results that show there is an anticorrelation between UV and infrared (IR) emission, as other wise expected. The largest concentrations of dust grains radiate IR photons and absorb UV photons.

  16. Keck/Deimos Spectroscopy of a GALEX UV Selecte Sample from the Medium Imaging Survey

    CERN Document Server

    Mallery, Ryan P; Salim, Samir; Small, Todd; Charlot, Stephane; Seibert, Mark; Wyder, Ted; Barlow, Tom A; Forster, Karl; Friedman, Peter G; Martin, D Christopher; Morissey, Patrick; Neff, Susan G; Schiminovivich, David; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Szalay, Alexander S; Welsh, Barry Y; Yi, Suk Young

    2007-01-01

    We report results from a pilot program to obtain spectroscopy for objects detected in the Galaxy Evolution Explorer (GALEX) Medium Imaging Survey (MIS). Our study examines the properties of galaxies detected by GALEX fainter than the Sloan Digital Sky Survey (SDSS) spectroscopic survey. This is the first study to extend the techinques of Salim et al. 2005 to estimate stellar masses, star formation rates (SFR) and the b (star formation history) parameter for star-forming galaxies out to z~0.7. We obtain redshifts for 50 GALEX MIS sources reaching NUV=23.9 (AB mag), having counterparts in the SDSS Data Release 4 (DR4). Of our sample, 43 are starforming galaxies with z<0.7, 3 have emission line ratios indicative of AGN with z<0.7, and 4 objects with z~1 are QSOs, 3 of which are not previously cataloged. We compare our sample to a much larger sample of ~50,000 matched GALEX/SDSS galaxies with SDSS spectroscopy; while our survey is shallow, the optical counterparts to our sources reach ~3 magnitudes fainter ...

  17. The Galaxy Evolution Explorer (GALEX). Its legacy of UV surveys, and science highlights

    CERN Document Server

    Bianchi, Luciana

    2014-01-01

    The Galaxy Evolution Explorer (GALEX) imaged the sky in the Ultraviolet (UV) for almost a decade, delivering the first sky surveys at these wavelengths. Its database contains far-UV (FUV, $\\lambda$$_{eff}$ $\\sim$ 1528\\AA) and near-UV (NUV, $\\lambda$$_{eff}$ $\\sim$ 2310\\AA) images of most of the sky, including deep UV-mapping of extended galaxies, over 200 million source measurements, and more than 100,000 low-resolution UV spectra. The GALEX archive will remain a long-lasting resource for statistical studies of hot stellar objects, QSOs, star-forming galaxies, nebulae and the interstellar medium. It provides an unprecedented road-map for planning future UV instrumentation and follow-up observing programs in the UV and at other wavelengths. We review the characteristics of the GALEX data, and describe final catalogs and available tools, that facilitate future exploitation of this database. We also recall highlights from the science results uniquely enabled by GALEX data so far.

  18. A Deep ROSAT HRI Observation of NGC 1313

    CERN Document Server

    Schlegel, E M; Colbert, E J M; Miller, S; Schlegel, Eric M.; Petre, Robert; Miller, Scott

    2000-01-01

    We describe a series of observations of NGC 1313 using the ROSAT HRI with a combined exposure time of 183.5 ksec. The observations span an interval between 1992 and 1998; the purpose of observations since 1994 was to monitor the X-ray flux of SN1978K, one of several luminous sources in the galaxy. No diffuse emission is detected in the galaxy to a level of ~1-2x10^37 ergs/s/arcmin^-2. A total of eight sources are detected in the summed image within the D_25 diameter of the galaxy. The luminosities of five of the eight range from \\~6x10^37 to ~6x10^38 erg/s; these sources are most likely accreting X-ray binaries, similar to sources obseved in M31 and M33. The remaining three sources all emit above 10^39 erg/s. We present light curves of the five brightest sources. Variability is detected at the 99.9% level from four of these. We identify one of the sources as an NGC 1313 counterpart of a Galactic X-ray source. The light curve, though crudely sampled, most closely resembles that of a Galactic black hole candida...

  19. X-ray flashes in ROSAT PSPC data

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.; Li, H.; Fenimore, E.E. [Los Alamos National Lab., NM (United States); Wang, Q.D. [Northwestern Univ., Evanston, IL (United States)

    1998-12-01

    The authors find 24 short (200--2,500s) X-ray flashes from all the ROSAT Position Sensitive Proportional Counter (PSPC) observations above galactic latitude 30 degrees ({approximately} 9.6 Msec) and some observations toward low latitudes ({approximately} 2.4 Msec). The brightest flash is quite extraordinary. Its flux rises from nondetection by a factor of > 200 in less than 100 sec. Its spectrum can be fitted either by a thermal plasma model with kT {ge} 2.4 keV, or by a single power-law with the photon number index of {approx} {minus}1.7. Photon statistics are not sufficient to obtain spectra for other flashes. The flash event fields can vary from optically crowded regions to blank fields. Although eight flashes are found from observations from nearby galaxies, and three of them are within the optical extent of their corresponding galaxies, they could not statistically establish that there are two different populations between nearby galaxies and control fields.

  20. ROSAT PSPC observations of NGC 7469 and Ark 120

    Science.gov (United States)

    Brandt, W. N.; Fabian, A. C.; Nandra, K.; Tsuruta, S.

    1993-01-01

    We present spatial, temporal and spectral analyses of ROSAT Position Sensitive Proportional Counter (PSPC) observations of the Seyfert 1 galaxies NGC 7469 and Ark 120. Both of these sources show evidence for excess emission and more complex 0.1- 2.5 keV spectra than are predicted by simple extrapolations of higher energy power laws. We find that the spectrum of NGC 7469 can be explained by models that have secondary power-law, secondary bremsstrahlung, secondary blackbody or emission-line components. We find evidence for 0.1-2.5 keV intensity variability of NGC 7469. The spectrum of Ark 120 is better described by models with secondary continuum components than by models with sharper spectral features. We discuss the agreement between X-ray and ultraviolet observations of these sources and examine the observations in the context of accretion disc reflection models. The inner parts of discs are likely to be reflective below approximately 0.24 keV, and this reflectivity complicates simple models of the soft excess.

  1. ROSAT Timing of the LMC Pulsar 0540-69

    CERN Document Server

    Eikenberry, S S; Ransom, S M

    1997-01-01

    We present a timing study of the young rotation-powered pulsar 0540-69 in the Large Magellanic Cloud, based on 130 kiloseconds of archival ROSAT data spanning a $\\sim 3$-year period. We use ``$f- \\dot f$'' techniques to measure the pulsar frequency as a function of frequency derivative at 17 independent epochs. From these measurements we derive a timing solution with a braking index $n = 2.5^{+0.6}_{-0.7}$, and we compare this solution to previous timing studies of 0540-69. Using this frequency-based solution, we create 27 pulse profiles and perform a time-of-arrival (TOA) analysis to investigate further the pulsar's timing behavior. While we can successfully fit smooth spin-down models to subsets of the TOAs spanning up to 2 years, we are unable to obtain acceptable phase-coherent fits to the entire 3-year set of TOAs. This behavior provides the first clear evidence for timing noise in 0540-69. We discuss the implications of these results for understanding previous studies of the timing behavior of 0540-69.

  2. Deep Galex Observations of the Coma Cluster: Source Catalog and Galaxy Counts

    Science.gov (United States)

    Hammer, D.; Hornschemeier, A. E.; Mobasher, B.; Miller, N.; Smith, R.; Arnouts, S.; Milliard, B.; Jenkins, L.

    2010-01-01

    We present a source catalog from deep 26 ks GALEX observations of the Coma cluster in the far-UV (FUV; 1530 Angstroms) and near-UV (NUV; 2310 Angstroms) wavebands. The observed field is centered 0.9 deg. (1.6 Mpc) south-west of the Coma core, and has full optical photometric coverage by SDSS and spectroscopic coverage to r-21. The catalog consists of 9700 galaxies with GALEX and SDSS photometry, including 242 spectroscopically-confirmed Coma member galaxies that range from giant spirals and elliptical galaxies to dwarf irregular and early-type galaxies. The full multi-wavelength catalog (cluster plus background galaxies) is 80% complete to NUV=23 and FUV=23.5, and has a limiting depth at NUV=24.5 and FUV=25.0 which corresponds to a star formation rate of 10(exp -3) solar mass yr(sup -1) at the distance of Coma. The GALEX images presented here are very deep and include detections of many resolved cluster members superposed on a dense field of unresolved background galaxies. This required a two-fold approach to generating a source catalog: we used a Bayesian deblending algorithm to measure faint and compact sources (using SDSS coordinates as a position prior), and used the GALEX pipeline catalog for bright and/or extended objects. We performed simulations to assess the importance of systematic effects (e.g. object blends, source confusion, Eddington Bias) that influence source detection and photometry when using both methods. The Bayesian deblending method roughly doubles the number of source detections and provides reliable photometry to a few magnitudes deeper than the GALEX pipeline catalog. This method is also free from source confusion over the UV magnitude range studied here: conversely, we estimate that the GALEX pipeline catalogs are confusion limited at NUV approximately 23 and FUV approximately 24. We have measured the total UV galaxy counts using our catalog and report a 50% excess of counts across FUV=22-23.5 and NUV=21.5-23 relative to previous GALEX

  3. Exploring Cosmic Voids with GALEX: Stellar Populations and Primordial Jeans Mass Objects

    Science.gov (United States)

    Gregg, Michael

    This proposed research program will revolutionize the study of cosmic voids and their inhabitant galaxy populations. By combining archival GALEX photometry with SDSS data for thousands of galaxies in hundreds of voids, we will be able to characterize voids, void galaxies, and the formation and evolution of galaxies in the lowest density environments of the Universe. In addition, we propose to use the joint GALEX-SDSS database to search in several of the nearest cosmic voids for the original building blocks of galaxy formation: surviving Jeans mass primordial objects which formed right after recombination during the earliest stages of structure formation in the Universe. Our program will first characterize known void galaxies in the UV using the extensive GALEX NUV and FUV imaging archives. Adding GALEX UV photometry to SDSS optical enables estimating star formation rates and also separating stars from unresolved galaxies. Based on this effort, we will look for trends in galaxy properties with location within a void and with global void properties such as size and underdensity. We are particularly interested in identifying and characterizing the early type galaxy population in voids. While most void galaxies are blue, there do exist ellipticals in voids; comparison with ellipticals in denser regions will inform elliptical galaxy models in new ways, and teach us about the oldest and earliest stages of galaxy formation in voids. Early type galaxies are easy to miss in void redshift surveys, even with the comprehensive nature of SDSS, because most have relied on emission line searches or infrared excess. Our approach is fundamentally different, using an enhanced GALEX UV-optical selection technique which we have developed specifically for this work. A search for early type objects is necessary to fully understand void galaxy populations. In parallel, we will use our UV-optical selection technique to search for primordial Jeans mass sized objects in the nearest voids

  4. The heavily polluted atmosphere of the DAZ white dwarf GALEX J193156.8+011745

    CERN Document Server

    Vennes, S; Nemeth, P

    2010-01-01

    We report on the discovery of a new heavily polluted white dwarf. The DAZ white dwarf GALEX J193156.8+011745 was identified in a joint GALEX/GSC survey of ultraviolet-excess objects. Optical spectra obtained at ESO NTT show strong absorption lines of magnesium and silicon and a detailed abundance analysis based on VLT-Kueyen UVES spectra reveal super-solar abundances of silicon and magnesium, and near-solar abundances of oxygen, calcium, and iron. The overall abundance pattern bears the signature of ongoing accretion onto the white dwarf atmosphere. The infrared spectral energy distribution shows an excess in the H and K bands likely associated with the accretion source.

  5. UV Properties of Galactic Globular Clusters with GALEX II. Integrated colors

    CERN Document Server

    Dalessandro, Emanuele; Rood, Robert T; Ferraro, Francesco R; Sohn, Sangmo T; Lanzoni, Barbara; O'Connell, Robert W

    2012-01-01

    We present ultraviolet (UV) integrated colors of 44 Galactic globular clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV and NUV bands. This data-base is the largest homogeneous catalog of UV colors ever published for stellar systems in our Galaxy. The proximity of GGCs makes it possible to resolve many individual stars even with the somewhat low spatial resolution of GALEX. This allows us to determine how the integrated UV colors are driven by hot stellar populations, primarily horizontal branch stars and their progeny. The UV colors are found to be correlated with various parameters commonly used to define the horizontal branch morphology. We also investigate how the UV colors vary with parameters like metallicity, age, helium abundance and concentration. We find for the first time that GCs associated with the Sagittarius dwarf galaxy have (FUV-V) colors systematically redder than GGCs with the same metallicity. Finally, we speculate about the presence of an interesting trend, s...

  6. X ray observations of late-type stars using the ROSAT all-sky survey

    Science.gov (United States)

    Linsky, Jeffrey L.; Fleming, Thomas A.

    1992-03-01

    The ROSAT mission made the first x ray survey of the entire sky using an imaging detector. Although ROSAT is a joint NASA/German project and involves direct American participation during its second phase of pointed observations, the all-sky survey remains the sole property of the German investigators. NASA grant represented the first use of ROSAT data analysis funds to support direct American participation in the ROSAT all-sky survey. The project involved a collaborative agreement between the Joint Institute for Laboratory Astrophysics (JILA) and the Max-Planck-Institut fur Extraterrestrische Physik (MPE) where JILA supplied MPE with a post-doctoral research associate with experience in the field of stellar (coronal) x ray emission to work within their ROSAT group. In return, members of the cool star research group at JILA were given the opportunity to collaborate on projects involving ROSAT all-sky survey data. Both sides have benefitted (and still benefit) from this arrangement since MPE suffers from a shortage of researchers who are interested in x ray emission from 'normal' stars and white dwarfs. MPE has also drawn upon experience in optical identification of x ray sources from the Einstein Extended Medium Sensitivity Survey in planning their own identification strategies for the ROSAT all-sky survey. The JILA cool stars group has benefitted since access to all-sky survey data has expanded the scope of their already extensive research programs involving multiwavelength observations of late-type stars. ROSAT was successfully launched on 1 June 1990 and conducted the bulk of the survey from 30 July 1990 to 25 January 1991. Data gaps in the survey have subsequently been made up. At the time of this writing (February 1992), the survey data have been processed once with the Standard Analysis Software System (SASS). A second processing will soon begin with improvements made to the SASS to correct errors and bugs found while carrying out scientific projects with data

  7. The impact of encounters on the members of Local Group Analogs. A view from GALEX

    OpenAIRE

    Buson, L.M.; Bettoni, D.; Bianchi, L.; A. Buzzoni; Marino, A.; Rampazzo, R.

    2008-01-01

    The bright galaxy population of the Local Group Analog (LGA) LGG 225 has been imaged with the Galaxy Evolution Explorer (GALEX) through its Far- and Near-UV wavebands. A significant fraction of the group members appear to underwent recent/on-going interaction episodes that strongly disturbed overall galaxy morphology. UV-bright regions, sites of intense star formation activity accompanied by intense dust extinction, mark the galaxy outskirts forming irregular structures and tails. Compared to...

  8. A Search for Rapidly Pulsating Hot Subdwarf Stars in the GALEX Survey

    Science.gov (United States)

    Boudreaux, Thomas M.; Barlow, Brad N.; Fleming, Scott W.; Vasquez Soto, Alan; Million, Chase; Reichart, Dan E.; Haislip, Josh B.; Linder, Tyler R.; Moore, Justin P.

    2017-08-01

    NASA’s Galaxy Evolution Explorer (GALEX) provided near- and far-UV observations for approximately 77% of the sky over a 10-year period; however, the data reduction pipeline initially only released single NUV and FUV images to the community. The recently released Python module gPhoton changes this, allowing calibrated time-series aperture photometry to be extracted easily from the raw GALEX data set. Here we use gPhoton to generate light curves for all hot subdwarf B (sdB) stars that were observed by GALEX, with the intention of identifying short-period, p-mode pulsations. We find that the spacecraft’s short visit durations, uneven gaps between visits, and dither pattern make the detection of hot subdwarf pulsations difficult. Nonetheless, we detect UV variations in four previously known pulsating targets and report their UV pulsation amplitudes and frequencies. Additionally, we find that several other sdB targets not previously known to vary show promising signals in their periodograms. Using optical follow-up photometry with the Skynet Robotic Telescope Network, we confirm p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3, and report it as the most recent addition to the sdBV r class of variable stars.

  9. gPhoton: A Time-Tagged Database of Every GALEX Photon and Early Science Results

    Science.gov (United States)

    Fleming, Scott W.; Million, Chase; Shiao, Bernie; Thompson, Randy; Tseng, Shui-Ay; Rogers, Anthony; Smith, Myron; White, Richard L.; Levay, Karen

    2014-06-01

    The Galaxy Evolution Explorer (GALEX) mission observed a large fraction of the sky in FUV and NUV at time resolutions of five thousandths of a second, spanning a decade of operation. Due to technical limitations when the data were first archived, the ability to use GALEX data at such high time resolutions was limited: the primary data products were images that were combined into several-minute integrations, along with source catalogs.MAST is pleased to introduce gPhoton, a time-tagged database of every photon event detected by GALEX during its lifetime; some 1.5 trillion events in total. This database is accompanied by both a python-based software package and a web interface. These tools allow users to create calibrated lightcurves, intensity maps, and animated movies from any set of photons selected across any tile. Users can specify custom apertures sizes, coordinates, and time steps down to the level of seconds. We present some early science cases with gPhoton, which include studies of flare stars, Be stars, and unique opportunities with objects in the Kepler field.

  10. The Identification of RR Lyrae and Delta Scuti Stars from Variable GALEX Ultraviolet Sources

    CERN Document Server

    Kinman, T D

    2014-01-01

    We identify the RR Lyrae and delta Scuti (DSCT) stars in three catalogs of GALEX variable sources. The NUV amplitude of RR Lyrae stars is about twice that in V-band, so we find a larger percentage of low amplitude variables than catalogs such as Abbas et al (2014). Interestingly, the (NUV-V)_0 color is sensitive to metallicity and can be used to distinguish between variables of the same period but differing [Fe/H]. This color is also more sensitive to T_eff than optical colors and can be used to identify the red edge of the instability gap. We find 8 DSCT stars, 17 RRc stars, 1 RRd star and 84 RRab stars in the GALEX variable catalogs of Welsh et al (2005) and Wheatley et al (2008). We also classify 6 DSCT stars, 5 RRc stars and 18 RRab stars among the 55 variable GALEX sources identified as "stars" or RR Lyraes in the catalog of Gezari et al (2013). We provide ephemerides and light curves for the 26 variables that were not previously known.

  11. Ongoing Formation of Bulges and Black Holes in the Local Universe: New Insights from GALEX

    CERN Document Server

    Kauffmann, G; Budavari, T; Charlot, S; Hoopes, C G; Martin, D C; Seibert, M; Barlow, T A; Bianchi, L; Conrow, T; Donas, J; Forster, K; Friedman, P G; Lee, Y W; Madore, B F; Milliard, B; Morrissey, P F; Neff, S G; Rich, R M; Schiminovich, D; Small, T; Szalay, A S; Wyder, T K; Yi, S K; Kauffmann, Guinevere; Heckman, Timothy M.; Budavari, Tamas; Charlot, Stephane; Hoopes, Charles G.; Seibert, Mark; Barlow, Tom A.; Bianchi, Luciana; Conrow, Tim; Donas, Jose; Forster, Karl; Friedman, Peter G.; Lee, Young-Wook; Madore, Barry F.; Milliard, Bruno; Morrissey, Patrick F.; Neff, Susan G.; Schiminovich, David; Small, Todd; Szalay, Alex S.; Wyder, Ted K.

    2006-01-01

    We analyze a volume-limited sample of massive bulge-dominated galaxies with data from both the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX) satellite. The galaxies have central velocity dispersions greater than 100 km/s and stellar surface mass densities that lie above the value where galaxies transition from actively star forming to passive systems. The sample is limited to redshifts 0.03GALEX NUV data provide high sensitivity to low rates of global star formation in these systems. Our sample of bulge-dominated galaxies exhibits a much larger dispersion in NUV-r colour than in optical g-r colour. Nearly all of the galaxies with bluer NUV-r colours are AGN. Both GALEX images and SDSS colour profiles demonstrate that the excess UV light is associated with an extended disk. We find that galaxies with red outer regions almost never have a young bulge or a strong...

  12. A Science-enhanced Database of GALEX UV spectra to Characterize Interstellar Dust

    Science.gov (United States)

    Bianchi, Luciana

    The Galaxy Evolution Explorer (GALEX) has performed the first surveys of the sky in the Ultraviolet (UV). Its unprecedented database, including almost 300 million photometric source measurements in far-UV (FUV) and near-UV (NUV), offers unique sensitivity for studying selected classes of astrophysical objects, such as hot stars, star-forming galaxies, and zimaging data have been amply mined; science-enhanced source catalogs enable comprehensive investigations long after the mission is concluded. GALEX has also collected 125,564 UV spectra (range 1344-2831Ang; resolution about 200(FUV) - 120(NUV)): a homogeneous template tenfold larger and at fainter fluxes than the IUE target sample. Yet, this unique resource has hardly been exploited, due to poor calibration and lack of standard quality assessment of the complex grism spectral extraction. The homogeneous set of >120,000 UV spectra distributed all over the sky will enable - among other investigations - derivation of UV extinction curves for thousands of sightlines throughout the Milky Way (MW), yielding information on properties of interstellar dust that cannot be obtained otherwise, and, furthermore, validating extinction maps derived from vastly larger photometric samples. Our proposed map of MW dust properties will be 3D, since Gaia will provide accurate distances for all stellar sources. The first step to make this study possible will be to classify all sources in the [grism, hence serendipitous] GALEX spectroscopic sample, and to assess quality and flux calibration. We will combine multi-band photometry of the spectral sources (GALEX, SDSS, Pan-STARRs, ...), any existing information (e.g., from SIMBAD), available IUE spectra (about 100) and SDSS spectra (8,000), besides examining the UV spectral features. Hot stellar sources constitute over half of the GALEX spectroscopic sample. For those with spectra of sufficient quality (about 9,000 in NUV, >1,000 in FUV+NUV) we will derive UV extinction curves by the

  13. Active Galactic Nuclei Selected from GALEX Spectroscopy: The Ionizing Source Spectrum at z ~ 1

    Science.gov (United States)

    Barger, Amy J.; Cowie, Lennox L.

    2010-08-01

    We use a complete sample of Lyα-emission-line-selected active galactic nuclei (AGNs) obtained from nine deep blank fields observed with the grism spectrographs on the Galaxy Evolution Explorer (GALEX) satellite to measure the normalization and the spectral shape of the AGN contribution to the ionizing background (rest-frame wavelengths 700-900 Å) at z ~ 1. Our sample consists of 139 sources selected in the redshift range z = 0.65-1.25 in the near-ultraviolet (NUV; 2371 Å central wavelength) channel. The area covered is 8.2 deg2 to a NUV magnitude of 20.5 (AB) and 0.92 deg2 at the faintest magnitude limit of 21.8. The GALEX AGN luminosity function agrees well with those obtained using optical and X-ray AGN samples, and the measured redshift evolution of the ionizing volume emissivity is similar to that previously obtained by measuring the GALEX far-ultraviolet (FUV; 1528 Å central wavelength) magnitudes of an X-ray-selected sample. For the first time, we are able to construct the shape of the ionizing background at z ~ 1 in a fully self-consistent way. Based in part on data obtained from the Multimission Archive at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for Multimission Archive at STScI (MAST) for non-HST data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts. Based in part on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

  14. Predicting Lyman-alpha and Mg II Fluxes from K and M Dwarfs Using GALEX Ultraviolet Photometry

    CERN Document Server

    Shkolnik, Evgenya L; Peacock, Sarah; Barman, Travis S

    2014-01-01

    A star's UV emission can greatly affect the atmospheric chemistry and physical properties of closely orbiting planets with the potential for severe mass loss. In particular, the Lyman-alpha emission line at 1216 Angstroms, which dominates the far-ultraviolet spectrum, is a major source of photodissociation of important atmospheric molecules such as water and methane. The intrinsic flux of Lyman-alpha, however, cannot be directly measured due to the absorption of neutral hydrogen in the interstellar medium and contamination by geocoronal emission. To date, reconstruction of the intrinsic Lyman-alpha line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM nearby stars, 28 of which have also been observed by the Galaxy Evolution Explorer (GALEX). Our investigation provides a correlation between published intrinsic Lyman-alpha and GALEX far- and near-ultraviolet chromospheric fluxes for K and M stars. The negative correlations between the ratio of the Lyman-alpha to the GALEX fluxes reveal ...

  15. Clustering Properties of restframe UV selected galaxies I: the correlation length derived from GALEX data in the local Universe

    CERN Document Server

    Milliard, Bruno; Blaizot, Jeremy; Arnouts, Stephane; Schiminovich, David; Budavari, Tamas; Donas, Jose; Treyer, Marie; Laget, Michel; Viton, Maurice; Wyder, Ted K; Szalay, A S; Barlow, Tom A; Forster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Neff, Susan G; Seibert, Mark; Small, Todd; Bianchi, Luciana; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Rich, R Michael; Welsh, Barry Y; Yi, Sukyoung K; Xu, C K

    2007-01-01

    We present the first measurements of the angular correlation function of galaxies selected in the far (1530 A) and near (2310 A) Ultraviolet from the GALEX survey fields overlapping SDSS DR5 in low galactic extinction regions. The area used covers 120 sqdeg (GALEX - MIS) down to magnitude AB = 22, yielding a total of 100,000 galaxies. The mean correlation length is ~ 3.7 \\pm 0.6 Mpc and no significant trend is seen for this value as a function of the limiting apparent magnitude or between the GALEX bands. This estimate is close to that found from samples of blue galaxies in the local universe selected in the visible, and similar to that derived at z ~ 3 for LBGs with similar rest frame selection criteria. This result supports models that predict anti-biasing of star forming galaxies at low redshift, and brings an additional clue to the downsizing of star formation at z<1.

  16. Data Mining for Dwarf Novae in SDSS, GALEX and Astrometric Catalogues

    CERN Document Server

    Wils, Patrick; Drake, Andrew J; Southworth, John

    2009-01-01

    By cross matching blue objects from SDSS with GALEX and the astrometric catalogues USNO-B1.0, GSC2.3 and CMC14, 64 new dwarf nova candidates with one or more observed outbursts have been identified. 14 of these systems are confirmed as cataclysmic variables through existing and follow-up spectroscopy. A study of the amplitude distribution and an estimate of the outburst frequency of these new dwarf novae and those discovered by the Catalina Real-time Transient Survey (CRTS) indicates that besides systems that are faint because they are farther away, there also exists a population of intrinsically faint dwarf novae with rare outbursts.

  17. The impact of encounters on the members of Local Group Analogs. A view from GALEX

    CERN Document Server

    Buson, L M; Bianchi, L; Buzzoni, A; Marino, A; Rampazzo, R

    2008-01-01

    The bright galaxy population of the Local Group Analog (LGA) LGG 225 has been imaged with the Galaxy Evolution Explorer (GALEX) through its Far- and Near-UV wavebands. A significant fraction of the group members appear to underwent recent/on-going interaction episodes that strongly disturbed overall galaxy morphology. UV-bright regions, sites of intense star formation activity accompanied by intense dust extinction, mark the galaxy outskirts forming irregular structures and tails. Compared to the Local Group, LGG 225 seems thus to be experiencing a more intense and active evolutionary phase.

  18. The Impact of Encounters on the Members of Local Group Analogs. A View from GALEX

    Science.gov (United States)

    Buson, L. M.; Bettoni, D.; Bianchi, L.; Buzzoni, A.; Marino, A.; Rampazzo, R.

    2009-03-01

    The bright galaxy population of the Local Group Analog (LGA) LGG 225 has been imaged with the Galaxy Evolution Explorer (GALEX) through its Far- and Near-UV wavebands. A significant fraction of the group members appear to underwent recent/on-going interaction episodes that strongly disturbed overall galaxy morphology. UV-bright regions, sites of intense star formation activity accompanied by intense dust extinction, mark the galaxy outskirts forming irregular structures and tails. Compared to the Local Group, LGG 225 seems thus to be experiencing a more intense and active evolutionary phase.

  19. The 160 Square Degree ROSAT Survey: The revised catalog of 201 clusters with spectroscopic redshifts

    DEFF Research Database (Denmark)

    Mullis, C.R.; McNamara, B.R.; Quintana, H.;

    2003-01-01

    We present the revised catalog of galaxy clusters detected as extended X-ray sources in the 160 Square Degree ROSAT Survey, including spectroscopic redshifts and X-ray luminosities for 200 of the 201 members. The median redshift is z(median) = 0.25, and the median X-ray luminosity is L-X,L-median......We present the revised catalog of galaxy clusters detected as extended X-ray sources in the 160 Square Degree ROSAT Survey, including spectroscopic redshifts and X-ray luminosities for 200 of the 201 members. The median redshift is z(median) = 0.25, and the median X-ray luminosity is L...

  20. A catalog of 203 galaxy clusters serendipitously detected in the ROSAT PSPC pointed observations

    DEFF Research Database (Denmark)

    Vikhlinin, A.; McNamara, B.R.; Forman, W.;

    1998-01-01

    We present a catalog of 203 clusters of galaxies serendipitously detected in 647 ROSAT PSPC high Galactic latitude pointings covering 158 deg(2). This is one of the largest X-ray-selected cluster samples, comparable in size only to the ROSAT All-Sky Survey sample of nearby clusters (Ebeling et al......), corresponding to very poor groups, to similar to 5 x 10(44) ergs s(-1), corresponding to rich clusters. The cluster redshifts range from z = 0.015 to z > 0.5. The catalog lists X-ray fluxes, core radii, and spectroscopic redshifts for 73 clusters and photometric redshifts for the remainder. Our detection method...... confirmed clusters. The number of false detections and their flux distribution are in perfect agreement with simulations. The log N-log S relation for clusters derived from our catalog shows excellent agreement with counts of bright clusters derived from the Einstein Extended Medium Sensitivity Survey...

  1. ROSAT/ASCA observations of the mixed-morphology supernova remnant W28

    Science.gov (United States)

    Rho, J.; Borkowski, K. J.

    2002-01-01

    We present three sets of ROSAT PSPC and four sets of ASCA observations of the supernova remnant (SNR) W28. The overall shape of x-ray emission in W28 is elliptical, dominated by a centrally-concentrated interior emission, sharply peaked at the center. There are also partial northeastern and southwestern shells, and both central and shell x-ray emission is highly patchy.

  2. The Timescale-dependent Color Variability of Quasars Viewed with /GALEX

    Science.gov (United States)

    Zhu, Fei-Fan; Wang, Jun-Xian; Cai, Zhen-Yi; Sun, Yu-Han

    2016-11-01

    In a recent work by Sun et al., the color variation of quasars, namely the bluer-when-brighter trend, was found to be timescale dependent using the SDSS g/r band light curves in Stripe 82. Such timescale dependence, i.e., bluer variation at shorter timescales, supports the thermal fluctuation origin of the UV/optical variation in quasars, and can be modeled well with the inhomogeneous accretion disk model. In this paper, we extend the study to much shorter wavelengths in the rest frame (down to extreme UV) using GALaxy Evolution eXplorer (GALEX) photometric data of quasars collected in two ultraviolet bands (near-UV and far-UV). We develop Monte Carlo simulations to correct for possible biases due to the considerably larger photometric uncertainties in the GALEX light curves (particularly in the far-UV, compared with the SDSS g/r bands), which otherwise could produce artificial results. We securely confirm the previously discovered timescale dependence of the color variability with independent data sets and at shorter wavelengths. We further find that the slope of the correlation between the amplitude of the color variation and timescale appears even steeper than predicted by the inhomogeneous disk model, which assumes that disk fluctuations follow a damped random walk (DRW) process. The much flatter structure function observed in the far-UV compared with that at longer wavelengths implies deviation from the DRW process in the inner disk, where rest-frame extreme UV radiation is produced.

  3. The Timescale-Dependent Color Variability of Quasars Viewed with GALEX

    CERN Document Server

    Zhu, Fei-Fan; Cai, Zhen-Yi; Sun, Yu-Han

    2016-01-01

    In recent work done by Sun et. al., the color variation of quasars, namely the bluer-when-brighter trend, was found to be timescale-dependent using SDSS $g/r$ band light curves in the Stripe 82. Such timescale dependence, i.e., bluer variation at shorter timescales, supports the thermal fluctuation origin of the UV/optical variation in quasars, and can be well modeled with the inhomogeneous accretion disk model. In this paper, we extend the study to much shorter wavelengths in the rest frame (down to extreme UV), using GALaxy Evolution eXplorer (GALEX) photometric data of quasars collected in two ultraviolet bands (near-UV and far-UV). We develop Monte-Carlo simulations to correct possible biases due to the considerably larger photometric uncertainties in GALEX light curves (particularly in far-UV, comparing with SDSS $g/r$ bands), which otherwise could produce artificial results. We securely confirm the previously discovered timescale dependence of the color variability with independent datasets and at short...

  4. UV Properties of Galactic Globular Clusters with GALEX I. The Color-Magnitude Diagrams

    CERN Document Server

    Schiavon, Ricardo P; Sohn, Sangmo T; Rood, Robert T; O'Connell, Robert W; Ferraro, Francesco R; Lanzoni, Barbara; Beccari, Giacomo; Rey, Soo-Chang; Rhee, Jaehyon; Rich, R Michael; Yoon, Suk-Jin; Lee, Young-Wook

    2012-01-01

    We present GALEX data for 44 Galactic globular clusters obtained during 3 GALEX observing cycles between 2004 and 2008. This is the largest homogeneous data set on the UV photometric properties of Galactic globular clusters ever collected. The sample selection and photometric analysis are discussed, and color-magnitude diagrams are presented. The blue and intermediate-blue horizontal branch is the dominant feature of the UV color-magnitude diagrams of old Galactic globular clusters. Our sample is large enough to display the remarkable variety of horizontal branch shapes found in old stellar populations. Other stellar types that are obviously detected are blue stragglers and post core-He burning stars. The main features of UV color-magnitude diagrams of Galactic globular clusters are briefly discussed. We establish the locus of post-core He burning stars in the UV color-magnitude diagram and present a catalog of candidate AGB-manqu \\'e, post early-AGB, and post-AGB stars within our cluster sample.

  5. The GALEX Arecibo SDSS Survey. VI. Second Data Release and Updated Gas Fraction Scaling Relations

    CERN Document Server

    Catinella, Barbara; Kauffmann, Guinevere; Fabello, Silvia; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Cooper, Andrew P; Wang, Jing

    2012-01-01

    We present the second data release from the GALEX Arecibo SDSS Survey (GASS), an ongoing large Arecibo program to measure the HI properties for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025GALEX) imaging surveys, and are observed until detected or until a gas mass fraction limit of a few per cent is reached. This second data installment includes new Arecibo observations of 240 galaxies, and marks the 50% of the complete survey. We present catalogs of the HI, optical and ultraviolet parameters for these galaxies, and their HI-line profiles. Having more than doubled the size of the sample since the first data release, we also revisit the main scaling relations of the HI mass fraction with galaxy stellar mass, stellar mass surface density, concentration index, and NUV-r color, as well as the gas fraction plane introduced in our earli...

  6. DEEP GALEX UV SURVEY OF THE KEPLER FIELD. I. POINT SOURCE CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Olmedo, Manuel; Chávez, Miguel; Bertone, Emanuele [Instituto Nacional de Astrofísica Optica y Electrónica Luis Enrique Erro #1, CP 72840, Tonantzintla, Puebla (Mexico); Lloyd, James [Department of Astronomy, Cornell University, Ithaca, NY (United States); Mamajek, Eric E. [University of Rochester, Department of Physics and Astronomy, Rochester, NY 14627-0171 (United States); Martin, D. Christopher; Neill, James D., E-mail: olmedo@inaoep.mx [California Institute of Technology, 1200 East California Boulevard, MC 278-17, Pasadena, CA 91125 (United States)

    2015-11-10

    We report observations of a deep near-ultraviolet (NUV) survey of the Kepler field made in 2012 with the Galaxy Evolution Explorer (GALEX) Complete All-Sky UV Survey Extension (CAUSE). The GALEX-CAUSE Kepler survey (GCK) covers 104 square degrees of the Kepler field and reaches a limiting magnitude of NUV ≃ 22.6 at 3σ. Analysis of the GCK survey has yielded a catalog of 669,928 NUV sources, of which 475,164 are cross-matched with stars in the Kepler Input Catalog. Approximately 327 of 451 confirmed exoplanet host stars and 2614 of 4696 candidate exoplanet host stars identified by Kepler have NUV photometry in the GCK survey. The GCK catalog should enable the identification and characterization of UV-excess stars in the Kepler field (young solar-type and low-mass stars, chromospherically active binaries, white dwarfs, horizontal branch stars, etc.), and elucidation of various astrophysics problems related to the stars and planetary systems in the Kepler field.

  7. A GALEX Ultraviolet Imaging Survey of Galaxies in the Local Volume

    CERN Document Server

    Lee, Janice C; Kennicutt, Robert C; Jr.,; Bothwell, Matthew; Dalcanton, Julianne; Funes, José G; J., S; Johnson, Benjamin; Sakai, Shoko; Skillman, Evan; Tremonti, Christy; van Zee, Liese

    2010-01-01

    We present results from a GALEX ultraviolet (UV) survey of a complete sample of 390 galaxies within ~11 Mpc of the Milky Way. The UV data are a key component of the composite Local Volume Legacy (LVL), an ultraviolet-to-infrared imaging program designed to provide an inventory of dust and star formation in nearby spiral and irregular galaxies. The ensemble dataset is an especially valuable resource for studying star formation in dwarf galaxies, which comprise over 80% of the sample. We describe the GALEX survey programs which obtained the data and provide a catalog of far-UV (~1500 Angstroms) and near-UV (~2200 Angstroms) integrated photometry. General UV properties of the sample are briefly discussed. We compute two measures of the global star formation efficiency, the SFR per unit HI gas mass and the SFR per unit stellar mass, to illustrate the significant differences that can arise in our understanding of dwarf galaxies when the FUV is used to measure the SFR instead of H-alpha. We find that dwarf galaxies...

  8. Probing Shock Breakout with Serendipitous GALEX Detections of Two SNLS Type II-P Supernovae

    CERN Document Server

    Gezari, Suvi; Basa, Stephane; Martin, D Chris; Neill, James D; Woosley, S E; Hillier, D John; Astier, Pierre; Balam, Dave; Balland, Christophe; Bazin, Gurvan; Carlberg, Ray; Conley, Alex; Forster, Karl; Fouchez, Dominique; Friedman, Peter G; Guy, Julien; Hardin, Delphine; Hook, Isobel; Howell, D Andrew; Du, Jeremy Le; Lidman, Chris; Mazure, Alain; Morrissey, Patrick; Neff, Susan G; Pain, Reynald; Perrett, Kathy; Pritchet, Chris; Regnault, Nicolas; Schiminovich, David; Sullivan, Mark; Wyder, Ted K

    2008-01-01

    We report the serendipitous detection by GALEX of fast ( 1 mag) UV emission from two Type II Plateau (II-P) supernovae (SNe) at z=0.185 and 0.324 discovered by the Supernova Legacy Survey (SNLS). Optical photometry and VLT spectroscopy 2 weeks after the GALEX detections link the onset of UV emission to the time of shock breakout. Using radiation hydrodymanics and non-LTE radiative transfer simulations, and starting from a standard red supergiant (RSG; Type II-P SN progenitor) star evolved self-consistently from the main sequence to iron core collapse, we model the shock breakout phase and the 55 hours that follow. Although our one-temperature treatment prevents us from modeling the radiative precursor, the small RSG atmospheric scale height suggests a < 2000 s duration. A duration of many hours would require an extended low-density envelope, incompatible with our RSG envelope structure. In our model, the breakout signature is a luminous (M_FUV ~ -20) thermal < 1 hr-long soft X-ray burst (lambda_peak ~ 9...

  9. GALEX Observations of Diffuse UV Radiation at High Spatial Resolution from the Sandage Nebulosity

    CERN Document Server

    Sujatha, N V; Karnataki, Abhay; Henry, Richard Conn; Bianchi, Luciana

    2008-01-01

    Using the GALEX ultraviolet imagers we have observed a region of nebulosity first identified as starlight scattered by interstellar dust by Sandage (1976). Apart from airglow and zodiacal emission, we have found a diffuse UV background of between 500 and 800 \\phunit in both the \\galex FUV (1350 -- 1750 \\AA) and NUV (1750 -- 2850 \\AA). Of this emission, up to 250 \\phunit is due to \\htwo fluorescent emission in the FUV band; the remainder is consistent with scattering from interstellar dust. We have estimated the optical constants to be $a = 0.3; g = 0.7$ in the FUV and $a = 0.5; g = 0.7$ in the NUV, implying highly forward scattering grains, plus an extragalactic contribution of as much as 150 \\phunit. These are the highest spatial resolution observations of the diffuse UV background to date and show an intrinsic scatter beyond that expected from instrumental noise alone. Further modeling is required to understand the nature of this scatter and its implications for the ISM.

  10. Interesting Features in the Combined GALEX and Sloan Color Diagrams of Solar-like Galactic Populations

    CERN Document Server

    Smith, Myron; Shiao, Bernard

    2014-01-01

    We report on intriguing photometric properties of Galactic stars observed in the GALEX satellite's far-UV and near-UV bandbasses as well as from the SDSS survey and the Kepler Input Catalog. First, the FUV-NUV color distribution of stars in the Kepler field consists of 2 distinct peaks. Second, curiously, for stars with spectral types G or later the mean FUV-NUV color becomes much bluer, contrary to expectation. we have found in two samples of mid-F through K type stars that ~14-18% of them exhibit FUV-excesses relative to their NUV fluxes and spectral types. Nearly the same fractions are also discovered among members of the Kepler Eclipsing Binary Catalog and in the published list of Kepler Objects of Interest. These UV-excess ("UVe") colors are confirmed by the UV continuum slopes in GALEX spectra. The SDSS spectra of some UVe stars exhibit metallic line weakening especially in the blue. This suggests an enhanced contribution of UV flux relative to photospheric flux of a solar-type single star. We consider ...

  11. Phase Coherent Timing of RX J0806.3+1527 with ROSAT and CHANDRA

    CERN Document Server

    Strohmayer, T E

    2003-01-01

    RX J0806.3+1527 is an ultra-compact, double degenerate binary with the shortest known orbital period (321.5 s). Hakala et al. (2003) have recently reported new optical measurements of the orbital frequency of the source which indicate that the frequency has increased over the ~9 years since the earliest ROSAT observations. They find two candidate solutions for the long term change in the frequency; df/dt = 3 or 6 x 10E-16 Hz/s. Here we present the results of a phase coherent timing study of the archival ROSAT and Chandra data for RX J0806.3+1527 in the light of these new constraints. We find that the ROSAT -- Chandra timing data are consistent with both of the solutions reported by Hakala et al., but that the higher df/dt = 6.1 x 10E-16 Hz/s solution is favored at the ~97 % level. Such a large df/dt can be accomodated by an ~1 Msun detached double degenerate system powered in the X-ray by electrical energy (Wu et al. 2002). With such a large df/dt the system provides a unique opportunity to explore the intera...

  12. A catalog of 203 galaxy clusters serendipitously detected in the ROSAT PSPC pointed observations

    DEFF Research Database (Denmark)

    Vikhlinin, A.; McNamara, B.R.; Forman, W.

    1998-01-01

    We present a catalog of 203 clusters of galaxies serendipitously detected in 647 ROSAT PSPC high Galactic latitude pointings covering 158 deg(2). This is one of the largest X-ray-selected cluster samples, comparable in size only to the ROSAT All-Sky Survey sample of nearby clusters (Ebeling et al....... 1997). We detect clusters in the inner 17.'5 of the ROSAT PSPC field of view using the spatial extent of their X-ray emission. Fluxes of detected clusters range from 1.6 x 10(-14) to 8 x 10(-12) ergs s(-1) cm(-2) in the 0.5-2 keV energy band. X-ray luminosities range from 10(42) ergs s(-1......), corresponding to very poor groups, to similar to 5 x 10(44) ergs s(-1), corresponding to rich clusters. The cluster redshifts range from z = 0.015 to z > 0.5. The catalog lists X-ray fluxes, core radii, and spectroscopic redshifts for 73 clusters and photometric redshifts for the remainder. Our detection method...

  13. New active galactic nuclei detected in ROSAT All Sky Survey galaxies - The complete dataset

    CERN Document Server

    Kollatschny, W; Pietsch, W; Bischoff, K; Zetzl, M

    2008-01-01

    The ROSAT ALL Sky Survey Bright Source Catalogue (RASS-BSC) has been correlated with the Catalogue of Principal Galaxies (PGC) to identify new extragalactic counterparts. 550 reliable optical counterparts have been detected. We took optical spectra of 176 X-ray candidates and companions at ESO, Calar Alto observatory and McDonald observatory. We discuss the redshift-, linewidth-, as well as optical and X-ray luminosity distribution of our ROSAT selected sample. 139 galaxies of our 166 X-ray counterparts have been identified as AGN with 93 being Seyfert 1 galaxies (61%). Eighteen of them (20%) are Narrow Line Seyfert 1 galaxies. 34 X-ray candidates (21%) are LINERs and only eight candidates (5%) are Seyfert 2. The ratio of the number of Seyfert 1 galaxies to Seyfert 2 galaxies is about 11/1. Optical surveys result in ratios of 1/1.4. The high fraction of detected Seyfert 1 galaxies is explained by the sensitivity of the ROSAT to soft X-rays which are heavily absorbed in type 2 AGN. Two X-ray candidates are HII...

  14. The Ultraviolet Sky: final catalogs of unique UV sources from GALEX, and characterization of the UV-emitting sources across the sky, and of the Milky Way extinction

    Science.gov (United States)

    Bianchi, Luciana; Conti, A.; Shiao, B.; Keller, G. R.; Thilker, D. A.

    2014-01-01

    The legacy of the Galaxy Evolution Explorer (GALEX), which imaged the sky at Ultraviolet (UV) wavelengths for about 9 years, is its unprecedented database with more than 200 million source measurements in far-UV (FUV) and near-UV (NUV), as well as wide-field imaging of extended objects. GALEX's data, the first substantial sky surveys at UV wavelengths, offer an unprecedented view of the sky and a unique opportunity for an unbiased characterization of several classes of astrophysical objects, such as hot stars, QSOs at red-shift about 1, UV-peculiar QSOs, star-forming galaxies, among others. Bianchi et al. (2013, J. Adv. Space Res. (2013), DOI: http://dx.doi.org/10.1016/j.asr.2013.07.045) have constructed final catalogs of UV sources, with homogeneous quality, eliminating duplicate measurements of the same source ('unique' source catalogs), and excluding rim artifacts and bad photometry. The catalogs are constructed improving on the recipe of Bianchi et al. 2011 (MNRAS, 411, 2770, which presented the earlier version of these catalogs) and include all data for the major surveys, AIS and MIS. Considering the fields where both FUV and NUV detectors were exposed, the catalogs contain about 71 and 16.6 million unique sources respectively. We show several maps illustrating the content of UV sources across the sky, globally, and separately for bright/faint, hot, stellar/extragalactic objects. We matched the UV-source catalogs with optical-IR data from the SDSS, GSC2, 2MASS surveys. We are also in the process of matching the catalogs with preliminary PanSTARRS1 (PS1) 3pi survey photometry which already provides twice the sky coverage of SDSS, at slightly fainter magnitude limits. The sources' SED from FUV to optical wavelengths enables classification, derivation of the object physical parameters, and ultimately also a map of the Milky Way extinction. The catalogs will be available on MAST, Vizier (where the previous version already is), and in reduced form (for agile

  15. The DENIS & 2MASS Near Infrared Surveys

    CERN Document Server

    Mamon, G A

    1996-01-01

    The DENIS and 2MASS near infrared surveys are presented. Their applications in extragalactic astronomy and cosmology are listed. The prospects for a rapid spectroscopic followup survey of a near infrared selected sample of nearly $10^5$ galaxies are illustrated with Monte-Carlo simulations.

  16. A data base of synthetic photometry in the GALEX ultraviolet bands for the stellar sources observed with the International Ultraviolet Explorer

    CERN Document Server

    Beitia-Antero, Leire

    2016-01-01

    The Galaxy Evolution Explorer (GALEX) has produced the largest photometric catalogue of ultraviolet (UV) sources. As such, it has defined the new standard bands for UV photometry: the near UV band (NUV) and the far UV band (FUV). However, due to brightness limits, the GALEX mission has avoided the Galactic plane which is crucial for astrophysical research and future space missions. The International Ultraviolet Explorer (IUE) satellite obtained 63,755 spectra in the low dispersion mode during its 18 years lifetime. We have derived the photometry in the GALEX bands for the stellar sources in the IUE Archive to extend the GALEX data base with observations including the Galactic plane.Good quality spectra have been selected for all IUE classes of stellar sources. The GALEX FUV and NUV magnitudes have been computed using the GALEX transmission curves, as well as the conversion equations between flux and magnitudes provided by the mission (galexgi.gsfc.nasa.gov). Consistency between GALEX and IUE synthetic photome...

  17. Binarity in Cool Asymptotic Giant Branch Stars: A Galex Search for Ultraviolet Excesse

    CERN Document Server

    Sahai, R; de Paz, A Gil; Contreras, C Sánchez

    2008-01-01

    The search for binarity in AGB stars is of critical importance for our understanding of how planetary nebulae acquire the dazzling variety of aspherical shapes which characterises this class. However, detecting binary companions in such stars has been severely hampered due to their extreme luminosities and pulsations. We have carried out a small imaging survey of AGB stars in ultraviolet light (using GALEX) where these cool objects are very faint, in order to search for hotter companions. We report the discovery of significant far-ultraviolet excesses towards nine of these stars. The far-ultraviolet excess most likely results either directly from the presence of a hot binary companion, or indirectly from a hot accretion disk around the companion.

  18. GALEX and Optical Observations of GW Librae During the Long Decline from Superoutburst

    CERN Document Server

    Bullock, Eric; Mukadam, Anjum S; Borges, Bernardo W; Fraga, Luciano; Gänsicke, Boris T; Harrison, Thomas E; Henden, Arne; Holtzman, Jon; Howell, Steve B; Lawson, Warrick A; Levine, Stephen; Plotkin, Richard M; Seibert, Mark; Templeton, Matthew; Teske, Johanna; Vrba, Frederick J

    2011-01-01

    The prototype of accreting, pulsating white dwarfs (GW Lib) underwent a large amplitude dwarf nova outburst in 2007. We used ultraviolet data from GALEX and ground-based optical photometry and spectroscopy to follow GW Lib for three years following this outburst. Several variations are apparent during this interval. The optical shows a superhump modulation in the months following outburst while a 19 min quasi-periodic modulation lasting for several months is apparent in the year after outburst. A long timescale (about 4 hr) modulation first appears in the UV a year after outburst and increases in amplitude in the following years. This variation also appears in the optical 2 years after outburst but is not in phase with the UV. The pre-outburst pulsations are not yet visible after 3 years, likely indicating the white dwarf has not returned to its quiescent state.

  19. Spatial Clustering from GALEX-SDSS samples: Star Formation History and large-scale clustering

    CERN Document Server

    Heinis, Sebastien; Szalay, A S; Arnouts, Stephane; Aragon-Calvo, Miguel A; Wyder, Ted K; Barlow, Tom A; Foster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Neff, Susan G; Schiminovich, David; Seibert, Mark; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Rich, R Michael; Yi, Sukyoung K

    2009-01-01

    We measure the projected spatial correlation function w_p(r_p) from a large sample combining GALEX ultraviolet imaging with the SDSS spectroscopic sample. We study the dependence of the clustering strength for samples selected on (NUV - r)_abs color, specific star formation rate (SSFR), and stellar mass. We find that there is a smooth transition in the clustering of galaxies as a function of this color from weak clustering among blue galaxies to stronger clustering for red galaxies. The clustering of galaxies within the "green valley" has an intermediate strength, and is consistent with that expected from galaxy groups. The results are robust to the correction for dust extinction. The comparison with simple analytical modeling suggests that the halo occupation number increases with older star formation epochs. When splitting according to SSFR, we find that the SSFR is a more sensitive tracer of environment than stellar mass.

  20. Spectral Classification of Optical Counterparts to ROSAT All-Sky Survey X-ray Sources

    CERN Document Server

    Dragomir, D; Rutledge, R E; Dragomir, Diana; Roy, Philippe; Rutledge, Robert E.

    2007-01-01

    Previous work statistically identified 5492 optical counterparts, with approximately 90% confidence, from among the approximately 18,000 X-ray sources appearing in the ROSAT All-Sky Survey Bright Source Catalog (RASS/BSC). Using low resolution spectra in the wavelength range 3700-7900 angstroms, we present spectroscopic classifications for 195 of these counterparts which have not previously been classified. Of these 195, we find 168 individual stars of F, G, K or M type, 6 individual stars of unknown type, 6 double stars, 6 AGN or galaxies and 7 unclassifiable objects; the spectra of the 2 remaining objects were saturated.

  1. A search for hidden white dwarfs in the ROSAT EUV survey

    CERN Document Server

    Burleigh, M R; Fleming, T; Burleigh, Matt; Barstow, Martin; Fleming, Tom

    1997-01-01

    The ROSAT WFC survey has provided us with evidence for the existence of a previously unidentified sample of hot white dwarfs (WD) in non-interacting binary systems, through the detection of EUV and soft X-ray emission. These stars are hidden at optical wavelengths due to their close proximity to much more luminous main sequence (MS) companions (spectral type K or earlier). However, for companions of spectral type A5 or later the white dwarfs are easily visible at far-UV wavelengths, and can be identified in spectra taken by IUE. Eleven white dwarf binary systems have previously been found in this way from ROSAT, EUVE and IUE observations (e.g. Barstow et al. 1994). In this paper we report the discovery of three more such systems through our programmes in recent episodes of IUE. The new binaries are HD2133, RE J0357+283 (whose existence was predicted by Jeffries, Burleigh and Robb 1996), and BD+27 1888. In addition, we have independently identified a fourth new WD+MS binary, RE J1027+322, which has also been r...

  2. Extensive Serendipitous X-ray Coverage of a Flare Star with ROSAT

    CERN Document Server

    Silverman, J D; Green, P J; Saar, S H

    2000-01-01

    We report the serendipitous discovery of a flare star observed with the ROSAT X-ray observatory. From optical spectra, which show strong and variable emission lines of the hydrogen Balmer series and neutral helium, we classify this object as a M3.0Ve star, and estimate a distance of 52 pc from published photometry. Due to the star's close proximity (13.6') to the calibration source and RS CVn binary AR Lacertae, long term X-ray coverage is available in the ROSAT archive (~50 hours spanning 6.5 years). Two large flare events occurred early in the mission (6-7/1990), and the end of a third flare was detected in 6/1996. One flare, observed with the Position Sensitive Proportional Counter (PSPC), had a peak luminosity Lx=1.1x10^{30} erg/s, an e-folding rise time of 2.2 hours and a decay time of 7 hours. This decay time is one of the longest detected on a dMe star, providing evidence for the possibility of additional heating during the decay phase. A large HRI flare (peak Lx=2.9x10^{30} erg/s) is also studied. The...

  3. ROSAT X-ray observations of the dwarf galaxy Holmberg II

    CERN Document Server

    Kerp, J; Brinks, E; Kerp, Juergen; Walter, Fabian; Brinks, Elias

    2002-01-01

    We present a study of the irregular dwarf galaxy Holmberg II based on ROSAT PSPC observations (total exposure time: 22 ksec). Holmberg II is a nearby (3.2 Mpc), well-studied dwarf irregular galaxy. It is famous for its interstellar medium which is dominated by expanding structures such as HI holes and shells. We search for X-ray emission from point sources as well as for diffuse emission, down to the detection limit of the ROSAT data. Using X-ray hardness ratio diagrams we differentiate between thermal plasma and power-law X-ray spectra which helps to determine the nature of the individual sources. Correlating the X-ray data with complementary observations ranging from the far-ultraviolet to the radio regime we increase the probability of correctly identifying sources belonging to Holmberg II. We did not detect soft X-ray emission originating from hot gas within supergiant HI shells above our luminosity sensitivity limit of (L_limit(0.1 - 2.1 keV) ~ 10^{37}erg/s). This finding can probably be attributed to bl...

  4. A deep ROSAT survey 10, X-ray luminous narrow emission line galaxies

    CERN Document Server

    Griffiths, R E; Georgantopoulos, I; Boyle, B J; Stewart, G C; Shanks, T; Fruscione, A; Griffiths, Richard E; Della Ceca, Roberto; Georgantopoulos, Ioannis; Boyle, Brian J; Stewart, Gordon C; Shanks, Tom; Fruscione, Antonella

    1996-01-01

    X-ray luminous narrow emision-line galaxies (NELG) have been previously identified and proposed as an important class of extragalactic X-ray sources, with a potentially significant contribution to the total extragalactic X-ray flux at energies below \\sim 10 keV. In order to investigate and clarify this possibility, we have used a sample of NELG found in 5 deep ROSAT fields and similar samples belonging to the Cambridge-Cambridge ROSAT Serendipity Survey and to the {\\it Einstein} Observatory Extended Medium Sensitivity Survey sample. The principal results of this investigation are as follows: a) for a given optical luminosity, the typical X-ray luminosity of NELGs is about one or two orders of magnitude higher than that of normal galaxies; b) the ratio of the surface density of NELGs compared with BLAGN increases from about 0.04 at fx >= 6 x 10^{-13} erg cm^{-2} s^{-1} to about 0.1 at fx >= 10^{-14} erg cm^{-2} s^{-1}, suggesting that the surface density of NL galaxies might be very close to that of BLAGN at f...

  5. The ROSAT deep survey; 5, X-rays Sources and Optical Identifications in the Marano Field

    CERN Document Server

    Zamorani, G; Hasinger, G; Burg, R; Giacconi, R; Schmidt, M; Trümper, J E; Ciliegi, P; Gruppioni, C; Marano, B

    1999-01-01

    We present the X-ray data and the optical identifications for a deep ROSAT PSPC observation in the "Marano field". In the inner region of the ROSAT field (15' radius) we detected 50 X-ray sources with Sx >= 3.7x10^(-15) erg/cm^2/s. When corrected for the different sensitivity over the field, the estimated observed surface density at Sx >= 4x10^(-15) erg/cm^2/s is 272+/-40 sources/sq.deg. Four X-ray sources, corresponding to 8% of the total sample, have been detected in radio images with a flux limit of about 0.2 mJy. Careful statistical analysis of multicolour CCD data in the error boxes of the 50 X-ray sources has led to the identification of 42 sources, corresponding to 84% of the X-ray sample. These 42 reliable identifications are 33 AGNs (including two radio galaxies and one BL Lac candidate; 79% of the identified sources), 2 galaxies, 3 groups or clusters of galaxies and 4 stars. We also show that it is likely that a few of the 8 unidentified sources are such because the derived X-ray positions may be of...

  6. X-ray emission on hybird stars: ROSAT observations of alpha Trianguli Australis and iota Aurigae

    Science.gov (United States)

    Kashyap, V.; Rosner, R.; Harnden, F. R., Jr.; Maggio, A.; Micela, G.; Sciortino, S.

    1994-01-01

    We report on deep ROSAT observations of two Hybrid atmosphere stars, alpha TrA and iota Aur, and our analysis of these observations. We detect high-energy transient phenomena on alpha TrA and consider the implications of this discovery to the atmospheres of Hybrid stars. We detect iota Aur in the high-energy passband of ROSAT, implying the existence of multimillion degree plasma on the star. Our major results include the following: discovery of two large flare events, detected during pointed observations of alpha TrA; the demonstration that the flare emission most likely comes from the giant itself, rather than from a previously unseen low-mass companion star; the demonstration that the plasma characteristics associated with the flares and with the 'quiescent' component are essentially indistinguishable; and that the geometric dimensions of the emitting plasma are considerably smaller than the critical dimension characterizing stable 'hot' coronal loop structures. Our results suggest that alpha TrA does not have any steady X-ray emission consistent with theoretical expectations, and support the argument that Hybrid stars constitute a transitional type of object in which large-scale magnetic dynamo activity ceases, and the dominant spatial scales characterizing coronal structure rapidly decline as such stars evolve across the X-ray 'Dividing Line' in the H-R diagram.

  7. ROSAT PSPC and HRI observations of the composite starburst/Seyfert 2 galaxy NGC 1672

    CERN Document Server

    Brandt, W N; Iwasawa, K

    1996-01-01

    The nearby barred spiral galaxy NGC 1672 is thought to have a weak Seyfert nucleus in addition to its strong starburst activity. Observations with the PSPC and HRI instruments on board the ROSAT X-ray satellite show that three X-ray sources with luminosities (1--2)\\times 10^{40} erg/s are clearly identified with NGC 1672. The strongest X-ray source lies at the nucleus, and the other two lie near the ends of the prominent bar, locations that are also bright in H-alpha and near-infrared images. The nuclear source is resolved by the HRI on about the scale of the recently identified nuclear ring, and one of the sources at the ends of the bar is also probably resolved. The X-ray spectrum of the nuclear source is quite soft, having a Raymond--Smith plasma temperature of about 0.7 keV and little evidence for intrinsic absorption. The ROSAT band X-ray flux of the nuclear source appears to be dominated not by X-ray binary emission but rather by diffuse gas emission. While the properties of the nuclear source are gener...

  8. The CfA-Rosat Survey of Distant Clusters of Galaxies

    Science.gov (United States)

    McNamara, Brian

    1998-01-01

    We (Vikhlinin, McNamara, Forman, Jones, Hornstrup, Quintana) have completed a new survey of distant clusters of galaxies, which we use to to study cluster evolution over cosmological timescales. The clusters were identified as extended X-ray sources in 650 ROSAT PSPC images of high Galactic latitude fields. Our catalog of approximately 230 extended X-ray sources covers 160 square degrees on the sky. Ours is the largest of the several ROSAT serendipitous cluster surveys in progress (e.g. SHARC, Rosati, WARPS etc.). Using V,R,I imagery obtained at several observatories, we find that greater than 90% of the X-ray sources are associated with distant clusters of galaxies. We have obtained spectroscopic redshifts for nearly 80 clusters in our catalog, and we have measured photometric redshifts for the remaining clusters. Our sample contains more than 20 clusters at z > 0.5. I will discuss the logN-logS relationship for our clusters. Because our large survey area, we are able to confirm the evolution of the most luminous distant clusters first seen in the Einstein Extended Medium Sensitivity Survey. In addition, I will discuss the relationships between optical richness, core radius, and X-ray luminosity for distant, X-ray-selected clusters.

  9. A Limit on the Number of Isolated Neutron Stars Detected in the ROSAT Bright Source Catalog

    CERN Document Server

    Rutledge, R E; Bogosavljevic, M; Mahabal, A A; Rutledge, Robert E.; Fox, Derek W.; Bogosavljevic, Milan; Mahabal, Ashish

    2003-01-01

    The challenge in searching for non-radio-pulsing isolated neutron stars (INSs) is in excluding association with objects in the very large error boxes (~13", 1 sigma radius) typical of sources from the largest X-ray all-sky survey, the ROSAT All-Sky-Survey/Bright Source Catalog (RASS/BSC). We search for candidate INSs using statistical analysis of optical (USNO-A2), infrared (IRAS), and radio (NVSS) sources near the ROSAT X-ray localization, and show that this selection would find 20% of the INSs in the RASS/BSC. This selection finds 32 candidates at declinations greater than -39 deg, among which are two previously known INSs, seventeen sources which we show are not INSs, and thirteen the classification of which are as yet undetermined. These results require a limit of <67 INSs (90% confidence, full sky, assuming isotropy) in the RASS/BSC. This limit modestly constrains a naive and optimistic model for cooling NSs in the galaxy.

  10. Discovery of intermediate redshift galaxy clusters in the ROSAT NEP field. [North Ecliptic Pole

    Science.gov (United States)

    Burg, R.; Giacconi, R.; Huchra, J.; Mackenty, J.; Mclean, B.; Geller, M.; Hasinger, G.; Marzke, R.; Schmidt, M.; Truemper, J.

    1992-01-01

    We report preliminary results from a program to identify optical counterparts of ROSAT sources in the North Ecliptic Pole (NEP) region. The most striking X-ray feature reported by Hasinger et al. (1991) is an extended low surface brightness region of X-ray emission. Within the two X-ray contours of highest count rate we find a cluster of galaxies at a redshift of 0.09 and an early-type galaxy at a redshift of 0.03. X-ray emission from these objects may provide an explanation for the observed X-ray morphology. We also find evidence that other X-ray sources in this region are coincident with clusters or groups of galaxies at redshifts between 0.08 and 0.09. The presence of at least five X-ray detected clusters or groups in this narrow redshift band within a 1.5 deg radius field seems to indicate the existence of a moderate redshift supercluster. The existence of these clusters will have major implications for the study of large-scale structure through X-ray surveys such as ROSAT.

  11. THE DETECTION RATE OF EARLY UV EMISSION FROM SUPERNOVAE: A DEDICATED GALEX/PTF SURVEY AND CALIBRATED THEORETICAL ESTIMATES

    Energy Technology Data Exchange (ETDEWEB)

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer [Department of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Kulkarni, Shrinivas R.; Kasliwal, Mansi M. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Ben-Ami, Sagi [Smithsonian Astrophysical Observatory, Harvard-Smithsonian Ctr. for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Chelouche, Doron; Rafter, Stephen [Physics Department, Faculty of Natural Sciences, University of Haifa, 31905 Haifa (Israel); Behar, Ehud; Laor, Ari [Physics Department, Technion Israel Institute of Technology, 32000 Haifa (Israel); Poznanski, Dovi; Nakar, Ehud; Maoz, Dan [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Trakhtenbrot, Benny [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27 Zurich 8093 (Switzerland); Neill, James D.; Barlow, Thomas A.; Martin, Christofer D., E-mail: noam.ganot@gmail.com [California Institute of Technology, 1200 East California Boulevard, MC 278-17, Pasadena, CA 91125 (United States); Collaboration: ULTRASAT Science Team; WTTH consortium; GALEX Science Team; Palomar Transient Factory; and others

    2016-03-20

    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core-collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early ultraviolet (UV) emission from SNe. Six SNe II and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX near-UV (NUV) data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 R{sub ⊙}, explosion energies of 10{sup 51} erg, and ejecta masses of 10 M{sub ⊙}. Exploding blue supergiants and Wolf–Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition, and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase (<1 day after explosion) for several ground-based surveys (PTF, ZTF, and LSST). We show that the proposed wide-field UV explorer ULTRASAT mission is expected to find >85 SNe per year (∼0.5 SN per deg{sup 2}), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.

  12. The detection rate of early UV emission from supernovae: A dedicated GALEX/PTF survey and calibrated theoretical estimates

    CERN Document Server

    Ganot, Noam; Ofek, Eran O; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R; Ben-Ami, Sagi; Kasliwal, Mansi M; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Udi; Maoz, Dan; Trakhtenbrot, Benny; Neill, James D; Barlow, Thomas A; Martin, Christofer D; Gezari, Suvi; Arcavi, Iair; Bloom, Joshua s; Nugent, Peter E; Sullivan, Mark

    2014-01-01

    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 R_solar, explosion energies of 10^51 erg, and ejecta masses of 10 M_solar. Exploding blue supergiants and Wolf-Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition and explosion energy per u...

  13. Catalogs of Hot White Dwarfs in the Milky Way from GALEX's Ultraviolet Sky Surveys. Constraining Stellar Evolution

    CERN Document Server

    Bianchi, Luciana; Herald, James; Girardi, Leo; Zabot, Alexandre; Marigo, Paola; Martin, Christopher

    2010-01-01

    We present comprehensive catalogs of hot star candidates in the Milky Way, selected from GALEX far-UV (FUV, 1344-1786 AA) and near-UV (NUV, 1771-2831 AA) imaging. The FUV and NUV photometry allows us to extract the hottest stellar objects, in particular hot white dwarfs (WD), which are elusive at other wavelengths because of their high temperatures and faint optical luminosities. We generated catalogs of UV sources from two GALEX's surveys: AIS (All-Sky Imaging Survey, depth ABmag~19.9/20.8 in FUV/NUV) and MIS (Medium-depth Imaging Survey, depth ~22.6/22.7mag). The two catalogs (from GALEX fifth data release) contain 65.3/12.6 million (AIS/MIS) unique UV sources with error(NUV)0.1 isolates binaries with largely differing Teff's, and some intruding QSOs. Available spectroscopy for a subsample indicates that hot-star candidates with NUV-r<0.1 have negligible contamination by non-stellar ob jects. We discuss the distribution of sources in the catalogs, and the effects of error and color cuts on the samples. T...

  14. Circumstellar Dust, PAHs, and Stellar Populations in Early-Type Galaxies: Insights from GALEX and WISE

    CERN Document Server

    Simonian, Gregory V

    2016-01-01

    A majority of early-type galaxies contain interstellar dust, yet the origin of this dust, and why the dust sometimes exhibits unusual PAH ratios, remains a mystery. If the dust is internally produced, the most likely origin is the large number of AGB stars associated with the old stellar population. We present GALEX and WISE elliptical aperture photometry of $\\sim350$ early-type galaxies with Spitzer mid-infrared spectroscopy and/or ancillary data from ATLAS3D, to characterize their circumstellar dust and the shape of the radiation field that illuminates the interstellar PAHs. We find that circumstellar dust is ubiquitous in early-type galaxies, which indicates some tension between stellar population age estimates and models for circumstellar dust production in very old stellar populations. We also use dynamical masses from ATLAS3D to show that WISE W1 (3.4 $\\mu$m) mass-to-light ratios are inconsistent with model predictions for a single IMF, as found by previous work. While the stellar population differences...

  15. The GALEX Arecibo SDSS Survey. IV. Baryonic Mass-Velocity-Size Relations of Massive Galaxies

    CERN Document Server

    Catinella, Barbara; Schiminovich, David; Lemonias, Jenna; Scannapieco, Cecilia; Wang, Jing; Fabello, Silvia; Hummels, Cameron; Moran, Sean M; Wu, Ronin; Cooper, Andrew P; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Saintonge, Amélie

    2011-01-01

    We present dynamical scaling relations for a homogeneous and representative sample of ~500 massive galaxies, selected only by stellar mass (>10^10 Msun) and redshift (0.025GALEX Arecibo SDSS Survey. We compare baryonic Tully-Fisher (BTF) and Faber-Jackson (BFJ) relations for this sample, and investigate how galaxies scatter around the best fits obtained for pruned subsets of disk-dominated and bulge-dominated systems. The BFJ relation is significantly less scattered than the BTF when the relations are applied to their maximum samples, and is not affected by the inclination problems that plague the BTF. Disk-dominated, gas-rich galaxies systematically deviate from the BFJ relation defined by the spheroids. We demonstrate that by applying a simple correction to the stellar velocity dispersions that depends only on the concentration index of the galaxy, we are able to bring disks and spheroids onto the same dynamical relation -- in other words, we obtain a generalized BFJ re...

  16. The GALEX Arecibo SDSS Survey II: The Star Formation Efficiency of Massive Galaxies

    CERN Document Server

    Schiminovich, David; Kauffmann, Guinevere; Fabello, Silvia; Wang, Jing; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Basu-Zych, Antara R; Blanton, Michael R; Brinchmann, Jarle; Budavari, Tamas; Goncalves, Thiago; Johnson, Benjamin D; Kennicutt, Robert C; Madore, Barry F; Martin, Christopher D; Rich, Michael R; Tacconi, Linda J; Thilker, David A; Wild, Vivienne; Wyder, Ted K

    2010-01-01

    We use measurements of the HI content, stellar mass and star formation rates in ~190 massive galaxies with stellar masses greater than 10^10 Msun, obtained from the Galex Arecibo SDSS Survey (GASS) described in Paper I (Catinella et al. 2010) to explore the global scaling relations associated with the bin-averaged ratio of the star formation rate over the HI mass, which we call the HI-based star formation efficiency (SFE). Unlike the mean specific star formation rate, which decreases with stellar mass and stellar mass surface density, the star formation efficiency remains relatively constant across the sample with a value close to SFE = 10^-9.5 yr^-1 (or an equivalent gas consumption timescale of ~3 Gyr). Specifically, we find little variation in SFE with stellar mass, stellar mass surface density, NUV-r color and concentration. We interpret these results as an indication that external processes or feedback mechanisms that control the gas supply are important for regulating star formation in massive galaxies....

  17. Classical Novae in Andromeda: Light Curves from the Palomar Transient Factory and GALEX

    CERN Document Server

    Cao, Yi; Neill, James D; Kulkarni, S R; Lou, Yu-Qing; Ben-Ami, Sagi; Bloom, Joshua S; Cenko, S Bradley; Law, Nicholas M; Nugent, Peter E; Ofek, Eran O; Poznanski, Dovi; Quimby, Robert M

    2012-01-01

    We present optical light curves of twenty-nine novae in M31 during the 2009 and 2010 observing seasons of the Palomar Transient Factory (PTF). The dynamic and rapid cadences in PTF monitoring of M31, from one day to even ten minutes, provide excellent temporal coverage of nova light curves, enabling us to record the photometric evolution of M31 novae in unprecedented detail. We also detect eight of these novae in the near ultraviolet (UV) band with the Galaxy Evolution Explorer (GALEX) satellite. Novae M31N2009-10b and 2010-11a show prominent UV emission peaking a few days prior to their optical maxima, possibly implying aspherical outbursts. Additionally, our blue-shifted spectrum of the recent outburst of PT And (M31N2010-12a) indicates that it is a recurrent nova in M31 and not a dwarf nova in the Milky Way as was previously assumed. Finally, we systematically searched for novae in all confirmed globular clusters of M31 and found only M31N 2010-10f associated with Bol 126. The specific nova rate in the M31...

  18. Accretion and diffusion in the DAZ white dwarf GALEX J1931+0117

    CERN Document Server

    Vennes, Stephane; Nemeth, Peter

    2010-01-01

    We present an analysis of high-dispersion and high signal-to-noise ratio spectra of the DAZ white dwarf GALEX J1931+0117. The spectra obtained with the VLT-Kueyen/UV-Visual Echelle Spectrograph show several well-resolved Si II spectral lines enabling a study of pressure effects on line profiles. We observed large Stark shifts in silicon lines in agreement with laboratory measurements. A model atmosphere analysis shows that the magnesium, silicon and iron abundances exceed solar abundances, while the oxygen and calcium abundances are below solar. Also, we compared the observed line profiles to synthetic spectra computed with variable accretion rates and vertical abundance distributions assuming diffusion steady-state. The inferred accretion rates vary from dM/dt=2x10^6 for calcium to 2x10^9 g/s for oxygen and indicate that the accretion flow is dominated by oxygen, silicon and iron while being deficient in carbon, magnesium and calcium. The lack of radial velocity variations between two measurement epochs sugg...

  19. GALEX Ultraviolet Photometry of Globular Clusters in M31: Three Year Results and a Catalog

    CERN Document Server

    Rey, S C; Sohn, S T; Yoon, S J; Chung, C; Yi, S K; Lee, Y W; Rhee, J; Bianchi, L; Madore, B F; Lee, K; Barlow, T A; Forster, K; Friedman, P G; Martin, D C; Morrissey, P; Neff, S G; Schiminovich, D; Seibert, M; Small, T; Wyder, T K; Donas, J; Heckman, T M; Milliard, B; Szalay, A S; Welsh, B Y; Rey, Soo-Chang; Sohn, Sangmo T.; Yoon, Suk-Jin; Chung, Chul; Yi, Sukyoung K.; Lee, Young-Wook; Rhee, Jaehyon; Bianchi, Luciana; Madore, Barry F.; Lee, Kyungsook; Barlow, Tom A.; Forster, Karl; Friedman, Peter G.; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Seibert, Mark; Small, Todd; Wyder, Ted K.; Donas, Jose; Heckman, Timothy M.; Milliard, Bruno; Szalay, Alex S.; Welsh, Barry Y.

    2006-01-01

    We present ultraviolet (UV) photometry of M31 globular clusters (GCs) found in 23 Galaxy Evolution Explorer (GALEX) images covering the entirety of M31. We detect 485 and 273 GCs (and GC candidates) in the near-ultraviolet (NUV; 2267 A) and far-ultraviolet (FUV; 1516 A), respectively. Comparing M31 data with those of Galactic GCs in the UV with the aid of population models, we find that the age ranges of old GCs in M31 and the Galactic halo are similar. Three metal-rich ([Fe/H]>-1) GCs in M31 produce significant FUV flux making their FUV-V colors unusually blue for their metallicities. These are thought to be analogs of the two peculiar Galactic GCs NGC 6388 and NGC 6441 with extended blue HB stars. Based on the models incorporating helium enriched subpopulations in addition to the majority of the population that have a normal helium abundance, we suggest that even small fraction of super-helium-rich subpopulations in GCs can reproduce the observed UV bright metal-rich GCs. Young clusters in M31 show distinct...

  20. GALEX J184559.8-413827: a new extreme helium star identified using SALT★

    Science.gov (United States)

    Jeffery, C. Simon

    2017-09-01

    A high-resolution spectrum of the helium-rich 'hot subdwarf' GALEX J184559.8-413827 (J1845-4138) obtained with SALT HRS demonstrates it to be the first extreme helium (EHe) star to be discovered in nearly 40 years. A quantitative analysis demonstrates it to have an atmosphere described by Teff = 26 170 ± 750 K, log g/cm s-2 = 4.22 ± 0.10 and a surface chemistry characterized by CNO-processed helium, a 1 per cent contamination of hydrogen (by number) and a metallicity 0.4 dex subsolar. Its distance and position are consistent with membership of the Galactic bulge. Its sharp absorption lines place strong constraints on both the rotation and microturbulent velocities. Spectroscopically, J1845-4138 closely resembles the pulsating EHe star V652 Her, generally considered to be the product of a double helium white dwarf merger evolving to become a helium-rich sdO star.

  1. The GALEX Arecibo SDSS survey: III. Evidence for the Inside-Out Formation of Galactic Disks

    CERN Document Server

    Wang, Jing; Overzier, Roderik; Catinella, Barbara; Schminovich, David; Heckman, Timothy M; Moran, Sean M; Haynes, Martha P; Giovanelli, Riccardo; Kong, Xu

    2010-01-01

    We analyze a sample of galaxies with stellar masses greater than $10^{10} M_{\\odot}$ and with redshifts in the range $0.025GALEX Arecibo SDSS Survey (GASS) or from the Arecibo Legacy Fast ALFA survey (ALFALFA). At a given value of $M_*$, our sample consists primarily of galaxies that are more HI-rich than average. We constructed a series of three control samples for comparison with these HI-rich galaxies. As expected, HI-rich galaxies differ strongly from galaxies of same stellar mass that are selected without regard to HI content. The majority of these differences are attributable to the fact that galaxies with more gas are bluer and more actively star-forming. In order to identify those galaxy properties that are causally connected with HI content, we compare results derived for the HI sample with those derived for galaxies matched in stellar mass, size and NUV-$r$ colour. The only photometric property that is clearly attributable to incre...

  2. Simultaneous spectroscopic and photometric analysis of galaxies with STARLIGHT: CALIFA $+$ GALEX

    CERN Document Server

    Fernández, R López; Delgado, R M González; Asari, N Vale; Pérez, E; García-Benito, R; de Amorim, A L; Lacerda, E A D; Cortijo-Ferrero, C; Sánchez, S F

    2016-01-01

    We present an extended version of the spectral synthesis code STARLIGHT designed to incorporate both $\\lambda$-by-$\\lambda$ spectra and photometric fluxes in the estimation of stellar population properties of galaxies. The code is tested with simulations and data for 260 galaxies culled from the CALIFA survey, spatially matching the 3700--7000 \\AA\\ optical datacubes to GALEX near and far UV images. The sample spans E--Sd galaxies with masses from $10^9$ to $10^{12} M_\\odot$ and stellar populations all the way from star-forming to old, passive systems. Comparing results derived from purely optical fits with those which also consider the NUV and FUV data we find that: (1) The new code is capable of matching the input UV data within the errors while keeping the quality of the optical fit essentially unchanged. (2) Despite being unreliable predictors of the UV fluxes, purely optical fits yield stellar population properties which agree well with those obtained in optical+UV fits for nearly 90% of our sample. (3) T...

  3. VizieR Online Data Catalog: Synthetic GALEX photometry for IUE sources (Beitia-Antero+, 2016)

    Science.gov (United States)

    Beitia-Antero, L.; Gomez de Castro, A. I.

    2016-10-01

    Synthetic photometry in the GALEX bands for stellar sources observed with the IUE in low dispersion mode is provided. Only high signal-to-noise ratio photometric observations have been used (see bibliographic reference). There are two catalogues: maincat contains synthetic magnitudes for non-variable stars; fuvvar contains synthetic FUV magnitudes for variable stars. Non-variable means that no variation in the UV flux has been detected by IUE. For each entry, coordinates, FUV and NUV magnitudes and magnitude errors are provided. SUMMARY OF CONTENTS: maincat includes FUV and/or NUV synthetic magnitudes for 1722 stars. FUV magnitude is provided for 1628 sources, ranging from FUV=1.81 to FUV=18.65mag. NUV magnitude is provided for 999 stars, ranging from NUV=3.34 to NUV=17.74mag. Also the number of observations used for the calculation is indicated. fuvvar includes FUV synthetic magnitude and error as well as observation date and time for each one of the 88 variable sources in FUV. (2 data files).

  4. CLASSICAL NOVAE IN ANDROMEDA: LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY AND GALEX

    Energy Technology Data Exchange (ETDEWEB)

    Cao Yi; Lou Yuqing [Tsinghua Center for Astrophysics (THCA), Department of Physics, Tsinghua University, Beijing 100084 (China); Kasliwal, Mansi M.; Neill, James D.; Kulkarni, S. R.; Quimby, Robert M. [Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Ben-Ami, Sagi [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Bloom, Joshua S.; Cenko, S. Bradley; Nugent, Peter E. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Law, Nicholas M. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, M5S 3H4 Ontario (Canada); Ofek, Eran O. [Benoziyo Center for Astrophysics, Faculty of Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Poznanski, Dovi, E-mail: ycao@astro.caltech.edu [School of Physics and Astronomy, Tel-Aviv University, Tel Aviv 69978 (Israel)

    2012-06-20

    We present optical light curves of 29 novae in M31 during the 2009 and 2010 observing seasons of the Palomar Transient Factory (PTF). The dynamic and rapid cadences in PTF monitoring of M31, from one day to ten minutes, provide excellent temporal coverage of nova light curves, enabling us to record the photometric evolution of M31 novae in unprecedented detail. We also detect eight of these novae in the near-ultraviolet (UV) band with the Galaxy Evolution Explorer (GALEX) satellite. Novae M31N 2009-10b and M31N 2010-11a show prominent UV emission peaking a few days prior to their optical maxima, possibly implying aspherical outbursts. Additionally, our blueshifted spectrum of the recent outburst of PT And (M31N 2010-12a) indicates that it is a recurrent nova in M31 and not a dwarf nova in the Milky Way as was previously assumed. Finally, we systematically searched for novae in all confirmed globular clusters (GCs) of M31 and found only M31N 2010-10f associated with Bol 126. The specific nova rate in the M31 GC system is thus about one per year, which is not enhanced relative to the rate outside the GC system.

  5. Lyman alpha emitting galaxies at 0.2 < z < 0.35 from GALEX spectroscopy

    CERN Document Server

    Deharveng, Jean-Michel; Barlow, Tom A; Peroux, Celine; Milliard, Bruno; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Schiminovich, David; Forster, Karl; Seibert, Mark; Wyder, Ted K; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Neff, Susan G; Rich, R Michael; Szalay, A S; Welsh, Barry Y; Yi, Sukyoung K

    2008-01-01

    The GALEX (Galaxy Evolution Explorer) spectroscopic survey mode, with a resolution of about 8 A in the FUV (1350 - 1750 A) and about 20 A in the NUV (1950 - 2750 A) is used for a systematic search of Ly-a emitting galaxies at low redshift. This aims at filling a gap between high-redshift surveys and a small set of objects studied in detail in the nearby universe. A blind search of 7018 spectra extracted in 5 deep exposures (5.65 sq.deg) has resulted in 96 Ly-a emitting galaxy candidates in the FUV domain, after accounting for broad-line AGNs. The Ly-a EWs (equivalent width) are consistent with stellar population model predictions and show no trends as a function of UV color or UV luminosity, except a possible decrease in the most luminous that may be due to small-number statistics. Their distribution in EW is similar to that at z about 3 but their fraction among star-forming galaxies is smaller. Avoiding uncertain candidates, a sub-sample of 66 objects in the range 0.2 < z < 0.35 has been used to build ...

  6. Galaxy Groups: A 2MASS Catalog

    CERN Document Server

    Tully, R Brent

    2015-01-01

    A galaxy group catalog is built from the sample of the 2MASS Redshift Survey almost complete to Ks=11.75 over 91% of the sky. Constraints in the construction of the groups were provided by scaling relations determined by close examination of well defined groups with masses between 10^11 and 10^15 Msun. Group masses inferred from Ks luminosities are statistically in agreement with masses calculated from application of the virial theorem. While groups have been identified over the full redshift range of the sample, the properties of the nearest and farthest groups are uncertain and subsequent analysis has only considered groups with velocities between 3,000 and 10,000 km/s. The 24,044 galaxies in this range are identified with 13,607 entities, 3,461 of them with two or more members. A group mass function is constructed. The Sheth-Tormen formalism provides a good fit to the shape of the mass function for group masses above 6/h x 10^12 Msun but the count normalization is poor. Summing all the mass associated with...

  7. ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, Timothy J.; Travnicek, P.

    2012-01-01

    We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction.

  8. Variability of Soft X-ray Spectral Shape in Blazars Observed by ROSAT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In previous paper we have shown that the soft X-ray spectra of two types of Seyfert 1 galaxies behave statistically differently with increasing intensity.In order to see how the spectrum of blazars changes, we made plots of Hardness Ratio 1 versus Count Rates (HR1-Cts) for 18 blazars observed by ROSAT/PSPC.According to our criteria, ten showed a positive HR1-Cts correlation, two a negative correlation, and the remaining six, no clear correlation. Thus, most blazars of our sample show a hardening spectrum during overall flux increase, though some vary randomly. By investigating the photon index of these objects and different radiation theories, we argue that relative dominance between the synchrotron and inverse Compton emission in the soft X-ray band can well account for the differing spectral behaviours and that the different spectral variations might represent a sequence of synchrotron peaked frequency.

  9. A Survey of Unclassified ROSAT-BSC Sources for qLMXB Candidates

    Science.gov (United States)

    Dufour, Francois; Rutledge, Robert E.

    2014-08-01

    Spectroscopic measurements of the thermal emission of neutron stars in quiescent low-mass X-ray binaries (qLMXBs) are one of only three methods to constrain the equation of state of cold nuclear matter. Up to now, this method has been limited in its application to qLMXBs within globular clusters, due to the high distance uncertainty of qLMXBs in the field. Gaia parallax measurements will soon allow the use of field qLMXBs with sufficiently bright optical counterparts in this key test of physics. We propose to undertake a survey of unclassified ROSAT BSC sources with high apparent X-ray to infrared flux ratios for H(alpha) excess, a tell-tale sign of accretion disks, in order to select qLMXBs candidates for X-ray followup.

  10. Interesting features in the combined Galex and Sloan color diagrams of solar-like galactic populations

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Myron A.; Shiao, Bernard [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bianchi, Luciana, E-mail: myronmeister@gmail.com, E-mail: shiao@stsci.edu, E-mail: bianchi@pha.jhu.edu [Johns Hopkins University, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-06-01

    We report on intriguing photometric properties of Galactic stars observed in the Galaxy Evolution Explorer (GALEX) satellite's far-UV (FUV) and near-UV (NUV) bandpasses, as well as from the ground-based Sloan Digital Sky Survey (SDSS) and the Kepler Input Catalog. The first property is that the (FUV – NUV) color distribution of stars in the Kepler field consists of two well-separated peaks. A second and more perplexing property is that for stars with spectral types G or later the mean (FUV – NUV) color becomes much bluer, contrary to expectation. Investigating this tendency further, we found in two samples of mid-F through K type stars that 17%-22% of them exhibit FUV excesses relative to their NUV fluxes and spectral types. A correction for FUV incompleteness of the FUV magnitude-limited star sample brings this ratio to 14%-18%. Nearly the same fractions are also discovered among members of the Kepler Eclipsing Binary Catalog and in the published list of Kepler Objects of Interest. These UV-excess ('UVe') colors are confirmed by the negative UV continuum slopes in GALEX spectra of members of the population. The SDSS spectra of some UVe stars exhibit metallic line weakening, especially in the blue. This suggests an enhanced contribution of UV flux relative to photospheric flux of a solar-type single star. We consider the possibility that the UV excesses originate from various types of hot stars, including white dwarf DA and sdB stars, binaries, and strong chromosphere stars that are young or in active binaries. The space density of compact stars is too low to explain the observed frequency of the UVe stars. Our model atmosphere-derived simulations of colors for binaries with main-sequence pairs with a hot secondary demonstrate that the color loci conflict with the observed sequence. As a preferred alternative we are left with the active chromospheres explanation, whether in active close binaries or young single stars, despite the expected paucity

  11. Circumstellar dust, PAHs and stellar populations in early-type galaxies: insights from GALEX and WISE

    Science.gov (United States)

    Simonian, Gregory V.; Martini, Paul

    2017-02-01

    A majority of early-type galaxies contain interstellar dust, yet the origin of this dust, and why the dust sometimes exhibits unusual polycyclic aromatic hydrocarbon (PAH) ratios, remains a mystery. If the dust is internally produced, it likely originates from the large number of asymptotic giant branch stars associated with the old stellar population. We present GALEX and WISE elliptical aperture photometry of ˜310 early-type galaxies with Spitzer mid-infrared spectroscopy and/or ancillary data from ATLAS3D, to characterize their circumstellar dust and the shape of the radiation field that illuminates the interstellar PAHs. We find that circumstellar dust is ubiquitous in early-type galaxies, which indicates some tension between stellar population age estimates and models for circumstellar dust production in very old stellar populations. We also use dynamical masses from ATLAS3D to show that WISE W1 (3.4 μm) mass-to-light ratios are consistent with the initial mass function variation found by previous work. While the stellar population differences in early-type galaxies correspond to a range of radiation field shapes incident upon the diffuse dust, the ratio of the ionization-sensitive 7.7 μm/11.3 μm PAH feature does not correlate with the shape of the radiation field, nor to variations with the size-sensitive 11.3 μm/17 μm ratio. The 7.7 μm/11.3 μm PAH ratio does tend to be smaller in galaxies with proportionally greater H2 emission, which is evidence that processing of primarily smaller grains by shocks is responsible for the unusual ratios, rather than substantial differences in the overall PAH size or ionization distribution.

  12. The effects of the WISE/ GALEX photometry for the SED-fitting with M31 star clusters and candidates

    Science.gov (United States)

    Fan, Zhou; Wang, Song

    2017-10-01

    Spectral energy distribution (SED) fitting of stellar population synthesis models is an important and popular way to constrain the physical parameters—e.g., the ages, metallicities, masses for stellar population analysis. The previous works suggest that both blue-bands and red-bands photometry works for the SED-fitting. Either blue-domained or red-domained SED-fitting usually lead to the unreliable or biased results. Meanwhile, it seems that extending the wavelength coverage could be helpful. Since the Galaxy Evolution Explorer ( GALEX) and Wide-field Infrared Survey Explorer (WISE) provide the FUV/NUV and mid-infrared W1/W2 band data, we extend the SED-fitting to a wider wavelength coverage. In our work, we analyzed the effect of adding the FUV/NUV and W1/W2 band to the optical and near-infrared UBVRIJHK bands for the fitting with the (Bruzual and Charlot in Mon. Not. R. Astron. Soc. 344, 1000, 2003) (BC03) models and galev models. It is found that the FUV/NUV bands data affect the fitting results of both ages and metallicities much more significantly than that of the WISE W1/W2 band with the BC03 models. While for the galev models, the effect of the WISE W1/W2 band for the metallicity fitting seems comparable to that of GALEX FUV/NUV bands, but for age the effect of the W1/W2 band seems less crucial than that of the FUV/NUV bands. Thus we conclude that the GALEX FUV/NUV bands are more crucial for the SED-fitting of ages and metallicities, than the other bands, and the high-quality UV data (with high photometry precision) are required.

  13. Tracing the evolution of nearby early-type galaxies in low density environments. The Ultraviolet view from GALEX

    CERN Document Server

    Rampazzo, R; Marino, A; Bianchi, L; Bressan, A; Buson, L M; Clemens, M; Panuzzo, P; Zeilinger, W W; 10.1007/s10509-010-0586-5

    2011-01-01

    We detected recent star formation in nearby early-type galaxies located in low density environments, with GALEX Ultraviolet (UV) imaging. Signatures of star formation may be present in the nucleus and in outer rings/arm like structures. Our study suggests that such star formation may be induced by different triggering mechanisms, such as the inner secular evolution driven by bars, and minor accretion phenomena. We investigate the nature of the (FUV-NUV) color vs. Mg2 correlation, and suggest that it relates to "downsizing" in galaxy formation.

  14. Supernova 2009kf: An Ultraviolet Bright Type IIP Supernova Discovered With Pan-Starrs 1 and Galex

    Science.gov (United States)

    2010-07-01

    reserved. Printed in the U.S.A. SUPERNOVA 2009kf: AN ULTRAVIOLET BRIGHT TYPE IIP SUPERNOVA DISCOVERED WITH PAN-STARRS 1 AND GALEX M. T. Botticella1, C...January 29; accepted 2010 May 12; published 2010 June 16 ABSTRACT We present photometric and spectroscopic observations of a luminous Type IIP Supernova ...magnitude MNUV = −21.5 ± 0.5 mag suggests such SNe could be discovered out to z ∼ 2.5 in the PS1 survey. Key words: stars: evolution – supernovae

  15. ASCA observations of deep ROSAT fields V. The X-ray spectrum of hard X-ray selected QSOs

    CERN Document Server

    Pappa, A; Georgantopoulos, I; Griffiths, R E; Boyle, B J; Shanks, T

    2001-01-01

    We present an analysis of the \\rosat and \\asca spectra of 21 broad line AGN (QSOs) with $z\\sim 1$ detected in the 2-10 keV band with the \\asca \\gis. The summed spectrum in the \\asca band is well described by a power-law with $\\Gamma=1.56\\pm0.18$, flatter that the average spectral index of bright QSOs and consistent with the spectrum of the X-ray background in this band. The flat spectrum in the \\asca band could be explained by only a moderate absorption ($\\sim 10^{22} \\rm cm^{-2}$) assuming the typical AGN spectrum ie a power-law with $\\Gamma$=1.9. This could in principle suggest that some of the highly obscured AGN, required by most X-ray background synthesis models, may be associated with normal blue QSOs rather than narrow-line AGN. However, the combined 0.5-8 keV \\asca-\\rosat spectrum is well fit by a power-law of $\\Gamma=1.7\\pm0.2$ with a spectral upturn at soft energies. It has been pointed out that such an upturn may be an artefact of uncertainties in the calibration of the ROSAT or ASCA detectors. Nev...

  16. Improving Photometric Redshifts using GALEX Observations for the SDSS Stripe 82 and the Next Generation of SZ Cluster Surveys

    CERN Document Server

    Niemack, Michael D; Verde, Licia; Menanteau, Felipe; Panter, Ben; Spergel, David

    2008-01-01

    Four large-area Sunyaev-Zeldovich (SZ) experiments -- APEX-SZ, SPT, ACT, and Planck -- promise to detect clusters of galaxies through the distortion of Cosmic Microwave Background photons by hot (> 10^6 K) cluster gas (the SZ effect) over thousands of square degrees. A large observational follow-up effort to obtain redshifts for these SZ-detected clusters is under way. Given the large area covered by these surveys, most of the redshifts will be obtained via the photometric redshift (photo-z) technique. Here we demonstrate, in an application using ~3000 SDSS stripe 82 galaxies with r<20, how the addition of GALEX photometry (FUV, NUV) greatly improves the photometric redshifts of galaxies obtained with optical griz or ugriz photometry. In the case where large spectroscopic training sets are available, empirical neural-network-based techniques (e.g., ANNz) can yield a photo-z scatter of $\\sigma_z = 0.018 (1+z)$. If large spectroscopic training sets are not available, the addition of GALEX data makes possible...

  17. VizieR Online Data Catalog: z~1 Lyα emitters. I. 135 candidates from GALEX (Wold+, 2014)

    Science.gov (United States)

    Wold, I. G. B.; Barger, A. J.; Cowie, L. L.

    2016-06-01

    We construct a flux-limited sample of 135 candidate z~1 Lyα emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search method. As described in Barger et al. (2012ApJ...749..106B), we converted multiple GALEX NUV grism images into a 3D (two spatial axes and one wavelength axis) data cube. Each background subtracted data cube consists of thirty 20Å narrowband slices covering a wavelength range of 2030-2630Å and a 50'*50' field of view (FOV). Spectroscopic observations were primarily obtained with the DEep Imaging Multi-Object Spectrograph (DEIMOS) on Keck II in a series of runs in 2012-2013. The observations were made with the ZD600 line/mm grating blazed at 7500Å. This gives a resolution of ~5Å with a 1'' slit and a wavelength coverage of 5300Å. We observed our southern and equatorial fields (COSMOS and CDFS) with the Robert Stobie Spectrograph on SALT from 2011 to 2013. The observations were made with the pg1300 grating with the grating angle adjusted to ensure spectral coverage of lines redward of [Ne V]. This gives a resolution of ~4Å with a 1.5" slit and a wavelength coverage of 2000Å. In Tables 2-5, we list all of the LAE candidates in the Chandra Deep Field-South (CDFS), GROTH, NGPDWS, and COSMOS fields ordered by redshift. (4 data files).

  18. The GALEX Arecibo SDSS Survey. I. Gas Fraction Scaling Relations of Massive Galaxies and First Data Release

    CERN Document Server

    Catinella, Barbara; Kauffmann, Guinevere; Fabello, Silvia; Wang, Jing; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Basu-Zych, Antara R; Blanton, Michael R; Brinchmann, Jarle; Budavári, Tamás; Gonçalves, Thiago; Johnson, Benjamin D; Kennicutt, Robert C; Madore, Barry F; Martin, Christopher D; Rich, Michael R; Tacconi, Linda J; Thilker, David A; Wild, Vivienne; Wyder, Ted K

    2009-01-01

    We introduce the GALEX Arecibo SDSS Survey (GASS), an on-going large program that is gathering high quality HI-line spectra using the Arecibo radio telescope for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025GALEX imaging surveys. The galaxies are observed until detected or until a low gas mass fraction limit (1.5-5%) is reached. This paper presents the first Data Release, consisting of ~20% of the final GASS sample. We use this data set to explore the main scaling relations of HI gas fraction with galaxy structure and NUV-r colour. A large fraction (~60%) of the galaxies in our sample are detected in HI. We find that the atomic gas fraction decreases strongly with stellar mass, stellar surface mass density and NUV-r colour, but is only weakly correlated with galaxy bulge-to-disk ratio (as measured by the concentration index of the r-band light). We also find that the fraction of galaxies with signifi...

  19. The Ultraviolet View of the Magellanic Clouds from GALEX: A First Look at the LMC Source Catalog

    CERN Document Server

    Simons, Raymond; Bianchi, Luciana; Wyder, Ted

    2014-01-01

    The Galaxy Evolution Exporer (GALEX) has performed unprecedented imaging surveys of the Magellanic Clouds (MC) and their surrounding areas including the Magellanic Bridge (MB) in near-UV (NUV, 1771-2831\\AA) and far-UV (FUV, 1344-1786\\AA) bands at 5" resolution. Substantially more area was covered in the NUV than FUV, particularly in the bright central regions, because of the GALEX FUV detector failure. The 5$\\sigma$ depth of the NUV imaging varies between 20.8 and 22.7 (ABmag). Such imaging provides the first sensitive view of the entire content of hot stars in the Magellanic System, revealing the presence of young populations even in sites with extremely low star-formation rate surface density like the MB, owing to high sensitivity of the UV data to hot stars and the dark sky at these wavelengths. The density of UV sources is quite high in many areas of the LMC and SMC. Crowding limits the quality of source detection and photometry from the standard mission pipeline processing. We performed custom-photometry...

  20. The colour of the Deep ROSAT X-ray sky fluctuations

    CERN Document Server

    Ceballos, M T; Carrera, F J; Barcons, Xavier; Carrera, Francisco J.

    1996-01-01

    We have carried out a fluctuation analysis in four bands (R4, R5, R6 and R7 corresponding to 0.44-1.01 keV, 0.56-1.21 keV, 0.73-1.56 keV and to 1.05-2.04 keV respectively) of two very deep ROSAT PSPC observations in directions where the galactic H{\\small I} column is minimal. This has enabled us to study the average spectrum of the sources contributing to 0.5-2 keV fluxes $\\sim 10^{-15} \\rm \\ergpcmsqps$. The best fit spectral energy index for the average faint source spectrum, $\\alpha=0.95^{+0.10}_{-0.15}$, is still steeper than the one measured for the extragalactic XRB at these energies population of sources harder than the AGNs contributing to the source counts at these fluxes. We find that a population of X-ray sources with energy spectral index $\\alpha\\sim 0.4-0.6$ would contribute $(30\\pm 20)$ per cent to the source counts at these fluxes if the rest of them are AGNs with energy spectral index

  1. The particle background of the Rosat PSPC. [Position Sensitive Proportional Counter

    Science.gov (United States)

    Snowden, S. L.; Plucinsky, P. P.; Briel, U.; Hasinger, G.; Pfeffermann, E.

    1992-01-01

    In order to permit quantitative studies of the diffuse cosmic X-ray background and of extended X-ray sources, the particle induced background of the Roentgen Satellite, Rosat, Position Sensitive Proportional Counter (PSPC) is parameterized. Data collected during 210,000 s of PSPC operation have been analyzed and the temporal, spectral, and spatial distributions investigated. About 77 percent of the residual events originate within the detector while the remainder enter through the counter window. During typical conditions, the count rate of the residual events is well correlated with the Master Veto (MV) count rate. The spectrum of these events is well described by a flat component plus a soft power law and an Al K-alpha line at 1.5 keV. Also during typical conditions, the ratio between the power law and flat components remains constant to +/- 4 while the relative Al K-alpha contribution increases with increasing MV count rate. The distribution of the counts over the field of view is uniform except for a slight radial dependence and shadowing caused by blockage of the externally produced component by the window support structure.

  2. The Lensing Cluster MS0440+0204 Seen by HST, ROSAT and ASCA; 1, Cluster Properties

    CERN Document Server

    Gioia, I M; Lefèvre, O; Falco, E E; Luppino, G A; Hammer, F

    1997-01-01

    We present an analysis of the properties of the lensing cluster MS0440+0204 at z=0.1965. MS0440+0204 has been observed with a variety of telescopes at diverse wavelengths: from the ground with CFHT, MMT and KECK and from Earth orbit with HST, ROSAT and ASCA. Mass determinations are separately obtained from galaxy virial motions and X-ray profile fitting. A simple beta-model fit to the X-ray data yields a mass of (1.3+/-0.2) x10^{14} M_sun within 583 kpc of the cluster center, but more general models fit all of our data better and allow a wider range of masses that are consistent with the lensing data. In addition, the X-ray data yield a mass distribution profile that is well described by a beta model with a core radius of 26.7 kpc. The velocity dispersion of galaxies yields a mass of 4.8^{+1.5}_{-0.94} x 10^{14} M_sun within 900 kpc. In the inner 24.5arcsec there are 24 arcs that appear to be strong gravitationally lensed images of background sources. Models of the cluster mass distribution and its lensing pr...

  3. ROSAT HRI X-ray Observations of the Open Globular Cluster NGC 288

    CERN Document Server

    Sarazin, C L; Rood, R T; Ferraro, F R; Paltrinieri, B; Sarazin, Craig L.; Irwin, Jimmy A.; Rood, Robert T.; Ferraro, Francesco R.; Paltrinieri, Barbara

    1999-01-01

    A ROSAT HRI X-ray image was obtained of the open globular cluster NGC288, which is located near the South Galactic Pole. This is the first deep X-ray image of this system. We detect a Low Luminosity Globular Cluster X-ray source (LLGCX) RXJ005245.0-263449 with an X-ray luminosity of (5.5+-1.4)x10^32 ergs/s (0.1-2.0 keV), which is located very close to the cluster center. There is evidence for X-ray variability on a time scale of <~1 day. The presence of this LLGCX in such an open cluster suggests that dense stellar systems with high interaction rates are not needed to form LLGCXs. HST images will be used to attempt to identify RXJ005245.0-263449. We also searched for diffuse X-ray emission from NGC 288. Upper limits on the X-ray luminosities are L_X^h < 9.5x10^32 ergs/s (0.52-2.02 keV) and L_X^s < 9.3x10^32 ergs/s (0.11-0.41 keV). These imply upper limits to the diffuse X-ray to optical light ratios in NGC 288 which are lower than the values observed for X-ray faint early-type galaxies. This indicate...

  4. A multiband study of Hercules A. I. ROSAT observations of the intracluster medium

    CERN Document Server

    Gizani, N A B; Gizani, Nectaria A. B.

    2004-01-01

    We have made ROSAT PSPC and HRI X-ray observations to study the intracluster gas surrounding the powerful radio source Hercules A. The cluster is luminous in X-rays (L_bol = 4.8x10^37 W), and the host of the radio source is the central dominating galaxy of the cluster. The X-ray surface brightness profile is well fitted by a modified King beta model, but the cluster is elongated parallel to the radio source, especially on the scale of the radio lobes. Fits to individual quadrants give a core radius 50 per cent larger along the radio axis. Part of this elongation appears to be associated with enhanced X-ray emission superimposed on the outer radio lobes. There are no obvious depressions in the X-ray emission coincident with the radio lobes, as expected if the relativistic plasma displaces the ICM. However, we show that these depressions may be quite weak. From the surface brightness profile for the PSPC data the X-ray emission extends out to ~ 2.2 Mpc radius. In the absence of the powerful jets, we would expec...

  5. The Cambridge-Cambridge ROSAT serendipity survey; 1, X-ray-luminous galaxies

    CERN Document Server

    Boyle, B J; Wilkes, B J; Elvis, M; Boyle, B J; Mcmahon, R G; Wilkes, B J; Elvis, M

    1994-01-01

    We report on the first results obtained from a new optical identification programme of 123 faint X-ray sources with S(0.5--2\\,{\\rm keV)}>2\\times 10^{-14}\\,erg\\,s^{-1}\\,cm^{-2}\\, serendipitously detected in {\\it ROSAT} PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Although the majority of the sample (68 objects) are QSOs, we have also identified 12 narrow emission line galaxies which have extreme X-ray luminosities (10^{42} < L_{\\rm X} < 10^{43.5}\\,erg\\,s^{-1}). Subsequent spectroscopy reveals them to be a mixture of starburst galaxies and Seyfert 2 galaxies in approximately equal numbers. Combined with potentially similar objects identified in the {\\it Einstein} Extended Medium Sensitivity Survey, these X-ray-luminous galaxies exhibit a rate of cosmological evolution, L_{\\rm X} \\propto (1+z)^{2.5\\pm1.0}, consistent with that derived for X-ray QSOs. This evolution, coupled with the steep slope determined for the faint end...

  6. The Cambridge-Cambridge ROSAT serendipity survey; 2, classification of x-ray luminous galaxies

    CERN Document Server

    Boyle, B J; Wiles, B J; Elvis, M; Boyle, B J; McMahon, R G; Wiles, B J; Elvis, M

    1995-01-01

    We present the results of an intermediate-resolution (1.5\\AA) spectroscopic study of 17 X-ray luminous narrow emission-line galaxies previously identified in the Cambridge-Cambridge {\\it ROSAT} Serendipity Survey and the {\\it Einstein} Extended Medium Sensitivity Survey. Emission-line ratios reveal that the sample is composed of ten Seyfert and seven starburst galaxies. Measured linewidths for the narrow H\\alpha emission lines lie in the range 170-460\\,km\\,s^{-1}. Five of the objects show clear evidence for asymmetry in the [OIII]\\lambda5007 emission-line profile. Broad H\\alpha emission is detected in six of the Seyfert galaxies, which range in type from Seyfert 1.5 to 2. Broad H\\beta emission is only detected in one Seyfert galaxy. The mean full width at half maximum for the broad lines in the Seyfert galaxies is {\\rm FWHM = 3900\\pm 1750\\,km\\,s^{-1}}. Broad ({\\rm FWHM = 2200\\pm 600\\,km\\,s^{-1}}) H\\alpha emission is also detected in three of the starburst galaxies, which could originate from stellar winds or ...

  7. Solar Wind Charge Exchange contribution to the ROSAT All Sky Survey Maps

    CERN Document Server

    Uprety, Y; Collier, M R; Cravens, T; Galeazzi, M; Koutroumpa, D; Kuntz, K D; Lallement, R; Lepri, S T; Liu, W; McCammon, D; Morgan, K; Porter, F S; Prasai, K; Snowden, S L; Thomas, N E; Ursino, E; Walsh, B M

    2016-01-01

    DXL (Diffuse X-ray emission from the Local Galaxy) is a sounding rocket mission designed to quantify and characterize the contribution of Solar Wind Charge eXchange (SWCX) to the Diffuse X-ray Background (DXB) and study the properties of the Local Hot Bubble (LHB). The detectors are large-area thin-window proportional counters with a spectral response similar to that of the PSPC used in the ROSAT All Sky Survey (RASS). A direct comparison of DXL and RASS data for the same part of the sky allowed us to quantify the SWCX contribution to all 6 RASS bands (R1-R7). We find that the SWCX contribution at l=140 deg, b=0 deg, where the DXL path crosses the Galactic plane is 32%+-12% (statistical)+-5%(systematic) for R1, 45%+-8%+-5% for R2, 22%+-11%+-4% for R4, 14%+-12%+-4% for R5, and negligible for R6 and R7 bands. We can also estimate the contribution to the whole sky. We find that the average SWCX contribution in the whole sky is 25%+-10%+-7% for R1, 30%+-6%+-6% for R2, 9%+-5%+-2% for R4, 7%+-5%+-1% for R5, and neg...

  8. Sharp Chandra View of ROSAT All-Sky Survey Bright Sources: I. Improvement of Positional Accuracy

    CERN Document Server

    Gao, Shuang; Liu, Jifeng

    2016-01-01

    The ROSAT All-Sky Survey (RASS) represents one of the most complete and sensitive soft X-ray all-sky surveys to date. However, the deficient positional accuracy of the RASS Bright Source Catalog (BSC) and subsequent lack of firm optical identifications affect the multi-wavelength studies of X-ray sources. The widely used positional errors $\\sigma_{pos}$ based on the Tycho Stars Catalog (Tycho-1) have previously been applied for identifying objects in the optical band. The considerably sharper Chandra view covers a fraction of RASS sources, whose $\\sigma_{pos}$ could be improved by utilizing the sub-arcsec positional accuracy of Chandra observations. We cross-match X-ray objects between the BSC and \\emph{Chandra} sources extracted from the Advanced CCD Imaging Spectrometer (ACIS) archival observations. A combined counterparts list (BSCxACIS) with \\emph{Chandra} spatial positions weighted by the X-ray flux of multi-counterparts is employed to evaluate and improve the former identifications of BSC with the other...

  9. The space density of cataclysmic variables: constraints from the ROSAT North Ecliptic Pole Survey

    CERN Document Server

    Pretorius, M L; O'Donoghue, D; Henry, J P; Gioia, I M; Mullis, C R

    2007-01-01

    We use the ROSAT North Ecliptic Pole (NEP) survey to construct a small, but purely X-ray flux-limited sample of cataclysmic variable stars (CVs). The sample includes only 4 systems, 2 of which (RX J1715.6+6856 and RX J1831.7+6511) are new discoveries. We present time-resolved spectroscopy of the new CVs and measure orbital periods of 1.64 \\pm 0.02 h and 4.01\\pm 0.03 h for RX 1715.6+6856 and RX J1831.7+6511, respectively. We also estimate distances for all the CVs in our sample, based mainly on their apparent brightness in the infrared. The space density of the CV population represented by our small sample is (1.1 +2.3/-0.7) 10^-5 pc^-3. We can also place upper limits on the space density of any sub-population of CVs too faint to be included in the NEP survey. In particular, we show that if the overall space density of CVs is as high as 2 10^-4 pc^-3 (as has been predicted theoretically), the vast majority of CVs must be fainter than L_X \\simeq 2 10^29 erg/s.

  10. BMW a ROSAT-HRI source catalogue obtained with a wavelet transform detection algorithm

    CERN Document Server

    Panzera, M R; Covino, S; Guzzo, L; Israel, G L; Lazzati, D; Mignani, R P; Moretti, A; Tagliaferri, G

    2001-01-01

    In collaboration with the Observatories of Palermo and Rome and the SAX-SDC we are constructing a multi-site interactive archive system featuring specific analysis tools. In this context we developed a detection algorithm based on the Wavelet Transform (WT) and performed a systematic analysis of all ROSAT-HRI public data (~3100 observations +1000 to come). The WT is specifically suited to detect and characterize extended sources while properly detecting point sources in very crowded fields. Moreover, the good angular resolution of HRI images allows the source extension and position to be accurately determined. This effort has produced the BMW (Brera Multiscale Wavelet) catalogue, with more than 19,000 sources detected at the ~4.2sigma level. For each source detection we have information on the position, X-ray flux and extension. This allows for instance to select complete samples of extended X-ray sources such as candidate clusters of galaxies or SNR's. Details about the detection algorithm and the catalogue ...

  11. The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). V. Ultraviolet diffuse emission and cirrus properties in the Virgo cluster direction

    CERN Document Server

    Boissier, S; Voyer, E; Bianchi, S; Pappalardo, C; Guhathakurta, P; Heinis, S; Cortese, L; Duc, P -A; Cuillandre, J -C; Davies, J I; Smith, M W L

    2015-01-01

    CONTEXT: The Virgo direction has been observed at many wavelengths in the recent years, in particular in the ultraviolet with GALEX. The far ultraviolet (FUV) diffuse light detected by GALEX bears interesting information on the large scale distribution of Galactic dust, owing to the GALEX FUV band sensitivity and resolution. AIMS: We aim to characterise the ultraviolet large scale distribution of diffuse emission in the Virgo direction. A map of this emission may become useful for various studies by identifying regions where dust affects observations by either scattering light or absorbing radiation. METHODS: We construct mosaics of the FUV and near ultraviolet diffuse emission over a large sky region (RA 12 to 13 hours, DEC 0 to 20 degrees) surrounding the Virgo cluster, using all the GALEX available data in the area. We test for the first time the utilisation of the FUV diffuse light as a Galactic extinction E(B-V) tracer. RESULTS: The FUV diffuse light scattered on cirrus reveals details in their geometry....

  12. Solar Wind Charge Exchange Contribution to the ROSAT All Sky Survey Maps

    Science.gov (United States)

    Uprety, Y.; Chiao, M.; Collier, M. R.; Cravens, T.; Galeazzi, M.; Koutroumpa, D.; Kuntz, K. D.; Lallement, R.; Lepri, S. T.; Liu, W.; McCammon, D.; Morgan, K.; Porter, F. S.; Prasai, K.; Snowden, S. L.; Thomas, N. E.; Ursino, E.; Walsh, B. M.

    2016-10-01

    DXL (Diffuse X-ray emission from the Local Galaxy) is a sounding rocket mission designed to estimate the contribution of solar wind charge eXchange (SWCX) to the diffuse X-ray background and to help determine the properties of the Local Hot Bubble. The detectors are large area thin-window proportional counters with a spectral response that is similar to that of the PSPC used in the ROSAT All Sky Survey (RASS). A direct comparison of DXL and RASS data for the same part of the sky viewed from quite different vantage points in the solar system, and the assumption of approximate isotropy for the solar wind, allowed us to quantify the SWCX contribution to all six RASS bands (R1-R7, excluding R3). We find that the SWCX contribution at l=140^\\circ ,b=0^\\circ , where the DXL path crosses the Galactic plane, is 33 % +/- 6 % ({statistical})+/- 12 % ({systematic}) for R1, 44 % +/- 6 % +/- 5 % for R2, 18 % +/- 12 % +/- 11 % for R4, 14 % +/- 11 % +/- 9 % for R5, and negligible for the R6 and R7 bands. Reliable models for the distribution of neutral H and He in the solar system permit estimation of the contribution of interplanetary SWCX emission over the the whole sky and correction of the RASS maps. We find that the average SWCX contribution in the whole sky is 26 % +/- 6 % +/- 13 % for R1, 30 % +/- 4 % +/- 4 % for R2, 8 % +/- 5 % +/- 5 % for R4, 6 % +/- 4 % +/- 4 % for R5, and negligible for R6 and R7.

  13. A method for correcting aspect solution errors in ROSAT HRI observations of compact sources

    Science.gov (United States)

    Morse, Jon A.

    1994-01-01

    X-ray point sources observed with the ROSAT High Resolution Imager (HRI) often appear elongated over scales of approximately 5 sec-10 sec from the image core. This elongation has been attributed to errors in the attitude correction as the satellite is wobbled during the observations, and affects sources with both soft and hard X-ray spectra. In this paper, I report the results of an attempt to rid a high signal-to-noise observation of the soft X-ray point source HZ 43 of its characteristic elongation. I divided the observation into 181 separate images, each containing photons from only a small region on the detector through which the source passed during the satellite's wobble. By measuring the positions of the individual image centroids, I found clear evidence for systematic offsets from a common mean by up to approximately +/- 3 sec in both right ascension and declination as a function of phase in the satellite wobble. Shifting the subimages to a common center and then restacking them into a single image measurably improved the symmetry of the point-spread function. HRI observations are wobbled primarily to smooth out variations in the pixel-to-pixel sensitivity of the detector and also to extend the lifetime of the microchannel plates in the detector since these decay at a given location as a function of the number of photons detected. However, the elongations introduced by the aspect errors inhibit the identification of possible extended X-ray emission associated with sources such as pulsars and active galactic nuclei. In light of these results, I suggest that until the aspect errors are understood, observations of compact sources, where this effect may be important, should not be wobbled.

  14. GALEX observations of the UV surface brightness and color profiles of the Local Group elliptical galaxy M32 (NGC221)

    CERN Document Server

    De Paz, A G; Sohn, Y J; Lee, Y W; Seibert, M; Rich, R M; Bianchi, L; Barlow, T A; Byun, Y I; Donas, J; Forster, K; Friedman, P G; Heckman, T M; Jelinsky, P N; Malina, R F; Martin, D C; Milliard, B; Morrissey, P F; Neff, S G; Schiminovich, D; Siegmund, O H W; Small, T; Szalay, A S; Welsh, B Y; Wyder, T K

    2004-01-01

    M32, the compact elliptical-galaxy companion to the Andromeda spiral galaxy has been imaged by the Galaxy Evolution Explorer (GALEX) in two ultraviolet bands, centered at ~1500 (FUV) and 2300 Angstroms (NUV). The imaging data have been carefully decomposed so as to properly account for the complicated background contamination from the disk of M31. We have derived the surface brightness and color profiles finding a slightly positive color gradient of Delta(FUV-B)/Delta log(r)=+0.15+/-0.03 within one effective radius. Earlier data from the Ultraviolet Imaging Telescope suggested that M32 had an extremely large (negative) FUV-optical color gradient (Delta(FUV-B)/Delta log(r)<-2), inverted with respect to the majority of gradients seen in giant elliptical galaxies. Our new results show that, despite of its very low UV-upturn, M32 has similar UV properties to those observed in luminous elliptical galaxies.

  15. Clustering Properties of restframe UV selected galaxies II: Migration of Star Formation sites with cosmic time from GALEX and CFHTLS

    CERN Document Server

    Heinis, Sebastien; Arnouts, Stephane; Blaizot, Jeremy; Schiminovich, David; Budavari, Tamas; Ilbert, Olivier; Treyer, Marie; Wyder, Ted K; McCracken, Henry J; Barlow, Tom A; Forster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Neff, Susan G; Seibert, Mark; Small, Todd; Bianchi, Luciana; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Rich, R Michael; Szalay, Alexander S; Welsh, Barry Y; Yi, Sukyoung K; Xu, C K

    2007-01-01

    We analyze the clustering properties of ultraviolet selected galaxies by using GALEX-SDSS data at z 2) to low redshift (b ~ 0.79^{+0.1}_{-0.08}). When accounting for the fraction of the star formation activity enclosed in the different samples, our results suggest that the bulk of star formation migrated from high mass dark matter halos at z>2 (10^12 < M_min < 10^13 M_sun, located in high density regions), to less massive halos at low redshift (M_min < 10^12 M_sun, located in low density regions). This result extends the ``downsizing'' picture (shift of the star formation activity from high stellar mass systems at high z to low stellar mass at low z) to the dark matter distribution.

  16. Color Transformations for the 2MASS Second Incremental Data Release

    CERN Document Server

    Carpenter, J M

    2001-01-01

    Transformation equations are presented to convert colors and magnitudes measured in the AAO, ARNICA, CIT, DENIS, ESO, LCO (Persson standards), MSSSO, SAAO, and UKIRT photometric systems to the photometric system inherent to the 2MASS Second Incremental Data Release. The transformations have been derived by comparing 2MASS photometry with published magnitudes and colors for stars observed in these systems. Transformation equations have also been derived indirectly for the Bessell & Brett (1988) and Koornneef (1983) homogenized photometric systems.

  17. Optical Spectroscopy of 2MASS Color-Selected Ultracool Subdwarfs

    CERN Document Server

    Burgasser, A J; Kirkpatrick, J D; Burgasser, Adam J.; Cruz, Kelle L.

    2006-01-01

    We present Gemini GMOS and Magellan LDSS-3 optical spectroscopy for seven ultracool subdwarf candidates color-selected from the Two Micron All Sky Survey. Five are identified as late-type subdwarfs, including the previously reported sdM9.5 SSSPM 1013-1356 and L subdwarf 2MASS 1626+3925, and a new sdM8.5 2MASS 0142+0523. 2MASS 1640+1231 exhibits spectral features intermediate between a late-type M dwarf and subdwarf, similar to the previously identified high proper motion star SSSPM 1444-2019, and we classify both sources as mild subdwarfs, d/sdM9. 2MASS 1227-0447 is a new ultracool extreme subdwarf, spectral type esdM7.5. Spectral model fits yield metallicities that are consistent with these metallicity classifications. Effective temperatures track with numerical subtype within a metallicity class, although they are not equivalent across metallicity classes. As a first attempt to delineate subtypes in the L subdwarf regime we classify 2MASS 1626+3925 and the previously identified 2MASS 0532+8246 as sdL4 and s...

  18. Solar Wind Charge Exchange Contribution To The ROSAT Sky Survey Maps

    Science.gov (United States)

    Uprety, Y.; Chiao, M.; Collier, M. R.; Cravens, T.; Galeazzi, M.; Koutroumpa, D.; Kuntz, K. D.; Lallement, R.; Lepri, S. T.; Liu, W.; McCammon, D.; Morgan, K.; Porter, F. S.; Prasai, K.; Snowden, S. L.; Thomas, N. E.; Ursino, E.; Walsh, B. M.

    2016-01-01

    DXL (Diffuse X-ray emission from the Local Galaxy) is a sounding rocket mission designed to estimate the contribution of solar wind charge eXchange (SWCX) to the diffuse X-ray background and to help determine the properties of the Local Hot Bubble. The detectors are large area thin-window proportional counters with a spectral response that is similar to that of the PSPC (Position Sensitive Proportional Counters) used in the ROSAT All Sky Survey (RASS). A direct comparison of DXL and RASS data for the same part of the sky viewed from quite different vantage points in the solar system, and the assumption of approximate isotropy for the solar wind, allowed us to quantify the SWCX contribution to all six RASS bands (R1-R7, excluding R3). We find that the SWCX contribution at l = 140 degrees, b = 0 degrees, where the DXL path crosses the Galactic plane, is 33 percent plus or minus 6 percent (statistical) plus or minus 12 percent (systematic) for R1, 44 percent plus or minus 6 percent plus or minus 5 percent for R2, 18 percent plus or minus 12 percent plus or minus 11 percent for R4, 14 percent plus or minus 11 percent plus or minus 9 percent for R5, and negligible for the R6 and R7 bands. Reliable models for the distribution of neutral H and He in the solar system permit estimation of the contribution of interplanetary SWCX emission over the the whole sky and correction of the RASS maps. We find that the average SWCX contribution in the whole sky is 26 percent plus or minus 6 percent plus or minus 13 percent for R1, 30 percent plus or minus 4 percent plus or minus 4 percent for R2, 8 percent plus or minus 5 percent plus or minus 5 percent for R4, 6 percent plus or minus 4 percent plus or minus 4 percent for R5, and negligible for R6 and R7.

  19. Solar Wind Charge Exchange Contribution To The ROSAT Sky Survey Maps

    Science.gov (United States)

    Uprety, Y.; Chiao, M.; Collier, M. R.; Cravens, T.; Galeazzi, M.; Koutroumpa, D.; Kuntz, K. D.; Lallement, R.; Lepri, S. T.; Liu, W.; hide

    2016-01-01

    DXL (Diffuse X-ray emission from the Local Galaxy) is a sounding rocket mission designed to estimate the contribution of solar wind charge eXchange (SWCX) to the diffuse X-ray background and to help determine the properties of the Local Hot Bubble. The detectors are large area thin-window proportional counters with a spectral response that is similar to that of the PSPC (Position Sensitive Proportional Counters) used in the ROSAT All Sky Survey (RASS). A direct comparison of DXL and RASS data for the same part of the sky viewed from quite different vantage points in the solar system, and the assumption of approximate isotropy for the solar wind, allowed us to quantify the SWCX contribution to all six RASS bands (R1-R7, excluding R3). We find that the SWCX contribution at l = 140 degrees, b = 0 degrees, where the DXL path crosses the Galactic plane, is 33 percent plus or minus 6 percent (statistical) plus or minus 12 percent (systematic) for R1, 44 percent plus or minus 6 percent plus or minus 5 percent for R2, 18 percent plus or minus 12 percent plus or minus 11 percent for R4, 14 percent plus or minus 11 percent plus or minus 9 percent for R5, and negligible for the R6 and R7 bands. Reliable models for the distribution of neutral H and He in the solar system permit estimation of the contribution of interplanetary SWCX emission over the the whole sky and correction of the RASS maps. We find that the average SWCX contribution in the whole sky is 26 percent plus or minus 6 percent plus or minus 13 percent for R1, 30 percent plus or minus 4 percent plus or minus 4 percent for R2, 8 percent plus or minus 5 percent plus or minus 5 percent for R4, 6 percent plus or minus 4 percent plus or minus 4 percent for R5, and negligible for R6 and R7.

  20. Surface temperature of a magnetized neutron star and interpretation of the ROSAT data. 1: Dipole fields

    Science.gov (United States)

    Page, Dany

    1995-01-01

    We model the temperature distribution at the surface of a magnetized neutron star and study the effects on the observed X-ray spectra and light curves. Generalrelativistic effects, i.e., redshift and lensing, are fully taken into account. Atmospheric effects on the emitted spectral flux are not included: we consider only blackbody emission at the local effective temperature. In this first paper we restrict ourselves to dipole fields. General features are studied and compared with the ROSAT data from the pulsars 0833 - 45 (Vela), 0656 + 14, 0630 + 178 (Geminga), and 1055 - 52, the four cases for which there is strong evidence that thermal radiation from the stellar surface is detected. The composite spectra we obtain are not very different from a blackbody spectrum at the star's effective temperature. We conclude that, as far as blackbody spectra are considered, temperature estimates using single-temperature models give results practically identical to our composite models. The change of the (composite blackbody) spectrum with the star's rotational phase is also not very large and may be unobservable inmost cases. Gravitational lensing strongly suppresses the light curve pulsations. If a dipole field is assumed, pulsed fractions comparable to the observed ones can be obtained only with stellar radii larger than those which are predicted by current models of neutron star struture, or with low stellar masses. Moreover, the shapes of the theoretical light curves with dipole fields do not correspond to the observations. The use of magnetic spectra may raise the pulsed fraction sufficiently but will certainly make the discrepancy with the light curve shapes worse: dipole fields are not sufficient to interpret the data. Many neutron star models with a meson condensate or hypersons predict very small radii, and hence very strong lensing, which will require highly nondipolar fields to be able to reproduce the observed pulsed fractions, if possible at all: this may be a new

  1. The optimal window for the 2MASS dipole

    CERN Document Server

    Chodorowski, Michal; Ciecielag, Pawel; Colombi, Stephane

    2007-01-01

    A comparison of the 2MASS flux dipole to the CMB dipole can serve as a method to constrain a combination of the cosmological parameter Omega_m and the luminosity bias of the 2MASS survey. For this constraint to be as tight as possible, it is necessary to maximize the correlation between the two dipoles. This can be achieved by optimizing the survey window through which the flux dipole is measured. Here we explicitly construct such a window for the 2MASS survey. The optimization essentially reduces to excluding from the calculation of the flux dipole galaxies brighter than the limiting magnitude K_min = 5 of the near-infrared K_s band. The misalignment angle between the two dipoles is a sensitive measure of their correlation: the higher the correlation, the smaller the expectation value of the angle. When our window is employed, the observed misalignment angle is expected to decrease with almost 90% confidence.

  2. The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). I : The UV luminosity function of the central 12 sq.deg

    NARCIS (Netherlands)

    Boselli, A.; Boissier, S.; Heinis, S.; Cortese, L.; Ilbert, O.; Hughes, T.; Cucciati, O.; Davies, J.; Ferrarese, L.; Giovanelli, R.; Haynes, M. P.; Baes, M.; Balkowski, C.; Brosch, N.; Chapman, S. C.; Charmandaris, V.; Clemens, M. S.; Dariush, A.; Looze, I. De; Alighieri, S. di Serego; Duc, P. -A.; Durrell, P. R.; Emsellem, E.; Erben, T.; Fritz, J.; Garcia-Appadoo, D. A.; Gavazzi, G.; Grossi, M.; Jordán, A.; Hess, K. M.; Huertas-Company, M.; Hunt, L. K.; Kent, B. R.; Lambas, D. G.; Lancon, A.; MacArthur, L. A.; Madden, S. C.; Magrini, L.; Mei, S.; Momjian, E.; Olowin, R. P.; Papastergis, E.; Smith, M. W. L.; Solanes, J. M.; Spector, O.; Spekkens, K.; Taylor, J. E.; Valotto, C.; Driel, W. van; Verstappen, J.; Vlahakis, C.; Vollmer, B.; Xilouris, E. M.

    2011-01-01

    The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) is a complete blind survey of the Virgo cluster covering about 40 sq. deg. in the far UV (FUV, lambda_eff=1539A, Delta-lambda=442A) and about 120 sq. deg. in the near UV (NUV, lambda_eff=2316A, Delta-lambda=1060A). The goal of the survey is to

  3. THE GALEX/S{sup 4}G UV–IR COLOR–COLOR DIAGRAM: CATCHING SPIRAL GALAXIES AWAY FROM THE BLUE SEQUENCE

    Energy Technology Data Exchange (ETDEWEB)

    Bouquin, Alexandre Y. K.; Gil de Paz, Armando; Gallego, Jesús [Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Boissier, Samuel [Aix Marseille Université, CNGRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Muñoz-Mateos, Juan-Carlos [European Southern Observatory, Casilla 19001, Santiago 19 (Chile); Sheth, Kartik [National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Zaritsky, Dennis [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Laine, Jarkko [Astronomy Division, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Peletier, Reynier F. [Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen (Netherlands); Röck, Benjamin R.; Knapen, Johan H., E-mail: abouquin@fis.ucm.es [Instituto de Astrofísica de Canarias, Vía Láctea, S/N, E-38205 La Laguna (Spain)

    2015-02-10

    We obtained GALEX FUV, NUV, and Spitzer/IRAC 3.6 μm photometry for >2000 galaxies, available for 90% of the S{sup 4}G sample. We find a very tight GALEX blue sequence (GBS) in the (FUV–NUV) versus (NUV–[3.6]) color–color diagram, which is populated by irregular and spiral galaxies, and is mainly driven by changes in the formation timescale (τ) and a degeneracy between τ and dust reddening. The tightness of the GBS provides an unprecedented way of identifying star-forming galaxies and objects that are just evolving to (or from) what we call the GALEX green valley (GGV). At the red end of the GBS, at (NUV–[3.6]) > 5, we find a wider GALEX red sequence (GRS) mostly populated by E/S0 galaxies that has a perpendicular slope to that of the GBS and of the optical red sequence. We find no such dichotomy in terms of stellar mass (measured by M{sub [3.6]}) since both massive (M{sub ⋆}>10{sup 11}M{sub ⊙}) blue- and red-sequence galaxies are identified. The type that is proportionally more often found in the GGV is the S0-Sa’s, and most of these are located in high-density environments. We discuss evolutionary models of galaxies that show a rapid transition from the blue to the red sequence on a timescale of 10{sup 8} yr.

  4. THE 2MASS REDSHIFT SURVEY-DESCRIPTION AND DATA RELEASE

    Energy Technology Data Exchange (ETDEWEB)

    Huchra, John P.; Berlind, Perry; Calkins, Michael; Falco, Emilio; Mink, Jessica D.; Tokarz, Susan [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Macri, Lucas M. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843 (United States); Masters, Karen L. [Institute for Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); Jarrett, Thomas H. [Infrared Processing and Analysis Center, California Institute of Technology, 770 S Wilson Ave., Pasadena, CA 91125 (United States); Crook, Aidan C. [Microsoft Corp., 1 Microsoft Way, Redmond, WA 98052 (United States); Cutri, Roc [SEPNet (South East Physics Network) (United Kingdom); Erdogdu, Pirin; Lahav, Ofer [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); George, Teddy [Canada-France-Hawaii Telescope, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Hutcheson, Conrad M. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94309 (United States); Mader, Jeff [Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Martimbeau, Nathalie [Planetarium de Montreal, 1000 rue Saint-Jacques, Montreal, Quebec H3C 1G7 (Canada); Schneider, Stephen [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Skrutskie, Michael [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Westover, Michael, E-mail: lmacri@tamu.edu, E-mail: karen.masters@port.ac.uk [McKinsey and Co., 1420 Fifth Ave., Ste 3100, Seattle, WA 98101 (United States)

    2012-04-01

    We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby universe. The Two Micron All Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available online. The 2MASS XSC contains nearly a million galaxies with K{sub s} {<=} 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b| = 5 Degree-Sign for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby universe. We selected a sample of 44,599 2MASS galaxies with K{sub s} {<=} 11.75 mag and |b| {>=} 5 Degree-Sign ({>=}8 Degree-Sign toward the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 h{sup -1} Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly complete sub-sample of 20,860 galaxies with K{sub s} {<=} 11.25 mag and |b| {>=} 10 Degree-Sign .

  5. First Detection of UV emission from a Detached Dust Shell: GALEX Observations of the Carbon AGB Star U Hya

    CERN Document Server

    Sanchez, E; Ramstedt, S; Stassun, K G

    2014-01-01

    We present the discovery of an extended ring of ultraviolet emission surrounding the AGB star U Hya in archival observations performed by the Galaxy Evolution Explorer (GALEX). This is the third discovery of extended UV emission from a carbon AGB star and the first from an AGB star with a detached shell. From imaging and photometric analysis of the FUV and NUV images, we determined that the ultraviolet ring has a radius of $\\sim 110^{\\prime\\prime}$, thus indicating that the emitting material is likely associated with the detached shell seen in the infrared. We find that scattering of the central point source of NUV and FUV emission by the dust shell is negligible. Moreover, we find that scattering of the interstellar radiation field by the dust shell can contribute at most $\\sim10%$ of the FUV flux. Morphological and photometric evidence suggests that shocks caused by the star's motion through space and, possibly, shock-excited H$_2$ molecules are the most likely origins of the UV flux. In contrast to previou...

  6. The shortest period sdB plus white dwarf binary CD-30 11223 (GALEX J1411-3053)

    CERN Document Server

    Vennes, S; O'Toole, S J; Nemeth, P; Burton, D

    2012-01-01

    We report on the discovery of the shortest period binary comprising a hot subdwarf star (CD-30 11223, GALEX J1411-3053) and a massive unseen companion. Photometric data from the All Sky Automated Survey show ellipsoidal variations of the hot subdwarf primary and spectroscopic series revealed an orbital period of 70.5 minutes. The large velocity amplitude suggests the presence of a massive white dwarf in the system (M_2/M_sun > 0.77) assuming a canonical mass for the hot subdwarf (0.48 M_sun), although a white dwarf mass as low as 0.75 M_sun is allowable by postulating a subdwarf mass as low as 0.44 M_sun. The amplitude of ellipsoidal variations and a high rotation velocity imposed a high-inclination to the system (i > 68 deg) and, possibly, observable secondary transits (i > 74 deg). At the lowest permissible inclination and assuming a subdwarf mass of ~0.48 M_sun, the total mass of the system reaches the Chandrasekhar mass limit at 1.35 M_sun and would exceed it for a subdwarf mass above 0.48 M_sun. The syst...

  7. GALEX Observations of "Passive Spirals" in the Cluster Cl 0024+17: Clues to the Formation of S0 Galaxies

    CERN Document Server

    Moran, S M; Treu, T; Salim, S; Rich, R M; Smith, G P; Kneib, J P; Moran, Sean M.; Ellis, Richard S.; Treu, Tommaso; Salim, Samir; Smith, Graham P.; Kneib, Jean-Paul

    2006-01-01

    We present new results from deep GALEX UV imaging of the cluster Cl 0024+17 at z~0.4. Rest-frame far UV emission is detected from a large fraction of so-called ``passive spiral galaxies'' -a significant population which exhibits spiral morphology with little or no spectroscopic evidence for ongoing star formation. This population is thought to represent infalling galaxies whose star formation has been somehow truncated by environmental processes, possibly in morphological transition to S0 galaxies. Compared to normal cluster spirals, we find that passive spirals are redder in FUV-optical color, while exhibiting much stronger UV emission than cluster E/S0s - as expected for recently-truncated star formation. By modeling the different temporal sensitivities of UV and spectroscopic data to recent activity, we show that star formation in passive spirals decayed on timescales of less than 1 Gyr, consistent with `gas starvation' - a process where the cluster environment prevents cold gas from accreting onto the spi...

  8. Pressure shifts and abundance gradients in the atmosphere of the DAZ white dwarf GALEX J193156.8+011745

    CERN Document Server

    Vennes, S; Nemeth, P

    2011-01-01

    We present a detailed model atmosphere analysis of high-dispersion and high signal-to-noise ratio spectra of the heavily polluted DAZ white dwarf GALEX J1931+0117. The spectra obtained with the VLT-Kueyen/UV-Visual Echelle Spectrograph show several well-resolved Si II spectral lines enabling a study of pressure effects on line profiles. We observed large Stark shifts in silicon lines in agreement with theoretical predictions and laboratory measurements. Taking into account Stark shifts in the calculation of synthetic spectra we reduced the scatter in individual line radial velocity measurements from ~ 3 to < 1 km/s. We present revised abundances of O, Mg, Si, Ca, and Fe based on a critical review of line broadening parameters and oscillator strengths. The new measurements are generally in agreement with our previous analysis with the exception of magnesium with a revised abundance a factor of two lower than previously estimated. The magnesium, silicon and iron abundances exceed solar abundances, but the ox...

  9. Galaxy evolution in nearby galaxy groups. III. A GALEX view of NGC 5846, the largest group in the local universe

    CERN Document Server

    Marino, Antonietta; Rampazzo, Roberto; Bianchi, Luciana

    2016-01-01

    We explore the co-evolution of galaxies in nearby groups (V < 3000 km/s) with a multi-wavelength approach. We analyze GALEX far-UV (FUV) and near-UV (NUV) imaging and SDSS u,g,r,i,z data of groups spanning a large range of dynamical phases. We characterize the photometric properties of spectroscopically-confirmed galaxy members and investigate the global properties of the groups through a dynamical analysis. Here we focus on NGC 5846, the third most massive association of Early-Type Galaxies (ETG) after the Virgo and Fornax clusters. The group, composed of 90 members, is dominated by ETGs (about 80 per cent), and among ETGs about 40\\% are dwarfs. Results are compared with those obtained for three groups in the LeoII cloud, which are radically different both in member-galaxy population and dynamical properties. The FUV-NUV cumulative colour distribution and the normalized UV luminosity function (LF) significantly differ due to the different fraction of late-type galaxy population. The UV LF of NGC 5846 rese...

  10. A Comprehensive GALEX Ultraviolet Catalog of Star Clusters in M31 and a Study of the Young Clusters

    CERN Document Server

    Kang, Yongbeom; Bianchi, Luciana; Lee, Kyungsook; Kim, YoungKwang; Sohn, Sangmo Tony

    2011-01-01

    We present a comprehensive catalog of 700 confirmed star clusters in the field of M31 compiled from three major existing catalogs. We detect 418 and 257 star clusters in Galaxy Evolution Explorer (GALEX) near-ultraviolet (NUV) and far-ultraviolet (FUV) imaging, respectively. Our final catalog includes photometry of star clusters in up to 16 passbands ranging from FUV to NIR as well as ancillary information such as reddening, metallicity, and radial velocities. In particular, this is the most extensive and updated catalog of UV integrated photometry for M31 star clusters. Ages and masses of star clusters are derived by fitting the multi-band photometry with model spectral energy distribution (SED); UV photometry enables more accurate age estimation of young clusters. Our catalog includes 182 young clusters with ages less than 1 Gyr. Our estimated ages and masses of young clusters are in good agreement with previously determined values in the literature. The mean age and mass of young clusters are about 300 Myr...

  11. The 2MASS Redshift Survey - Description and Data Release

    CERN Document Server

    Huchra, John P; Masters, Karen L; Jarrett, Thomas H; Berlind, Perry; Calkins, Michael; Crook, Aidan C; Cutri, Roc; Erdogdu, Pirin; Falco, Emilio; George, Teddy; Hutcheson, Conrad M; Lahav, Ofer; Mader, Jeff; Mink, Doug; Martimbeau, Nathalie; Schneider, Stephen; Skrutskie, Michael; Tokarz, Susan; Westover, Michael

    2011-01-01

    We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby Universe. The 2 Micron All-Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available on-line. The 2MASS XSC contains nearly a million galaxies with Ks =5 deg (>= 8 deg towards the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 10,882 galaxies and used previously-obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 Mpc, detected galaxy groups, and estimated the values...

  12. Discovery of Four New X-ray Selected Quasars and Two New SeyfertGalaxies from ROSAT Sources%新发现的4个X选类星体和个赛弗特星系

    Institute of Scientific and Technical Information of China (English)

    赵永恒; 施建荣; 赵刚

    2000-01-01

    We present optical identifications of six previously unknown X-raysources that are present in the source catalog of ROSAT PSPC and RASSobservations. The optical spectroscopy was carried out with the 2.16 mtelescope at the Xinglong Station of Beijing Astronomical Observatory in1997—1998. And we have identified four active galactic nuclei andtwo Seyfert galaxies.%1997—1998年期间,使用2.16 m望远镜对ROSAT X射线源进行光学证认, 证认出4个ROSAT X射线源是新发现的类星体, 2个ROSAT X射线源是新发现的赛弗特星系.

  13. Photometric redshifts of galaxies from SDSS and 2MASS

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Jia-Sheng Huang; Qiu-Sheng Gu

    2009-01-01

    In order to find the physical parameters which determine the accuracy of pho- tometric redshifts, we compare the spectroscopic and photometric redshifts (photo-z's) for a large sample of ~ 80 000 SDSS-2MASS galaxies. Photo-z's in this paper are es- timated by using the artificial neural network photometric redshift method (ANNz). For a subset of~40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshifi distribution very well with rms of 0.016. Our main results are as follows: (1) Using magnitudes directly as input parameters produces more accurate photo-z's than using colors; (2) The inclusion of 2MASS (3, H, Ks) bands does not improve photo-z's significantly, which indicates that near infrared data might not be important for the low-redshift sample; (3) Adding the concentration index (essentially the steepness of the galaxy brightness profile) as an extra input can improve the photo-z's estimation up to~10 percent; (4) Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index (g - r), we can improve the accuracy of photo-z's significantly; (5) Our analysis shows that the outliers (where there is a big difference between the spectroscopic and photometric redshifts) are mainly correlated with galaxy types, e.g., most outliers are late-type (blue) galaxies.

  14. Multiple Components of the Luminous Compact X-ray Source at the Edge of Holmberg II observed by ASCA and ROSAT

    CERN Document Server

    Miyaji, T; Hasinger, G; Miyaji, Takamitsu; Lehmann, Ingo; Hasinger, Guenther

    2001-01-01

    We report the results of the analysis of ASCA/ROSAT observations of the compact luminous X-ray source found at the edge of the nearby star-forming dwarf galaxy Holmberg II (UGC 4305).Our ASCA spectrum revealed that the X-ray emission extends to the hard band and can be best described by a power-law with a photon spectral index of 1.9. The ASCA spectrum does not fit with a multi-color disk blackbody. The joint ASCA-ROSAT spectrum suggests two components to the spectrum: the hard power-law component and a warm thermal plasma kT~0.3[keV]. An additional absorption over that of our galaxy is required. The wobble correction of the ROSAT HRI image has clearly unveiled the existence of an extended component which amounts to 27+/-5% of the total X-ray emission. These observations indicate that there are more than one component in the X-ray emission. The properties of the point-like component is indicative of an accretion onto an intermediate mass blackhole, unless a beaming is taking place. We argue that the extended ...

  15. GALEX-SDSS-WISE Legacy Catalog (GSWLC): Star Formation Rates, Stellar Masses and Dust Attenuations of 700,000 Low-redshift Galaxies

    CERN Document Server

    Salim, Samir; Janowiecki, Steven; da Cunha, Elisabete; Dickinson, Mark; Boquien, Médéric; Burgarella, Denis; Salzer, John J; Charlot, Stéphane

    2016-01-01

    In this paper, we present GALEX-SDSS-WISE Legacy Catalog (GSWLC), a catalog of physical properties (stellar masses, dust attenuations and star formation rates (SFRs)) of ~700,000 galaxies with SDSS redshifts below 0.3. GSWLC contains galaxies within the GALEX footprint, regardless of a UV detection, covering 90% of SDSS. The physical properties were obtained from UV/optical SED fitting following Bayesian methodology of Salim et al. (2007), with improvements such as blending corrections for low-resolution UV photometry, flexible dust attenuation laws, and emission line corrections. GSWLC includes mid-IR SFRs derived from IR templates based upon 22 micron WISE observations. These estimates are independent of UV/optical SED fitting, in order to separate possible systematics. The paper argues that the comparison of specific SFRs (SSFRs) is more informative and physically motivated than the comparison of SFRs. SSFRs resulting from the UV/optical SED fitting are compared to the mid-IR SSFRs, and to SSFRs from three...

  16. GALEX Detection of Shock Breakout in Type II-P Supernova PS1-13arp: Implications for the Progenitor Star Wind

    CERN Document Server

    Gezari, S; Sanders, N E; Soderberg, A M; Hung, T; Heinis, S; Smartt, S J; Rest, A; Scolnic, D; Chornock, R; Berger, E; Foley, R J; Huber, M E; Stubbs, P Price C W; Riess, A G; Kirshner, R P; Smith, K; Wood-Vasey, W M; Schiminovich, D; Martin, D C; Burgett, W S; Chambers, K C; Flewelling, H; Kaiser, N; Tonry, J L; Wainscoat, R

    2015-01-01

    We present the GALEX detection of a UV burst at the time of explosion of an optically normal Type II-P supernova (PS1-13arp) from the Pan-STARRS1 survey at z=0.1665. The temperature and luminosity of the UV burst match the theoretical predictions for shock breakout in a red supergiant, but with a duration a factor of ~50 longer than expected. We compare the $NUV$ light curve of PS1-13arp to previous GALEX detections of Type IIP SNe, and find clear distinctions that indicate that the UV emission is powered by shock breakout, and not by the subsequent cooling envelope emission previously detected in these systems. We interpret the ~ 1 d duration of the UV signal with a shock breakout in the wind of a red supergiant with a pre-explosion mass-loss rate of ~ 10^-3 Msun yr^-1. This mass-loss rate is enough to prolong the duration of the shock breakout signal, but not enough to produce an excess in the optical plateau light curve or narrow emission lines powered by circumstellar interaction. This detection of non-st...

  17. Heavy metals in a light white dwarf: Abundances of the metal-rich, extremely low-mass GALEX J1717+6757

    CERN Document Server

    Hermes, J J; Koester, D; Bours, M C P; Townsley, D M; Farihi, J; Marsh, T R; Littlefair, Stuart; Dhillon, V S; Gianninas, A; Breedt, E; Raddi, R

    2014-01-01

    Using the Hubble Space Telescope, we detail the first abundance analysis enabled by far-ultraviolet spectroscopy of a low-mass (~0.19 Msun) white dwarf (WD), GALEX J1717+6757, which is in a 5.9-hr binary with a fainter, more-massive companion. We see absorption from nine metals, including roughly solar abundances of Ca, Fe, Ti, and P. We detect a significantly sub-solar abundance of C, and put upper limits on N and O that are also markedly sub-solar. Updated diffusion calculations indicate that all metals should settle out of the atmosphere of this 14,900 K, log(g) = 5.67 WD in the absence of radiative forces in less than 20 yr, orders of magnitude faster than the cooling age of hundreds of Myr. We demonstrate that ongoing accretion of rocky material that is often the cause of atmospheric metals in isolated, more massive WDs is unlikely to explain the observed abundances in GALEX J1717+6757. Using new radiative levitation calculations, we determine that radiative forces can counteract diffusion and support ma...

  18. The GALEX Time Domain Survey. II. Wavelength-Dependent Variability of Active Galactic Nuclei in the Pan-STARRS1 Medium Deep Survey

    CERN Document Server

    Hung, T; Jones, D O; Kirshner, R P; Chornock, R; Berger, E; Rest, A; Huber, M; Narayan, G; Scolnic, D; Waters, C; Wainscoat, R; Martin, D C; Forster, K; Neill, J D

    2016-01-01

    We analyze the wavelength-dependent variability of a sample of spectroscopically confirmed active galactic nuclei (AGN) selected from near-UV ($NUV$) variable sources in the GALEX Time Domain Survey that have a large amplitude of optical variability (difference-flux S/N $>$ 3) in the Pan-STARRS1 Medium Deep Survey (PS1 MDS). By matching GALEX and PS1 epochs in 5 bands ($NUV$, $g_{P1}$, $r_{P1}$, $i_{P1}$, $z_{P1}$) in time, and taking their flux difference, we create co-temporal difference-flux spectral energy distributions ($\\Delta f$SEDs) using two chosen epochs for each of the 23 objects in our sample on timescales of about a year. We confirm the "bluer-when-brighter" trend reported in previous studies, and measure a median spectral index of the $\\Delta f$SEDs of $\\alpha_{\\lambda}$ = 2.1 that is consistent with an accretion disk spectrum. We further fit the $\\Delta f$SEDs of each source with a standard accretion disk model in which the accretion rate changes from one epoch to the other. In our sample, 17 o...

  19. The Fundamental Planes of E+A galaxies and GALEX UV-excess early-type galaxies: Revealing their intimate connection

    CERN Document Server

    Choi, Yumi; Yoon, Suk-Jin

    2009-01-01

    Strong Balmer absorption lines and the lack of Ha and [OII] emission lines signify that E+As are post-starburst systems. Recent studies suggest that E+As may undergo the transition from the `blue cloud' to the `red sequence' and eventually migrate to red sequence ETGs. An observational validation of this scenario is to identify the intervening galaxy population between E+As and the red-sequence. Motivated by recent findings with GALEX that a large fraction of ETGs exhibit UV-excess as a sign of RSF, we investigate the possible connection of the UV-excess galaxies to E+As. In particular, we examine the FP scaling relations of the largest sample of ~1,000 E+As selected from the SDSS and ~20,000 morphologically-selected SDSS ETGs with GALEX UV data. The FP parameters, combined with stellar population indicators, reveal a certain group of UV-excess ETGs that bridges between E+As and quiescent red galaxies. The newly identified galaxies are the post-starburst systems characterized by UV-excess but no Ha emission. ...

  20. The Spatial Clustering of ROSAT All-Sky Survey AGNs II. Halo Occupation Distribution Modeling of the Cross Correlation Function

    CERN Document Server

    Miyaji, Takamitsu; Coil, Alison L; Aceves, Hector

    2010-01-01

    This is the second paper of a series that reports on our investigation of the clustering properties of AGNs in the ROSAT All-Sky Survey (RASS) through cross-correlation functions (CCFs) with Sloan Digital Sky Survey (SDSS) galaxies. In this paper, we apply the Halo Occupation Distribution (HOD) model to the CCFs between the RASS Broad-line AGNs with SDSS Luminous Red Galaxies (LRGs) in the redshift range 0.16

  1. Evolution of cluster X-ray luminosities and radii: Results from the 160 square degree rosat survey

    DEFF Research Database (Denmark)

    Vikhlinin, A.; McNamara, B.R.; Forman, W.

    1998-01-01

    -X > 3 x 10(44) ergs s(-1) in the 0.5-2 keV band. We detect a factor of 3-4 deficit of such luminous clusters at z > 0.3 compared with the present. The evolution is much weaker or absent at modestly lower luminosities, (1-3) x 10(44) ergs s(-1). At still lower luminosities, we find no evolution from...... the analysis of the log N-log S relation. The results in the two upper L, bins are in agreement with the Einstein Extended Medium-Sensitivity Survey evolution result (Gioia et al.; Henry ct al.), which was obtained using a completely independent cluster sample. The low-L-X results are in agreement with other...... ROSAT surveys (e.g., Rosati et al.; Jones et al.). We also compare the distribution of core radii of nearby and distant (z > 0.4) luminous (with equivalent temperatures of 4-7 keV) clusters and detect no evolution. The ratio of average core radius for z similar to 0.5 and z clusters is 0.9 +/- 0...

  2. A Limit on the Number of Isolated Neutron Stars Detected in the ROSAT All-Sky Survey Bright Source Catalog

    CERN Document Server

    Turner, Monica L; Letcavage, Ryan; Shevchuk, Andrew S H; Fox, Derek B

    2010-01-01

    Using new and archival observations made with the Swift satellite and other facilities, we examine 147 X-ray sources selected from the ROSAT All-Sky-Survey Bright Source Catalog (RASS/BSC) to produce a new limit on the number of isolated neutron stars (INSs) in the RASS/BSC, the most constraining such limit to-date. Independent of X-ray spectrum and variability, the number of INSs is <=48 (90% confidence). Restricting attention to soft (having an effective temperature of < 200 eV), non-variable X-ray sources -- as in a previous study -- yields an all-sky limit of <=31 INSs. In the course of our analysis, we identify five new high-quality INS candidates for targeted follow-up observations. A future all-sky X-ray survey with eROSITA, or another mission with similar capabilities, can be expected to increase the detected population of X-ray-discovered INSs from the 8 to 50 in the BSC, to (for a disk population) 240 to 1500, which will enable a more detailed study of neutron star population models.

  3. The Brera Multi-scale Wavelet (BMW) ROSAT HRI source catalog; 2, application to the HRI and first results

    CERN Document Server

    Campana, S; Panzera, M R; Tagliaferri, G; Campana, Sergio; Lazzati, Davide; Panzera, Maria Rosa; Tagliaferri, Gianpiero

    1999-01-01

    The wavelet detection algorithm (WDA) described in the accompanying paper by Lazzati et al. is made suited for a fast and efficient analysis of images taken with the High Resolution Imager (HRI) instrument on board the ROSAT satellite. An extensive testing is carried out on the detection pipeline: HRI fields with different exposure times are simulated and analysed in the same fashion as the real data. Positions are recovered with few arcsecond errors, whereas fluxes are within a factor of two from their input values in more than 90% of the cases in the deepest images. At variance with the ``sliding-box'' detection algorithms, the WDA provides also a reliable description of the source extension, allowing for a complete search of e.g. supernova remnant or cluster of galaxies in the HRI fields. A completeness analysis on simulated fields shows that for the deepest exposures considered (~120 ks) a limiting flux of the algorithm on real HRI fields selected for their crowding and/or presence of extended or bright s...

  4. A Galactic Plane Relative Extinction Map from 2MASS

    CERN Document Server

    Fröbrich, D; Murphy, G C; Scholz, A

    2005-01-01

    We present three 14400 square degree relative extinction maps of the Galactic Plane (|b|<20degrees) obtained from 2MASS using accumulative star counts (Wolf diagrams). This method is independent of the colour of the stars and the variation of extinction with wavelength. Stars were counted in 3.5'x3.5' boxes, every 20". 1x1degree surrounding fields were chosen for reference, hence the maps represent local extinction enhancements and ignore any contribution from the ISM or very large clouds. Data reduction was performed on a Beowulf-type cluster (in approximately 120 hours). Such a cluster is ideal for this type of work as areas of the sky can be independently processed in parallel. We studied how extinction depends on wavelength in all of the high extinction regions detected and within selected dark clouds. On average a power law opacity index (\\beta) of 1.0 to 1.8 in the NIR was deduced. The index however differed significantly from region to region and even within individual dark clouds. That said, genera...

  5. Effective temperature scale and bolometric corrections from 2MASS photometry

    CERN Document Server

    Masana, E; Ribas, I

    2006-01-01

    This paper presents a method to determine effective temperatures, angular semi-diameters and bolometric corrections for population I and II FGK type stars based on V and 2MASS IR photometry. Accurate calibration is accomplished by using a sample of solar analogues, whose average temperature is assumed to be equal to the solar effective temperature of 5777 K. By taking into account all possible sources of error we estimate associated uncertainties better than 1% in effective temperature and in the range 1.0-2.5% in angular semi-diameter for unreddened stars. Comparison of our new temperatures with other determinations extracted from the literature indicates, in general, remarkably good agreement. These results suggest that the effective temperaure scale of FGK stars is currently established with an accuracy better than 0.5%-1%. The application of the method to a sample of 10999 dwarfs in the Hipparcos catalogue allows us to define temperature and bolometric correction (K band) calibrations as a function of (V-...

  6. 2MASS analytical study of four open cluster candidates

    Science.gov (United States)

    Bisht, D.; Yadav, R. K. S.; Durgapal, A. K.

    2017-04-01

    The astrophysical parameters of four poorly studied open star clusters namely Teutsch 126, Teutsch 54, Teutsch 61 and Czernik 3, have been estimated using the Two Micron All Sky Survey (2MASS) database. The stellar density distributions and color-magnitude diagrams are used to determine their structural parameters (cluster center, cluster radius, core radius, tidal radius, Galactocenteric coordinates and the distance from the Galactic plane). We have also derived age, color excesses, total mass, relaxation time, luminosity and mass function for each clusters. The mass function slopes for these clusters are derived as 1.59 ± 0.62, 1.31 ± 0.60, 1.22 ± 0.75 and 1.62 ± 0.56 for Teutsch 126, Teutsch 54, Teutsch 61 and Czernik 3 respectively. These values are very close with the Salpeter value (x = 1.35) within the errors. The effect of mass-segregation are observed in the clusters Teutsch 126 and Teutsch 61. Estimated values of dynamical relaxation time are less than age of the clusters under study. This concludes that these objects are dynamically relaxed. The possible reason for relaxation may be due to the dynamical evolution or imprint of star formation or both.

  7. Galaxy groups in the 2MASS Redshift Survey

    CERN Document Server

    Lu, Yi; Shi, Feng; Mo, H J; Tweed, Dylan; Wang, Huiyuan; Zhang, Youcai; Li, Shijie; Lim, S H

    2016-01-01

    A galaxy group catalog is constructed from the 2MASS Redshift Survey (2MRS) with the use of a halo-based group finder. The halo mass associated with a group is estimated using a `GAP' method based on the luminosity of the central galaxy and its gap with other member galaxies. Tests using mock samples shows that this method is reliable, particularly for poor systems containing only a few members. On average 80% of all the groups have completeness >0.8, and about 65% of the groups have zero contamination. Halo masses are estimated with a typical uncertainty $\\sim 0.35\\,{\\rm dex}$. The application of the group finder to the 2MRS gives 29,904 groups from a total of 43,246 galaxies at $z \\leq 0.08$, with 5,286 groups having two or more members. Some basic properties of this group catalog is presented, and comparisons are made with other groups catalogs in overlap regions. With a depth to $z\\sim 0.08$ and uniformly covering about 91% of the whole sky, this group catalog provides a useful data base to study galaxies...

  8. Chemically peculiar stars as seen with 2MASS

    CERN Document Server

    Herdin, A; Netopil, M

    2016-01-01

    The chemically peculiar (CP) stars of the upper main sequence are well suited for investigating the impact of magnetic fields and diffusion on the surface layers of slowly rotating stars. They can even be traced in the Magellanic Clouds and are important to the understanding of the stellar formation and evolution. A systematic investigation of the near-infrared (NIR), 2MASS JHKs, photometry for the group of CP stars has never been performed. Nowadays, there is a great deal of data available in the NIR that reach very large distances. It is therefore very important for CP stars to be unambiguously detected in the NIR region and for these detections to be used to derive astrophysical parameters (age and mass) by applying isochrone fitting. Furthermore, we investigated whether the CP stars behave in a different way to normal-type stars in the various photometric diagrams. For our analysis, we carefully compiled a sample of CP and apparently normal (non-peculiar) type stars. Only stars for which high-quality (i.e...

  9. The ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) I. Newly identified X-ray luminous clusters at z>=0.2

    CERN Document Server

    Chon, Gayoung

    2011-01-01

    We report 19 intermediate redshift clusters newly detected in the ROSAT All-Sky survey that are spectroscopically confirmed. They form a part of 911 objects in the REFLEX II cluster catalogue with a limiting flux of 1.8\\times10^12 erg/s/cm2 in the 0.1-2.4 keV ROSAT band at redshift z >= 0.2. In addition we report three clusters from the REFLEX III supplementary catalogue, which contains objects below the REFLEX II flux limit but satisfies the redshift constraint above. These clusters are spectroscopically followed-up by our ESO NTT-EFOSC2 campaigns for the redshift measurement. We describe our observing and data reduction methods. We show how X-ray properties such as spectral hardness ratio and source extent can be used as important diagnostics in selecting galaxy cluster candidates. Physical properties of the clusters are subsequently calculated from the X-ray observations. This sample contains the high mass and intermediate-redshift galaxy clusters for astrophysical and cosmological applications.

  10. Flares from a new Integral hard X-ray source, IGR J17407-2808, likely associated with the ROSAT source SBM 10

    DEFF Research Database (Denmark)

    Kretschmar, P.; Mereghetti, S.; Hermsen, W.;

    2004-01-01

    was not detected. The last flare, with peak fluxes of 0.8±0.1 Crab and 0.6±0.1 Crab in the energy ranges 20-40 keV and 40-60 keV respectively, triggered an automatic alert message of the Integral Burst Alert System (IBAS Alert #2010) which led to the discovery of the source (Gotz et al., GCN Circ. #2793......This new hard X-ray source, IGR J17407-2808, is positionally coincident with a faint ROSAT source listed as no. 10 in the catalogue of sources in the Galactic Center region by Sidoli, Belloni & Mereghetti 2001, A&A 368, 835 and as 2RXP J174040.9-280852 in the ROSAT Source Browser. No other...... observations of [SBM2001] 10 have been published up to date. The flares were observed with the IBIS instrument in the 20-60 keV energy range, starting at MJD 53287.6310 and over a timespan of 2000 seconds finishing in a strong flare at MJD 53287.6327. Before and after this time period the source...

  11. The Fundamental Planes of E+A galaxies and GALEX UV-excess early-type galaxies: revealing their intimate connection

    Science.gov (United States)

    Choi, Yumi; Goto, Tomotsugu; Yoon, Suk-Jin

    2009-05-01

    Strong Balmer absorption lines and the lack of Hα and [OII] emission lines signify that E+A galaxies are post-starburst systems. Recent studies suggest that E+As may undergo the transition from the `blue cloud' to the `red sequence' and eventually migrate to red-sequence early-type galaxies. An observational validation of this scenario is to identify the intervening galaxy population between E+As and the red sequence. Motivated by recent findings with Galaxy Evolution Explorer (GALEX) that an unexpectedly large fraction of early-type galaxies exhibit ultraviolet (UV) excess (i.e. blue UV - optical colours) as a sign of recent star formation (RSF), we investigate the possible connection of the UV-excess galaxies to E+As. In particular, we examine the Fundamental Plane (FP) scaling relations of the currently largest sample of ~1000 E+As selected from the Sloan Digital Sky Survey (SDSS) and ~20000 morphologically selected SDSS early-type galaxies with GALEX UV data. The FP parameters, combined with stellar population indicators, reveal a certain group of UV-excess early types that bridge between E+As and quiescent red galaxies. The newly identified galaxies are the post-starburst systems characterized by UV-excess but no Hα emission. This is essentially a conceptual generalization of `E+A', in that the Balmer absorption line in the `E+A' definition is replaced with UV - optical colours that are far more sensitive to RSF than the Balmer lines. We refer to these UV-excess galaxies as `E+a' galaxies (named after `E+A'), which stand for elliptical (`E') galaxies with a minority of A-type (`a') young stars. The species are either (1) galaxies that experienced starbursts weaker than those observed in E+As (1 ~ 10 per cent of E+As, `mild E+As') or (2) the products of passively evolved E+As after quenching star formation quite a while ago (~1 Gyr, `old E+As'). We suggest that the latter type of E+a galaxies (i.e. old `E+As') represents the most recent arrival to the red

  12. The Variability of Hardness Ratio 1 observed by ROSAT:Narrow-Line Seyfert 1 Galaxies versus Broad-Line Seyfert 1 Galaxies

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We examined the correlation between the ROSAT Hardness Ratio 1and Count Rates eight Narrow-line Seyfert 1 Galaxies (NLS1s) and 14 Broad-lineSeyfert1 Galaxies (BLS1s). We found that six of the NLS1s show a positive HR1-CTs correlation, and seven of the BLS1s, a negative correlation. The other twoNLS1s and seven BLS1s do not show any clear HR1-CTs correlation. Thus, thespectral behavior is statistically different for the NLS1s and BLS1s. The differentin NLS1s and weak in BLS1s, plus a power law component, common to both, whichsoftens with increasing flux.

  13. The GALEX Arecibo SDSS Survey. VIII. Final Data Release -- The Effect of Group Environment on the Gas Content of Massive Galaxies

    CERN Document Server

    Catinella, Barbara; Cortese, Luca; Fabello, Silvia; Hummels, Cameron B; Moran, Sean M; Lemonias, Jenna J; Cooper, Andrew P; Wu, Ronin; Heckman, Timothy M; Wang, Jing

    2013-01-01

    We present the final data release from the GALEX Arecibo SDSS Survey (GASS), a large Arecibo program that measured the HI properties for an unbiased sample of ~800 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025

  14. The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). I: The UV luminosity function of the central 12 sq.deg

    CERN Document Server

    Boselli, A; Heinis, S; Cortese, L; Ilbert, O; Hughes, T; Cucciati, O; Davies, J; Ferrarese, L; Giovanelli, R; Haynes, M P; Baes, M; Balkowski, C; Brosch, N; Chapman, S C; Charmandaris, V; Clemens, M S; Dariush, A; De Looze, I; Alighieri, S di Serego; Duc, P -A; Durrell, P R; Emsellem, E; Erben, T; Fritz, J; Garcia-Appadoo, D A; Gavazzi, G; Grossi, M; Jordán, A; Hess, K M; Huertas-Company, M; Hunt, L K; Kent, B R; Lambas, D G; Lancon, A; MacArthur, L A; Madden, S C; Magrini, L; Mei, S; Momjian, E; Olowin, R P; Papastergis, E; Smith, M W L; Solanes, J M; Spector, O; Spekkens, K; Taylor, J E; Valotto, C; van Driel, W; Verstappen, J; Vlahakis, C; Vollmer, B; Xilouris, E M

    2011-01-01

    The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) is a complete blind survey of the Virgo cluster covering about 40 sq. deg. in the far UV (FUV, lambda_eff=1539A, Delta-lambda=442A) and about 120 sq. deg. in the near UV (NUV, lambda_eff=2316A, Delta-lambda=1060A). The goal of the survey is to study the ultraviolet (UV) properties of galaxies in a rich cluster environment, spanning a wide luminosity range from giants to dwarfs, and regardless of prior knowledge of their star formation activity. The UV data will be combined with those in other bands (optical: NGVS; far-infrared - submm: HeViCS; HI: ALFALFA) and with our multizone chemo-spectrophotometric models of galaxy evolution to make a complete and exhaustive study of the effects of the environment on the evolution of galaxies in high density regions. We present here the scientific objectives of the survey, describing the observing strategy and briefly discussing different data reduction techniques. Using UV data already in-hand for the central 12 sq. de...

  15. The WIRED Survey. I. A Bright IR Excess Due to Dust Around the Heavily Polluted White Dwarf Galex J193156.8+011745

    Science.gov (United States)

    Debes, John H.; Hoard, D. W.; Kilic, Mukremin; Wachter, Stefanie; Leisawitz, David T.; Cohen, Martin; Kirkpatrick, J. Davy; Griffith, Roger L.

    2011-01-01

    With the launch of the Wide-Field Infrared Survey Explorer (WISE), a new era of detecting planetary debris around white dwarfs (WDs) has begun with the WISE InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED survey will be sensitive to substellar objects and dusty debris around WDs out to distances exceeding 100 pc, well beyond the completeness level of local WDs and covering a large fraction of known WDs detected with the SDSS DR4 WD catalog. In this paper, we report an initial result of the WIRED survey, the detection of the heavily polluted hydrogen WD (spectral type DAZ) GALEX Jl93156.S-KlI1745 at 3.35 and 4.6/Lm. We find that the excess is consistent with either a narrow dusty ring with an inner radius of 29 RWD. outer radius of 40 RWD, and a face-on inclination, or a disk with an inclination of 70 , an inner radius of 23 RWD. and an outer radius of 80 RWD. We also report initial optical spectroscopic monitoring of several metal lines present in the photosphere and find no variability in the line strengths or radial velocities of the lines. We rule out all but planetary mass companions to GALEXl931 out to 0.5 AU.

  16. The WIRED Survey I: A Bright IR Excess Due to Dust Around the Heavily Polluted White Dwarf GALEX J193156.8+011745

    CERN Document Server

    Debes, J H; Kilic, M; Wachter, S; Leisawitz, D T; Cohen, M; Kirkpatrick, J D; Griffith, R L

    2010-01-01

    With the launch of the Wide-Field Infrared Survey Explorer (WISE), a new era of detecting planetary debris around white dwarfs has begun with the WISE InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED Survey will be sensitive to substellar objects and dusty debris around white dwarfs out to distances exceeding 100 pc, well beyond the completeness level of local WDs and covering a large fraction of known WDs detected with the SDSS DR4 white dwarf catalogue. In this paper we report an initial result of the WIRED survey, the detection of the heavily polluted hydrogen white dwarf (spectral type DAZ) GALEX J193156.8+011745 at 3.35 and 4.6 \\micron. We find that the excess is consistent with either a narrow dusty ring with an inner radius of 29 $R_{\\rm WD}$, outer radius of 40 $R_{\\rm WD}$, and a face-on inclination, or a disk with an inclination of 70$^\\circ$, an inner radius of 23 $R_{\\rm WD}$, and an outer radius of 80 $R_{\\rm WD}$. We also report initial optical spectroscopic monitoring of several m...

  17. GALEX and Optical Light Curves of WX LMi, SDSSJ103100.5+202832.2 and SDSSJ121209.31+013627.7

    CERN Document Server

    Linnell, Albert P; Plotkin, Richard M; Holtzman, Jon; Seibert, Mark; Harrison, Thomas E; Howell, Steve B

    2010-01-01

    {\\it GALEX} near ultraviolet (NUV) and far-ultraviolet (FUV) light curves of three extremely low accretion rate polars show distinct modulations in their UV light curves. While these three systems have a range of magnetic fields from 13 to 70 MG, and of late type secondaries (including a likely brown dwarf in SDSSJ121209.31+013627.7), the accretion rates are similar, and the UV observations imply some mechanism is operating to create enhanced emission zones on the white dwarf. The UV variations match in phase to the two magnetic poles viewed in the optical in WX LMi and to the single poles evident in the optical in SDSSJ1212109.31+013627.7 and SDSSJ103100.55+202832.2. Simple spot models of the UV light curves show that if hot spots are responsible for the UV variations, the temperatures are on the order of 10,000-14,000K. For the single pole systems, the size of the FUV spot must be smaller than the NUV and in all cases, the geometry is likely more complicated than a simple circular spot.

  18. A long-term study of AGN X-ray variability . Structure function analysis on a ROSAT-XMM quasar sample

    Science.gov (United States)

    Middei, R.; Vagnetti, F.; Bianchi, S.; La Franca, F.; Paolillo, M.; Ursini, F.

    2017-03-01

    Context. Variability in the X-rays is a key ingredient in understanding and unveiling active galactic nuclei (AGN) properties. In this band, flux variations occur on short timescales (hours) as well as on larger timescales. While short timescale variability is often investigated in single source studies, only a few works are able to explore flux variation on very long timescales. Aims: This work aims to provide a statistical analysis of the AGN long term X-ray variability. We study variability on the largest time interval ever investigated for the 0.2-2 keV band, up to approximately 20 yr rest-frame for a sample of 220 sources. Moreover, we study variability for 2700 quasars up to approximatley eight years rest-frame in the same (soft) band. Methods: We built our source sample using the 3XMM serendipitous source catalogue data release 5, and data from ROSAT All Sky Survey Bright and Faint source catalogues. To ensure that we selected AGN only, we used the Sloan Digital Sky Survey quasar catalogues data releases 7 and 12. Combining ROSAT and XMM-Newton observations, we investigated variability using the structure function analysis which describes the amount of variability as a function of the lag between the observations. Results: Our work shows an increase of the structure function up to 20 yr. We find no evidence of a plateau in the structure function on these long timescales. Conclusions: The increase of the structure function at long time lags suggests that variability in the soft X-rays can be influenced by flux variations originated in the accretion disk or that they take place in a region large enough to justify variation on such long timescales.

  19. Search for young stars among ROSAT All-Sky Survey X-ray sources in and around the R CrA dark cloud

    Science.gov (United States)

    Neuhäuser, R.; Walter, F. M.; Covino, E.; Alcalá, J. M.; Wolk, S. J.; Frink, S.; Guillout, P.; Sterzik, M. F.; Comerón, F.

    2000-10-01

    We present the ROSAT All-Sky Survey data in a 126 deg2 area in and around the CrA star forming region. With low-resolution spectroscopy of unidentified ROSAT sources we could find 19 new pre-main sequence stars, two of which are classical T Tauri stars, the others being weak-lined. The spectral types of these new T Tauri stars range from F7 to M6. The two new classical T Tauri stars are located towards two small cloud-lets outside of the main CrA cloud. They appear to be ~ 10 Myrs old, by comparing their location in the H-R diagram with isochrones for an assumed distance of 130 pc, the distance of the main CrA dark cloud. The new off-cloud weak-line T Tauri stars may have formed in similar cloudlets, which have dispersed recently. High-resolution spectra of our new T Tauri stars show that they have significantly more lithium absorption than zero-age main-sequence stars of the same spectral type, so that they are indeed young. From those spectra we also obtained rotational and radial velocities. For some stars we found the proper motion in published catalogs. The direction and velocity of the 3D space motion - south relative to the galatic plane - of the CrA T Tauri stars is consistent with the dark cloud being formed originally by a high-velocity cloud impact onto the galactic plane, which triggered the star formation in CrA. We also present VRIJHK photometry for most of the new T Tauri stars to derive their luminosities, ages, and masses. Partly based on observations collected at the 1.52 m and 3.5 m telescopes of the European Southern Observatory, Chile, in programs 55.E-0549, 57.E-0646, and 63.L-0023, and on observations collected at the 0.9 m, 1.5 m, and 4.0 m CTIO telescope.

  20. Star-galaxy separation strategies for WISE-2MASS all-sky infrared galaxy catalogues

    Science.gov (United States)

    Kovács, András; Szapudi, István

    2015-04-01

    We combine photometric information of the Wide-Field Infrared Survey Explorer (WISE) and Two Micron All Sky Survey (2MASS) all-sky infrared data bases, and demonstrate how to produce clean and complete galaxy catalogues for future analyses. Adding 2MASS colours to WISE photometry improves star-galaxy separation efficiency substantially at the expense of losing a small fraction of the galaxies. We find that 93 per cent of the WISE objects within W1 training set from the Sloan Digital Sky Survey PhotoObj table with known star-galaxy separation, and determined redshift distribution of our sample from the Galaxy and Mass Assembly spectroscopic survey. Varying the combination of photometric parameters input into our algorithm we show that W1WISE - J2MASS is a simple and effective star-galaxy separator, capable of producing results comparable to the multidimensional SVM classification. We present a detailed description of our star-galaxy separation methods, and characterize the robustness of our tools in terms of contamination, completeness, and accuracy. We explore systematics of the full sky WISE-2MASS galaxy map, such as contamination from moon glow. We show that the homogeneity of the full sky galaxy map is improved by an additional J2MASS galaxy catalogue we present in this paper covers 21 200 deg2 with dusty regions masked out, and has an estimated stellar contamination of 1.2 per cent and completeness of 70.1 per cent among 2.4 million galaxies with zmed ≈ 0.14. WISE-2MASS galaxy maps with well controlled stellar contamination will be useful for spatial statistical analyses, including cross-correlations with other cosmological random fields, such as the cosmic microwave background. The same techniques also yield a statistically controlled sample of stars as well.

  1. The Properties of the Diffuse X-ray Background from the DXL sounding rocket mission (plus ROSAT, XMM-Newton and Suzaku data)

    Science.gov (United States)

    Galeazzi, Massimiliano

    2017-08-01

    Understanding the properties of the different components of the Diffuse X-ray Background (DXB) is made particularly difficult by their similar spectral signature.The University of Miami has been working on disentangling the different DXB components for many years, using a combination of proprietary and archival data from XMM-Newton, Suzaku, and Chandra, and a sounding rocket mission (DXL) specifically designed to study the properties of Local Hot Bubble (LHB) and Solar Wind Charge eXchange (SWCX) using their spatial signature. In this talk we will present:(a) Results from the DXL mission, specifically launch #2, to study the properties of the SWCX and LHB (and GH) and their contribution to the ROSAT All Sky Survey Bands(b) Results from a Suzaku key project to characterize the SWCX and build a semi-empirical model to predict the SWCX line emission for any time, any direction. A publicly available web portal for the model will go online by the end of the year(c) Results from XMM-Newton deep surveys to study the angular correlation of the Warm-Hot Intergalactic Medium (WHIM) in the direction of the Chandra Deep Field South.DXL launch #3, schedule for January 2018 and the development of the DXG sounding rocket mission to characterize the GH-CGM emission using newly developed micropore optics will also be discussed.

  2. On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; Holmstrom, M.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, T. J.; Travnicek, P.; Walsh, B. M.

    2014-01-01

    We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed.

  3. The X-ray Properties of Nearby Abell Clusters from the ROSAT All-Sky Survey: The Sample and Correlations with Optical Properties

    CERN Document Server

    Ledlow, M J; Owen, F N; Burns, J O; Ledlow, Michael J.; Voges, Wolfgang; Owen, Frazer N.; Burns, Jack O.

    2003-01-01

    We present an analysis of the X-ray emission for a complete sample of 288 Abell clusters spanning the redshift range 0.016<= z <= 0.09 from the ROSAT All-Sky Survey. This sample is based on our 20cm VLA survey of nearby Abell clusters. We find an X-ray detection rate of 83%. We report cluster X-ray fluxes and luminosities and two different flux ratios indicative of the concentration and extent of the emission. We examine correlations between the X-ray luminosity, Abell Richness, and Bautz-Morgan and Rood-Sastry cluster morphologies. We find a strong correlation between Lx and cluster richness coupled to a dependence on the optical morphological type. These results are consistent with the observed scatter between X-ray luminosity and temperature and a large fraction of cooling flows. For each cluster field we also report the positions, peak X-ray fluxes, and flux-ratios of all X-ray peaks above 3-sigma significance within a box of 2x2 Mpc centered on Abell's position.

  4. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) III. Construction of the first flux-limited supercluster sample

    CERN Document Server

    Chon, Gayoung; Nowak, Nina

    2012-01-01

    We present the first supercluster catalogue constructed with the extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster survey (REFLEX II) data, which comprises 919 X-ray selected galaxy clusters. Based on this cluster catalogue we construct a supercluster catalogue using a friends-of-friends algorithm with a linking length depending on the local cluster density. The resulting catalogue comprises 164 superclusters at redshift z<=0.4. We study the properties of different catalogues such as the distributions of the redshift, extent and multiplicity by varying the choice of parameters. In addition to the main catalogue we compile a large volume-limited cluster sample to investigate the statistics of the superclusters. We also compare the X-ray luminosity function for the clusters in superclusters with that for the field clusters with the flux- and volume-limited catalogues. The results mildly support the theoretical suggestion of a top-heavy X-ray luminosity function of galaxy clusters in regions of high cluste...

  5. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II)\\\\ II. Construction and Properties of the Survey

    CERN Document Server

    Böhringer, Hans; Collins, Chris A; Guzzo, Luigi; Nowak, Nina; Bobrovskyi, Sergei

    2014-01-01

    Galaxy clusters provide unique laboratories to study astrophysical processes on large scales and are important probes for cosmology. X-ray observations are currently the best means of detecting and characterizing galaxy clusters. In this paper we describe the construction of the REFLEX II galaxy cluster survey based on the southern part of the ROSAT All-Sky Survey. REFLEX II extends the REFLEX I survey by a factor of about two down to a flux limit of $1.8 \\times 10^{-12}$ erg s$^{-1}$ cm$^{-2}$ (0.1 - 2.4 keV). We describe the determination of the X-ray parameters, the process of X-ray source identification, and the construction of the survey selection function. The REFLEX II cluster sample comprises currently 915 objects. A standard selection function is derived for a lower source count limit of 20 photons in addition to the flux limit. The median redshift of the sample is $z = 0.102$. Internal consistency checks and the comparison to several other galaxy cluster surveys imply that REFLEX II is better than 9...

  6. Rosat PSPC observations of the Seyfert 1 galaxies Ark 564, NGC 985, Kaz 163, Mrk 79 and RX J 2256.6+0525

    CERN Document Server

    Brandt, W N; Nandra, K; Reynolds, C S; Brinkmann, W; Brandt, W N; Fabian, A C; Nandra, K; Reynolds, C S; Brinkmann, W

    1994-01-01

    We present spatial, temporal and spectral analyses of ROSAT Position Sensitive Proportional Counter (PSPC) observations of the Seyfert 1 galaxies Ark 564, NGC 985, Kaz 163, Mrk 79 and RX J2256.6+0525. Ark 564 is a powerful narrow-line Seyfert 1 with strong Fe II emission. Several similar narrow-line Seyfert 1 galaxies have recently been found to have remarkably steep soft X-ray continua as well as rapid X-ray variability. We find that Ark 564 also has a very steep (\\Gamma > 3) 0.1--2.5 keV spectrum and varies by \\sim 20 per cent in 1500 s. We examine models for Ark 564 in light of both its X-ray and optical characteristics, and suggest a possible connection between the steep X-ray spectra of narrow-line Seyfert 1 galaxies and their narrow lines. NGC 985 has a large soft excess, a warm absorber, or both. The three other Seyferts have systematically steeper spectra than are typically observed for Seyferts in higher energy Ginga data, indicating that they also harbour further spectral complexity. Kaz 163 shows \\...

  7. XID Cross-Association of ROSAT/Bright Source Catalog X-ray Sources with USNO A2 Optical Point Sources

    CERN Document Server

    Rutledge, R E; Prince, T A; Lonsdale, C; Rutledge, Robert E.; Brunner, Robert J.; Prince, Thomas A.; Lonsdale, Carol

    2000-01-01

    We quantitatively cross-associate the 18811 ROSAT Bright Source Catalog (RASS/BSC) X-ray sources with optical sources in the USNO-A2 catalog, calculating the the probability of unique association (Pid) between each candidate within 75 arcsec of the X-ray source position, on the basis of optical magnitude and proximity. We present catalogs of RASS/BSC sources for which the probability of association is >98%, >90%, and >50%, which contain 2705, 5492, and 11301 unique USNO-A2 optical counterparts respectively down to the stated level of significance. We include in this catalog a list of objects in the SIMBAD database within 10 arcsec of the USNO position, as an aid to identification and source classification. The catalog is more useful than previous catalogs which either rely on plausibility arguments for association, or do not aid in selecting a counterpart between multiple off-band sources in the field. We find that a fraction ~65.8% of RASS/BSC sources have an identifiable optical counterpart, down to the mag...

  8. The Hamburg/RASS Catalogue of optical identifications. Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources

    CERN Document Server

    Zickgraf, F J; Hagen, H J; Reimers, D; Voges, W

    2003-01-01

    We present the Hamburg/RASS Catalogue (HRC) of optical identifications of X-ray sources at high-galactic latitude. The HRC includes all X-ray sources from the ROSAT Bright Source Catalogue (RASS-BSC) with galactic latitude |b| >= 30 degr and declination delta >= 0 degr. In this part of the sky covering ~10 000 deg^2 the RASS-BSC contains 5341 X-ray sources. For the optical identification we used blue Schmidt prism and direct plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) which are now available in digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82% of the selected RASS-BSC an identification could be given. For the rest either no counterpart was visible in the error circle or a plausible identification was not possible. With ~42% AGN represent the largest group of X-ray emitters, \\~31% have a stellar counterpart, whereas galaxies and cluster of galaxies comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources no object was visible on our blue dire...

  9. 2MASS Data Mining and the M, L, and T Dwarf Archives

    CERN Document Server

    Kirkpatrick, J D

    2002-01-01

    Studies of brown dwarfs as a distinct galactic population have been largely pioneered by dedicated, vast-area surveys at deep optical and near-infrared wavebands. The Two Micron All Sky Survey has, because of its full-sky coverage and depth, been the most successful at providing new targets for further study. The author briefly reviews some of the ways in which 2MASS data have been used by brown dwarf researchers. One of the by-products -- namely the 2MASS Team's follow-up spectroscopy of brown dwarf candidates -- is potentially valuable as a scientific resource itself and is also being released to the public.

  10. GALEX-SDSS-WISE Legacy Catalog (GSWLC): Star Formation Rates, Stellar Masses, and Dust Attenuations of 700,000 Low-redshift Galaxies

    Science.gov (United States)

    Salim, Samir; Lee, Janice C.; Janowiecki, Steven; da Cunha, Elisabete; Dickinson, Mark; Boquien, Médéric; Burgarella, Denis; Salzer, John J.; Charlot, Stéphane

    2016-11-01

    In this paper, we present the GALEX-SDSS-WISE Legacy Catalog (GSWLC), a catalog of physical properties (stellar masses, dust attenuations, and star formation rates [SFRs]) for ˜700,000 galaxies with Sloan Digital Sky Survey (SDSS) redshifts below 0.3. GSWLC contains galaxies within the Galaxy Evolution Explorer footprint, regardless of a UV detection, covering 90% of SDSS. The physical properties were obtained from UV/optical spectral energy distribution (SED) fitting following Bayesian methodology of Salim et al., with improvements such as blending corrections for low-resolution UV photometry, flexible dust attenuation laws, and emission-line corrections. GSWLC also includes mid-IR SFRs derived from IR templates based on 22 μ {{m}} Wide-field Infrared Survey Explorer observations. These estimates are independent of UV/optical SED fitting, in order to separate possible systematics. The paper argues that the comparison of specific SFRs (sSFRs) is more informative and physically motivated than the comparison of SFRs. The sSFRs resulting from the UV/optical SED fitting are compared to the mid-IR sSFRs and to sSFRs from three published catalogs. For “main-sequence” galaxies with no active galactic nucleus (AGN) all sSFRs are in very good agreement (within 0.1 dex on average). In particular, the widely used aperture-corrected SFRs from the MPA/JHU catalog show no systematic offsets, in contrast to some integral field spectroscopy results. For galaxies below the main sequence (log sSFR \\lt -11), mid-IR (s)SFRs based on fixed luminosity-SFR conversion are severely biased (up to 2 dex) because the dust is primarily heated by old stars. Furthermore, mid-IR (s)SFRs are overestimated by up to 0.6 dex for galaxies with AGNs, presumably due to nonstellar dust heating. UV/optical (s)SFRs are thus preferred to IR-based (s)SFRs for quenched galaxies and those that host AGNs.

  11. FU Ori-type outburst of 2MASS J06593158-0405277

    Science.gov (United States)

    Maehara, Hiroyuki; Kojima, Tadashi; Fujii, Mitsugu

    2014-11-01

    We report the discovery of an FU Ori-type outburst of 2MASS J06593158-0405277. The outburst was discovered by T. Kojima from the survey image obtained with a 85mm f/2.8 lens and Canon EOS 60D DSLR camera on 2014-11-03.821 UT at mag 11.0.

  12. Extinction within 10 degrees of the Galactic Centre using 2MASS

    CERN Document Server

    Dutra, C M; Bica, L D; Barbuy, B

    2003-01-01

    We extract J and K_s magnitudes from the 2MASS Point Source Catalog for approximately 6 million stars with 8 < K_s < 13 in order to build an A_K extinction map within 10 degrees of the Galactic centre. The extinction was determined by fitting the upper giant branch of (K_s, J-K_s) colour-magnitude diagrams to a dereddened upper giant branch mean locus built from previously studied Bulge fields. The extinction values vary from A_K=0.05 in the edges of the map up to A_K=3.2 close to the Galactic centre. The 2MASS extinction map was compared to that recently derived from DENIS data. Both maps agree very well up to A_K=1.0. The 2MASS extinction values were also compared to those obtained from dust emission in the far infrared using DIRBE/IRAS. Several systematic effects likely to bias this comparison were addressed, including the presence of dust on the background of the bulk of 2MASS stars used in the extinction determination. For the region with $3^{\\circ}<|b|<5^{\\circ}$, where the dust contribution...

  13. A Statistical Survey of Peculiar L and T Dwarfs in SDSS, 2MASS, and WISE

    Science.gov (United States)

    Kellogg, Kendra; Metchev, Stanimir; Miles-Páez, Paulo A.; Tannock, Megan E.

    2017-09-01

    We present the final results from a targeted search for brown dwarfs with unusual near-infrared colors. From a positional cross-match of the Sloan Digital Sky Survey (SDSS), 2-Micron All-Sky Survey (2MASS), and Wide-Field Infrared Survey Explorer (WISE) catalogs, we have identified 144 candidate peculiar L and T dwarfs. Spectroscopy confirms that 20 of the objects are peculiar or are candidate binaries. Of the 420 objects in our full sample 9 are young (≲ 200 {Myr}; 2.1%) and another 8 (1.9%) are unusually red, with no signatures of youth. With a spectroscopic J-{K}s color of 2.58 ± 0.11 mag, one of the new objects, the L6 dwarf 2MASS J03530419+0418193, is among the reddest field dwarfs currently known and is one of the reddest objects with no signatures of youth known to date. We have also discovered another potentially very-low-gravity object, the L1 dwarf 2MASS J00133470+1109403, and independently identified the young L7 dwarf 2MASS J00440332+0228112, which was first reported by Schneider and collaborators. Our results confirm that signatures of low gravity are no longer discernible in low to moderate resolution spectra of objects older than ∼200 Myr. The 1.9% of unusually red L dwarfs that do not show other signatures of youth could be slightly older, up to ∼400 Myr. In this case a red J-{K}s color may be more diagnostic of moderate youth than individual spectral features. However, its is also possible that these objects are relatively metal-rich, and thus have enhanced atmospheric dust content.

  14. 2MASS Photometric Redshift catalog: a comprehensive three-dimensional census of the whole sky

    CERN Document Server

    Bilicki, Maciej; Peacock, John A; Cluver, Michelle E; Steward, Louise

    2014-01-01

    Key cosmological applications require the three-dimensional galaxy distribution on the entire celestial sphere. These include measuring the gravitational pull on the Local Group, estimating the large-scale bulk flow and testing the Copernican principle. However, the largest all-sky redshift surveys -- the 2MRS and IRAS PSCz -- have median redshifts of only z=0.03 and sample the very local Universe. There exist all-sky galaxy catalogs reaching much deeper -- SuperCOSMOS in the optical, 2MASS in the near-IR and WISE in the mid-IR -- but these lack complete redshift information. At present, the only rapid way towards larger 3D catalogs covering the whole sky is through photometric redshift techniques. In this paper we present the 2MASS Photometric Redshift catalog (2MPZ) containing 1 million galaxies, constructed by cross-matching 2MASS XSC, WISE and SuperCOSMOS all-sky samples and employing the artificial neural network approach (the ANNz algorithm), trained on such redshift surveys as SDSS, 6dFGS and 2dFGRS. T...

  15. WISE-2MASS all-sky infrared galaxy catalog for large scale structure

    CERN Document Server

    Kovács, András

    2014-01-01

    We combine photometric information of the WISE and 2MASS infrared all-sky surveys to produce a clean galaxy sample for large-scale structure research. Adding 2MASS colors improves star-galaxy separation substantially at the expense of loosing a small fraction of the galaxies: 93% of the WISE objects within the W1<15.2 mag limit have 2MASS observation as well. We use a class of supervised machine learning algorithms, Support Vector Machines (SVM), to classify objects in our large data set. We used SDSS PhotoObj table with known star-galaxy separation for a training set on classification, and the GAMA spectroscopic survey for determining the redshift distribution of our sample. Varying the combination of photometric parameters input into our algorithm revealed that W1-J is a simple and effective star-galaxy separator, capable of producing results comparable to the multi-dimensional SVM classification. The final catalog has an estimated ~2% stellar contamination among 5 million galaxies with median redshift o...

  16. SDSSJ14584479+3720215: A Benchmark JHK Blazar Light Curve from the 2MASS Calibration Scans

    CERN Document Server

    Davenport, James R A; Becker, Andrew C; Macleod, Chelsea L; Cutri, Roc M

    2015-01-01

    Active galactic nuclei (AGNs) are well-known to exhibit flux variability across a wide range of wavelength regimes, but the precise origin of the variability at different wavelengths remains unclear. To investigate the relatively unexplored near-IR variability of the most luminous AGNs, we conduct a search for variability using well sampled JHKs-band light curves from the 2MASS survey calibration fields. Our sample includes 27 known quasars with an average of 924 epochs of observation over three years, as well as one spectroscopically confirmed blazar (SDSSJ14584479+3720215) with 1972 epochs of data. This is the best-sampled NIR photometric blazar light curve to date, and it exhibits correlated, stochastic variability that we characterize with continuous auto-regressive moving average (CARMA) models. None of the other 26 known quasars had detectable variability in the 2MASS bands above the photometric uncertainty. A blind search of the 2MASS calibration field light curves for AGN candidates based on fitting C...

  17. Structure and stellar content analysis of the open cluster M11 with 2MASS photometry

    CERN Document Server

    Santos, J F C; Bica, E

    2005-01-01

    An overall analysis of the structure and stellar content of M11 is presented, thanks to the wide-angle 2MASS spatial coverage. We derive photometric and structural parameters and discuss the spatial dependance of the luminosity and mass functions. Photometric parameters basically agree with previous ones mostly based on the optical. We obtained a core radius of 1.23pc and a tidal radius of 29pc. In particular, the cluster is populous enough so that the tidal radius could be obtained by fitting the three-parameter King profile to the radial distribution of stars. We analyzed the spatial distribution of mass functions, finding that the the slope changes from -0.73 in the core to +2.88 in the outer halo. The spatial distribution of mass function slopes derived from 2MASS agrees with that derived from optical CCD data, which further confirms the reliability of 2MASS data for future analyses of this kind at comparable observational limits. We detect mass segregation up to distances from the center of ~20arcmin. We...

  18. Cosmological Parameters from the Comparison of the 2MASS Gravity Field with Peculiar Velocity Surveys

    CERN Document Server

    Pike, R W; Hudson, Michael J.

    2005-01-01

    We compare the peculiar velocity field within 65 $h^{-1}$ Mpc predicted from 2MASS photometry and public redshift data to three independent peculiar velocity surveys based on type Ia supernovae, surface brightness fluctuations in ellipticals, and Tully-Fisher distances to spirals. The three peculiar velocity samples are each in good agreement with the predicted velocities and produce consistent results for $\\beta_{K}=\\Omega\\sbr{m}^{0.6}/b_{K}$. Taken together the best fit $\\beta_{K} = 0.49 \\pm 0.04$. We explore the effects of morphology on the determination of $\\beta$ by splitting the 2MASS sample into E+S0 and S+Irr density fields and find both samples are equally good tracers of the underlying dark matter distribution, but that early-types are more clustered by a relative factor $b\\sbr{E}/b\\sbr{S} \\sim 1.6$. The density fluctuations of 2MASS galaxies in $8 h^{-1}$ Mpc spheres in the local volume is found to be $\\sigma\\sbr{8,K} = 0.9$. From this result and our value of $\\beta_{K}$, we find $\\sigma_8 (\\Omega\\...

  19. Chemical Abundances of the Highly Obscured Galactic Globular Clusters 2MASS GC02 and Mercer 5

    CERN Document Server

    Penaloza, Francisco; Vasquez, Sergio; Borissova, Jura; Kurtev, Radostin; Zoccali, Manuela

    2015-01-01

    We present the first high spectral resolution abundance analysis of two newly discovered Galactic globular clusters, namely Mercer 5 and 2MASS GC02 residing in regions of high interstellar reddening in the direction of the Galactic center. The data were acquired with the Phoenix high-resolution near-infrared echelle spectrograph at Gemini South (R~50000) in the 15500.0 A - 15575.0 A spectral region. Iron, Oxygen, Silicon, Titanium and Nickel abundances were derived for two red giant stars, in each cluster, by comparing the entire observed spectrum with a grid of synthetic spectra generated with MOOG. We found [Fe/H] values of -0.86 +/- 0.12 and -1.08 +/- 0.13 for Mercer 5 and 2MASS GC02 respectively. The [O/Fe], [Si/Fe] and [Ti/Fe] ratios of the measured stars of Mercer 5 follow the general trend of both bulge field and cluster stars at this metallicity, and are enhanced by > +0.3. The 2MASS GC02 stars have relatively lower ratios, but still compatible with other bulge clusters. Based on metallicity and abund...

  20. Efficient Selection and Classification of Infrared Excess Emission Stars Based on AKARI and 2MASS Data

    Science.gov (United States)

    Li, Jinzeng; Huang, Yafang

    2015-08-01

    The selection of young stellar objects (YSOs) based on excessive emission in the infrared is easily contaminated by post-main-sequence stars and various types of emission line stars with similar properties. We define here stringent criteria for an efficient selection and classification of stellar sources with infrared excess emission based on combined 2MASS and AKARI colors. First of all, bright dwarfs and giants with known spectral types were selected from the Hipparcos Catalogue and cross-identified with the 2MASS and AKARI Point Source Catalogues to produce the main-sequence and the post-main-sequence tracks, which appear as expected as tight tracks with very small dispersion. However, several of the main-sequence stars indicate excess emission in the color space. Further investigations based on the SIMBAD data help to clarify their nature as classical Be stars, which are found to be located in a well isolated region on each of the color-color (C-C) diagrams. Several kinds of contaminants were then removed based on their distribution on the C-C diagrams. A test sample of Herbig Ae/Be stars and classical T Tauri stars were cross-identified with the 2MASS and AKARI catalogs to define the loci of YSOs with different masses on the C-C diagrams. Well classified Class I and Class II sources were taken as a second test sample to discriminate between various types of YSOs at possibly different evolutionary stages. This helped to define the loci of different types of YSOs and a set of criteria for selecting YSOs based on their colors in the near- and mid-infrared. Candidate YSOs toward IC 1396 indicating excess emission in the near-infrared were employed to verify the validity of the new source selection criteria defined based on C-C diagrams compiled with the 2MASS and AKARI data. Optical spectroscopy and spectral energy distributions of the IC 1396 sample yield a clear identification of the YSOs and further confirm the criteria defined for exploring the nature and

  1. The newly discovered eclipsing cataclysmic star 2MASS J16211735 + 4412541 and its peculiarity

    Science.gov (United States)

    Kjurkchieva, Diana P.; Popov, Velimir A.; Vasileva, Doroteya L.; Petrov, Nikola I.

    2017-04-01

    We present our observations of the newly discovered, eclipsing cataclysmic star 2MASS J16211735 + 4412541 carried out two weeks after its outburst at the beginning of June 2016. Its main peculiarity is the big increasing of eclipse depth during outburst. We qualitatively modelled the folded light curves at quiescence and outburst in order to explain the reason for increase of the primary luminosity about two hundred times. The light curve fits revealed that such an effect can be reproduced by a flat disc whose radius and temperature are several times bigger than those of the primary at quiescence.

  2. Detection of a Nearby Halo Debris Stream in the WISE and 2MASS Surveys

    CERN Document Server

    Grillmair, Carl J; Masci, Frank J; Conroy, Tim; Sesar, Branimir; Eisenhardt, Peter R M; Wright, Edward L

    2013-01-01

    Combining the Wide-Field Infrared Survey Explorer All-Sky Release with the 2MASS Point Source Catalog, we detect a nearby, moderately metal-poor stellar debris stream spanning 24 degrees across the southern sky. The stream, which we designate Alpheus, is at an estimated distance of ~1.9 kpc. Its position, orientation, width, estimated metallicity, and to some extent its distance, are in approximate agreement with what one might expect of the leading tidal tail of the southern globular cluster NGC 288.

  3. The SDSS-2MASS-WISE Ten Dimensional Stellar Color Locus

    CERN Document Server

    Davenport, James R A; Becker, Andrew C; Ruan, John J; Hunt-Walker, Nicholas M; Covey, Kevin R; Lewis, Alexia R; AlSayyad, Yusra; Anderson, Lauren M

    2014-01-01

    We present the fiducial main sequence stellar locus traced by 10 photometric colors observed by SDSS, 2MASS, and WISE. Median colors are determined using 1,052,793 stars with r-band extinction less than 0.125. We use this locus to measure the dust extinction curve relative to the r-band, which is consistent with previous measurements in the SDSS and 2MASS bands. The WISE band extinction coefficients are larger than predicted by standard extinction models. Using 13 lines of sight, we find variations in the extinction curve in H, Ks, and WISE bandpasses. Relative extinction decreases towards Galactic anti-center, in agreement with prior studies. Relative extinction increases with Galactic latitude, in contrast to previous observations. This indicates a universal mid-IR extinction law does not exist due to variations in dust grain size and chemistry with Galactocentric position. A preliminary search for outliers due to warm circumstellar dust is also presented, using stars with high signal-to-noise in the W3-ban...

  4. Structure of the SMC - Stellar component distribution from 2MASS data

    CERN Document Server

    Gonidakis, I; Kontizas, E; Klein, U; Kontizas, M; Belcheva, M; Tsalmantza, P; Karampelas, A

    2008-01-01

    The spatial distribution of the SMC stellar component is investigated from 2MASS data. The morphology of the different age populations is presented. The center of the distribution is calculated and compared with previous estimations. The rotation of the stellar content and possible consequence of dark matter presence are discussed. The different stellar populations are identified through a CMD diagram of the 2MASS data. Isopleth contour maps are produced in every case, to reveal the spatial distribution. The derived density profiles are discussed. The older stellar population follows an exponential profile at projected diameters of about 5 kpc (~5 deg) for the major axis and ~4 kpc for the minor axis, centred at RA: 0h:51min, Dec: -73deg 7' (J2000.0). The centre coordinates are found the same for all the different age population maps and are in good accordance with the kinematical centre of the SMC. However they are found considerably different from the coordinates of the centre of the gas distribution. The f...

  5. The IC 5146 star forming complex and its surroundings with 2MASS, WISE and Spitzer

    Science.gov (United States)

    Nunes, N. A.; Bonatto, C.; Bica, E.

    2016-02-01

    Throughout the last decade sensitive infrared observations obtained by the Spitzer Space Telescope significantly increased the known population of YSOs associated with nearby molecular clouds. With such a census recent studies have characterized pre-main sequence stars (PMS) and determined parameters from different wavelengths. Given the restricted Spitzer coverage of some of these clouds, relative to their extended regions, these YSO populations may represent a limited view of star formation in these regions. We are taking advantage of mid-infrared observations from the NASA Wide Field Infrared Survey Explorer (WISE), which provides an all sky view and therefore full coverage of the nearby clouds, to assess the degree to which their currently known YSO population may be representative of a more complete population. We extend the well established classification method of the Spitzer Legacy teams to archived WISE observations. We have adopted 2MASS photometry as a "standard catalogue" for comparisons. Besides the massive embedded cluster IC 5146 we provide a multiband view of five new embedded clusters in its surroundings that we discovered with WISE. In short, the analysis involves the following for the presently studied cluster sample: (i) extraction of 2MASS/WISE/Spitzer photometry in a wide circular region; (ii) field-star decontamination to enhance the intrinsic Colour-magnitude diagram (CMD) morphology (essential for a proper derivation of reddening, age, and distance from the Sun); and (iii) construction of Colour-magnitude filters, for more contrasted stellar radial density profiles (RDPs).

  6. Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data

    CERN Document Server

    Kirkpatrick, J Davy; Burgasser, Adam J; Schurr, Steven D; Cutri, Roc M; Cushing, Michael C; Cruz, Kelle L; Sweet, Anne C; Knapp, Gillian R; Barman, Travis S; Bochanski, John J; Roellig, Thomas L; McLean, Ian S; McGovern, Mark R; Rice, Emily L

    2010-01-01

    We have conducted a 4030-square-deg near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to DSS images, we find that 107 of our proper motion candidates lack counterparts at B-, R-, and I-bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and fi...

  7. Detection of Radio Emission from the Hyperactive L Dwarf 2MASS J13153094-2649513AB

    CERN Document Server

    Burgasser, Adam J; Zauderer, B Ashley; Berger, Edo

    2012-01-01

    We report the detection of radio emission from the unusually active L5e + T7 binary 2MASS J13153094-2649513AB made with the Australian Telescope Compact Array. Observations at 5.5 GHz reveal an unresolved source with a continuum flux of 370+/-50 microJy, corresponding to a radio luminosity of L_rad = nuL_nu = (9+/-3)x10^23 erg/s and log10(L_rad/L_bol) = -5.44+/-0.22. No detection is made at 9.0 GHz to a 5 sigma limit of 290 microJy, consistent with a power law spectrum S_nu ~ nu^-a with a > 0.5. The emission is quiescent, with no evidence of variability or bursts over 3 hr of observation, and no measurable polarization (V/I < 34%). 2MASS J1315-2649AB is one of the most radio-luminous ultracool dwarfs detected in quiescent emission to date, comparable in strength to other cool sources detected in outburst. Its detection indicates no decline in radio flux through the mid-L dwarfs. It is unique among L dwarfs in having strong and persistent Halpha and radio emission, indicating the coexistence of a cool, neut...

  8. Spatial dependence of 2MASS luminosity and mass functions in the old open cluster NGC 188

    CERN Document Server

    Bonatto, C; Santos, J F C

    2005-01-01

    Luminosity and mass functions in the old open cluster NGC 188 are analysed by means of J and H 2MASS photometry. Within the uncertainties, the observed projected radial density profile of NGC 188 departs from the two-parameter King model in two inner regions, which reflects the non-virialized dynamical state and possibly, some degree of non-sphericity in the spatial shape of this old open cluster. Fits with two and three-parameter King models to the radial distribution of stars resulted in a core radius of 1.3 pc and a tidal radius of 21 pc. The present 2MASS analysis resulted in significant slope variations with distance in the mass function $\\phi(m)\\propto m^{-(1+\\chi)}$, being flat in the central parts ($\\chi=0.6\\pm0.7$) and steep in the cluster outskirts ($\\chi=7.2\\pm0.6$). The overall mass function has a slope $\\chi=1.9\\pm0.7$, slightly steeper than a standard Salpeter mass function. Solar metallicity Padova isochrone fits to the near-infrared colour-magnitude diagram of NGC 188 resulted in an age of $7....

  9. Discovery of an X-ray Emitting Contact Binary System 2MASS J11201034$-$2201340

    CERN Document Server

    Hu, Chin-Ping; Chou, Yi; Liu, L; Qian, S -B; Hui, C Y; Kong, Albert K H; Lin, L C C; Tam, P H T; Li, K L; Ngeow, Chow-Choong; Chen, W P; Ip, Wing-Huen

    2016-01-01

    We report the detection of orbital modulation, a model solution, and X-ray properties of a newly discovered contact binary, 2MASS J11201034$-$2201340. We serendipitously found this X-ray point source outside the error ellipse when searching for possible X-ray counterparts of $\\gamma$-ray millisecond pulsars among the unidentified objects detected by the {\\it Fermi Gamma-ray Space Telescope}. The optical counterpart of the X-ray source (unrelated to the $\\gamma$-ray source) was then identified using archival databases. The long-term CRTS survey detected a precise signal with a period of $P=0.28876208(56)$ days. A follow-up observation made by the SLT telescope of Lulin Observatory revealed the binary nature of the object. Utilizing archived photometric data of multi-band surveys, we construct the spectral energy distribution, which is well fitted by a K2V spectral template. The fitting result of the orbital profile using the Wilson--Devinney code suggests that 2MASS J11201034-2201340 is a short-period A-type c...

  10. Coordinates and 2MASS and OGLE identifications for all stars in Arp's 1965 finding chart for Baade's Window

    CERN Document Server

    Church, Ross P; Feltzing, Sofia

    2011-01-01

    Aims: We seek to provide 2MASS and OGLE identifications and coordinates for all stars in the finding chart published by Arp\\,(1965). This chart covers the low extinction area around NGC 6522, also known as Baade's window, at coordinates (l,b)=(1.02,-3.92). Methods: A cross correlation, using numerical techniques, was performed between a scan of the original finding chart from Arp (1965) and 2MASS and OGLE-II images and stellar coordinates. Results: We provide coordinates for all stars in Arp's finding chart and 2MASS and OGLE identifications wherever possible. Two identifications in quadrant II do not appear in the original finding chart.

  11. The IC 5146 star forming complex and its surroundings with 2MASS, WISE and Spitzer

    CERN Document Server

    Nunes, N A; Bica, E

    2016-01-01

    Throughout the last decade sensitive infrared observations obtained by the Spitzer Space Telescope significantly increased the known population of YSOs associated with nearby molecular clouds. With such a census recent studies have characterized pre-main sequence stars (PMS) and determined parame- ters from different wavelengths. Given the restricted Spitzer coverage of some of these clouds, relative to their extended regions, these YSO populations may represent a limited view of star formation in these regions. We are taking advantage of mid-infrared observations from the NASA Wide Field Infrared Survey Explorer (WISE), which provides an all sky view and therefore full coverage of the nearby clouds, to assess the degree to which their currently known YSO population may be representative of a more complete population. We extend the well established classification method of the Spitzer Legacy teams to archived WISE observations. We have adopted 2MASS photometry as a standard catalogue for comparisons. Besides ...

  12. 2MASS wide field extinction maps: II. The Ophiuchus and the Lupus cloud complexe

    CERN Document Server

    Lombardi, Marco; Alves, Joao

    2008-01-01

    We present an extinction map of a ~1,700 deg sq region that encloses the Ophiuchus, the Lupus, and the Pipe dark complexes using 42 million stars from the Two Micron All Sky Survey (2MASS) point source catalog. The use of a robust and optimal near-infrared method to map dust column density (Nicer, described in Lombardi & Alves 2001) allow us to detect extinction as low as A_K = 0.05 mag with a 2-sigma significance, and still to have a resolution of 3 arcmin on our map. We also present a novel, statistically sound method to characterize the small-scale inhomogeneities in molecular clouds. Finally, we investigate the cloud structure function, and show that significant deviations from the results predicted by turbulent models are observed.

  13. Distance estimates to five open clusters based on 2mass data of red clump giants

    Science.gov (United States)

    Chen, Li; Gao, Xinhua

    2013-02-01

    Red clump (RC) giants are excellent standard candles in the Milky Way and the Large Magellanic Cloud. The near-infrared K-band intrinsic luminosity of RC giants exhibits only a small variance and a weak dependence on chemical composition and age. In addition, RCs are often easily recognizable in the color-magnitude diagrams of open clusters, which renders them extremely useful distance indicators for some intermediate-age or old open clusters. Here we determine the distance moduli of five Galactic open clusters covering a range of metallicities and ages, based on RC giants in the cluster regions using 2mass photometric data. We compare our result with those from main-sequence fitting and also briefly discuss the advantages and disadvantages of RC-based cluster distance determination.

  14. 2MASS photometry and kinematical studies of open cluster NGC 188

    CERN Document Server

    Elsanhoury, W H; Chupina, N V; Vereshchagin, S V; Sariya, Devesh P; Yadav, R K S; Jiang, Ing-Guey

    2016-01-01

    In this paper, we present our results for the photometric and kinematical studies of old open cluster NGC 188. We determined various astrophysical parameters like limited radius, core and tidal radii, distance, luminosity and mass functions, total mass, relaxation time etc. for the cluster using 2MASS catalog. We obtained the cluster's distance from the Sun as 1721+/-41 pc and log (age)= 9.85+/-0.05 at Solar metallicity. The relaxation time of the cluster is smaller than the estimated cluster age which suggests that the cluster is dynamically relaxed. Our results agree with the values mentioned in the literature. We also determined the cluster's apex coordinates as (281.88 deg, -44.76 deg) using AD-diagram method. Other kinematical parameters like space velocity components, cluster center and elements of Solar motion etc. have also been computed.

  15. New infrared star clusters in the Northern and Equatorial Milky Way with 2MASS

    CERN Document Server

    Bica, E; Soares, J; Barbuy, B

    2003-01-01

    We carried out a survey of infrared star clusters and stellar groups on the 2MASS J, H and K_s all-sky release Atlas in the Northern and Equatorial Milky Way (350 < l < 360, 0 < l < 230). The search in this zone complements that in the Southern Milky Way (Dutra et al. 2003a). The method concentrates efforts on the directions of known optical and radio nebulae. The present study provides 167 new infrared clusters, stellar groups and candidates. Combining the two studies for the whole Milky Way, 346 infrared clusters, stellar groups and candidates were discovered, whereas 315 objects were previously known. They constitute an important new sample for future detailed studies.

  16. Discovery of an X-Ray-emitting Contact Binary System 2MASS J11201034-2201340

    Science.gov (United States)

    Hu, Chin-Ping; Yang, Ting-Chang; Chou, Yi; Liu, L.; Qian, S.-B.; Hui, C. Y.; Kong, Albert K. H.; Lin, L. C. C.; Tam, P. H. T.; Li, K. L.; Ngeow, Chow-Choong; Chen, W. P.; Ip, Wing-Huen

    2016-06-01

    We report the detection of orbital modulation, a model solution, and the X-ray properties of a newly discovered contact binary, Two Micron All Sky Survey (2MASS) J11201034-2201340. We serendipitously found this X-ray point source outside the error ellipse when searching for possible X-ray counterparts of γ-ray millisecond pulsars among the unidentified objects detected by the Fermi Gamma-ray Space Telescope. The optical counterpart of the X-ray source (unrelated to the γ-ray source) was then identified using archival databases. The long-term Catalina Real-Time Transient Survey detected a precise signal with a period of P=0.28876208(56) days. A follow-up observation made by the Super Light Telescope of Lulin Observatory revealed the binary nature of the object. Utilizing archived photometric data of multi-band surveys, we construct the spectral energy distribution (SED), which is well fit by a K2V spectral template. The fitting result of the orbital profile using the Wilson-Devinney code suggests that 2MASS J11201034-2201340 is a short-period A-type contact binary and the more massive component has a cool spot. The X-ray emission was first noted in observations made by Swift, and then further confirmed and characterized by an XMM-Newton observation. The X-ray spectrum can be described by a power law or thermal Bremsstrahlung. Unfortunately, we could not observe significant X-ray orbital modulation. Finally, according to the SED, this system is estimated to be 690 pc from Earth with a calculated X-ray intensity of (0.7-1.5)× {10}30 erg s-1, which is in the expected range of an X-ray emitting contact binary.

  17. ROSAT巡天X射线选活动星系核的光学证认%Optical Identification of ROSAT Survey X-ray Selected AGN

    Institute of Scientific and Technical Information of China (English)

    孙艳春; 白宇; 何香涛; 陈阳; 吴江华; 李庆康; Green Richard F.; Voges Wolfgang

    2012-01-01

    获得完备的样本一直是类星体统计分析工作中至关重要的第一步.类星体巡天选择候选体的方法主要有射电波段筛选、色指数筛选、无缝光谱筛选、X射线波段筛选、对红外源或变源进行筛选和零自行的方法.单独运用任一方法都有选择效应,采用多波段方法可以极大地提高样本的完备性.阐述了使用多波段方法选择活动星系核样本的研究现状,提出多波段类星体巡天方法和选源判据,给出ROSAT巡天中F.1002,F.Coma,F.836和F.Leo 4个天区以及空源的15年来X射线选活动星系核的选源和光学新证认的AGN结果,表明多波段类星体巡天方法能有效地提高观测效率.%The completeness of sample is especially important for the research of quasar, and using data in one wavelength, such as in radio, infrared, optical or X-ray selection, to make candidate selection always suffers significant selection effect to some extent. Fortunately, some large area surveys have become increasingly prevalent across all wavelengths over the past decade, such as SDSS, NVSS, FIRST, RASS, etc. These surveys make it possible to select candidates in multiple wavelengths and the resulting sample is more complete.A summary of quasar candidate selection methods employed by previous surveys and our method of Multi-wavelength Quasar Survey (MWQS) are presented in Sect.l. Because the most effective way to maximize completeness is to select candidates in multi-wavelength, the MWQS has combined data from RASS, UKST, FIRST and NVSS in multiple wavelengths, to greatly reduce selection effects and the survey can produce a quasar sample more complete than that of any previous surveys. The MWQS includes four fields of sky, each covering an area of 6°×6°, and blank field sources in all sky. Two of the four survey fields are the rich Leo and Coma clusters and others are F.1002 and F.836. In Sect.2, the candidate selectionprocedures in three wavelengths are given

  18. HEASARC Astronomical Archive: GLIESE2MAS - Gliese Catalog Stars with Accurate Coordinates and 2MASS Cross-Identifications

    Data.gov (United States)

    National Aeronautics and Space Administration — This table contains precise epoch 2000 coordinates and cross-identifications to sources in the 2MASS Point Source Catalog for nearly all stars in the Gliese,...

  19. Uv-bright Nearby Early-type Galaxies Observed in the Mid-infrared: Eidence for a Multi-stage Formation History by Way of WISE and GALEX Imaging

    Science.gov (United States)

    Petty, S. M.; Neill, J. D.; Jarrett, T. H.; Blain, A. W.; Farrah, D. G.; Rich, R. M.; Tsai, C.-W.; Benford, D. J.; Bridge, C. R.; Lake, S. E.; Masci, F. J.; Wright, E. L.

    2013-01-01

    In the local universe, 10% of massive elliptical galaxies are observed to exhibit a peculiar property: a substantial excess of ultraviolet emission than what is expected from their old, red stellar populations. Several origins for this ultraviolet excess (UVX) have been proposed including a population of hot young stars and a population of old, blue horizontal branch or extended horizontal branch (BHB or EHB) stars that have undergone substantial mass loss from their outer atmospheres. We explore the radial distribution of UVX in a selection of 49 nearby E/S0-type galaxies by measuring their extended photometry in the UV through mid-infrared (mid-IR) with the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the Wide-field Infrared Survey Explorer (WISE). We compare UV/optical and UV/mid-IR colors with the Flexible Stellar Population Synthesis models, which allow for the inclusion of EHB stars. We find that combined WISE mid-IR and GALEX UV colors are more effective in distinguishing models than optical colors, and that the UV/mid-IR combination is sensitive to the EHB fraction. There are strong color gradients, with the outer radii bluer than the inner half-light radii by approx.1 mag. This color difference is easily accounted for with an increase in the BHB fraction of 0.25 with radius. We estimated that the average ages for the inner and outer radii are 7.0 +/- 0.3 Gyr, and 6.2 +/- 0.2 Gyr, respectively, with the implication that the outer regions are likely to have formed approx. 1 Gyr after the inner regions. Additionally, we find that metallicity gradients are likely not a significant factor in the color difference. The separation of color between the inner and outer regions, which agrees with a specific stellar population difference (e.g., higher EHB populations), and the approx. 0.5-2 Gyr age difference suggests multi-stage formation. Our results are best explained by inside-out formation: rapid star formation within the core at early

  20. 2MASS J03105986+1648155AB - A new binary at the L/T transition

    CERN Document Server

    Stumpf, M B; Bouy, H; Henning, Th; Hippler, S

    2010-01-01

    The transition from the L to the T spectral type of brown dwarfs is marked by a very rapid transition phase, remarkable brightening in the J-band and a higher binary frequency. Despite being an active area of inquiry, this transition regime still remains one of the most poorly understood phases of brown dwarf evolution. We resolved the L dwarf 2MASS J03105986+1648155 for the first time into two almost equally bright components straddling the L/T transition. Since such a co-eval system with common age and composition provides crucial information of this special transition phase, we monitored the system over 3 years to derive first orbital parameters and dynamical mass estimates, as well as a spectral type determination. We obtained resolved high angular resolution, near-IR images with HST and the adaptive optics instrument NACO at the VLT including the laser guide star system PARSEC. Based on two epochs of astrometric data we derive a minimum semi-major axis of 5.2 +- 0.8 AU. The assumption of a face-on circul...

  1. 2MASS J154043.42-510135.7: a new addition to the 5 pc population

    CERN Document Server

    Perez-Garrido, A; Bejar, V J S; Ruiz, M T; Gauza, B; Rebolo, R; Osorio, M R Zapatero

    2014-01-01

    The aim of the project is to find the stars nearest to the Sun and to contribute to the completion of the stellar and substellar census of the solar neighbourhood. We identified a new late-M dwarf within 5 pc, looking for high proper motion sources in the 2MASS-WISE cross-match. We collected astrometric and photometric data available from public large-scale surveys. We complemented this information with low-resolution optical and near-infrared spectroscopy with instrumentation on the ESO NTT to confirm the nature of our candidate. We also present a high-quality medium-resolution VLT/X-shooter spectrum covering the 400 to 2500 nm wavelength range. We classify this new neighbour as an M7.0$\\pm$0.5 dwarf using spectral templates from the Sloan Digital Sky Survey and spectral indices. Lithium absorption at 670.8 nm is not detected in the X-shooter spectrum, indicating that the M7 dwarf is older than 600 Myr and more massive than 0.06 M$_{\\odot}$. We also derive a trigonometric distance of 4.4 pc, in agreement wit...

  2. Using the 2-MASS photometric redshift survey to optimize LIGO follow-up observations

    Science.gov (United States)

    Antolini, Elisa; Heyl, Jeremy S.

    2016-10-01

    The initial discovery of Laser Interferometer Gravitational-Wave Observatory (LIGO) on 2015 September 14 was the inspiral merger and ring-down of the black hole binary at a distance of about 500 Mpc or a redshift of about 0.1. The search for electromagnetic counterparts for the inspiral of binary black holes is impeded by coarse initial source localizations and a lack of a compelling model for the counterpart; therefore, rapid electromagnetic follow-up is required to understand the astrophysical context of these sources. Because astrophysical sources of gravitational radiation are likely to reside in galaxies, it would make sense to search first in regions where the LIGO-Virgo probability is large and where the density of galaxies is large as well. Under the assumption that the probability of a gravitational-wave event from a given region of space is proportional to the density of galaxies within the probed volume, one can calculate an improved localization of the position of the source simply by multiplying the LIGO-Virgo skymap by the density of galaxies in the range of redshifts. We propose using the 2-MASS photometric redshift galaxy catalogue for this purpose and demonstrate that using it can dramatically reduce the search region for electromagnetic counterparts.

  3. HI line observations of 2MASS galaxies in the Zone of Avoidance

    CERN Document Server

    Van Driel, W; Kraan-Korteweg, R C; Ragaigne, D Monnier

    2009-01-01

    A pilot survey has been made to obtain 21cm HI emission line profiles for 197 objects in the Zone of Avoidance (ZoA) that were classified as galaxies in the 2MASS all-sky near-infrared Extended Source Catalog (2MASX). 116 of the sources were observed using the Nancay radio telescope, in the 325 to 11,825 km/s range, and the other 81 sources were observed at Arecibo in the -500 to 11,000 km/s range, and for 9 also in the 9,500 to 21,000 km/s range. Global HI line parameters are presented for the 22 and 29 2MASX objects that were detected at Nancay and Arecibo, respectively, as well as upper limits for the undetected 2MASX objects. Whereas object 2MASX J08170147-3410277 appears to be a very massive galaxy with an HI mass of 4.6 x 10E10 Msun, it is clear that only radio synthesis HI imaging observations will allow a firm conclusion on this. Overall, the global properties of the detected galaxies match those of other ZoA HI surveys. Although the detections are as yet too sparse to give further insight into suspec...

  4. WISE/2MASS-SDSS Brown Dwarfs candidates using Virtual Observatory tools

    CERN Document Server

    Aberasturi, M; Martin, E L

    2011-01-01

    Massive imaging surveys in different passbands are the main contributors to the discovery of brown dwarfs (BDs). The Virtual Observatory (VO) represents an adequate framework to efficiently handle these vast datasets and filter them out according to specific requirements. Having an statistically significant number of BDs is mandatory to better understand their general properties as well as to identify peculiar objects. WISE, an all-sky survey in the infrared, provides an excellent opportunity to significantly increase the number of BDs, in particular those at the lower end of the temperature scale. The main aim of this work is to demonstrate that VO tools are efficient to identify BDs by cross correlating public catalogues released by large imaging surveys. Using VO tools we have performed a cross-match of the WISE Preliminary Release, the 2MASS Point Source and SDSS Data Release 7 catalogues over the whole area of sky that they have in common. Photometric and proper motion criteria were used to obtain a list...

  5. A 2MASS Analysis of the Stability of Southern Bok Globules

    CERN Document Server

    Racca, Germán A; de la Reza, Ramiro

    2008-01-01

    We used near-infrared 2MASS data to construct visual extinction maps of a sample of Southern Bok globules utilizing the NICE method. We derived radial extinction profiles of dense cores identified in the globules and analyzed their stability against gravitational collapse with isothermal Bonnor-Ebert spheres. The frequency distribution of the stability parameter xi_max of these cores shows that a large number of them are located in stable states, followed by an abrupt decrease of cores in unstable states. This decrease is steeper for globules with associated IRAS point sources than for starless globules. Moreover, globules in stable states have a Bonnor-Ebert temperature of T = 15 +- 6 K, while the group of critical plus unstable globules has a different temperature of T = 10 +- 3 K. Distances were estimated to all the globules studied in this work and the spectral class of the IRAS sources was calculated. No variations were found in the stability parameters of the cores and the spectral class of their associ...

  6. Peering through the Dust: NuSTAR Observations of Two FIRST-2MASS Red Quasars

    CERN Document Server

    LaMassa, Stephanie M; Glikman, Eilat; Urry, C Megan; Stern, Daniel; Yaqoob, Tahir; Lansbury, George B; Civano, Francesca; Boggs, Steve E; Brandt, W N; Chen, Chien-Ting J; Christensen, Finn E; Craig, William W; Hailey, Chuck J; Harrison, Fiona; Hickox, Ryan C; Koss, Michael; Ricci, Claudio; Treister, Ezequiel; Zhang, Will

    2016-01-01

    Some reddened quasars appear to be transitional objects in the merger-induced black hole growth/galaxy evolution paradigm, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured ($N_{\\rm H,Z} = 2.1\\pm0.2 \\times10^{22}$ cm$^{-2}$) and F2M 1227+3214 is mildly absorbed ($N_{\\rm H,Z} = 3.4^{+0.8}_{-0.7}\\times10^{21}$ cm$^{-2}$) along the line-of-sight, heavier global obscuration may be present in both sources, with $N_{\\rm H,S} = 3.7^{+4.1}_{-2.6} \\times 10^{23}$ cm$^{-2}$ and $< 5.5\\times10^{23}$ cm$^{-2}$, for F2M 0830+3759 and F2M 1227+3214, respectively. F2M 0830+3759 also has an excess of soft X-ray emission below 1 keV which i...

  7. New Neighbors from 2MASS Activity and Kinematics at the Bottom of the Main Sequence

    CERN Document Server

    Gizis, J E; Reid, I N; Kirkpatrick, J D; Liebert, J; Williams, R J; Gizis, John E.; Monet, David G.; Liebert, James; Williams, Rik J.

    2000-01-01

    We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with K_s6 Angstroms) ultracool M dwarfs are consistent with an ordinary old disk stellar population, while the kinematics of inactive ultracool M dwarfs are more typical of a 0.5 Gyr old population. The early L dwarfs in the sample have kinematics consistent with old ages, suggesting that the hydrogen burning limit is near spectral types L2-L4. We use the available data on M and L dwarfs to show that chromospheric activity drops with decreasing mass and temperature, and that at a given (M8 or later) spectral type, the younger field (brown) dwarfs are less active than many of the older, more massive field stellar dwarfs. Thus, contrary to the well-known stellar age-activity relationship, low activity in field ultracool dwarfs can be an indication of comparative youth and substellar mass.

  8. Luminosity profiles of advanced mergers of galaxies using 2MASS data

    CERN Document Server

    Chitre, A; Chitre, Aparna; Jog, Chanda J.

    2002-01-01

    A sample of 27 disturbed galaxies that show signs of interaction but have a single nucleus were selected from the Arp and the Arp-Madore catalogues. For these, the K_s band images from the Two Micron All Sky Survey (2MASS) are analysed to obtain their radial luminosity profiles and other structural parameters. We find that in spite of their similar optical appearance, the sample galaxies vary in their dynamical properties, and fall into two distinct classes. The first class consists of galaxies which can be described by a single r^{1/4} law and the second class consists of galaxies that show an outer exponential disk. A few galaxies that have disturbed profiles cannot be fit into either of the above classes. However, all the galaxies are similar in all other parameters such as the far-infrared colours, the molecular hydrogen content and the central velocity dispersion. Thus, the dynamical parameters of these sets seem to be determined by the ratio of the initial masses of the colliding galaxies. We propose th...

  9. Allsky NICER and NICEST extinction maps based on the 2MASS near-infrared survey

    CERN Document Server

    Juvela, M

    2016-01-01

    Extinction remains one of the most reliable methods of measuring column density of nearby Galactic interstellar clouds. The current and ongoing near-infrared surveys enable the mapping of extinction over large sky areas. We produce allsky extinction maps using the 2MASS near-infrared survey. We use the NICER and NICEST methods to convert the near-infrared colour excesses to extinction estimates. The results are presented in Healpix format at the resolutions of 3.0, 4.5, and 12.0 arcmin. The main results of this study are the calculated J-band extinction maps. The comparison with earlier large-scale extinction mappings shows good correspondence but also demonstrates the presence of resolution-dependent bias. A large fraction of the bias can be corrected by using the NICEST method. For individual regions, best extinction estimates are obtained by careful analysis of the local stellar population and the use of the highest resolution afforded by the stellar density. However, the uniform allsky maps should still b...

  10. Discovery of a Very Young Field L Dwarf, 2MASS J01415823-4633574

    CERN Document Server

    Kirkpatrick, J D; Burgasser, A J; McGovern, M R; McLean, I S; Tinney, C G; Lowrance, P J; Barman, Travis S.; Burgasser, Adam J.; Govern, Mark R. Mc; Lean, Ian S. Mc; Tinney, Christopher G.; Lowrance, Patrick J.

    2006-01-01

    While following up L dwarf candidates selected photometrically from the Two Micron All Sky Survey, we uncovered an unusual object designated 2MASS J01415823-4633574. Its optical spectrum exhibits very strong bands of vanadium oxide but abnormally weak absorptions by titanium oxide, potassium, and sodium. Morphologically such spectroscopic characteristics fall intermediate between old, field early-L dwarfs (log(g)~5) and very late M giants (log(g)~0), leading us to favor low gravity as the explanation for the unique spectral signatures of this L dwarf. Such a low gravity can be explained only if this L dwarf is much lower in mass than a typical old field L dwarf of similar temperature and is still contracting to its final radius. These conditions imply a very young age. Further evidence of youth is found in the near-infrared spectrum, including a triangular-shaped H-band continuum reminiscent of young brown dwarf candidates discovered in the Orion Nebula Cluster. Using the above information along with comparis...

  11. Variable stars in the VVV globular clusters. I. 2MASS-GC02 and Terzan10

    CERN Document Server

    Alonso-García, Javier; Catelan, Márcio; Ramos, Rodrigo Contreras; Gran, Felipe; Amigo, Pía; Leyton, Paul; Minniti, Dante

    2014-01-01

    The VISTA Variables in the Via Lactea (VVV) ESO Public Survey is opening a new window to study the inner Galactic globular clusters using their variable stars. These globular clusters have been neglected in the past due to the difficulties caused by the presence of an elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RRLyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the interrogations brought by the intriguing Oosterhoff dichotomy in the Galactic globular cluster system. In a series of papers we plan to explore the variable stars in the globular clusters falling inside the field of the VVV survey. In this first paper we search and study the variables present in two highly-reddened, moderately metal-poor, faint, inner Galactic globular clusters: 2MASS-GC02 and Terzan10. We report the discovery of sizable populations of RR ...

  12. CCD BVRI and 2MASS photometry of the poorly studied open cluster NGC 6631

    Directory of Open Access Journals (Sweden)

    A.L. Tadross

    2014-12-01

    Full Text Available Here we have obtained the BVRI CCD photometry down to a limiting magnitude of V∼20 for the southern poorly studied open cluster NGC 6631. It is observed from the 1.88 m Telescope of Kottamia Observatory in Egypt. About 3300 stars have been observed in an area of ∼10′×10′ around the cluster center. The main photometric parameters have been estimated and compared with the results that determined for the cluster using JHKs 2MASS photometric database. The cluster’s diameter is estimated to be 10 arcmin; the reddening E(B-V=0.68 ± 0.10 mag, E(J-H=0.21 ± 0.10 mag, the true modulus (m-Mo=12.16 ± 0.10 mag, which corresponds to a distance of 2700 ± 125 pc and age of 500 ± 50 Myr.

  13. M Dwarfs From The SDSS, 2MASS and WISE Surveys: Identification, Characterisation and Unresolved Ultracool Companionship

    Science.gov (United States)

    Cook, Neil James

    2016-08-01

    The aim of this thesis is to use a cross-match between WISE, 2MASS and SDSS to identify a large sample of M dwarfs. Through the careful characterisation and quality control of these M dwarfs I aim to identify rare systems (i.e. unresolved UCD companions, young M dwarfs, late M dwarfs and M dwarfs with common proper motion companions). Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. This is done by using an optimised method for identifying M dwarfs which may have unresolved ultracool companions. To do this I construct a catalogue of 440 694 M dwarf candidates, from WISE, 2MASS and SDSS, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints I isolate a sub-sample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). I present 1 082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, I estimate that the occurrence of unresolved ultracool companions amongst my M dwarf + ultracool dwarf candidates should be at least four times the average for my full M dwarf catalogue. I discuss yields of candidates based on my simulations. The possible contamination and bias from misidentified M dwarfs is then discussed, from chance alignments with other M dwarfs and UCDs, from chance alignments with giant stars, from chance alignments with galaxies, and from blended systems (via visual inspection). I then use optical spectra from LAMOST to spectral type a subset of my M dwarf + ultracool dwarf candidates. These candidates need confirming as true M dwarf + ultracool dwarf systems thus I present a new method I developed to

  14. Variable stars in the VVV globular clusters. I. 2MASS-GC 02 and Terzan 10

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-García, Javier; Dékány, István; Catelan, Márcio; Ramos, Rodrigo Contreras; Gran, Felipe; Leyton, Paul; Minniti, Dante [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile); Amigo, Pía, E-mail: jalonso@astro.puc.cl, E-mail: idekany@astro.puc.cl, E-mail: mcatelan@astro.puc.cl, E-mail: rcontrer@astro.puc.cl, E-mail: fgran@astro.puc.cl, E-mail: pia.amigo@uv.cl, E-mail: pleyton@astro.puc.cl, E-mail: dante@astrofisica.cl [Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile)

    2015-03-01

    The VISTA Variables in the Vía Láctea (VVV) ESO Public Survey is opening a new window to study inner Galactic globular clusters (GCs) using their variable stars. These GCs have been neglected in the past due to the difficulties caused by the presence of elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RR Lyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the questions raised by the intriguing Oosterhoff dichotomy in the Galactic GC system. In a series of papers we plan to explore variable stars in the GCs falling inside the field of the VVV survey. In this first paper, we search for and study the variables present in two highly reddened, moderately metal-poor, faint, inner Galactic GCs: 2MASS-GC 02 and Terzan 10. We report the discovery of sizable populations of RR Lyrae stars in both GCs. We use near-infrared period–luminosity relations to determine the color excess of each RR Lyrae star, from which we obtain both accurate distances to the GCs and the ratios of the selective-to-total extinction in their directions. We find the extinction toward both clusters to be elevated, non-standard, and highly differential. We also find both clusters to be closer to the Galactic center than previously thought, with Terzan 10 being on the far side of the Galactic bulge. Finally, we discuss their Oosterhoff properties, and conclude that both clusters stand out from the dichotomy followed by most Galactic GCs.

  15. New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence

    Science.gov (United States)

    Gizis, John E.; Monet, David G.; Reid, I. Neill; Kirkpatrick, J. Davy; Liebert, James; Williams, Rik J.

    2000-08-01

    We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with Ksmass function that is smooth across the stellar/substellar limit. We show the observed frequency of Hα emission peaks at ~100% for M7 dwarfs and then decreases for cooler dwarfs. In absolute terms, however, as measured by the ratio of Hα to bolometric luminosity, none of the ultracool M dwarfs can be considered very active compared to earlier M dwarfs, and we show that the decrease that begins at spectral type M6 continues to the latest L dwarfs. We find that flaring is common among the coolest M dwarfs and estimate the frequency of flares at 7% or higher. We show that the kinematics of relatively active (EW>6 Å) ultracool M dwarfs are consistent with an ordinary old disk stellar population, while the kinematics of inactive ultracool M dwarfs are more typical of a 0.5 Gyr old population. The early L dwarfs in the sample have kinematics consistent with old ages, suggesting that the hydrogen-burning limit is near spectral types L2-L4. We use the available data on M and L dwarfs to show that chromospheric activity drops with decreasing mass and temperature and that at a given (M8 or later) spectral type, the younger field (brown) dwarfs are less active than many of the older, more massive field stellar dwarfs. Thus, contrary to the well-known stellar age-activity relationship, low activity in field ultracool dwarfs can be an indication of comparative youth and substellar mass.

  16. Lipoprotein-Associated Phospholipase A2 Mass Level Is Increased in Elderly Subjects with Type 2 Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    J. Fortunato

    2014-01-01

    Full Text Available Objective. Lipoprotein-associated phospholipase A2 (Lp-PLA2 is extensively expressed by advanced atherosclerotic lesions and may play a role in plaque instability. We selected a group of elderly subjects that underwent transcatheter aortic valve implantation (TAVI or balloon angioplasty (BA and separated them into two groups, diabetic and nondiabetic, to compare the level of Lp-PLA2 mass between them. Methods. 44 patients aged 79.6±5.6 years with symptomatic severe aortic valve stenosis underwent TAVI (n=35 or BA (n=9. 21 subjects had confirmed type 2 diabetes mellitus. Lp-PLA2 mass was measured using an enzyme-linked immunosorbent assay kit (USCN Life Science, China before and 3 days after the procedure. Results. Lp-PLA2 mass was significantly elevated in this population (1296±358 ng/mL before TAVI; 1413±268 ng/mL before BA and further increased after TAVI (1604±437 ng/mL, P<0.01 or BA (1808±303 ng/mL, P<0.01. Lp-PLA2 mass was significantly increased on the diabetic group before these interventions. Conclusion. Lp-PLA2 may be a novel biomarker for the presence of rupture-prone atherosclerotic lesions in elderly patients. Levels of Lp-PLA2 in diabetic patients may accompany the higher amount of small dense LDL particles seen in these subjects.

  17. Association of Lp-PLA2 Mass and Aysmptomatic Intracranial and Extracranial Arterial Stenosis in Hypertension Patients

    Science.gov (United States)

    Wang, Yan; Zhang, Jin; Qian, Yuesheng; Tang, Xiaofeng; Ling, Huawei; Chen, Kemin; Gao, Pingjin; Zhu, Dingliang

    2015-01-01

    Background and Purpose Intracranial arterial stenosis (ICAS) is a common cause of ischemic stroke in Asians, whereas whites tend to have more extracranial lesions. Lipoprotein-associated phospholipase A2 (Lp-PLA2) has been associated with ischemic stroke by a large amount of work. However, there are few studies focusing on the relationship of Lp-PLA2 and asymptomatic ICAS or extracranial arterial stenosis (ECAS). Wehereby sought to explore the relationship of Lp-PLA2 and ICAS, ECAS and concurrent stenosis in stroke-free hypertensive patients in Chinese population. Methods All the subjects were evaluated for the presence and severity of ICAS and ECAS through computerized tomographic angiography (CTA) covered the whole brain down to the level of aortic arch. Lp-PLA2 mass was measured by enzyme linked immunoassay. The association of Lp-PLA2 and vascular stenosis was analyzed through multivariate logistic regression. Results Among 414 participants, 163 (39.4%) had no ICAS or ECAS, 63 (15.2%) had ECAS only, 111 (26.8%) had ICAS only and 77 (18.6%) had concurrent extraintracranial stenosis. Lp-PLA2 mass was significantly associated with isolated ICAS (OR: 2.3; 95% CI: 1.14-4.64), and concurrent stenosis (OR: 3.93; 95% CI: 1.62-9.51), but was not related to isolated ECAS (OR: 1.54; 95% CI: 0.68-3.48). Lp-PLA2 mass was also associated with moderate to severe ICAS no matter how was the ECAS. Moreover, patients with higher Lp-PLA2 mass showed more sever ICAS and had more intracranial arterial lesions. Conclusion This study revealed the association of Lp-PLA2 mass with ICAS in stroke-free hypertensive patients in Chinese population. The further long-term cohort study was warranted to elucidate the concrete effect of Lp-PLA2 on the asymptomatic ICAS. PMID:26098634

  18. Proper motions of ROSAT discovered isolated neutron stars measured with Chandra: First X-ray measurement of the large proper motion of RX J1308.6+2127/RBS 1223

    Science.gov (United States)

    Motch, C.; Pires, A. M.; Haberl, F.; Schwope, A.; Zavlin, V. E.

    2008-02-01

    The unprecedented spatial resolution of the Chandra observatory opens the possibility to detect with relatively high accuracy proper motions at X-ray wavelengths. We have conducted an astrometric study of three of the ``Magnificent Seven'', the thermally emitting radio quiet isolated neutron stars (INSs) discovered by ROSAT. These three INSs (RX J0420.0-5022, RX J0806.4-4123 and RX J1308.6+2127/RBS 1223) either lack an optical counterpart or have one too faint to be used for astrometric purposes. We obtained ACIS observations 3 to 5 years apart to constrain or measure the displacement of the sources on the X-ray sky using as reference the background of extragalactic or remote galactic X-ray sources. Upper limits of 138 mas/yr and 76 mas/yr on the proper motion of RX J0420.0-5022 and RX J0806.4-4123, respectively, have already been presented in [7]. Here we report the very significant measurement (~10 sigma) of the proper motion of the third INS of our program, RX J1308.6+2127/RBS 1223. Comparing observations obtained in 2002 and 2007 reveals a displacement of 1.1 arcsec implying a yearly proper motion of 223 mas, the second fastest measured for the ROSAT discovered INSs. The source is rapidly moving away from the galactic plane at a speed which precludes any significant accretion of matter from the interstellar medium. Its transverse velocity of ~740 (d/700 pc) km/s might be the largest of the ``Magnificent Seven'' and among the fastest recorded for neutron stars. RX J1308.6+2127/RBS 1223 is thus a young high velocity cooling neutron star. The source may have its origin in the closest part of the Scutum OB2 association about 0.8 Myr ago, an age consistent with that expected from cooling curves, but significantly younger than inferred from pulse timing measurements (1.5 Myr).

  19. Characterization of the Praesepe Star Cluster by Photometry and Proper Motions With 2MASS, PPMXL, and Pan-STARRS

    Science.gov (United States)

    2014-03-20

    distinct from that of the field stars , so contamination is minimized when identifying member stars . Third, in contrast to a star cluster at birth , for...reserved. Printed in the U.S.A. CHARACTERIZATION OF THE PRAESEPE STAR CLUSTER BY PHOTOMETRY AND PROPER MOTIONS WITH 2MASS, PPMXL, AND Pan-STARRS P. F. Wang1...properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or

  20. Proper motions of ROSAT discovered isolated neutron stars measured with Chandra: First X-ray measurement of the large proper motion of RX J1308.6+2127/RBS 1223

    CERN Document Server

    Motch, C; Haberl, F; Schwope, A; Zavlin, V E

    2007-01-01

    The unprecedented spatial resolution of the Chandra observatory opens the possibility to detect with relatively high accuracy proper motions at X-ray wavelengths. We have conducted an astrometric study of three of the "Magnificent Seven", the thermally emitting radio quiet isolated neutron stars (INSs) discovered by ROSAT. These three INSs (RX J0420.0-5022, RX J0806.4-4123 and RX J1308.6+2127/RBS 1223) either lack an optical counterpart or have one too faint to be used for astrometric purposes. We obtained ACIS observations 3 to 5 years apart to constrain or measure the displacement of the sources on the X-ray sky using as reference the background of extragalactic or remote galactic X-ray sources. Upper limits of 138 mas/yr and 76 mas/yr on the proper motion of RX J0420.0-5022 and RX J0806.4-4123, respectively, have already been presented in Motch et al. (2007). Here we report the very significant measurement (~ 10 sigma) of the proper motion of the third INS of our program, RX J1308.6+2127/RBS1223. Comparing...

  1. An efficient method to identify galaxy clusters by using SuperCOSMOS, 2MASS and WISE data

    Institute of Scientific and Technical Information of China (English)

    XU WeiWei; WEN ZhongLue; HAN JinLin

    2014-01-01

    The survey data of Wide-field Infrared Survey Explorer (WISE) provide an opportunity for the identification of galaxy clusters.We present an efficient method for detecting galaxy clusters by combining the WISE data with SuperCOSMOS and 2MASS data.After performing star-galaxy separation,we calculate the number of companion galaxies around the galaxies with photometric redshifts previously estimated by the SuperCOSMOS,2MASS and WISE data.A scaled richness Rscal ≥ 30 is set as a criterion to identify clusters.From a sky area of 275 deg2 of the Sloan Digital Sky Survey Stripe 82 region,we identify 302 clusters in the redshift range of 0.1 < z < 0.35,247 (82%) of which are previously known SDSS clusters.The results suggest that our method is efficient for identifying galaxy clusters by using the all sky data of the SuperCOSMOS,2MASS and WISE.

  2. Clouds, Gravity and Metallicity in Blue L dwarfs: The Case of 2MASS J11263991-5003550

    CERN Document Server

    Burgasser, Adam J; Kirkpatrick, J Davy; Cruz, Kelle L; Swift, Brandon J

    2007-01-01

    Optical and near-infrared spectroscopy of the newly discovered peculiar L dwarf 2MASS J11263991-5003550 are presented. Folkes et al. identified this source as a high proper motion L9+/-1 dwarf based on its strong H2O absorption at 1.4 micron. We find that the optical spectrum of 2MASS J1126-5003 is in fact consistent with that of a normal L4.5 dwarf with notably enhanced FeH absorption at 9896 A. However, its near-infrared spectrum is unusually blue, with strong H2O and weak CO bands similar in character to several recently identified ``blue L dwarfs''. Using 2MASS J1126-5003 as a case study, and guided by trends in the condensate cloud models of Burrows et al. and Marley et al., we find that the observed spectral peculiarities of these sources can be adequately explained by the presence of thin and/or large-grained condensate clouds as compared to normal field L dwarfs. Atypical surface gravities or metallicities alone cannot reproduce the observed peculiarities, although they may be partly responsible for t...

  3. SPATIALLY RESOLVED OBSERVATIONS OF THE BIPOLAR OPTICAL OUTFLOW FROM THE BROWN DWARF 2MASS J12073347-3932540

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, E. T.; Ray, T. P. [Dublin Institute for Advanced Studies, School of Cosmic Physics, 31 Fitzwilliam Place, Dublin 2 (Ireland); Comeron, F. [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Bacciotti, F. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Kavanagh, P. J. [Institut fuer Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Eberhard Karls Universitaet, D-72076 Tuebingen (Germany)

    2012-12-20

    Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M{sub JUP} BD 2MASS J12073347-3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [O I]{lambda}6300 emission line. Follow-up observations consisting of spectra and [S II], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow position angle (P.A.) at {approx}65 Degree-Sign . The [O I]{lambda}6300 emission line region is spatially resolved and the outflow is detected in the [S II] images. The detection is firstly in the form of an elongation of the point-spread function (PSF) along the direction of the outflow P.A. Four faint knot-like features (labeled A-D) are also observed to the southwest of 2MASS J12073347-3932540 along the same P.A. suggested by the spectra and the elongation in the PSF. Interestingly, D, the feature furthest from the source, is bow shaped with the apex pointing away from 2MASS J12073347-3932540. A color-color analysis allows us to conclude that at least feature D is part of the outflow under investigation while A is likely a star or galaxy. Follow-up observations are needed to confirm the origin of B and C. This is a first for a BD, as BD optical outflows have to date only been detected using spectro-astrometry. This result also demonstrates for the first time that BD outflows can be collimated and episodic.

  4. 2MASS wide field extinction maps: IV. The Orion, Mon R2, Rosette, and Canis Major star forming regions

    OpenAIRE

    Lombardi, M.; Alves,J.; Lada, C. J.

    2011-01-01

    We present a near-infrared extinction map of a large region (approximately 2200 deg^2) covering the Orion, the Monoceros R2, the Rosette, and the Canis Major molecular clouds. We used robust and optimal methods to map the dust column density in the near-infrared (NICER and NICEST) towards ~19 million stars of the Two Micron All Sky Survey (2MASS) point source catalog. Over the relevant regions of the field, we reached a 1-sigma error of 0.03 mag in the K-band extinction with a resolution of 3...

  5. VizieR Online Data Catalog: BV light curves of 2MASS J06451725+4122158 (Jeon+, 2010)

    Science.gov (United States)

    Jeon, Y.-B.; Kim, S.-L.; Nemec, J. M.

    2010-03-01

    Optical photometric observations of 2MASS 06451725+4122158 were made using the BOAO 1.8m telescope in Korea and the LOAO 1.0m robotic telescope located in Arizona. At BOAO, V band CCD images were obtained on 16 nights, from 2006 January 3 to 2007 February 14. At LOAO, both B and V images were made on seven nights, from 2006 January 6 to 13. The overlapping observations from the two different time zones enabled observations to be made of the stars uninterruptedly for as many as 19hr in a day (2006 January 6-7). (2 data files).

  6. The Information Of The Milky Way From 2MASS Whole Sky Star Count: The Bimodal Color Distributions

    CERN Document Server

    Chang, Chan-Kao; Ko, Chung-Ming; Peng, Ting-Hung

    2012-01-01

    The J-Ks color distribution (CD) with a bin size of 0.05 magnitude for the entire Milky Way has been carried out by using the Two Micron All Sky Survey Point Source Catalog (2MASS PSC). The CDs are bimodal, which has a red peak at 0.8 < J-Ks < 0.85 and a blue peak at 0.3 < J-Ks < 0.4. The colors of the red peak are more or less the same for the whole sky, but that of the blue peak depend on Galactic latitude, (J-Ks ~ 0.35 at low Galactic latitudes and 0.35 < J-Ks < 0.4 for other sky areas). The blue peak dominates the bimodal CDs at low Galactic latitudes and becomes comparable with the red peak in other sky regions. In order to explain the bimodal distribution and the global trend shown by the all sky 2MASS CDs, we assemble an empirical HR diagram, which is composed by observational-based near infrared HR diagrams and color magnitude diagrams, and incorporate a Milky Way model. In the empirical HR diagram, the main sequence stars turnoff the thin disk is relatively bluer, (J-Ks)0 = 0.31, wh...

  7. A Catalog of Candidate Field Horizontal-Branch and A-Type Stars. III. A 2MASS-Cleaned Version

    CERN Document Server

    Beers, T C; Rossi, S; Wilhelm, R; Marsteller, B; Beers, Timothy C.; Almeida, Tiago; Rossi, Silvia; Wilhelm, Ronald; Marsteller, Brian

    2006-01-01

    We present coordinates and available photometric information (either from previous or recent broadband UBV observations, and near-infrared photometry from the 2MASS Point Source Catalog) for 12056 stars (11516 of which are unique) identified in the HK Survey of Beers and colleagues as candidate field horizontal-branch or A-type stars. These stars, in the apparent magnitude range 10 <= B <= 16.0, were selected using an objective-prism/interference-filter survey technique. The availability of 2MASS information permits assembly of a cleaned version of this catalog, comprising likely blue horizontal-branch (BHB) stars or blue stragglers in the color interval -0.2 <= (B-V)o <= +0.2, which are of particular interest for investigation of the structure, kinematics, and dynamics of the thick disk and inner halo of the Milky Way, the total mass and mass profile of the Galaxy, and as potential foreground/background objects in efforts to bracket distances to high velocity clouds of H I. A comparison of the st...

  8. Detection, size, measurement and structural analysis limits for the 2MASS, UKIDSS-LAS & VISTA VIKING surveys

    CERN Document Server

    Andrews, Stephen K; Driver, Simon P; Robotham, Aaron S G

    2013-01-01

    The 2MASS, UKIDSS-LAS and VISTA VIKING surveys have all now observed the GAMA 9hr region in the $K_s$ band. Here we compare the detection rates, photometry, basic size measurements, and single-component GALFIT structural measurements for a sample of 37,591 galaxies. We explore the sensitivity limits where the data agree for a variety of issues including: detection, star-galaxy separation, photometric measurements, size and ellipticity measurements, and S\\'{e}rsic measurements. We find that 2MASS fails to detect at least 20% of the galaxy population within all magnitude bins, however for those that are detected we find photometry is robust ($\\pm$ 0.2 mag) to 14.7 AB mag and star-galaxy separation to 14.8 AB mag. For UKIDSS-LAS we find incompleteness starts to enter at a flux limit of 18.9 AB mag, star-galaxy separation is robust to 16.3 AB mag and structural measurements are robust to 17.7 AB mag. VISTA VIKING data is complete to approximately 20.0 AB mag and structural measurements appear robust to 18.8 AB ma...

  9. 2MASS J18082002-5104378: The brightest (V=11.9) ultra metal-poor star

    CERN Document Server

    Melendez, Jorge; Tucci-Maia, Marcelo; Ramirez, Ivan; Li, Ting S; Perez, Gabriel

    2016-01-01

    Context. The most primitive metal-poor stars are important for studying the conditions of the early galaxy and are also relevant to big bang nucleosynthesis. Aims. Our objective is to find the brightest (V<14) most metal-poor stars. Methods. Candidates were selected using a new method, which is based on the mismatch between spectral types derived from colors and observed spectral types. They were observed first at low resolution with EFOSC2 at the NTT/ESO to obtain an initial set of stellar parameters. The most promising candidate, 2MASS J18082002-5104378 (V=11.9), was observed at high resolution (R=50 000) with UVES at the VLT/ESO, and a standard abundance analysis was performed. Results. We found that 2MASS J18082002-5104378 is an ultra metal-poor star with stellar parameters Teff = 5440 K, log g = 3.0 dex, vt = 1.5 km/s, [Fe/H] = -4.1 dex. The star has [C/Fe]<+0.9 in a 1D analysis, or [C/Fe]<=+0.5 if 3D effects are considered; its abundance pattern is typical of normal (non-CEMP) ultra metal-poor ...

  10. Multi-wavelength characterization of stellar flares on low-mass stars using SDSS and 2MASS time domain surveys

    CERN Document Server

    Davenport, James R A; Kowalski, Adam F; Hawley, Suzanne L; Schmidt, Sarah J; Hilton, Eric J; Sesar, Branimir; Cutri, Roc

    2012-01-01

    We present the first rates of flares from M dwarf stars in both red optical and near infrared (NIR) filters. We have studied ~50,000 M dwarfs from the SDSS Stripe 82 area, and 1,321 M dwarfs from the 2MASS Calibration Scan Point Source Working Database that overlap SDSS imaging fields. We assign photometric spectral types from M0 to M6 using (r-i) and (i-z) colors for every star in our sample. Stripe 82 stars each have 50-100 epochs of data, while 2MASS Calibration stars have ~1900 epochs. From these data we estimate the observed rates and theoretical detection thresholds for flares in eight photometric bands as a function of spectral type. Optical flare rates are found to be in agreement with previous studies, while the frequency per hour of NIR flare detections is found to be more than two orders of magnitude lower. An excess of small amplitude flux increases in all bands exhibits a power-law distribution, which we interpret as the result of flares below our detection thresholds. In order to investigate the...

  11. Analysis of the diffuse near-IR emission from 2MASS deep integration data foregrounds vs the cosmic infrared background

    CERN Document Server

    Odenwald, S; Mather, J C; Skrutskie, M F; Cutri, R M

    2003-01-01

    This is one of two papers in which we report the detection of structure in the cosmic infrared background (CIB) between 1.25 - 2.2 micron through the use of data from the Two Micron Sky Survey (2MASS). This paper concentrates on data assembly, analysis and the estimate of the various foreground contributions; the companion paper (Kashlinsky, Odenwald, Mather, Skrutskie, Cutri 2002, hereafter KOMSC) presents the cosmological results for the CIB fluctuations and their implications. By using repeated observations of a specific calibration star field, we were able to achieve integration times in excess of 3900 seconds compared to the 7.8 seconds in the standard 2MASS data product. This yielded a point source detection limit (3 \\sigma) of +18.5^m in K_s band. The resulting co-added images were processed to remove point sources to a limiting surface brightness of +20^m/arcsec$^2 or 40 nW/m^2/sr. The remaining maps contained over 90% of the pixels and were Fourier transformed to study the spatial structure of the di...

  12. 2MASS wide field extinction maps: IV. The Orion, Mon R2, Rosette, and Canis Major star forming regions

    CERN Document Server

    Lombardi, Marco; lada, Charles

    2011-01-01

    We present a near-infrared extinction map of a large region (approximately 2200 deg^2) covering the Orion, the Monoceros R2, the Rosette, and the Canis Major molecular clouds. We used robust and optimal methods to map the dust column density in the near-infrared (NICER and NICEST) towards ~19 million stars of the Two Micron All Sky Survey (2MASS) point source catalog. Over the relevant regions of the field, we reached a 1-sigma error of 0.03 mag in the K-band extinction with a resolution of 3 arcmin. We measured the cloud distances by comparing the observed density of foreground stars with the prediction of galactic models, thus obtaining d_{Orion A} = (371 +/- 10) pc, d_{Orion B} = (398 +/- 12) pc, $d_{Mon R2} = (905 +/- 37) pc, $d_{Rosette} = (1330 +/- 48) pc, and $d_{CMa} = (1150 +/- 64) pc, values that compare very well with independent estimates.

  13. Near-infrared photometry and spectroscopy of the low Galactic latitude globular cluster 2MASS-GC03

    CERN Document Server

    Carballo-Bello, Julio A; Borissova, J; Smith, L C; Kurtev, R; Lucas, P W; Bidin, Ch Moni; Alonso-Garcia, J; Minniti, D; Palma, T; Dekany, I; Medina, N; Moyano, M; Villanueva, V; Kuhn, M A

    2016-01-01

    We present deep near-infrared photometry and spectroscopy of the globular cluster 2MASS-GC03 projected in the Galactic disk using MMIRS on the Clay telescope (Las Campanas Observatory) and VISTA Variables in the Via Lactea survey (VVV) data. Most probable cluster member candidates were identified from near-infrared photometry. Out of ten candidates that were followed-up spectroscopically, five have properties of cluster members, from which we calculate = -0.9 +- 0.2 and a radial velocity of v_r > = -78 +- 12km/s. A distance of 10.8kpc is estimated from 3 likely RRLyrae members. Given that the cluster is currently at a distance of 4.2kpc from the Galactic center, the cluster's long survival time of an estimated 11.3 +- 1.2Gyr strengthens the case for its globular-cluster nature. The cluster has a hint of elongation in the direction of the Galactic center.

  14. The Hyperactive L Dwarf 2MASS J13153094-2649513: Continued Emission and a Brown Dwarf Companion

    Science.gov (United States)

    Burgasser, Adam J.; Sitarski, Breann N.; Gelino, Christopher R.; Logsdon, Sarah E.; Perrin, Marshall D.

    2011-09-01

    We report new observations of the unusually active, high proper motion L5e dwarf 2MASS J13153094-2649513. Optical spectroscopy with Magellan/MagE reveals persistent nonthermal emission, with narrow H I Balmer, Na I and K I lines all observed in emission. Low-resolution near-infrared spectroscopy with the Infrared Telescope Facility/SpeX Spectrograph indicates the presence of a low-temperature companion, which is resolved through multi-epoch laser guide star adaptive optics imaging at the W. M. Keck Observatory. The co-moving companion is separated by 338 ± 4 mas, and its relative brightness (ΔKs = 5.09 ± 0.10) makes this system the second-most-extreme flux ratio very-low-mass binary identified to date. Resolved near-infrared spectroscopy with Keck/OSIRIS identifies the companion as a T7 dwarf. The absence of Li I absorption in combined-light optical spectroscopy constrains the system age to gsim0.8-1.0 Gyr, while the system's kinematics and unusually low mass ratio (M 2/M 1 = 0.3-0.6) suggest that it is even older. A coevality test of the components also indicates an older age, but reveals discrepancies between evolutionary and atmosphere model fits of the secondary, which are likely attributable to poor reproduction of its near-infrared spectrum. With a projected separation of 6.6 ± 0.9 AU, the 2MASS J1315-2649 system is too widely separated for mass exchange or magnetospheric interactions to be powering its persistent nonthermal emission. Rather, the emission is probably chromospheric in nature, consistent with an inversion in the age-activity relation in which strong magnetic fields are maintained by relatively old and massive ultracool dwarfs. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration, and made possible by the generous financial support of the W. M. Keck

  15. Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

    CERN Document Server

    Bouy, H; Pinte, C; Olofsson, J; Navascues, D Barrado y; Martín, E L; Pantin, E; Monin, J -L; Basri, G; Augereau, J -C; Ménard, F; Duvert, G; Duchêne, G; Marchis, F; Bayo, A; Bottinelli, S; Lefort, B; Guieu, S

    2008-01-01

    In order to improve our understanding of substellar formation, we have performed a compositional and structural study of a brown dwarf disk. We present the result of photometric, spectroscopic and imaging observations of 2MASS J04442713+2512164, a young brown dwarf (M7.25) member of the Taurus association. Our dataset, combined with results from the literature, provides a complete coverage of the spectral energy distribution from the optical to the millimeter including the first photometric measurement of a brown dwarf disk at 3.7mm, and allows us to perform a detailed analysis of the disk properties. The target was known to have a disk. High resolution optical spectroscopy shows that it is intensely accreting, and powers a jet and an outflow. The disk structure is similar to that observed for more massive TTauri stars. Spectral decomposition models of Spitzer/IRS spectra suggest that the mid-infrared emission from the optically thin disk layers is dominated by grains with intermediate sizes (1.5micron). Crys...

  16. Near-infrared photometry and spectroscopy of the low Galactic latitude globular cluster 2MASS-GC 03

    Science.gov (United States)

    Carballo-Bello, Julio A.; Ramírez Alegría, S.; Borissova, J.; Smith, L. C.; Kurtev, R.; Lucas, P. W.; Moni Bidin, Ch.; Alonso-García, J.; Minniti, D.; Palma, T.; Dékány, I.; Medina, N.; Moyano, M.; Villanueva, V.; Kuhn, M. A.

    2016-10-01

    We present deep near-infrared photometry and spectroscopy of the globular cluster 2MASS-GC 03 projected in the Galactic disc using MMT and Magellan Infrared Spectrograph on the Clay Telescope (Las Campanas Observatory) and VISTA Variables in the Via Lactea Survey data. Most probable cluster member candidates were identified from near-infrared photometry. Out of 10 candidates that were followed-up spectroscopically, 5 have properties of cluster members, from which we calculate = - 0.9 ± 0.2 and a radial velocity of = - 78 ± 12 km s-1. A distance of 10.8 kpc is estimated from three likely RR Lyrae members. Given that the cluster is currently at a distance of 4.2 kpc from the Galactic Centre, the cluster's long survival time of an estimated 11.3 ± 1.2 Gyr strengthens the case for its globular-cluster nature. The cluster has a hint of elongation in the direction of the Galactic Centre.

  17. 2MASS J035523.37+113343.7: A YOUNG, DUSTY, NEARBY, ISOLATED BROWN DWARF RESEMBLING A GIANT EXOPLANET

    Energy Technology Data Exchange (ETDEWEB)

    Faherty, Jacqueline K. [Department of Astronomy, Universidad de Chile Cerro Calan, Las Condes (Chile); Rice, Emily L.; Cruz, Kelle L.; Nunez, Alejandro [Department of Astrophysics , American Museum of Natural History, Central Park West at 79th Street, New York, NY 10034 (United States); Mamajek, Eric E., E-mail: jfaherty17@gmail.com, E-mail: jfaherty@amnh.org [Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile)

    2013-01-01

    We present parallax and proper motion measurements, near-infrared spectra, and Wide-field Infrared Survey Explorer photometry for the low surface gravity L5{gamma} dwarf 2MASS J035523.37+113343.7 (2M0355). We use these data to evaluate photometric, spectral, and kinematic signatures of youth as 2M0355 is the reddest isolated L dwarf yet classified. We confirm its low-gravity spectral morphology and find a strong resemblance to the sharp triangular shaped H-band spectrum of the {approx}10 Myr planetary-mass object 2M1207b. We find that 2M0355 is underluminous compared to a normal field L5 dwarf in the optical and Mauna Kea Observatory J, H, and K bands and transitions to being overluminous from 3 to 12 {mu}m, indicating that enhanced photospheric dust shifts flux to longer wavelengths for young, low-gravity objects, creating a red spectral energy distribution. Investigating the near-infrared color-magnitude diagram for brown dwarfs confirms that 2M0355 is redder and underluminous compared to the known brown dwarf population, similar to the peculiarities of directly imaged exoplanets 2M1207b and HR8799bcd. We calculate UVW space velocities and find that the motion of 2M0355 is consistent with young disk objects (<2-3 Gyr) and it shows a high likelihood of membership in the AB Doradus association.

  18. The discrepancy between dynamical and theoretical mass in the triplet-system 2MASS J10364483+1521394

    Science.gov (United States)

    Calissendorff, Per; Janson, Markus; Köhler, Rainer; Durkan, Stephen; Hippler, Stefan; Dai, Xiaolin; Brandner, Wolfgang; Schlieder, Joshua; Henning, Thomas

    2017-08-01

    We combine new Lucky Imaging astrometry from New Technology Telescope/AstraLux Sur with already published astrometry from the AstraLux Large M-dwarf Multiplicity Survey to compute orbital elements and individual masses of the 2MASS J10364483+1521394 triple system belonging to the Ursa-Major moving group. The system consists of one primary low-mass M-dwarf orbited by two less massive companions, for which we determine a combined dynamical mass of MB + C = 0.48 ± 0.14 M⊙. We show from the companions' relative motions that they are of equal mass (with a mass ratio of 1.00 ± 0.03), thus 0.24 ± 0.07 M⊙ individually, with a separation of 3.2 ± 0.3 AU, and we conclude that these masses are significantly higher (30%) than what is predicted by theoretical stellar evolutionary models. The biggest uncertainty remains the distance to the system, here adopted as 20.1 ± 2.0 pc based on trigonometric parallax, whose ambiguity has a major impact on the result. With the new observational data we are able to conclude that the orbital period of the BC pair is 8.41+0.04-0.02yr.

  19. Detection of small scale fluctuations in the near-IR cosmic infrared background from long exposure 2MASS fields

    CERN Document Server

    Kashlinsky, A; Mather, J; Skrutskie, M F; Cutri, R M

    2002-01-01

    We report first results for the cosmic infrared background (CIB) fluctuations at 1.25, 1.65 and 2.17 micron obtained from long exposures constructed from 2MASS standard star fields. We have co-added and analyzed scans from one such field with a total exposure time > 1 hour, and removed sources and other artifacts. The stars and galaxies were clipped out to K_s~19^m leaving only high-z galaxies (or possibly local low-surface-brightness systems). The residual component of the diffuse emission on scales from a few arc-sec to a few arc-min has a power-law slope consistent with emission produced by clustered galaxies. The noise (and residual artifacts) contribution to the signal is small and the colors of the signal are very different from Galactic stars or air-glow. We therefore identify the signal as CIB fluctuations from the faint unresolved galaxies. We show that the present-day galaxies with no evolution would produce a significant deficit in the observed CIB fluctuations. Thus the dominant contribution to th...

  20. Three-Dimensional Reddening Map for Stars from 2MASS Photometry: The Method and the First Results

    CERN Document Server

    Gontcharov, George

    2016-01-01

    The first results of the construction of a 3D reddening map for stars within 1600 pc of the Sun are presented. Analysis of the distribution of 70 million stars from the 2MASS catalog with the most accurate photometry on the (J-Ks) - Ks diagram supplemented with Monte Carlo simulations has shown that one of the maxima of this distribution corresponds to F-type dwarfs and subgiants with a mean absolute magnitude MKs=2.5m. The shift of this maximum toward large (J-Ks) with increasing $Ks$ reflects the reddening of these stars with increasing heliocentric distance. The distribution of the sample of stars over Ks, l, and b cells with corresponds to their distribution over 3D spatial cells. As a result, the reddening E(J-Ks) has been determined with an accuracy of 0.03m for spatial cells with a side of 100 pc. All of the known large absorbing clouds within 1600 pc of the Sun have manifested themselves in the results obtained. The distances to the near and far edges of the clouds have been determined with a relative...

  1. Cosmic flow from 2MASS redshift survey: The origin of CMB dipole and implications for LCDM cosmology

    CERN Document Server

    Lavaux, G; Mohayaee, R; Colombi, S

    2008-01-01

    We generate the peculiar velocity field for the 2MASS Redshift Survey (2MRS) catalog using an orbit-reconstruction algorithm. The reconstructed velocities of individual objects in 2MRS are well-correlated with the peculiar velocities obtained from high-precision observed distances within 3,000 km/s. We estimate the mean matter density to be 0.31 +/- 0.05 by comparing observed to reconstructed velocities in this volume. The reconstructed motion of the Local Group in the rest frame established by distances within 3,000 km/s agrees with the observed motion and is generated by fluctuations within this volume, in agreement with observations. Then, we reconstruct the velocity field of 2MRS in successively larger radii, to study the problem of convergence towards the CMB dipole. We find that less than half of the amplitude of the CMB dipole is generated within a volume enclosing the Hydra-Centaurus-Norma supercluster at around 40 Mpc/h. Although most of the amplitude of the CMB dipole seems to be recovered by 120 Mp...

  2. Evidence Against an Edge-On Disk Around the Extrasolar Planet 2MASS 1207 b and a New Thick Cloud Explanation for its Under-Luminosity

    CERN Document Server

    Skemer, Andrew J; Sz\\Hucs, László; Apai, Dániel; Pascucci, Ilaria; Biller, Beth A

    2011-01-01

    (Abridged) Since the discovery of the first directly-imaged, planetary-mass object, 2MASS 1207 b, several works have sought to explain a disparity between its observed temperature and luminosity. Given its known age, distance, and spectral type, 2MASS 1207 b is under-luminous by a factor of ~10 (~2.5 mags) when compared to standard models of brown-dwarf/giant-planet evolution. In this paper, we study three possible sources of 2MASS 1207 b's under-luminosity. First, we investigate Mohanty et al. (2007)'s hypothesis that a near edge-on disk might be responsible for 2MASS 1207 b's under-luminosity. We conclude that the hypothesis is unlikely due to the lack of variability seen in multi-epoch photometry and unnecessary due to the increasing sample of under-luminous brown-dwarfs/giant-exoplanets that cannot be explained by an edge-on disk. Next, we test the analogous possibility that a spherical shell of dust, could explain 2MASS 1207 b's under-luminosity. Models containing enough dust to create ~2.5 mags of extin...

  3. VizieR Online Data Catalog: 3D reddening map for stars from 2MASS phot. (Gontcharov, 2010)

    Science.gov (United States)

    Gontcharov, G. A.

    2016-07-01

    A three-dimensional reddening map for stars within 1100pc of the Sun are presented. Analysis of the distribution of 70 million stars from the 2MASS catalog with the most accurate photometry on the (J-Ks)-Ks diagram supplemented with Monte Carlo simulations has shown that one of the maxima of this distribution corresponds to F-type dwarfs and subgiants with a mean absolute magnitude MKs=2.5m. The shift of this maximum toward large (J-Ks) with increasing Ks reflects the reddening of these stars with increasing heliocentric distance. The distribution of the sample of stars over Ks, l, and b cells with a statistically significant number of stars in each cell corresponds to their distribution over three-dimensional spatial cells. As a result, the reddening E(J-Ks) has been determined with an accuracy of 0.03m for spatial cells with a side of 100pc. All of the known large absorbing clouds within 1100pc of the Sun have manifested themselves in the results obtained. The absorbing matter of the Gould Belt is shown to manifest itself at latitudes up to 40° and within 600pc of the Sun. The size and influence of the Gould Belt may have been underestimated thus far. The absorbing matter at latitudes up to 60° and within 1100pc of the Sun has been found to be distributed predominantly in the first and second quadrants in the southern hemisphere and in the third and fourth quadrants in the northern hemisphere. Also the data of the Rv (2012AstL...38...12G) and Av (2012AstL...38...87G) 3D maps are added. (1 data file).

  4. Effects ofγ-irradiation and Deformation Temperature on Tensile Properties of Pb-2 mass% Sb Alloy

    Institute of Scientific and Technical Information of China (English)

    Gh MOHAMMED; SEI-GAMAL

    2016-01-01

    Effects ofγ-irradiation and deformation temperature (T)on the tensile properties of Pb-2 mass% Sb alloys were studied.The samples were annealed at 458 K for 2 h in air,then water quenched after they wereγ-irradiated (the different doses were 0·5,1·0,1·5,and 2·0 MGy).The tensile properties were performed using stress-strain measurements at a constant strain rate (1·2×10-3 s-1 )and at different T (303-393 K).It was found that at con-stant dose,the fracture stress (σF )decreases while the fracture strain (εF )increases as T increases.At particular T,σF increases whileεF decreases with increasing dose.The strain-hardening exponent (n),which is the slope of the relation between ln(σ)and ln(ε)of the parabolic part of the stress-strain curve,was determined and its values in-crease as T increases and decrease as the dose increases.The value of the activation energy increases as the dose in-creases from 0·07 eV for un-irradiated sample to 0·1 eV for the 2 MGy-irradiated sample.These values are in ac-cordance with that needed for dislocation movement and ordering process.An interpretation of the results was given, based on the creation of point and line defects due toγ-irradiation,and that results in a distribution of beta phase (Sb-phase),leading to a difficulty in the movement of dislocations,so there is an increase in alloy hardness.

  5. Galactic model parameters of cataclysmic variables: Results from a new absolute magnitude calibration with 2MASS and WISE

    Science.gov (United States)

    Özdönmez, A.; Ak, T.; Bilir, S.

    2015-01-01

    In order to determine the spatial distribution, Galactic model parameters and luminosity function of cataclysmic variables (CVs), a J-band magnitude limited sample of 263 CVs has been established using a newly constructed period-luminosity-colours (PLCs) relation which includes J,Ks and W1-band magnitudes in 2MASS and WISE photometries, and the orbital periods of the systems. This CV sample is assumed to be homogeneous regarding to distances as the new PLCs relation is calibrated with new or re-measured trigonometric parallaxes. Our analysis shows that the scaleheight of CVs is increasing towards shorter periods, although selection effects for the periods shorter than 2.25 h dramatically decrease the scaleheight: the scaleheight of the systems increases from 192 pc to 326 pc as the orbital period decreases from 12 to 2.25 h. The z-distribution of all CVs in the sample is well fitted by an exponential function with a scaleheight of 213-10+11 pc. However, we suggest that the scaleheight of CVs in the Solar vicinity should be ∼300 pc and that the scaleheights derived using the sech2 function should be also considered in the population synthesis models. The space density of CVs in the Solar vicinity is found 5.58(1.35)×10-6 pc-3 which is in the range of previously derived space densities and not in agreement with the predictions of the population models. The analysis based on the comparisons of the luminosity function of white dwarfs with the luminosity function of CVs in this study show that the best fits are obtained by dividing the luminosity functions of white dwarfs by a factor of 350-450.

  6. The past photometric history of the FU Ori-type young eruptive star 2MASS J06593158-0405277 = V960 Mon

    CERN Document Server

    Jurdana-Sepic, R

    2015-01-01

    The known FU Ori-type young eruptive stars are exceedingly rare (a dozen or so confirmed objects) and 2MASS J06593158-0405277, with its 2014 outburst, is likely the latest addition to the family. All members have displayed just one such eruption in their recorded history, an event lasting for decades. To test the FU Ori nature of 2MASS J06593158-0405277, we have reconstructed its photometric history by measuring its brightness on Harvard photographic plates spanning the time interval 1899-1989. No previous large amplitude eruption similar to that initiated in 2014 has been found, as in bona fide FU Ori-type objects. The median value of the brightness in quiescence of 2MASS J06593158-0405277 is B=15.5, with the time interval 1935-1950 characterized by a large variability (~1 mag amplitude) that contrasts with the remarkable photometric stability displayed at later epochs. The variability during 1935-1950 can either be ascribed to some T Tau like activity of 2MASS J06593158-0405277 itself or to the also young a...

  7. Carotid intima media thickness is associated with plasma lipoprotein-associated phospholipase A(2) mass in nondiabetic subjects but not in patients with type 2 diabetes

    NARCIS (Netherlands)

    Constantinides, Alexander; van Pelt, L. Joost; van Leeuwen, Jeroen J. J.; de Vries, Rindert; Tio, Rene A.; van der Horst, Iwan C. C.; Sluiter, Wim J.; Dullaart, Robin P. F.

    2011-01-01

    Background A recent meta-analysis showed that both plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) mass and activity independently predict cardiovascular events. Notably, Lp-PLA(2) activity but not mass was found to be a determinant of cardiovascular outcome in type 2 diabetes mellitus.

  8. A TARGETED SEARCH FOR PECULIARLY RED L AND T DWARFS IN SDSS, 2MASS, AND WISE: DISCOVERY OF A POSSIBLE L7 MEMBER OF THE TW HYDRAE ASSOCIATION

    Energy Technology Data Exchange (ETDEWEB)

    Kellogg, Kendra; Metchev, Stanimir [Western University, Centre for Planetary and Space Exploration, 1151 Richmond St, London, ON N6A 3K7 (Canada); Geißler, Kerstin; Hicks, Shannon [Stony Brook University, Stony Brook, NY 11790 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, Mail Code 100-22, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Kurtev, Radostin, E-mail: kkellogg@uwo.ca, E-mail: smetchev@uwo.ca [Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Ave. Gran Bretaña 1111, Playa Ancha, Casilla 53, Valparaíso (Chile)

    2015-12-15

    We present the first results from a targeted search for brown dwarfs with unusual red colors indicative of peculiar atmospheric characteristics. These include objects with low surface gravities or with unusual dust content or cloud properties. From a positional cross-match of SDSS, 2MASS, and WISE, we have identified 40 candidate peculiar early-L to early-T dwarfs that are either new objects or have not been identified as peculiar through prior spectroscopy. Using low-resolution spectra, we confirm that 10 of the candidates are either peculiar or potential L/T binaries. With a J − K{sub s} color of 2.62 ± 0.15 mag, one of the new objects—the L7 dwarf 2MASS J11193254–1137466—is among the reddest field dwarfs currently known. Its proper motion and photometric parallax indicate that it is a possible member of the TW Hydrae moving group. If confirmed, it would be the lowest-mass (5–6 M{sub Jup}) free-floating member. We also report a new T dwarf, 2MASS J22153705+2110554, that was previously overlooked in the SDSS footprint. These new discoveries demonstrate that despite the considerable scrutiny already devoted to the SDSS and 2MASS surveys, our exploration of these data sets is not yet complete.

  9. Stellar populations in the Milky Way bulge region: towards solving the Galactic bulge and bar shapes using 2MASS data

    Science.gov (United States)

    Robin, A. C.; Marshall, D. J.; Schultheis, M.; Reylé, C.

    2012-02-01

    Exploring the bulge region of our Galaxy is an interesting but challenging quest because of its complex structure and the highly variable extinction. We re-analyse photometric near-infrared data in order to investigate why it is so hard to reach a consensus on the shape and density law of the bulge, as witnessed in the literature. The apparent orientation of the bulge seems to vary with the range of longitude, latitude, and the population considered. To solve the problem we have used the Besançon galaxy model to provide a scheme for parameter fitting of the structural characteristics of the bulge region. The fitting process allows the shape of the bulge's main structure to be determined. We explore various parameters and shapes for the bulge population, based on Ferrer's ellipsoids, and fit the shape of the inner disc in the same process. The results show that the main structure has a standard triaxial boxy shape with an orientation of about 13° with respect to the Sun-Galactic centre direction. But the fit is greatly improved when we add a second structure,which is a longer and thicker ellipsoid. We emphasize that our first ellipsoid represents the main boxy bar of the Galaxy and that the thick bulge population could be either (i) a classical bulge slightly flattened by the effect of the bar's potential; or (ii) an inner thick disc counterpart. With Ferrer's ellipsoid, the model shows a general agreement with 2MASS data at the level of 10% in the whole bulge region but does not produce the "double clump" feature. However, we show that the double clump seen at intermediate latitudes can be reproduced by adding a slight flare to the bar. To characterize the populations better, we further simulate several fields that have been surveyed in spectroscopy and for which a metallicity distribution function (MDF) are available. The model agrees well with these MDF measured along the minor axis if we assume that the main bar has a mean solar metallicity and the second

  10. High-precision 2MASS JHK{sub s} light curves and other data for RR Lyrae star SDSS J015450 + 001501: Strong constraints for nonlinear pulsation models

    Energy Technology Data Exchange (ETDEWEB)

    Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán [Konkoly Observatory, MTA CSFK, Konkoly Thege Miklós út 15-17, H-1121 Budapest (Hungary); Jones, Lynne; Becker, Andrew C.; Davenport, James R. A. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Cutri, Roc M., E-mail: rszabo@konkoly.hu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2014-01-01

    We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.

  11. A New 2MASS/2df Selected Sample of Pairs of Galaxies and Calibration of Merging Rate in the Local Universe

    Institute of Scientific and Technical Information of China (English)

    孙艳春; 徐聪; 何香涛

    2003-01-01

    We present a new sample of 37 close major-merger galaxy pairs, selected from the 2-degree field redshift survey of the two-micron all-sky survey (2MASS) galaxies. The selection criteria for our near-infrared pairs are more closely related to galaxy mass (a very important parameter in galaxy evolution models) than those for optical selected samples. Our sample benefits enormously from the high homogeneity and accuracy of the 2MASS database, and false matchings are minimized by the essentially three-dimensional selection procedure. Taking into account the biases, we find that 1.96 (±0.4)% of galaxies are in close major-merger pairs. This indicates a local merging rate of 1.0%, in good agreement with the results in recent studies of optical selected pairs in the local universe. The results derived with our sample have high confidence.

  12. The 2MASS Wide-Field T Dwarf Search. I. Discovery of a Bright T Dwarf Within 10 pc of the Sun

    CERN Document Server

    Burgasser, A J; McElwain, M W; Cutri, R M; Burgasser, A J; Skrutskie, M F; Burgasser, Adam J.; Elwain, Michael W. Mc; Cutri, Roc M.; Burgasser, Albert J.

    2002-01-01

    We present the discovery of a bright (J = 13.94$\\pm$0.03) T dwarf, 2MASS 1503+2525, identified in a new, wide-field search for T dwarfs using the recently completed Two Micron All Sky Survey (2MASS). The 1--2.5 $\\micron$ spectrum of this object exhibits the strong H$_2$O and CH$_4$ bands characteristic of mid- and late-type T dwarfs, and we derive a spectral type of T5.5 using both the Burgasser et al. and the Geballe et al. classification schemes. Based on its spectral type and the absolute magnitudes of known T dwarfs, we estimate the distance of this object as 8$\\pm$3 pc if it is single, likely within 10 pc of the Sun. Our new 2MASS search, which covers 74% of the sky and greatly expands on earlier color constraints, should identify 15--25 new T dwarfs with J $\\leq$ 16. Combined with the 20 known members of this class that already fall within our search criteria, our new sample will provide improved statistics for such key quantities as the binary fraction and the field substellar mass function. Furthermor...

  13. A Cross-Match of 2MASS and SDSS: Newly-Found L and T Dwarfs and an Estimate of the Space Densitfy of T Dwarfs

    CERN Document Server

    Metchev, Stanimir; Berriman, G Bruce; Looper, Dagny

    2007-01-01

    We report new L and T dwarfs found in a cross-match of the SDSS Data Release 1 and 2MASS. Our simultaneous search of the two databases effectively allows us to relax the criteria for object detection in either survey and to explore the combined databases to a greater completeness level. We find two new T dwarfs in addition to the 13 already known in the SDSS DR1 footprint. We also identify 22 new candidate and bona-fide L dwarfs, including a new young L2 dwarf and a peculiar L2 dwarf with unusually blue near-IR colors: potentially the result of mildly sub-solar metallicity. These discoveries underscore the utility of simultaneous database cross-correlation in searching for rare objects. Our cross-match completes the census of T dwarfs within the joint SDSS and 2MASS flux limits to the 97% level. Hence, we are able to accurately infer the space density of T dwarfs. We employ Monte Carlo tools to simulate the observed population of SDSS DR1 T dwarfs with 2MASS counterparts and find that the space density of T0-...

  14. The SW Sex-type star 2MASS J01074282+4845188: an unusual bright accretion disk with non-steady emission and a hot white dwarf

    CERN Document Server

    Khruzina, T; Kjurkchieva, D; 10.1051/0004-6361/201220385

    2013-01-01

    We present new photometric and spectral observations of the newly discovered nova-like eclipsing star 2MASS J01074282+4845188. To obtain a light curve solution we used model of a nova-like star whose emission sources are a white dwarf surrounded by an accretion disk, a secondary star filling its Roche lobe, a hot spot and a hot line. 2MASS J01074282+4845188 shows the deepest permanent eclipse among the known nova-like stars. It is reproduced by covering the very bright accretion disk by the secondary component. The luminosity of the disk is much bigger than that of the rest light sources. The determined high temperature of the disk is typical for that observed during the outbursts of CVs. The primary of 2MASS J01074282+4845188 is one of the hottest white dwarfs in CVs. The temperature of 5090 K of its secondary is also quite high and more appropriate for a long-period SW Sex star. It might be explained by the intense heating from the hot white dwarf and the hot accretion disk of the target. The high mass accr...

  15. Motion Verified Red Stars (MoVeRS): A Catalog of Proper Motion Selected Low-mass Stars from WISE, SDSS, and 2MASS

    CERN Document Server

    Theissen, Christopher A; Dhital, Saurav

    2015-01-01

    We present a photometric catalog of 8,735,004 proper motion selected low-mass stars (KML-spectral types) within the Sloan Digital Sky Survey (SDSS) footprint, from the combined SDSS Data Release 10 (DR10), Two-Micron All-Sky Survey (2MASS) Point Source Catalog (PSC), and Wide-field Infrared Survey Explorer (WISE) AllWISE catalog. Stars were selected using $r-i$, $i-z$, $r-z$, $z-J$, and $z-W1$ colors, and SDSS, WISE, and 2MASS astrometry was combined to compute proper motions. The resulting 3,518,150 stars were augmented with proper motions for 5,216,854 earlier type stars from the combined SDSS and United States Naval Observatory B1.0 catalog (USNO-B). We used SDSS+USNO-B proper motions to determine the best criteria for selecting a clean sample of stars. Only stars whose proper motions were greater than their $2$$\\sigma$ uncertainty were included. Our Motion Verified Red Stars (MoVeRS) catalog is available through SDSS CasJobs and VizieR.

  16. Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS

    CERN Document Server

    Covey, Kevin R; Schlegel, David J; Finkbeiner, Douglas P; Padmanabhan, Nikhil; Lupton, Robert H; Agüeros, Marcel A; Bochanski, John J; Hawley, Suzanne L; West, Andrew A; Seth, Anil C; Kimball, Amy E; Gogarten, Stephanie M; Claire, Mark; Haggard, Daryl; Kaib, Nathan A; Schneider, Donald P; Sesar, Branimir

    2007-01-01

    The Sloan Digital Sky Survey (SDSS) and Two Micron All Sky Survey (2MASS) are rich resources for studying stellar astrophysics and the structure and formation history of the Galaxy. As new surveys and instruments adopt similar filter sets, it is increasingly important to understand the properties of the ugrizJHKs stellar locus, both to inform studies of `normal' main sequence stars as well as for robust searches for point sources with unusual colors. Using a sample of ~600,000 point sources detected by SDSS and 2MASS, we tabulate the position and width of the ugrizJHKs stellar locus as a function of g-i color, and provide accurate polynomial fits. We map the Morgan-Keenan spectral type sequence to the median stellar locus by using synthetic photometry of spectral standards and by analyzing 3000 SDSS stellar spectra with a custom spectral typing pipeline. We develop an algorithm to calculate a point source's minimum separation from the stellar locus in a seven-dimensional color space, and use it to robustly id...

  17. MOTION VERIFIED RED STARS (MoVeRS): A CATALOG OF PROPER MOTION SELECTED LOW-MASS STARS FROM WISE, SDSS, AND 2MASS

    Energy Technology Data Exchange (ETDEWEB)

    Theissen, Christopher A.; West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Dhital, Saurav, E-mail: ctheisse@bu.edu [Department of Physical Sciences, Embry-Riddle Aeronautical University, 600 South Clyde Morris Blvd., Daytona Beach, FL 32114 (United States)

    2016-02-15

    We present a photometric catalog of 8,735,004 proper motion selected low-mass stars (KML-spectral types) within the Sloan Digital Sky Survey (SDSS) footprint, from the combined SDSS Data Release 10 (DR10), Two Micron All-Sky Survey (2MASS) point-source catalog (PSC), and Wide-field Infrared Survey Explorer (WISE) AllWISE catalog. Stars were selected using r − i, i − z, r − z, z − J, and z − W1 colors, and SDSS, WISE, and 2MASS astrometry was combined to compute proper motions. The resulting 3,518,150 stars were augmented with proper motions for 5,216,854 earlier type stars from the combined SDSS and United States Naval Observatory B1.0 catalog (USNO-B). We used SDSS+USNO-B proper motions to determine the best criteria for selecting a clean sample of stars. Only stars whose proper motions were greater than their 2σ uncertainty were included. Our Motion Verified Red Stars catalog is available through SDSS CasJobs and VizieR.

  18. The VMC survey -IX. Pilot study of the proper motion of stellar populations in the LMC from 2MASS and VISTA data

    CERN Document Server

    Cioni, M -R L; Moretti, M I; Piffl, T; Ripepi, V; Rubele, S; Scholz, R -D; Bekki, K; Clementini, G; Ivanov, V D; Oliveira, J M; van Loon, J Th

    2013-01-01

    We use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motion of stars of the LMC, in one tile of 1.5 deg^2 centred at (alpha, delta) = (05:59:23.136, -66:20:28.68) and including the South Ecliptic Pole, with respect to their 2MASS position over a time baseline of ~10 years and from VMC observations only, spanning a time range of ~1 year. Stars of different ages are selected from the (J-Ks) vs. Ks diagram and their average coordinate displacement is computed from the difference between Ks band observations for stars as faint as Ks=19 mag. Proper motions are derived by averaging up to seven 2MASS-VMC combinations in the first case and from the slope of the best fit line among the seven VMC epochs in the second case. Separate proper motion values are obtained for variable stars in the field. The proper motion of ~40,000 LMC stars in the tile, with respect to ~8000 background galaxies, obtained from VMC data alone, is mu_alpha cos(delta) = +...

  19. Deep 2MASS Photometry of M67 and Calibration of the Main Sequence J-Ks Color Difference as an Age Indicator

    CERN Document Server

    Sarajedini, Ata; Kirkpatrick, Allison

    2009-01-01

    We present an analysis of Two Micron All Sky Survey (2MASS) calibration photometry of the old open cluster M67 (NGC 2682). The proper motion-cleaned color-magnitude diagram (CMD) resulting from these data extends ~3 magnitudes deeper than one based on data from the point source catalog. The CMD extends from above the helium-burning red clump to a faint limit that is more than 7 magnitudes below the main sequence turnoff in the Ks band. After adopting a reddening of E(B-V) = 0.041 +/- 0.004 and a metal abundance of [Fe/H] = -0.009 +/- 0.009 based on a survey of published values, we fit the unevolved main sequence of M67 to field main sequence stars with 2MASS photometry and Hipparcos parallaxes. This analysis yields distance moduli of (m-M)Ks = 9.72 +/- 0.05 and (m-M)o = 9.70 +/- 0.05, which are consistent with published values. We compare the theoretical isochrones of Girardi et al. and Dotter et al. to the CMD of M67 and comment on the relative merits of each set of models. These comparisons suggest an age b...

  20. Astronomical Surveys and Big Data

    CERN Document Server

    Mickaelian, A M

    2015-01-01

    Recent all-sky and large-area astronomical surveys and their catalogued data over the whole range of electromagnetic spectrum are reviewed, from Gamma-ray to radio, such as Fermi-GLAST and INTEGRAL in Gamma-ray, ROSAT, XMM and Chandra in X-ray, GALEX in UV, SDSS and several POSS I and II based catalogues (APM, MAPS, USNO, GSC) in optical range, 2MASS in NIR, WISE and AKARI IRC in MIR, IRAS and AKARI FIS in FIR, NVSS and FIRST in radio and many others, as well as most important surveys giving optical images (DSS I and II, SDSS, etc.), proper motions (Tycho, USNO, Gaia), variability (GCVS, NSVS, ASAS, Catalina, Pan-STARRS) and spectroscopic data (FBS, SBS, Case, HQS, HES, SDSS, CALIFA, GAMA). An overall understanding of the coverage along the whole wavelength range and comparisons between various surveys are given: galaxy redshift surveys, QSO/AGN, radio, Galactic structure, and Dark Energy surveys. Astronomy has entered the Big Data era. Astrophysical Virtual Observatories and Computational Astrophysics play a...

  1. Type 1 low z AGN. I. Emission properties

    CERN Document Server

    Stern, Jonathan

    2012-01-01

    We analyze the emission properties of a new sample of 3,579 type 1 AGN, selected from the SDSS DR7 based on the detection of broad H-alpha emission. The sample extends over a broad H-alpha luminosity L_bHa of 10^40 - 10^44 erg s^-1 and a broad H-alpha FWHM of 1,000 - 25,000 km s^-1, which covers the range of black hole mass 10^6ROSAT, GALEX and 2MASS observations to form the SED from 2.2 mic to 2 keV. We find the following: 1. The distribution of the H-alpha FWHM values is independent of luminosity. 2. The observed mean optical-UV SED is well matched by a fixed shape SED of luminous quasars, which scales linearly with L_bHa, and a host galaxy contribution. 3. The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission line galaxies (NEG), consistent with a fixed fraction of ~3% of NEG hosting an AGN, regardless of the host luminosity. 4. The hosts of lower lumin...

  2. Astronomical Surveys, Catalogs, Databases, and Archives

    Science.gov (United States)

    Mickaelian, A. M.

    2016-06-01

    All-sky and large-area astronomical surveys and their cataloged data over the whole range of electromagnetic spectrum are reviewed, from γ-ray to radio, such as Fermi-GLAST and INTEGRAL in γ-ray, ROSAT, XMM and Chandra in X-ray, GALEX in UV, SDSS and several POSS I and II based catalogues (APM, MAPS, USNO, GSC) in optical range, 2MASS in NIR, WISE and AKARI IRC in MIR, IRAS and AKARI FIS in FIR, NVSS and FIRST in radio and many others, as well as most important surveys giving optical images (DSS I and II, SDSS, etc.), proper motions (Tycho, USNO, Gaia), variability (GCVS, NSVS, ASAS, Catalina, Pan-STARRS) and spectroscopic data (FBS, SBS, Case, HQS, HES, SDSS, CALIFA, GAMA). Most important astronomical databases and archives are reviewed as well, including Wide-Field Plate DataBase (WFPDB), ESO, HEASARC, IRSA and MAST archives, CDS SIMBAD, VizieR and Aladin, NED and HyperLEDA extragalactic databases, ADS and astro-ph services. They are powerful sources for many-sided efficient research using Virtual Observatory tools. Using and analysis of Big Data accumulated in astronomy lead to many new discoveries.

  3. A comprehensive study of the young open star cluster NGC 6611 based on deep VRI CCD images and 2MASS data

    Directory of Open Access Journals (Sweden)

    I.M. Selim

    2016-06-01

    Full Text Available In the present study, we have used Deep CCD images of the extremely young open star cluster NGC 6611, up to a limiting magnitude of V ∼ 22.86 mag in V, R and I passbands. The resulting color-magnitude V; (V–I diagram as well as their radial density profiles has been determined. Using 2MASS data, we confirmed the consistency between the 2MASS photometry, by fitting isochrones, the extinction E(V–I = 0.530 ± 0.04 mag, E(J–H = 0.31 ± 0.02, from the color magnitude diagram the cluster distance =2.2 ± 0.21 kpc and age = 3.6 Myr, based on the fitting of theoretical stellar isochrones of solar metallicity Z = 0.019. The distance modulus of the cluster is estimated at 12.3. The radial stellar density profiles and the cluster center have been determined by two methods. The core and cluster radii are determined from the radial stellar density profiles. Only about 40% of the cluster members are present in the core region. The cluster luminosity function has been calculated. The mass function slope of the entire cluster is ∼−0.67 ± 0.12. The effects of mass segregation, most probably due to dynamical evolution, have been observed in the cluster.

  4. Swift UV and X-rays from TCP J05002724+1334199 / CSS J050027.2+133420

    Science.gov (United States)

    Kuulkers, E.; Page, K. L.; Osborne, J. P.

    2015-12-01

    TCP J05002724+1334199 (or CSS J050027.2+133420) was discovered on UT 28 Nov 2015 13:22, at an optical magnitude of ~12.3. This source is coincident with a known ROSAT X-ray source, 1RXS J050027.7+133415 (as well as SDSS J050027.24+133419.9, GALEX J050027.2+133420).

  5. MULTI-WAVELENGTH CHARACTERIZATION OF STELLAR FLARES ON LOW-MASS STARS USING SDSS AND 2MASS TIME-DOMAIN SURVEYS

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, James R. A.; Becker, Andrew C.; Kowalski, Adam F.; Hawley, Suzanne L.; Schmidt, Sarah J.; Hilton, Eric J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Cutri, Roc, E-mail: jrad@astro.washington.edu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2012-03-20

    We present the first rates of flares from M dwarf stars in both red optical and near-infrared (NIR) filters. We have studied {approx}50,000 M dwarfs from the Sloan Digital Sky Survey (SDSS) Stripe 82 area and 1321 M dwarfs from the Two Micron All Sky Survey (2MASS) Calibration Scan Point Source Working Database that overlap SDSS imaging fields. We assign photometric spectral types from M0 to M6 using (r - i) and (i - z) colors for every star in our sample. Stripe 82 stars each have 50-100 epochs of data, while 2MASS Calibration stars have {approx}1900 epochs. From these data we estimate the observed rates and theoretical detection thresholds for flares in eight photometric bands as a function of spectral type. Optical flare rates are found to be in agreement with previous studies, while the frequency per hour of NIR flare detections is found to be more than two orders of magnitude lower. An excess of small-amplitude flux increases in all bands exhibits a power-law distribution, which we interpret as the result of flares below our detection thresholds. In order to investigate the recovery efficiency for flares in each filter, we extend a two-component flare model into the NIR. Quiescent M0-M6 spectral templates were used with the model to predict the photometric response of flares from u to K{sub s} . We determine that red optical filters are sensitive to flares with u-band amplitudes {approx}>2 mag, and NIR filters to flares with {Delta}u {approx}> 4.5 mag. Our model predicts that M0 stars have the best color contrast for J-band detections, but M4-M6 stars should yield the highest rate of NIR flares with amplitudes of {Delta}J {>=} 0.01 mag. Characterizing flare rates and photometric variations at longer wavelengths is important for predicting the signatures of M dwarf variability in next-generation surveys, and we discuss their impact on surveys such as the Large Synoptic Survey Telescope.

  6. Effect of planet ingestion on low-mass stars evolution: the case of 2MASS J08095427--4721419 star in the Gamma Velorum cluster

    CERN Document Server

    Tognelli, E; Degl'Innocenti, S

    2016-01-01

    We analysed the effects of planet ingestion on the characteristics of a pre-MS star similar to the Gamma Velorum cluster member 2MASS J08095427--4721419 (#52). We discussed the effects of changing the age $t_0$ at which the accretion episode occurs, the mass of the ingested planet and its chemical composition. We showed that the mass of the ingested planet required to explain the current [Fe/H]^#52 increases by decreasing the age $t_0$ and/or by decreasing the Iron content of the accreted matter. We compared the predictions of a simplified accretion method -- where only the variation of the surface chemical composition is considered -- with that of a full accretion model that properly accounts for the modification of the stellar structure. We showed that the two approaches result in different convective envelope extension which can vary up to 10 percent. We discussed the impact of the planet ingestion on a stellar model in the colour-magnitude diagram, showing that a maximum shift of about 0.06 dex in the col...

  7. Keck Laser Guide Star Adaptive Optics Monitoring of 2MASS J1534-2952AB: First Dynamical Mass Determination of a Binary T Dwarf

    CERN Document Server

    Liu, Michael C; Ireland, Michael J

    2008-01-01

    (Abridged) We present multi-epoch imaging of the T5.0+T5.5 binary 2MASS J1534-2952AB obtained with the Keck laser guide star adaptive optics system. Combined with an extensive (re-)analysis of archival HST imaging, we find a total mass of 0.056+/-0.003 Msun (59+/-3 Mjup). This is the first field binary for which both components are directly confirmed to be substellar. This is also the coolest and lowest mass binary with a dynamical mass determination to date. Using evolutionary models, we derive an age of 0.78+/-0.09 Gyr for the system, and we find Teff = 1028+/-17 K and 978+/-17 K and masses of 0.0287+/-0.0016 Msun (30.1+/-1.7 Mjup) and 0.0269+/-0.0016 Msun (28.2+/-1.7 Mjup) for the individual components. These precise measurements generally agree with previous studies of T dwarfs and affirm the current theoretical models. However, (1) the temperatures are about 100 K cooler than derived for similar objects and suggest that the ages of field brown dwarfs may be overestimated. Also, (2) the H-R diagram positi...

  8. A Search for Correlation of Ultra-High Energy Cosmic Rays with IRAS-PSCz and 2MASS-6dF Galaxies

    CERN Document Server

    Oikonomou, Foteini; Abdalla, Filipe B; Lahav, Ofer; Thomas, Shaun A; Waters, David; Waxman, Eli

    2014-01-01

    We study the arrival directions of 69 ultra-high energy cosmic rays (UHECRs) observed at the Pierre Auger Observatory (PAO) with energies exceeding 55 EeV. We investigate whether the UHECRs exhibit the anisotropy signal expected if the primary particles are protons that originate in galaxies in the local universe, or in sources correlated with these galaxies. We cross-correlate the UHECR angular positions with the positions of IRAS-PSCz and 2MASS-6dF galaxies (with median depth of 120 and 225 Mpc respectively) weighted for GZK and other particle propagation effects. This is the first time that the 6dF survey is used for a study of this type and the first time that the PSCz survey is used with the full 69 publicly released PAO events. We find the probability that the observed UHECR events are consistent with an isotropic hypothesis to be less than 5% for most of the parameter space considered. The observed correlation is consistent with the mean of the model distribution of UHECRs associated with PSCz and 6dF ...

  9. Effect of planet ingestion on low-mass stars evolution: the case of 2MASS J08095427-4721419 star in the Gamma Velorum cluster

    Science.gov (United States)

    Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

    2016-08-01

    We analysed the effects of planet ingestion on the characteristics of a pre-main-sequence star similar to the Gamma Velorum cluster member 2MASS J08095427-4721419 (#52). We discussed the effects of changing the age t0 at which the accretion episode occurs, the mass of the ingested planet and its chemical composition. We showed that the mass of the ingested planet required to explain the current [Fe/H]^{#52} increases by decreasing the age t0 and/or by decreasing the iron content of the accreted matter. We compared the predictions of a simplified accretion method - where only the variation of the surface chemical composition is considered - with that of a full accretion model that properly accounts for the modification of the stellar structure. We showed that the two approaches result in different convective envelope extension which can vary up to 10 per cent. We discussed the impact of the planet ingestion on a stellar model in the colour-magnitude diagram, showing that a maximum shift of about 0.06 dex in the colour and 0.07 dex in magnitude are expected and that such variations persist even much later the accretion episode. We also analysed the systematic bias in the stellar mass and age inferred by using a grid of standard non-accreting models to recover the characteristics of an accreting star. We found that standard non-accreting models can safely be adopted for mass estimate, as the bias is ≲ 6 per cent, while much more caution should be used for age estimate where the differences can reach about 60 per cent.

  10. A search for correlation of ultra-high energy cosmic rays with IRAS-PSCz and 2MASS-6dF galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Oikonomou, Foteini; Abdalla, Filipe B.; Lahav, Ofer; Thomas, Shaun A. [Astrophysics Group, Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Connolly, Amy [Department of Physics and CCAPP, The Ohio State University, 191 West Woodruff Avenue, Colombus, Ohio 43210 (United States); Waters, David [High Energy Physics Group, Department of Physics and Astronomy, University College London (United Kingdom); Waxman, Eli, E-mail: fotini@star.ucl.ac.uk, E-mail: connolly@physics.osu.edu, E-mail: fba@star.ucl.ac.uk, E-mail: o.lahav@ucl.ac.uk, E-mail: sat@star.ucl.ac.uk, E-mail: d.waters@ucl.ac.uk, E-mail: eli.waxman@weizmann.ac.il [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2013-05-01

    We study the arrival directions of 69 ultra-high energy cosmic rays (UHECRs) observed at the Pierre Auger Observatory (PAO) with energies exceeding 55 EeV. We investigate whether the UHECRs exhibit the anisotropy signal expected if the primary particles are protons that originate in galaxies in the local universe, or in sources correlated with these galaxies. We cross-correlate the UHECR arrival directions with the positions of IRAS-PSCz and 2MASS-6dF galaxies taking into account particle energy losses during propagation. This is the first time that the 6dF survey is used in a search for the sources of UHECRs and the first time that the PSCz survey is used with the full 69 PAO events. The observed cross-correlation signal is larger for the PAO UHECRs than for 94% (98%) of realisations from an isotropic distribution when cross-correlated with the PSCz (6dF). On the other hand the observed cross-correlation signal is lower than that expected from ∼>85% of realisations, had the UHECRs originated in galaxies in either survey. The observed cross-correlation signal does exceed that expected by 50% of the realisations if the UHECRs are randomly deflected by intervening magnetic fields by 5° or more. We propose a new method of analysing the expected anisotropy signal, by dividing the predicted UHECR source distribution into equal predicted flux radial shells, which can help localise and constrain the properties of UHECR sources. We find that the 69 PAO events are consistent with isotropy in the nearest of three shells we define, whereas there is weak evidence for correlation with the predicted source distribution in the two more distant shells in which the galaxy distribution is less anisotropic.

  11. Constraining the mass of the planet(s) sculpting a disk cavity. The intriguing case of 2MASS J16042165-2130284

    Science.gov (United States)

    Canovas, H.; Hardy, A.; Zurlo, A.; Wahhaj, Z.; Schreiber, M. R.; Vigan, A.; Villaver, E.; Olofsson, J.; Meeus, G.; Ménard, F.; Caceres, C.; Cieza, L. A.; Garufi, A.

    2017-01-01

    Context. The large cavities observed in the dust and gas distributions of transition disks may be explained by planet-disk interactions. At 145 pc, 2MASS J16042165-2130284 (J1604) is a 5-12 Myr old transitional disk with different gap sizes in the mm- and μm-sized dust distributions (outer edges at 79 and at 63 au, respectively). Its 12CO emission shows a 30 au cavity. This radial structure suggests that giant planets are sculpting this disk. Aims: We aim to constrain the masses and locations of plausible giant planets around J1604. Methods: We observed J1604 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) at the Very Large Telescope (VLT), in IRDIFS_EXT, pupil-stabilized mode, obtaining YJH-band images with the integral field spectrograph (IFS) and K1K2-band images with the Infra-Red Dual-beam Imager and Spectrograph (IRDIS). The dataset was processed exploiting the angular differential imaging (ADI) technique with high-contrast algorithms. Results: Our observations reach a contrast of ΔK,ΔYH 12 mag from 0".15 to 0".80 ( 22 to 115 au), but no planet candidate is detected. The disk is directly imaged in scattered light at all bands from Y to K, and it shows a red color. This indicates that the dust particles in the disk surface are mainly ≳0.3 μm-sized grains. We confirm the sharp dip/decrement in scattered light in agreement with polarized light observations. Comparing our images with a radiative transfer model we argue that the southern side of the disk is most likely the nearest. Conclusions: This work represents the deepest search yet for companions around J1604. We reach a mass sensitivity of ≳2-3 MJup from 22 to 115 au according to a hot start scenario. We propose that a brown dwarf orbiting inside of 15 au and additional Jovian planets at larger radii could account for the observed properties of J1604 while explaining our lack of detection. Based on observations made with the VLT, program 095.C-0673(A).The reduced images (FITS

  12. Five-minute grid of the total marine bird biomass densities surveyed off central California - selected neutral water temperature periods, 1980-2001 (CDAS data set AL2_MASS.shp)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — AL2_MASS is a polygon shapefile representing 5 minute x 5 minute latitude x longitude cells that house the overall total biomass densities (kg/sq.km.) of up to 76...

  13. A Stellar Population Synthesis Model for the Study of Ultraviolet Star Counts of the Galaxy

    CERN Document Server

    Pradhan, Ananta C; Robin, A C; Ghosh, S K; Vickers, John J

    2014-01-01

    GALEX, the first all sky imaging UV satellite, has imaged a large part of the sky providing an excellent opportunity for studying UV star counts. The aim of our study is to investigate in detail the observed UV star counts obtained by GALEX vis-a-vis the model simulated catalogs produced by the Besancon model of stellar population synthesis in various Galactic directions, and to explore the potential for studying the structure of our Galaxy from images in multiple NUV and FUV filters of the forthcoming Ultraviolet Imaging Telescope (UVIT) to be flown onboard ASTROSAT. We have upgraded the Besancon model of stellar population synthesis to include the UV bands of GALEX and UVIT. Depending on the availability of contiguous GALEX, SDSS, WISE and 2MASS overlapping regions, we have chosen a set of 19 GALEX fields which spread over a range of Galactic directions. We cross-matched GALEX sources with the WISE+2MASS and SDSS catalogs and UV stars in the GALEX catalog are identified by choosing a suitable IR colour, J -...

  14. Cluster Evolution in the Wide Angle ROSAT Pointed Survey (WARPS)

    CERN Document Server

    Schärf, C A; Perlman, E S; Ebeling, H; Wegner, G; Malkan, M A; Horner, D

    1998-01-01

    A new flux limited catalogue of low luminosity (Lx 0.3). The results are consistent with an unevolving population which does not exhibit the evolution seen in the higher luminosity cluster population. These observations can be qualitatively described by self-similarly evolving dark matter and preheated IGM models of X-ray cluster gas, with a power law index for the spectrum of matter density fluctuations n >= -1.

  15. Rotation Periods of Nine ROSAT Selected Solar-Type Stars

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We monitored 16 X-ray selected young solar-type stars for light variation and found appreciable periodic light variability with amplitudes of a few hundredths of a magnitude in nine of the objects. Using the method of Phase Dispersion Minimization (PDM) and Fourier analysis (software PERIOD04), the rotation periods of these stars were determined from the photometric data. The rotation periods of all nine stars are shorter than about 3 days.It is suggested that, as with the Pleiades cluster, small amplitude light variations are quite common among young solar-type stars with rotation periods around 3 days or less. This gives further evidence for the spin up of solar-type stars predicted by models of angular momentum evolution of pre-main sequence stars.

  16. The Late-Type Extension to MoVeRS (LaTE-MoVeRS): Proper Motion Verified Low-mass Stars and Brown Dwarfs from SDSS, 2MASS, and WISE

    Science.gov (United States)

    Theissen, Christopher A.; West, Andrew A.; Shippee, Guillaume; Burgasser, Adam J.; Schmidt, Sarah J.

    2017-03-01

    We present the Late-Type Extension to the Motion Verified Red Stars (LaTE-MoVeRS) catalog, containing 46,463 photometric late-type (>M5) dwarfs within the Sloan Digital Sky Survey (SDSS) footprint. Proper motions were computed for objects combining astrometry from the SDSS Data Release 12 (DR12), the Two-micron All-Sky Survey (2MASS) Point Source Catalog, and the Wide-field Infrared Survey Explorer (WISE) AllWISE data sets. LaTE-MoVeRS objects were required to have significant proper motion ({μ }{tot}≥slant 2{σ }{μ {tot}}). Using the LaTE-MoVeRS sample and Gaia Data Release 1, we estimate Gaia will be ∼64% complete for very low-mass objects (>M5) in comparison to the combined SDSS+2MASS+WISE data set (iSDSS CasJobs and VizieR.

  17. Interstellar Extinction Law toward the Galactic Center III: J, H, Ks bands in the 2MASS and the MKO systems, and 3.6, 4.5, 5.8, 8.0 micron in the Spitzer/IRAC system

    CERN Document Server

    Nishiyama, Shogo; Hatano, Hirofumi; Kato, Daisuke; Tanabe, Toshihiko; Sugitani, Koji; Nagata, Tetsuya

    2009-01-01

    We have determined interstellar extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 micron, using point sources detected in the IRSF/SIRIUS near-infrared survey and those in the 2MASS and Spitzer/IRAC/GLIMPSE II catalogs. The central region |l| 3 micron from a simple extrapolation of the power-law extinction at shorter wavelengths, in accordance with recent studies. The extinction law in the 2MASS JHKs bands has also been calculated, and a good agreement with that in the MKO system is found. In nearby molecular clouds and diffuse interstellar medium, the lack of reliable measurements of the total to selective extinction ratios hampers unambiguous determination of the extinction law; however, observational results toward these lines of sight cannot be reconciled with a single extinction law.

  18. Eight genetic loci associated with variation in lipoprotein-associated phospholipase A2 mass and activity and coronary heart disease: meta-analysis of genome-wide association studies from five community-based studies

    Science.gov (United States)

    Grallert, Harald; Dupuis, Josée; Bis, Joshua C.; Dehghan, Abbas; Barbalic, Maja; Baumert, Jens; Lu, Chen; Smith, Nicholas L.; Uitterlinden, André G.; Roberts, Robert; Khuseyinova, Natalie; Schnabel, Renate B.; Rice, Kenneth M.; Rivadeneira, Fernando; Hoogeveen, Ron C.; Fontes, João Daniel; Meisinger, Christa; Keaney, John F.; Lemaitre, Rozenn; Aulchenko, Yurii S.; Vasan, Ramachandran S.; Ellis, Stephen; Hazen, Stanley L.; van Duijn, Cornelia M.; Nelson, Jeanenne J.; März, Winfried; Schunkert, Heribert; McPherson, Ruth M.; Stirnadel-Farrant, Heide A.; Psaty, Bruce M.; Gieger, Christian; Siscovick, David; Hofman, Albert; Illig, Thomas; Cushman, Mary; Yamamoto, Jennifer F.; Rotter, Jerome I.; Larson, Martin G.; Stewart, Alexandre F.R.; Boerwinkle, Eric; Witteman, Jacqueline C.M.; Tracy, Russell P.; Koenig, Wolfgang; Benjamin, Emelia J.; Ballantyne, Christie M.

    2012-01-01

    Aims Lipoprotein-associated phospholipase A2 (Lp-PLA2) generates proinflammatory and proatherogenic compounds in the arterial vascular wall and is a potential therapeutic target in coronary heart disease (CHD). We searched for genetic loci related to Lp-PLA2 mass or activity by a genome-wide association study as part of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. Methods and results In meta-analyses of findings from five population-based studies, comprising 13 664 subjects, variants at two loci (PLA2G7, CETP) were associated with Lp-PLA2 mass. The strongest signal was at rs1805017 in PLA2G7 [P = 2.4 × 10−23, log Lp-PLA2 difference per allele (beta): 0.043]. Variants at six loci were associated with Lp-PLA2 activity (PLA2G7, APOC1, CELSR2, LDL, ZNF259, SCARB1), among which the strongest signals were at rs4420638, near the APOE–APOC1–APOC4–APOC2 cluster [P = 4.9 × 10−30; log Lp-PLA2 difference per allele (beta): −0.054]. There were no significant gene–environment interactions between these eight polymorphisms associated with Lp-PLA2 mass or activity and age, sex, body mass index, or smoking status. Four of the polymorphisms (in APOC1, CELSR2, SCARB1, ZNF259), but not PLA2G7, were significantly associated with CHD in a second study. Conclusion Levels of Lp-PLA2 mass and activity were associated with PLA2G7, the gene coding for this protein. Lipoprotein-associated phospholipase A2 activity was also strongly associated with genetic variants related to low-density lipoprotein cholesterol levels. PMID:22003152

  19. Research of CO2 mass transfer in direct methanol fuel cell%直接甲醇燃料电池中CO2传质的研究

    Institute of Scientific and Technical Information of China (English)

    胡青青; 倪红军; 李志扬; 汪兴兴

    2011-01-01

    In order to promote the effective mass transfer of CO2 in direct methanol fuel cell (DMFC) and improve the performance of DMFC, in this paper, the application prospects and the present problems of DMFC were summarized, the operation principle was simply introduced, the mass transfer mecharism of CO2 in the DMFC electrolyte was analyzed and the impact factors were illustrated. The previous study on the status of CO2 mass transfer was introduced, and a ne vision for CO2 mass transfer was brought forward.%为了促进直接甲醇燃科电池(DMFC)中CO2的有效传质,从而提高其性能,综述了DMFC的应用前景及面临的问题,简单介绍了DMFC工作的原理,分析了DMFC中CO2的传质机理并进一步阐述了其影响因素,介绍了前人对CO2传质研究的现状,并在此基础上提出了研究CO2的新设想.

  20. Analysis of the Effect of the CaCl2 Mass Fraction on the Efficiency of a Heat Pump Integrated Heat-Source Tower Using an Artificial Neural Network Model

    Directory of Open Access Journals (Sweden)

    Xiaoqing Wei

    2016-04-01

    Full Text Available An existing idle cooling tower can be reversibly used as a heat-source tower (HST to drive a heat pump (HP in cold seasons, with calcium chloride (CaCl2 aqueous solution commonly selected as the secondary working fluid in an indirect system due to its good thermo-physical properties. This study analyzed the effect of CaCl2 mass fraction on the effectiveness (ε of a closed HST and the coefficient of performance (COP of a HP heating system using an artificial neural network (ANN technique. CaCl2 aqueous solutions with five different mass fractions, viz. 3%, 9%, 15%, 21%, and 27%, were chosen as the secondary working fluids for the HSTHP heating system. In order to collect enough measured data, extensive field tests were conducted on an experimental test rig in Changsha, China which experiences hot summer and cold winter weather. After back-propagation (BP training, the three-layer (4-9-2 ANN model with a tangent sigmoid transfer function at the hidden layer and a linear transfer function at the output layer was developed for predicting the tower effectiveness and the COP of the HP under different inlet air dry-/wet-bulb temperatures, hot water inlet temperatures and CaCl2 mass fractions. The correlation coefficient (R, mean relative error (MRE and root mean squared error (RMSE were adopted to evaluate the prediction accuracy of the ANN model. The results showed that the R, MRE, and RMSE between the training values and the experimental values of ε (COP were 0.995 (0.996, 2.09% (1.89%, and 0.005 (0.060, respectively, which indicated that the ANN model was reliable and robust in predicting the performance of the HP. The findings of this paper indicated that in order to guarantee normal operation of the system, the freezing point temperature of the CaCl2 aqueous solution should be sufficiently (3–5 K below its lowest operating temperature or lower than the normal operating temperature by about 10 K. The tower effectiveness increased with

  1. Planets Around Low-Mass Stars (PALMS). VI. Discovery of a Remarkably Red Planetary-Mass Companion to the AB Dor Moving Group Candidate 2MASS J22362452+4751425

    CERN Document Server

    Bowler, Brendan; Mawet, Dimitri; Ngo, Henry; Malo, Lison; Mace, Gregory; McLane, Jacob; Lu, Jessica; Tristan, Isaiah; Hinkley, Sasha; Hillenbrand, Lynne; Shkolnik, Evgenya; Benneke, Bjorn; Best, William

    2016-01-01

    We report the discovery of an extremely red planetary-mass companion to 2MASS J22362452+4751425, a $\\approx$0.6 $M_{\\odot}$ late-K dwarf likely belonging to the $\\sim$120 Myr AB Doradus moving group. 2M2236+4751 b was identified in multi-epoch NIRC2 adaptive optics imaging at Keck Observatory at a separation of 3.7$"$, or 230 $\\pm$ 20 AU in projection at the kinematic distance of 63 $\\pm$ 5 pc to its host star. Assuming membership in the AB Dor group, as suggested from its kinematics, the inferred mass of 2M2236+4751 b is 11-14 $M_\\mathrm{Jup}$. Follow-up Keck/OSIRIS $K$-band spectroscopy of the companion reveals strong CO absorption similar to other faint red L dwarfs and lacks signs of methane absorption despite having an effective temperature of $\\approx$900-1200 K. With a ($J$-$K$)$_\\mathrm{MKO}$ color of 2.69 $\\pm$ 0.12 mag, the near-infrared slope of 2M2236+4751 b is redder than all of the HR 8799 planets and instead resembles the $\\approx$23 Myr isolated planetary-mass object PSO J318.5-22, implying th...

  2. Planets around Low-mass Stars (PALMS). VI. Discovery of a Remarkably Red Planetary-mass Companion to the AB Dor Moving Group Candidate 2MASS J22362452+4751425*

    Science.gov (United States)

    Bowler, Brendan P.; Liu, Michael C.; Mawet, Dimitri; Ngo, Henry; Malo, Lison; Mace, Gregory N.; McLane, Jacob N.; Lu, Jessica R.; Tristan, Isaiah I.; Hinkley, Sasha; Hillenbrand, Lynne A.; Shkolnik, Evgenya L.; Benneke, Björn; Best, William M. J.

    2017-01-01

    We report the discovery of an extremely red planetary-mass companion to 2MASS J22362452+4751425, a ≈0.6 M⊙ late-K dwarf likely belonging to the ∼120 Myr AB Doradus moving group. 2M2236+4751 b was identified in multi-epoch NIRC2 adaptive optics imaging at Keck Observatory at a separation of 3\\buildrel{\\prime\\prime}\\over{.} 7, or 230 ± 20 AU in projection at the kinematic distance of 63 ± 5 pc to its host star. Assuming membership in the AB Dor group, as suggested from its kinematics, the inferred mass of 2M2236+4751 b is 11–14 MJup. Follow-up Keck/OSIRIS K-band spectroscopy of the companion reveals strong CO absorption similar to other faint red L dwarfs and lacks signs of methane absorption, despite having an effective temperature of ≈900–1200 K. With a (J–K)MKO color of 2.69 ± 0.12 mag, the near-infrared slope of 2M2236+4751 b is redder than all of the HR 8799 planets and instead resembles the ≈23 Myr isolated planetary-mass object PSO J318.5–22, implying that similarly thick photospheric clouds can persist in the atmospheres of giant planets at ages beyond 100 Myr. In near-infrared color–magnitude diagrams, 2M2236+4751 b is located at the tip of the red L dwarf sequence and appears to define the “elbow” of the AB Dor substellar isochrone separating low-gravity L dwarfs from the cooler young T dwarf track. 2M2236+4751 b is the reddest substellar companion to a star and will be a valuable benchmark to study the shared atmospheric properties of young low-mass brown dwarfs and extrasolar giant planets. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  3. Development of cryocooler-cooled solenoid magnet fabricated with Bi-2212 ROSAT wire; Bi-2212 ROSAT wire wo mochiita reitoki dendo reikyaku sorenoido magunetto no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Azuma, K.; Morita, H.; Hara, N.; Okada, M. [Hitachi Ltd., Tokyo (Japan); Sato, J. [Hitachi Cable Ltd., Tokyo (Japan); Kitaguchi, H.; Kumakura, H.; Togano, K. [National Research Inst. for Metals, Tokyo (Japan)

    1999-11-10

    The asymmetry for external magnetic field is a small wire rod, while Bi-2212 ROSATwire keeps the transport current characteristics which tape wire rod is excellent. And, the wind ability becomes good by choosing the round cross section, and it is a wire rod, which is suitable for solenoidal coil. At present, refrigerating machine conduction cooling type solenoid magnet, which can generate central magnetic field 8T using this wire rod is developed. This time, the internal layer coil was manufactured, and the excitation test was carried out by the cooling system for the test. (NEDO)

  4. Development of cryocooler-cooled solenoid magnet fabricated with Bi-2212 ROSAT wire (2); Bi-2212 ROSAT wire wo mochiita reitoki dendo reikyaku sorenoido magunetto no kaihatsu (2)

    Energy Technology Data Exchange (ETDEWEB)

    Morita, H.; Tanaka, K.; Hara, N. [Hitachi Ltd., Tokyo (JP)] [and others

    2000-05-29

    The asymmetry for external magnetic field is a small wire rod, while Bi-2212ROSATwire keeps the transport current characteristics which tape wire rod is excellent. And, the windability becomes good by choosing the round cross section, and it is goodwill wire rod in the solenoidal coil. At present, it develops refrigerating machine conduction cooling type solenoid magnet system using this wire rod. This time, it produced refrigerating machine conduction cooling system, which could install new internal layer coil using the wire rod improved and magnet of 3 layers. (NEDO)

  5. Galex and Optical Observations of GW Librae during the Long Decline from Superoutburst

    Science.gov (United States)

    Bullock, Eric; Szkody, Paula; Mukadam, Anjum S.; Borges, Bernardo W.; Fraga, Luciano; Gansicke, Boris T.; Harrison, Thomas E.; Henden, Arne; Holtzman, Jon; Howell, Steve B.; hide

    2011-01-01

    The prototype of accreting, pulsating white dwarfs (GW Lib) underwent a large amplitude dwarf nova outburst in 2007. We used ultraviolet data from Galaxy Evolution Explorer and ground-based optical photometry and spectroscopy to follow GW Lib for three years following this outburst. Several variations are apparent during this interval. The optical shows a superhump modulation in the months following outburst, while a 19 minute quasi-periodic modulation lasting for several months is apparent in the year after outburst. A long timescale (about 4 hr) modulation first appears in the UV a year after outburst and increases in amplitude in the following years. This variation also appears in the optical two years after outburst but is not in phase with the UV. The pre-outburst pulsations are not yet visible after three years, likely indicating the white dwarf has not returned to its quiescent state.

  6. A CATALOG OF GALEX ULTRAVIOLET EMISSION FROM SPECTROSCOPICALLY CONFIRMED M DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Jones, David O. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); West, Andrew A., E-mail: djones@pha.jhu.edu [Astronomy Department of Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)

    2016-01-20

    We present a catalog of Galaxy Evolution Explorer Near-UV (NUV) and Far-UV (FUV) photometry for the Palomar/MSU and SDSS DR7 spectroscopic M dwarf catalogs. The catalog contains NUV measurements matched to 577 spectroscopically confirmed M dwarfs and FUV measurements matched to 150 spectroscopically confirmed M dwarfs. Using these data, we find that NUV and FUV luminosities strongly correlate with Hα emission, a typical indicator of magnetic activity in M dwarfs. We also examine the fraction of M dwarfs with varying degrees of strong line emission at NUV wavelengths. Our results indicate that the frequency of M dwarf NUV emission peaks at intermediate spectral types, with at least ∼30% of young M4–M5 dwarfs having some level of activity. For mid-type M dwarfs, we show that NUV emission decreases with distance from the Galactic plane, a proxy for stellar age. Our complete matched source catalog is available online.

  7. Deep X-ray and UV Surveys of Galaxies with Chandra, XMM-Newton, and GALEX

    Science.gov (United States)

    Hornschemeier, Ann

    2006-01-01

    Only with the deepest Chandra surveys has X-ray emission from normal and star forming galaxies (as opposed to AGN, which dominate the X-ray sky) been accessible at cosmologically interesting distances. The X-ray emission from accreting binaries provide a critical glimpse into the binary phase of stellar evolution and studies of the hot gas reservoir constrain past star formation. UV studies provide important, sensitive diagnostics of the young star forming populations and provide the most mature means for studying galaxies at 2 luminosity function of galaxies and important constraints on star formation scaling relations such as the X-ray-Star Formation Rate correlation and the X-ray/Stellar Mass correlation. We will discuss what we learn from these deep observations of Coma, including the recently established suppression of the X-ray emission from galaxies in the Coma outskirts that is likely associated with lower levels of past star formation and/or the results of tidal gas stripping.

  8. The diffuse soft excess emission in the Coma cluster from the ROSAT All-Sky Survey

    CERN Document Server

    Bonamente, Max; Bulbul, Esra

    2009-01-01

    RASS data near the North Galactic Pole was analyzed in order to study the large-scale distribution of soft X-ray emission from the Coma cluster. These RASS data constitute the only available X-ray observations of Coma that feature an in situ -- temporally and spatially contiguous -- background, with unlimited and continuous radial coverage. These unique characteristics of the RASS data are used to deliver a final assessment on whether the soft excess previously detected in the Coma cluster is due to background subtraction errors, or not. This paper confirms the presence of soft X-ray excess associated with Coma, and reports the detection of 1/4 keV band excess out to 5 Mpc from the cluster center, the largest soft excess halo discovered to date. We propose that the emission is related to filaments that converge towards Coma, and generated either by non-thermal radiation caused by accretion shocks, or by thermal emission from the filaments themselves.

  9. The Brera Multi-scale Wavelet (BMW) ROSAT HRI source catalog; 1, the algorithm

    CERN Document Server

    Lazzati, D; Rosati, P; Panzera, M R; Tagliaferri, G; Lazzati, Davide; Campana, Sergio; Rosati, Piero; Panzera, Maria Rosa; Tagliaferri, Gianpiero

    1999-01-01

    We present a new detection algorithm based on the wavelet transform for the analysis of high energy astronomical images. The wavelet transform, due to its multi-scale structure, is suited for the optimal detection of point-like as well as extended sources, regardless of any loss of resolution with the off-axis angle. Sources are detected as significant enhancements in the wavelet space, after the subtraction of the non-flat components of the background. Detection thresholds are computed through Monte Carlo simulations in order to establish the expected number of spurious sources per field. The source characterization is performed through a multi-source fitting in the wavelet space. The procedure is designed to correctly deal with very crowded fields, allowing for the simultaneous characterization of nearby sources. To obtain a fast and reliable estimate of the source parameters and related errors, we apply a novel decimation technique which, taking into account the correlation properties of the wavelet transf...

  10. VizieR Online Data Catalog: The BMW-HRI source catalogue (Panzera+, 2003)

    Science.gov (United States)

    Panzera, M. R.; Campana, S.; Covino, S.; Lazzati, D.; Mignani, R. P.; Moretti, A.; Tagliaferri, G.

    2002-11-01

    The BMW-HRI catalogue is generated from US and German ROSAT HRI observations for which data have been released to the US ROSAT archive at GSFC and to the German ROSAT archive at MPE up to December 2001. A total number of 4,303 observations with exposure times longer than 100 s were analyzed automatically using a wavelet detection algorithm. The catalogue consists of 29,089 sources (detection probability greater or equal 4.2 sigma). For each source name, position, count rate, flux and extension along with the relative errors are given.The catalogue also reports results of cross-correlations with existing catalogues at different wavelengths (FIRST, GSC2, 2MASS, and IRAS). (1 data file).

  11. Analysis of Globular Cluster Photometry from 2MASS

    Science.gov (United States)

    Sarajedini, Ata; Milliman, K.; Kirkpatrick, A.

    2007-12-01

    Using near-infrared color magnitude diagrams of over 30 Galactic globular clusters, we have measured the magnitude of the red giant branch (RGB) 'bump,' the level of the core-helium burning red clump, and the slope of the RGB. Our aim is to compare our values with those measured by other investigators for the same clusters as we all as to derive new relations between these quantities and cluster properties such as age and metallicity. We find a good correlation between our values and those in the literature albeit with significant scatter. This work will explore the reasons for this scatter and techniques to minimize its effects. This research was supported by an REU supplement to NSF CAREER grant AST00-94048.

  12. A Galactic Plane relative extinction map from 2MASS

    Science.gov (United States)

    Froebrich, D.; Ray, T. P.; Murphy, G. C.; Scholz, A.

    2005-03-01

    We present three 14 400 square degree relative extinction maps of the Galactic Plane (|b| Beowulf-type cluster (in approximately 120 hours). Such a cluster is ideal for this type of work as areas of the sky can be independently processed in parallel. We studied how extinction depends on wavelength in all of the high extinction regions detected and within selected dark clouds. On average a power law opacity index (β) of 1.0 to 1.8 in the NIR was deduced. The index however differed significantly from region to region and even within individual dark clouds. That said, generally it was found to be constant, or to increase, with wavelength within a particular region.

  13. Far infrared and submillimetre surveys: from IRAS to Akari, Herschel and Planck

    CERN Document Server

    Rowan-Robinson, Michael

    2015-01-01

    We discuss a new IRAS Faint Source Catalog galaxy redshift catalogue (RIFSCz) which incorporates data from Galex, SDSS, 2MASS, WISE, Akari and Planck. Akari fluxes are consistent with photometry from other far infrared and submillimetre missions provided an aperture correction is applied. Results from the Hermes-SWIRE survey in Lockman are also discussed briefly, and the strong contrast between the galaxy populations selected at 60 and 500 mu is summarized.

  14. New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: II. SDSS DR7 vs UKIDSS LAS DR6, SDSS DR7 vs UKIDSS LAS DR8, SDSS DR9 vs UKIDSS LAS DR10, and SDSS DR7 vs 2MASS

    CERN Document Server

    Lodieu, N; Osorio, M R Zapatero; Solano, E; Aberasturi, M; Martin, E L; Rodrigo, C

    2016-01-01

    We aim at developing an efficient method to search for late-type subdwarfs (metal-depleted dwarfs with spectral types >M5) to improve the current statistics. Our objectives are: improve our knowledge of metal-poor low-mass dwarfs, bridge the gap between the late-M and L types, determine their surface density, and understand the impact of metallicity on the stellar and substellar mass function. We carried out a search cross-matching the SDSS, 2MASS, and UKIDSS using STILTS, Aladin, and Topcat. We considered different photometric and proper motion criteria for our selection. We identified 29 and 71 late-type subdwarf candidates in each cross-correlation over 8826 and 3679 square degrees, respectively. We obtained low-resolution optical spectra for 71 of our candidates with GTC, NOT, and VLT and retrieved spectra for 30 candidates from the SDSS spectroscopic database. We classified 92 candidates based on 101 optical spectra using two methods: spectral indices and comparison with templates of known subdwarfs. We ...

  15. The UV and X-ray activity of the M dwarfs within 10pc of the Sun

    CERN Document Server

    Stelzer, B; Micela, G; Lopez-Santiago, J; Liefke, C

    2013-01-01

    We systematically study the X-ray and ultraviolet emission of a subsample of M dwarfs from a recent proper-motion survey, selecting all M dwarfs within 10pc to obtain a nearly volume-limited sample (~90% completeness). Archival ROSAT, XMM-Newton and GALEX data are combined with published spectroscopic studies of Halpha emission and rotation to obtain a broad picture of stellar activity on M dwarfs. We make use of synthetic model spectra to determine the relative contributions of photospheric and chromospheric emission to the ultraviolet flux. We also analyse the same diagnostics for a comparison sample of young M dwarfs in the TWHya association (~10Myrs). We find that generally the emission in the GALEX bands is dominated by the chromosphere but the photospheric component is not negligible in early-M field dwarfs. The surface fluxes for the Halpha, near-ultraviolet, far-ultraviolet and X-ray emission are connected via a power law dependence. We present here for the first time such flux-flux relations involvin...

  16. The VVDS-SWIRE-GALEX-CFHTLS surveys: Physical properties of galaxies at z below 1.2 from photometric data

    CERN Document Server

    Walcher, C J; Vergani, D; Arnouts, S; Buat, V; Charlot, S; Tresse, L; Le Fèvre, O; Bolzonella, M; Brinchmann, J; Pozzetti, L; Zamorani, G; Bottini, D; Garilli, B; Le Brun, V; MacCagni, D; Milliard, B; Scaramella, R; Scodeggio, M; Vettolani, G; Zanichelli, A; Adami, C; Bardelli, S; Cappi, A; Ciliegi, P; Contini, T; Franzetti, P; Foucaud, S; Gavignaud, I; Guzzo, L; Ilbert, O; Iovino, A; McCracken, H J; Marano, B; Marinoni, C; Mazure, A; Meneux, B; Merighi, R; Paltani, S; Pellò, R; Pollo, A; Radovich, M; Zucca, E; Lonsdale, C; Martin, D C

    2008-01-01

    We intend to show that it is possible to derive the physical parameters of galaxies from their broad-band spectral energy distribution out to a redshift of 1.2. This method has the potential to yield the physical parameters of all galaxies in a single field in a homogeneous way. We use an extensive dataset, assembled in the context of the VVDS survey, which reaches from the UV to the IR and covers a sample of 84073 galaxies over an area of 0.89 deg$^2$. We also use a library of 100000 model galaxies with a large variety of star formation histories (in particular including late bursts of star formation). We find that we can determine the physical parameters stellar mass, age and star formation rate with good confidence. We validate the star formation rate determinations in particular by comparing it to a sample of spectroscopically observed galaxies with an emission line measurement. We use our sample to build the number density function of galaxies as a function of stellar mass, specific star formation rate a...

  17. VizieR Online Data Catalog: New Dwarf novae in SDSS, GALEX and astrom. cat. (Wils+, 2010)

    Science.gov (United States)

    Wils, P.; Gansicke, B. T.; Drake, A. J.; Southworth, J.

    2015-07-01

    Here, we cross-match a number of large surveys to find faint outbursting dwarf novae, and make use of CRTS light curves to compare the properties of the previously known dwarf novae, those identified spectroscopically by SDSS, and the ones discovered in this paper. (3 data files).

  18. A Study on the Fundamental Characteristics of Open Cluster NGC 6791 Based on SDSS-DR8 and 2MASS Data%基于SDSS-DR8及2MASS数据的疏散星团NGC6791的基本性质研究

    Institute of Scientific and Technical Information of China (English)

    高新华; 陈力

    2011-01-01

    利用斯隆数字巡天(SDSS)第8次释放数据(DR8)的恒星光谱数据及2MASS(Two Micro All Sky Survey)近红外点源测光数据研究著名的疏散星团NGC6791,得到该星团的视向速度与金属丰度分别为Vr= -46.4±0.2 km·s-1和[Fe/H]= 0.32±0.11dex.利用星团中红团簇巨星作为理想“标准烛光”,结合2MASS近红外点源测光数据计算了该星团的绝对距离模数为(m-M)0=13.02±0.08 mag或4.02±0.15 kpc.与其他研究者给出的结果进行了比较,金属丰度、视向速度及绝对距离模数都符合得比较好.主要结论有3点:(1) NGC 6791是个极度富金属的星团;(2)在SDSS的光谱分辨能力以内,分离出的87颗团星之间不存在明显的金属丰度差异;(3)得到的距离模数对年龄、金属丰度及尘埃消光不敏感,是一种可靠的间接测量.%SDSS-DR8 (The Eighth Data Release of Sloan Digital Sky Survey) and 2MASS (Two Micro All Sky Survey) data are used to analyze the fundamental parameters of the open cluster NGC 6791. Using the radial velocities of 274 stars in the region of the cluster, we calculate the membership probability for each star with the maximum likelihood method. Based on the stars with high membership probabilities, we derive a mean radial velocity value VT = -46.4±0.2 km-s"1 and a mean metallicity value [Fe/H]= 0.32±0.11 dex. Using red clump giants in the cluster as a kind of excellent distance indicator, we derive an absolute distance modulus value (m - M)q - 13.02 ± 0.08 mag or distance 4.02 ± 0.15 kpc. We therefore confirm that NGC 6791 is extremely metal-rich, and within the resolution of SDSS spectra, NGC 6791 does not show any evidence of internal spread in metallicity. The radial velocity and metallicity obtained by us are in good agreement with the values reported by other authors based on high-resolution spectra. Our derived absolute distance modulus based on red clump giants is also consistent with the values obtained from main sequence

  19. The Unseen Population of F to K-type Companions to Hot Subdwarf Stars

    CERN Document Server

    Girven, J; Heber, U; Gänsicke, B T; Marsh, T R; Breedt, E; Copperwheat, C M; Pyrzas, S; Peña, P Longa

    2012-01-01

    We present a method to select hot subdwarf stars with A to M-type companions using photometric selection criteria. We cover a wide range in wavelength by combining GALEX ultraviolet data, optical photometry from the SDSS and the Carlsberg Meridian telescope, near-infrared data from 2MASS and UKIDSS. We construct two complimentary samples, one by matching GALEX, CMC and 2MASS, as well as a smaller, but deeper, sample using GALEX, SDSS and UKIDSS. In both cases, a large number of composite subdwarf plus main-sequence star candidates were found. We fit their spectral energy distributions with a composite model in order to estimate the subdwarf and companion star effective temperatures along with the distance to each system. The distribution of subdwarf effective temperature was found to primarily lie in the 20,000 - 30,000 K regime, but we also find cooler subdwarf candidates, making up ~5-10 per cent. The most prevalent companion spectral types were seen to be main-sequence stars between F0 and K0, while subdwa...

  20. The enhancement and decrement of the Sunyaev-Zel'dovich effect towards the ROSAT Cluster RXJ0658-5557The enhancement and decrement of the Sunyaev-Zeldovich effect towards the ROSAT Cluster RXJ0658-5557

    NARCIS (Netherlands)

    Andreani, P.; Böhringer, H.; Dall'Oglio, G.; Martinis, L.; Shaver, P. A.; Lemke, R.; Nyman, L. A. A.; Booth, R.; Pizzo, L.; Whyborn, N.

    1999-01-01

    Published in: Astrophys. J. 513 (1999) 23 citations recorded in [Science Citation Index] Abstract: We report simultaneous observations at 1.2 and 2 mm, with a double channel photometer on the SEST Telescope, of the X-ray cluster RXJ0658-5557 in search for the Sunyaev-Zel'dovich (S-Z). The S-Z data w

  1. The enhancement and decrement of the Sunyaev-Zel'dovich effect towards the ROSAT Cluster RXJ0658-5557The enhancement and decrement of the Sunyaev-Zeldovich effect towards the ROSAT Cluster RXJ0658-5557

    NARCIS (Netherlands)

    Andreani, P.; Böhringer, H.; Dall'Oglio, G.; Martinis, L.; Shaver, P. A.; Lemke, R.; Nyman, L. A. A.; Booth, R.; Pizzo, L.; Whyborn, N.

    1999-01-01

    Published in: Astrophys. J. 513 (1999) 23 citations recorded in [Science Citation Index] Abstract: We report simultaneous observations at 1.2 and 2 mm, with a double channel photometer on the SEST Telescope, of the X-ray cluster RXJ0658-5557 in search for the Sunyaev-Zel'dovich (S-Z). The S-Z data w

  2. Optical identification of radio-loud active galactic nuclei in the ROSAT-Green-Bank sample with SDSS spectroscopy

    Institute of Scientific and Technical Information of China (English)

    De-Liang Wang; Jian-Guo Wang; Xiao-Bo Dong

    2009-01-01

    Results of extended and refined optical identification of 181 radio/X-ray sources in the RASS-Green Bank (RGB) catalog are presented (Brinkmann et al.1997)which have been spectroscopically observed in the Sloan Digital Sky Survey (SDSS)DR5.The SDSS spectra of the optical counterparts are modeled in a careful and selfconsistent way by incorporating the host galaxy's starlight.Optical emission line parameters are presented,which are derived accurately and reliably,along with the radio 1.4-5 GHz spectral indices estimated using (non-simultaneous) archival data.For 72 sources,the identifications are presented for the first time.It is confirmed that the majority of strong radio/X-ray emitters are radio-loud active galactic nuclei (AGNs),particularly blazars.Taking advantage of the high spectral quality and resolution and our refined spectral modeling,we are able to disentangle narrow line radio galaxies (NLRGs),as vaguely termed in most previous identification work,into SeyfertⅡgalaxies and LINERs (low-ionization nuclear emission regions),based on the standard emission line diagnostics.The NLRGs in the RGB sample,mostly belonging to'weak line radio galaxies',are found to have optical spectra consistent predominantly with LINERs,and only a small fraction with SeyfertⅡgalaxies.A small number of LINERs have radio power as high as 1023-1026W Hz-1 at 5 GHz,being among the strongest radio emitting LINERs known so far.Two sources are identified with radio-loud narrow line Seyfert 1 galaxies (NLSIs),a class of rare objects.The presence is also confirmed of fiat-spectrum radio quasars whose radio-optical-X-ray effective spectral indices are similar to those of High-energy peaked BL Lacs (HBLs),as suggested by Padovani et al.,although it is still a debate as to whether this is the case for their actual spectral energy distributions.

  3. Single stars in the Hyades open cluster. Fiducial sequence for testing stellar and atmospheric models

    Science.gov (United States)

    Kopytova, Taisiya G.; Brandner, Wolfgang; Tognelli, Emanuele; Prada Moroni, Pier Giorgio; Da Rio, Nicola; Röser, Siegfried; Schilbach, Elena

    2016-01-01

    Context. Age and mass determinations for isolated stellar objects remain model-dependent. While stellar interior and atmospheric theoretical models are rapidly evolving, we need a powerful tool to test them. Open clusters are good candidates for this role. Aims: We aim to create a fiducial sequence of stellar objects for testing stellar and atmospheric models. Methods: We complement previous studies on the Hyades multiplicity by Lucky Imaging observations with the AstraLux Norte camera. This allows us to exclude possible binary and multiple systems with companions outside a 2-7 AU separation and to create a single-star sequence for the Hyades. The sequence encompasses 250 main-sequence stars ranging from A5V to M6V. Using the Tool for Astrophysical Data Analysis (TA-DA), we create various theoretical isochrones applying different combinations of interior and atmospheric models. We compare the isochrones with the observed Hyades single-star sequence on J vs. J-Ks, J vs. J-H, and Ks vs. H-Ks color-magnitude diagrams. As a reference we also compute absolute fluxes and magnitudes for all stars from X-ray to mid-infrared based on photometric measurements available in the literature(ROSAT X-ray, GALEX UV, APASS gri, 2MASS JHKs, and WISE W1 to W4). Results: We find that combinations of both PISA and DARTMOUTH stellar interior models with BT-Settl 2010 atmospheric models describe the observed sequence well. We use PISA in combination with BT-Settl 2010 models to derive theoretical predictions for physical parameters (Teff, mass, log g) of 250 single stars in the Hyades. The full sequence covers the mass range of 0.13-2.30 M⊙, and effective temperatures between 3060 K and 8200 K. Conclusions: Within the measurement uncertainties, the current generation of models agree well with the single-star sequence. The primary limitations are the uncertainties in the measurement of the distances to individual Hyades members, and uncertainties in the photometry. Gaia parallaxes

  4. A mid-IR study of Hickson Compact Groups II. Multi-wavelength analysis of the complete GALEX-Spitzer Sample

    CERN Document Server

    Bitsakis, T; da Cunha, E; Diaz-Santos, T; Floc'h, E Le; Magdis, G

    2011-01-01

    We present a comprehensive study on the impact of the environment of compact galaxy groups on the evolution of their members using a multi-wavelength analysis, from the UV to the infrared, for a sample of 32 Hickson compact groups (HCGs) containing 135 galaxies. Fitting the SEDs of all galaxies with the state-of-the-art model of da Cunha (2008) we can accurately calculate their mass, SFR, and extinction, as well as estimate their infrared luminosity and dust content. We compare our findings with samples of field galaxies, early-stage interacting pairs, and cluster galaxies with similar data. We find that classifying the groups as dynamically "old" or "young", depending on whether or not at least one quarter of their members are early-type systems, is physical and consistent with past classifications of HCGs based on their atomic gas content. [...ABRIDGED...] We also examine their SF properties, UV-optical and mid-IR colors, and we conclude that all the evidence point to an evolutionary scenario in which the e...

  5. Galex and Pan-STARRS1 Discovery of SN IIP 2010aq: The First Few Days After Shock Breakout in a Red Supergiant Star

    Science.gov (United States)

    2010-09-01

    Colgate 1974; Falk 1978; Klein & Chevalier 1978; Matzner & McKee 1999). The duration of this radiative precursor in the UV/X-rays is smeared out by light...Chevalier, R. A., & Fransson, C. 2008, ApJ, 683, L135 Colgate , S. A. 1974, ApJ, 187, 333 Couch, S. M., Wheeler, J. C., & Milosavljevic, M. 2009, ApJ, 696

  6. The SAURON project - XIII. SAURON-GALEX study of early-type galaxies : the ultraviolet colour-magnitude relations and Fundamental Planes

    NARCIS (Netherlands)

    Jeong, Hyunjin; Yi, Sukyoung K.; Bureau, Martin; Davies, Roger L.; Falcon-Barroso, Jesus; van de Ven, Glenn; Peletier, Reynier F.; Bacon, Roland; Cappellari, Michele; de Zeeuw, Tim; Emsellem, Eric; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Sarzi, Marc; van den Bosch, Remco C. E.

    2009-01-01

    We present Galaxy Evolution Explorer far-ultraviolet (FUV) and near-ultraviolet (NUV) imaging of 34 nearby early-type galaxies from the SAURON representative sample of 48 E/S0 galaxies, all of which have ground-based optical imaging from the MDM Observatory. The surface brightness profiles of nine g

  7. The SAURON project - XIII. SAURON-GALEX study of early-type galaxies: the ultraviolet colour-magnitude relations and Fundamental Planes

    NARCIS (Netherlands)

    Jeong, Hyunjin; K. Yi, Sukyoung; Bureau, Martin; L. Davies, Roger; Falcón-Barroso, Jesús; van de Ven, Glenn; Peletier, R.F.; Bacon, Roland; Cappellari, Michele; de Zeeuw, Tim; Emsellem, Eric; Krajnović, Davor; Kuntschner, Harald; M. McDermid, Richard; Sarzi, Marc; C. E. van den Bosch, Remco

    2009-01-01

    We present Galaxy Evolution Explorer far-ultraviolet (FUV) and near-ultraviolet (NUV) imaging of 34 nearby early-type galaxies from the SAURON representative sample of 48 E/S0 galaxies, all of which have ground-based optical imaging from the MDM Observatory. The surface brightness profiles of nine g

  8. 2MASS/SDSS Close Major-Merger Galaxy Pairs: Luminosity Functions and Merger Mass Dependence

    CERN Document Server

    Domingue, Donovan L; Jarrett, T H; Cheng, Y

    2009-01-01

    We select a close "major-merger candidate" galaxy pair sample in order to calculate the K_{s} luminosity function (LF) and pair fraction representative of the merger/interaction component of galaxy evolution in the local universe. The pair sample (projected separation 5 h$^{-1}$ kpc $\\leq$ r $\\leq$ 20 h$^{-1}$ kpc, $K_{s}$-band magnitude difference $\\Delta

  9. Two novel approaches for photometric redshift estimation based on SDSS and 2MASS databases

    CERN Document Server

    Wang, Dan; Liu, Chao; Zhao, Yong-Heng

    2007-01-01

    We investigate two training-set methods: support vector machines (SVMs) and Kernel Regression (KR) for photometric redshift estimation with the data from the Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey databases. We probe the performances of SVMs and KR for different input patterns. Our experiments show that the more parameters considered, the accuracy doesn't always increase, and only when appropriate parameters chosen, the accuracy can improve. Moreover for different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Finally the strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.

  10. Velocity-density correlations from the cosmicflows-3 distance catalogue and the 2MASS Redshift Survey

    Science.gov (United States)

    Nusser, Adi

    2017-09-01

    The peculiar velocity of a mass tracer is on average aligned with the dipole modulation of the surrounding mass density field. We present a first measurement of the correlation between radial peculiar velocities of objects in the cosmicflows-3 catalogue and the dipole moment of the 2MRS galaxy distribution in concentric spherical shells centred on these objects. Limiting the analysis to cosmicflows-3 objects with distances of 100h-1 Mpc, the correlation function is detected at a confidence level of ≳ 4σ. The measurement is found consistent with the standard ΛCDM model at the ≲ 1.7σ level. We formally derive the constraints 0.32 confidence level) or equivalently 0.34 type of correlations.

  11. DAO Spectroscopic classification of SN 2016bkr in 2MASS J11032043+7153141

    Science.gov (United States)

    Balam, D. D.; Graham, M. L.

    2016-04-01

    A spectrum was obtained of SN 2016bkr (ATEL #8857) on Apr. 8.41 UT using the 1.82-m Plaskett telescope (National Research Council of Canada) covering the range 385-710 nm (resolution 0.32 nm). Cross-correlation with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows 2016bkr to be a peculiar type-Ia supernova approximately 12 days post-maximum light.

  12. Einstein's Equations for Spin 2 Mass 0 from Noether's Converse Hilbertian Assertion

    Science.gov (United States)

    Pitts, J. Brian

    2016-11-01

    An overlap between the general relativist and particle physicist views of Einstein gravity is uncovered. Noether's 1918 paper developed Hilbert's and Klein's reflections on the conservation laws. Energy-momentum is just a term proportional to the field equations and a 'curl' term with identically zero divergence. Noether proved a converse "Hilbertian assertion": such "improper" conservation laws imply a generally covariant action.

  13. J/P=1/2+, J/P=3/2+ masses in statistical model

    CERN Document Server

    Kaur, Amanpreet

    2016-01-01

    The mass formulae for the baryon octet and decuplet are calculated. These formulae are function of constituent quark masses and spin spin interaction terms for the quarks inside the baryons. The coe?cients in the mass formulae is estimated by the statistical model for J/P=1/2+, J/P=3/2+, incorporating the contributions from \\sea" containing uu; dd; ss pairs and gluons . The measured masses are presented and found to be matching good with some of the experimental and theoretical data.

  14. DETERMINATION OF CO2 MASSES IN THE EXHAUST GASES OF THE MARINE DIESEL ENGINES

    Directory of Open Access Journals (Sweden)

    Doru COSOFRET

    2016-05-01

    Full Text Available Currently, reducing CO2 emissions that contribute to the greenhouse effect is currently under attention of the relevant international bodies. In the field of maritime transport, in 2011 International Maritime Organization (IMO has taken steps to reduce emissions of CO2 from the exhaust gases of marine diesel engines on ships, by imposing their energy efficiency standards. In this regard, we conducted a laboratory study on a 4-stroke diesel engine naturally aspirated by using to power it diesel and different blends of biodiesel with diesel fuel. The purpose of the study was to determine the formulas for calculating the mass flow rates of CO2 from exhaust gases’ concentrations experimentally determined. Determining the mass flow of CO2 is necessary to calculate the energy efficiency coefficient of the ship to assess the energy efficiency of the board of the limits imposed by the IMO.

  15. Einstein's Equations for Spin $2$ Mass $0$ from Noether's Converse Hilbertian Assertion

    CERN Document Server

    Pitts, J Brian

    2016-01-01

    An overlap between the general relativist and particle physicist views of Einstein gravity is uncovered. Noether's 1918 paper developed Hilbert's and Klein's reflections on the conservation laws. Energy-momentum is just a term proportional to the field equations and a 'curl' term with identically zero divergence. Noether proved a \\emph{converse} "Hilbertian assertion": such "improper" conservation laws imply a generally covariant action. Later and independently, particle physicists derived the nonlinear Einstein equations assuming the absence of negative-energy degrees of freedom ("ghosts") for stability, along with universal coupling: all energy-momentum including gravity's serves as a source for gravity. Those assumptions (all but) imply (for 0 graviton mass) that the energy-momentum is only a term proportional to the field equations and a symmetric "curl," which implies the coalescence of the flat background geometry and the gravitational potential into an effective curved geometry. The flat metric, though...

  16. Thermal compression waves. 2: Mass adjustment and vertical transfer of the total energy

    Science.gov (United States)

    Nicholls, Melville E.; Pielke, Roger A.

    1994-01-01

    A fully compressible model is used to simulate the mass adjustment that occurs in response to a prescribed heat source. Results illustrate the role that thermal compression waves have in this process. The vertical mass transport associated with compression waves decreases rapidly with height. Most of the mass transport occurs in the horizontal, with the vertical structure of the disturbance similar to that of a Lamb wave. The vertical transfer of total energy in a thermally driven mixed layer is also examined. It is shown that the upward transport of total energy is accomplished by a compression effect rather than by the exchange of warm and cold air by buoyant thermals. Model results are analyzed to determine budgets of total energy, mass and entropy. It is demonstrated that buoyant thermals are predominantly responsible for a transfer of entropy, rather than total energy. In the light of these results the notion of 'heat transport' in a fluid is discussed.

  17. $N_f=1+2$ mass dependence of the topological susceptibility

    CERN Document Server

    Frison, Julien; Yamada, Norikazu

    2016-01-01

    A massless up quark has long been proposed as a solution to the strong CP problem. While this solution is sometimes thought to have been excluded, it is actually still ill-defined. In this work, we study the mass dependence of the physical observable $\\chi_t$, the topological susceptibility. Assigning an unphysically large value to the down mass allows to be more sensitive to the non-perturbative effects behind the $m_u=0$ ambiguity. Preliminary results are presented for four masses of clover fermions.

  18. How well does CO emission measure the H2 mass of MCs?

    Science.gov (United States)

    Szűcs, László; Glover, Simon C. O.; Klessen, Ralf S.

    2016-07-01

    We present numerical simulations of molecular clouds (MCs) with self-consistent CO gas-phase and isotope chemistry in various environments. The simulations are post-processed with a line radiative transfer code to obtain 12CO and 13CO emission maps for the J = 1 → 0 rotational transition. The emission maps are analysed with commonly used observational methods, i.e. the 13CO column density measurement, the virial mass estimate and the so-called XCO (also CO-to-H2) conversion factor, and then the inferred quantities (i.e. mass and column density) are compared to the physical values. We generally find that most methods examined here recover the CO-emitting H2 gas mass of MCs within a factor of 2 uncertainty if the metallicity is not too low. The exception is the 13CO column density method. It is affected by chemical and optical depth issues, and it measures both the true H2 column density distribution and the molecular mass poorly. The virial mass estimate seems to work the best in the considered metallicity and radiation field strength range, even when the overall virial parameter of the cloud is above the equilibrium value. This is explained by a systematically lower virial parameter (i.e. closer to equilibrium) in the CO-emitting regions; in CO emission, clouds might seem (sub-)virial, even when, in fact, they are expanding or being dispersed. A single CO-to-H2 conversion factor appears to be a robust choice over relatively wide ranges of cloud conditions, unless the metallicity is low. The methods which try to take the metallicity dependence of the conversion factor into account tend to systematically overestimate the true cloud masses.

  19. How well does CO emission measure the H$_2$ mass of MCs?

    CERN Document Server

    Szűcs, László; Klessen, Ralf S

    2016-01-01

    We present numerical simulations of molecular clouds (MCs) with self-consistent CO gas-phase and isotope chemistry in various environments. The simulations are post-processed with a line radiative transfer code to obtain $^{12}$CO and $^{13}$CO emission maps for the $J=1\\rightarrow0$ rotational transition. The emission maps are analysed with commonly used observational methods, i.e. the $^{13}$CO column density measurement, the virial mass estimate and the so-called $X_{\\textrm{CO}}$ (also CO-to-H$_2$) conversion factor, and then the inferred quantities (i.e. mass and column density) are compared to the physical values. We generally find that most methods examined here recover the CO-emitting H$_{2}$ gas mass of MCs within a factor of two uncertainty if the metallicity is not too low. The exception is the $^{13}$CO column density method. It is affected by chemical and optical depth issues, and it measures both the true H$_{2}$ column density distribution and the molecular mass poorly. The virial mass estimate...

  20. DETECTION OF A NEARBY HALO DEBRIS STREAM IN THE WISE AND 2MASS SURVEYS

    Energy Technology Data Exchange (ETDEWEB)

    Grillmair, Carl J. [Spitzer Science Center, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Cutri, Roc; Masci, Frank J.; Conrow, Tim [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Eisenhardt, Peter R. M. [Jet Propulsion Laboratory, California Institute of Technology, MS 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Wright, Edward L., E-mail: carl@ipac.caltech.edu, E-mail: roc@ipac.caltech.edu, E-mail: fmasci@ipac.caltech.edu, E-mail: tim@ipac.caltech.edu, E-mail: bsesar@astro.caltech.edu, E-mail: peter.r.eisenhardt@jpl.nasa.gov, E-mail: wright@astro.ucla.edu [Department of Physics, University of California, Los Angeles, CA 90095 (United States)

    2013-06-01

    Combining the Wide-Field Infrared Survey Explorer All-Sky Release with the Two Micron All Sky Survey Point Source Catalog, we detect a nearby, moderately metal-poor stellar debris stream spanning 24° across the southern sky. The stream, which we designate Alpheus, is at an estimated distance of ∼1.9 kpc. Its position, orientation, width, estimated metallicity, and, to some extent, its distance, are in approximate agreement with what one might expect of the leading tidal tail of the southern globular cluster NGC 288.

  1. The quest for the perfect gravity anomaly: Part 2 - Mass effects and anomaly inversion

    Science.gov (United States)

    Keller, Gordon R.; Hildenbrand, T.G.; Hinze, W. J.; Li, X.; Ravat, D.; Webring, M.

    2006-01-01

    Gravity anomalies have become an important tool for geologic studies since the widespread use of high-precision gravimeters after the Second World War. More recently the development of instrumentation for airborne gravity observations, procedures for acquiring data from satellite platforms, the readily available Global Positioning System for precise vertical and horizontal control, improved global data bases, and enhancement of computational hardware and software have accelerated the use of the gravity method. As a result, efforts are being made to improve the gravity databases that are made available to the geoscience community by broadening their observational holdings and increasing the accuracy and precision of the included data. Currently the North American Gravity Database as well as the individual databases of Canada, Mexico, and the United States of America are being revised using new formats and standards. The objective of this paper is to describe the use of the revised standards for gravity data processing and modeling and there impact on geological interpretations. ?? 2005 Society of Exploration Geophysicists.

  2. Two Novel Approaches for Photometric Redshift Estimation based on SDSS and 2MASS

    Institute of Scientific and Technical Information of China (English)

    Dan Wang; Yan-Xia Zhang; Chao Liu; Yong-Heng Zhao

    2008-01-01

    We investigate two training-set methods: support vector machines (SVMs) and Kernel Regression (KR) for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey. We probe the performances of SVMs and KR for different input patterns. Our experiments show that with more parameters considered, the accuracy does not always increase, and only when appropriate parameters are chosen, the accuracy can improve. For different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.

  3. The Martian hydrologic cycle - Effects of CO2 mass flux on global water distribution

    Science.gov (United States)

    James, P. B.

    1985-01-01

    The Martian CO2 cycle, which includes the seasonal condensation and subsequent sublimation of up to 30 percent of the planet's atmosphere, produces meridional winds due to the consequent mass flux of CO2. These winds currently display strong seasonal and hemispheric asymmetries due to the large asymmetries in the distribution of insolation on Mars. It is proposed that asymmetric meridional advection of water vapor on the planet due to these CO2 condensation winds is capable of explaining the observed dessication of Mars' south polar region at the current time. A simple model for water vapor transport is used to verify this hypothesis and to speculate on the effects of changes in orbital parameters on the seasonal water cycle.

  4. A Multi-Wavelength Photometric Census of AGN and Star Formation Activity in the Brightest Cluster Galaxies of X-ray Selected Clusters

    CERN Document Server

    Green, T S; Stott, J P; Ebeling, H; Burgett, W S; Chambers, K C; Draper, P W; Metcalfe, N; Kaiser, N; Wainscoat, R J; Waters, C

    2016-01-01

    Despite their reputation as being "red and dead", the unique environment inhabited by Brightest Cluster Galaxies (BCGs) can often lead to a self-regulated feedback cycle between radiatively cooling intracluster gas and star formation and AGN activity in the BCG. However the prevalence of "active" BCGs, and details of the feedback involved, are still uncertain. We have performed an optical, UV and Mid-IR photometric analysis of the BCGs in 981 clusters at 0.03 < z < 0.5, selected from the ROSAT All Sky Survey. Using Pan-STARRS PS1 3pi, GALEX and WISE survey data we look for BCGs with photometric colours which deviate from that of the bulk population of passive BCGs - indicative of AGN and/or star formation activity within the BCG. We find that whilst the majority of BCGs are consistent with being passive, at least 14% of our BCGs show a significant colour offset from passivity in at least one colour index. And, where available, supplementary spectroscopy reveals the majority of these particular BCGs show...

  5. Discovery of an Apparent High Latitude Galactic Supernova Remnant

    CERN Document Server

    Fesen, Robert; Black, Christine; Koeppel, Ari

    2015-01-01

    Deep H$\\alpha$ images of a faint emission complex 4.0 x 5.5 degrees in angular extent and located far off the Galactic plane at l = 70.0 degrees, b=-21.5 degrees reveal numerous thin filaments suggestive of a supernova remnant's shock emission. Low dispersion optical spectra covering the wavelength range 4500 - 7500 A show only Balmer line emissions for one filament while three others show a Balmer dominated spectrum along with weak [N I] 5198, 5200 A, [O I] 6300, 6364 A, [N II] 6583 A, [S II] 6716, 6731 A and in one case [O III] 5007 A line emission. Many of the brighter H$\\alpha$ filaments are visible in near UV GALEX images presumably due to C III] 1909 A line emission. ROSAT All Sky Survey images of this region show a faint crescent shaped X-ray emission nebula coincident with the portion of the H$\\alpha$ nebulosity closest to the Galactic plane. The presence of long, thin Balmer dominated emission filaments with associated UV emission and coincident X-ray emission suggests this nebula is a high latitude ...

  6. A statistical study of the relation between soft X-ray excess and accretion disk

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    To study the origin of the soft X-ray excess,we compile a sample of 94 unobscured,radio-quiet QSOs and Seyfert galaxies with available data from GALEX and ROSAT.We find that 50 sources show strong soft X-ray excess and the other 44 show weak/no soft X-ray excess.Systematic analyses of the data indicate that the difference in soft X-rays is mainly but not only resulting from different accretion rates(in units of Eddington rate).The statistical study of the sources with soft X-ray excess shows that the strength of soft X-ray excess weakly and positively correlates with the Eddington ratio and increases with the increase of the strength of UV radiations relative to the X-rays.Provided that the UV emissions are from the thin disk,the correlations imply that the origin of soft X-ray excess is associated with the thin disk,either by means of Comptonization of the disk photons or in some other ways.

  7. K 1-6: an asymmetric planetary nebula with a binary central star

    CERN Document Server

    Frew, David J; Fitzgerald, Michael; Parker, Quentin; Danaia, Lena; McKinnon, David; Guerrero, Martín A; Hedberg, John; Hollow, Robert; An, Yvonne; Bor, Shu Han; Colman, Isabel; Graham-White, Claire; Li, Qing Wen; Mai, Juliette; Papadakis, Katerina; Picone-Murray, Julia; Hoang, Melanie Vo; Yean, Vivian

    2010-01-01

    We present new imaging data and archival multiwavelength observations of the little studied emission nebula K 1-6 and its central star. Narrow-band images in H-alpha (+ [NII]) and [OIII] taken with the Faulkes Telescope North reveal a stratified, asymmetric, elliptical nebula surrounding a central star which has the colours of a late G- or early K-type subgiant or giant. GALEX ultraviolet images reveal a very hot subdwarf or white dwarf coincident in position with this star. The cooler, optically dominant star is strongly variable with a period of 21.312 +/- 0.008 days, and is possibly a high amplitude member of the RS CVn class, although an FK Com classification is also possible. Archival ROSAT data provide good evidence that the cool star has an active corona. We conclude that K 1-6 is most likely an old bona fide planetary nebula at a distance of ~1.0 kpc, interacting with the interstellar medium, and containing a binary or ternary central star. The observations and data analyses reported in this paper wer...

  8. Ultraviolet and optical observations of tidal disruption events

    Directory of Open Access Journals (Sweden)

    Gezari S.

    2012-12-01

    Full Text Available Tidal disruption events are expected to produce a luminous flare of radiation from fallback accretion of tidally disrupted stellar debris onto the central supermassive black hole. The first convincing candidates for tidal disruption events were discovered in the soft X-rays: large-amplitude, luminous, extremely-soft X-ray flares from inactive galaxies in the ROSAT All-Sky survey. However, the sparsely sampled light curves and lack of multiwavelength observations for these candidates make it difficult to directly constrain the parameters of their events (e.g., Eddington ratio, mass of the black hole, type of star disrupted. Here I present a review of the recent progress made in studying tidal disruption events in detail from taking advantage of wide-field, multi-epoch observations of UV and optical surveys (GALEX, SDSS, PTF, Pan-STARRS1 to measure well-sampled light curves, trigger prompt multiwavelength follow-up observations, and measure rates. I conclude with the promising potential of the next generation of optical synoptic surveys, such as LSST, to probe black hole demographics with samples of thousands of tidal disruption events.

  9. Optical & Sunyaev-Zel'dovich Observations of a New Sample of Distant Rich Galaxy Clusters in the ROSAT All Sky Survey

    CERN Document Server

    Buddendiek, A; Greer, C H; Hoekstra, H; Sommer, M; Eifler, T; Erben, T; Erler, J; Hicks, A K; High, F W; Hildebrandt, H; Marrone, D P; Morris, R G; Muzzin, A; Reiprich, T H; Schirmer, M; Schneider, P; von der Linden, A

    2014-01-01

    Finding a sample of the most massive clusters with redshifts $z>0.6$ can provide an interesting consistency check of the $\\Lambda$CDM model. Here we present results from our search for clusters with $0.6

  10. Flares from a new Integral hard X-ray source, IGR J17407-2808, likely associated with the ROSAT source SBM 10

    DEFF Research Database (Denmark)

    Kretschmar, P.; Mereghetti, S.; Hermsen, W.

    2004-01-01

    ). The source was outside the FOV of the JEM-X and OMC monitor instruments during this flare. Note that the position of J17407-2808 is inconsistent with that of the X-ray burster SLX 1737-282 [AX J1740.7-2818] (in't Zand et al. 2002, A&A 389, L43), which is just ~11 arcmin away. The correct Integral attitude...

  11. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) V. Exploring a local underdensity in the Southern Sky

    CERN Document Server

    Boehringer, Hans; Bristow, Martyn; Collins, Chris A

    2014-01-01

    Several claims have been made that we are located in a locally underdense region of the Universe based on observations of supernovae and galaxy density distributions. Two recent studies of K-band galaxy surveys have provided new support for a local underdensity in the galaxy distribution out to distances of 200 - 300 Mpc. If confirmed, such large local underdensities would have important implications on the interpretation of local measurements of cosmological parameters. Galaxy clusters have been shown to be ideal probes to trace the large-scale structure of the Universe. In this paper we study the local density distribution in the southern sky with the X-ray detected galaxy clusters from the REFLEX II cluster survey. From the normalized comoving number density of clusters we find an average underdensity of ~30 - 40% in the redshift range out to z ~0.04 (~170 Mpc) in the southern extragalactic sky with a significance larger than 3.4sigma. On larger scales from 300 Mpc to over 1 Gpc the density distribution ap...

  12. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) VI. Effect of massive neutrinos on the cosmological constraints from clusters

    CERN Document Server

    Boehringer, Hans

    2015-01-01

    Clusters of galaxies are important probes for the large-scale structure that allow us to test cosmological models. With the REFLEX II galaxy cluster survey we previously derived tight constraints on the cosmological parameters for the matter density, Omega_m, and the amplitude parameter of the matter density fluctuations, sigma_8. Whereas in these previous studies no effect of massive neutrinos was taken into account, we explore these effects in the present publication. We derive cosmological constraints for the sum of the neutrino masses of the conventional three neutrino families in the range 0 to 0.6 eV. The influence on the constraints of Omega_m and sigma_8 for the expected mass range is weak. Interesting constraints on the neutrino properties can be derived by comparing the cluster data with those from the Planck cosmic microwave background observations. The current tension between the Planck results and clusters can formally be resolved with neutrino masses of about M_nu = 0.45 (+- 0.28, 1-sigma) eV. W...

  13. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) IV. X-ray Luminosity Function and First Constraints on Cosmological Parameters

    CERN Document Server

    Böhringer, H; Collins, C A

    2014-01-01

    The X-ray luminosity function is an important statistic of the census of galaxy clusters and an important means to probe the cosmological model of our Universe. Based on our recently completed REFLEX II cluster sample we construct the X-ray luminosity function of galaxy clusters for several redshift slices from $z = 0$ to $z = 0.4$ and discuss its implications. We find no significant signature of redshift evolution of the luminosity function in the redshift interval. We provide the results of fits of a parameterized Schechter function and extensions of it which provide a reasonable characterization of the data. Using a model for structure formation and galaxy cluster evolution we compare the observed X-ray luminosity function with predictions for different cosmological models. For the most interesting constraints for the cosmological parameters $\\Omega_m$ and $\\sigma_8$ we obatain $\\Omega_m \\sim 0.27 \\pm 0.03$ and $\\sigma_8 \\sim 0.80 \\pm 0.03$ based on the statistical uncertainty alone. Marginalizing over the...

  14. Multiwavelength View of SDSS Galaxies

    CERN Document Server

    Obric, M; Kauffmann, G; Lupton, R H; Tremonti, C A; Brinchmann, J; Charlot, S; Knapp, G R; Gunn, J E; Rockosi, C M; Schlegel, D J; Strauss, M A; Gacesa, M; Smolcic, V; Anderson, S; Voges, W; Blanton, M R; Eisenstein, D J

    2004-01-01

    We summarize the detection rates at wavelengths other than optical for \\~99,000 galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 1 ``main'' spectroscopic sample. The analysis is based on positional cross-correlation with source catalogs from ROSAT, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS surveys. We find that the rest-frame UV-IR broad-band galaxy SEDs form a remarkably uniform, nearly one parameter, family. As an example, the SDSS u and r band data, supplemented with redshift, can be used to predict K band magnitudes measured by 2MASS with an rms scatter of only 0.2 mag; when measurement uncertainties are taken into account, the astrophysical scatter appears not larger than ~0.1 mag.

  15. Simulated Galaxy Interactions as Probes of Merger Spectral Energy Distributions

    CERN Document Server

    Lanz, Lauranne; Zezas, Andreas; Smith, Howard A; Ashby, Matthew L N; Brassington, Nicola; Fazio, Giovanni G; Hernquist, Lars

    2014-01-01

    We present the first systematic comparison of ultraviolet-millimeter spectral energy distributions (SEDs) of observed and simulated interacting galaxies. Our sample is drawn from the Spitzer Interacting Galaxy Survey, and probes a range of galaxy interaction parameters. We use 31 galaxies in 14 systems which have been observed with Herschel, Spitzer, GALEX, and 2MASS. We create a suite of GADGET-3 hydrodynamic simulations of isolated and interacting galaxies with stellar masses comparable to those in our sample of interacting galaxies. Photometry for the simulated systems is then calculated with the SUNRISE radiative transfer code for comparison with the observed systems. For most of the observed systems, one or more of the simulated SEDs match reasonably well. The best matches recover the infrared luminosity and the star formation rate of the observed systems, and the more massive systems preferentially match SEDs from simulations of more massive galaxies. The most morphologically distorted systems in our sa...

  16. Global Star Formation Rates and Dust Emission Over the Galaxy Interaction Sequence

    CERN Document Server

    Lanz, Lauranne; Brassington, Nicola; Smith, Howard A; Ashby, Matthew L N; da Cunha, Elisabete; Fazio, Giovanni G; Hayward, Christopher C; Hernquist, Lars; Jonsson, Patrik

    2013-01-01

    We measured and modeled the spectral energy distributions (SEDs) in 28 bands from the ultraviolet to the far-infrared (FIR) for 31 interacting galaxies in 14 systems. The sample is drawn from the Spitzer Interacting Galaxy Survey, which probes a range of galaxy interaction parameters at multiple wavelengths with an emphasis on the infrared bands. The subset presented in this paper consists of all galaxies for which FIR Herschel SPIRE observations are publicly available. Our SEDs combine the Herschel photometry with multi-wavelength data from Spitzer, GALEX, Swift UVOT, and 2MASS. While the shapes of the SEDs are broadly similar across our sample, strongly interacting galaxies typically have more mid-infrared emission relative to their near-infrared and FIR emission than weakly or moderately interacting galaxies. We modeled the full SEDs to derive host galaxy star formation rates (SFR), specific star formation rates (sSFR), stellar masses, dust temperatures, dust luminosities, and dust masses. We find increase...

  17. VizieR Online Data Catalog: UV to IR fluxes of 221 early-type galaxies (Amblard+, 2014)

    Science.gov (United States)

    Amblard, A.; Riguccini, L.; Temi, P.; Im, S.; Fanelli, M.; Serra, P.

    2016-06-01

    We base our work on a sample of 225 early-type galaxies from Temi et al. 2009 (cat. J/ApJ/707/890). We present a large fraction of their SED from the ultraviolet to the far-infrared (Tables 1-4). We concentrate primarily on six instruments which span these wavelengths and have extensive sky coverage: Galaxy Evolution Explorer (GALEX; see Bianchi et al. 2001, cat. II/312) for the UV part, SDSS (see SDSS-DR9 in cat. V/139) for the optical, Two Micron All Sky Survey (2MASS; Cutri et al. 2003, cat. II/246) and IRAC-Spitzer for the NIR and MIR, and MIPS-Spitzer and IRAS for the mid and FIR. We also use public data from Herschel-SPIRE when available (see Table4). (5 data files).

  18. A search for new hot subdwarf stars by means of Virtual Observatory tools II

    CERN Document Server

    Pérez-Fernández, Esther; Solano, Enrique; Oreiro, Raquel; Rodrigo, Carlos

    2016-01-01

    Recent massive sky surveys in different bandwidths are providing new opportunities to modern astronomy. The Virtual Observatory (VO) represents the adequate framework to handle the huge amount of information available and filter out data according to specific requirements. In this work, we applied a selection strategy to find new, uncatalogued hot subdwarfs making use of VO tools. We used large area catalogues (GALEX, SDSS, SuperCosmos, 2MASS) to retrieve photometric and astrometric information of stellar objects. To these objects, we applied colour and proper motion filters, together with an effective temperature cutoff, aimed at separating hot subdwarfs from other blue objects such as white dwarfs, cataclysmic variables or main sequence OB stars. As a result, we obtained 437 new, uncatalogued hot subdwarf candidates. Based on previous results, we expect our procedure to have an overall efficiency of at least 80 per cent. Visual inspection of the 68 candidates with SDSS spectrum showed that 65 can be classif...

  19. Estimating stellar parameters and interstellar extinction from evolutionary tracks

    Science.gov (United States)

    Sichevsky, S.; Malkov, O.

    Developing methods for analyzing and extracting information from modern sky surveys is a challenging task in astrophysical studies. We study possibilities of parameterizing stars and interstellar medium from multicolor photometry performed in three modern photometric surveys: GALEX, SDSS, and 2MASS. For this purpose, we have developed a method to estimate stellar radius from effective temperature and gravity with the help of evolutionary tracks and model stellar atmospheres. In accordance with the evolution rate at every point of the evolutionary track, star formation rate, and initial mass function, a weight is assigned to the resulting value of radius that allows us to estimate the radius more accurately. The method is verified for the most populated areas of the Hertzsprung-Russell diagram: main-sequence stars and red giants, and it was found to be rather precise (for main-sequence stars, the average relative error of radius and its standard deviation are 0.03% and 3.87%, respectively).

  20. AVOCADO: A Virtual Observatory Census to Address Dwarfs Origins

    CERN Document Server

    Sánchez-Janssen, Rubén

    2011-01-01

    Dwarf galaxies are by far the most abundant of all galaxy types, yet their properties are still poorly understood -especially due to the observational challenge that their intrinsic faintness represents. AVOCADO aims at establishing firm conclusions on their formation and evolution by constructing a homogeneous, multiwavelength dataset for a statistically significant sample of several thousand nearby dwarfs (-18 < Mi < -14). Using public data and Virtual Observatory tools, we have built GALEX+SDSS+2MASS spectral energy distributions that are fitted by a library of single stellar population models. Star formation rates, stellar masses, ages and metallicities are further complemented with structural parameters that can be used to classify them morphologically. This unique dataset, coupled with a detailed characterization of each dwar's environment, allows for a fully comprehensive investigation of their origins and to track the (potential) evolutionary paths between the different dwarf types.

  1. AVOCADO: A Virtual Observatory Census to Address Dwarfs Origins

    Science.gov (United States)

    Sánchez-Janssen, Rubén; Sánchez-Janssen

    2011-12-01

    Dwarf galaxies are by far the most abundant of all galaxy types, yet their properties are still poorly understood-especially due to the observational challenge that their intrinsic faintness represents. AVOCADO aims at establishing firm conclusions on their formation and evolution by constructing a homogeneous, multiwavelength dataset for a statistically significant sample of several thousand nearby dwarfs (-18 < Mi < -14). Using public data and Virtual Observatory tools, we have built GALEX+SDSS+2MASS spectral energy distributions that are fitted by a library of single stellar population models. Star formation rates, stellar masses, ages and metallicities are further complemented with structural parameters that can be used to classify them morphologically. This unique dataset, coupled with a detailed characterization of each dwarf's environment, allows for a fully comprehensive investigation of their origins and to track the (potential) evolutionary paths between the different dwarf types.

  2. NUV-IR colours of red sequence galaxies in local clusters

    CERN Document Server

    Rawle, Timothy D; Lucey, John R; Hudson, Michael J; Wegner, Gary A

    2008-01-01

    We present GALEX near-UV (NUV) and 2MASS J band photometry for red sequence galaxies in local clusters. We define quiescent samples according to a strict emission threshold, removing galaxies with very recent star formation. We analyse the NUV-J colour-magnitude relation (CMR) and find that the intrinsic scatter is an order of magnitude larger than for the analogous optical CMR (~0.35 rather than 0.05 mag), in agreement with previous studies. Comparing the NUV-J colours with spectroscopically-derived stellar population parameters, we find a strong (> 5.5sigma) correlation with metallicity, only a marginal trend with age, and no correlation with the alpha/Fe ratio. We explore the origin of the large scatter and conclude that neither aperture effects nor the UV upturn phenomenon contribute significantly. We show that the scatter could be attributed to simple `frosting' by either a young or a low metallicity subpopulation.

  3. An Atlas of Galaxy Spectral Energy Distributions from the Ultraviolet to the Mid-Infrared

    CERN Document Server

    Brown, Michael J I; Smith, J -D T; da Cunha, Elisabete; Jarrett, T H; Imanishi, Masatoshi; Armus, Lee; Brandl, Bernhard R; Peek, J E G

    2013-01-01

    We present an atlas of 129 spectral energy distributions for nearby galaxies, with wavelength coverage spanning from the UV to the mid-infrared. Our atlas spans a broad range of galaxy types, including ellipticals, spirals, merging galaxies, blue compact dwarfs and luminous infrared galaxies. We have combined ground-based optical drift-scan spectrophotometry with infrared spectroscopy from Spitzer and Akari, with gaps in spectral coverage being filled using MAGPHYS spectral energy distribution models. The spectroscopy and models were normalized, constrained and verified with matched-aperture photometry measured from Swift, GALEX, SDSS, 2MASS, Spitzer and WISE images. The availability of 26 photometric bands allowed us to identify and mitigate systematic errors present in the data. Comparison of our spectral energy distributions with other template libraries and the observed colors of galaxies indicates that we have smaller systematic errors than existing atlases, while spanning a broader range of galaxy types...

  4. Peering through the dust: NuSTAR observations of two first-2MASS red quasars

    DEFF Research Database (Denmark)

    LaMassa, Stephanie M.; Ricarte, Angelo; Glikman, Eilat;

    2016-01-01

    Some reddened quasars appear to be transitional objects in the paradigm of merger-induced black hole growth/galaxy evolution, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer...

  5. VizieR Online Data Catalog: WISE and 2MASS photometry of M giant stars (Li+, 2016)

    Science.gov (United States)

    Li, J.; Smith, M. C.; Zhong, J.; Hou, J.; Carlin, J. L.; Newberg, H. J.; Liu, C.; Chen, L.; Li, L.; Shao, Z.; Small, E.; Tian, H.

    2016-08-01

    We cross-matched our LAMOST spectroscopically confirmed sample of M giants, M dwarfs, and QSOs (see section 2) to the ALLWISE Source Catalog in the NASA/IPAC Infrared Science Archive, using a search radius of 3". We also applied some cuts detailed in section 3. (1 data file).

  6. Cost comparison of 2 mass vaccination campaigns against influenza A H1N1 in New York City.

    Science.gov (United States)

    Kansagra, Susan M; McGinty, Meghan D; Morgenthau, Beth Maldin; Marquez, Monica L; Rosselli-Fraschilla, Annmarie; Zucker, Jane R; Farley, Thomas A

    2012-07-01

    Objectives. We estimated and compared total costs and costs per dose administered for 2 influenza A 2009 monovalent vaccine campaigns in New York City: an elementary school-located campaign targeting enrolled children aged 4 years and older, and a community-based points-of-dispensing campaign for anyone aged 4 years and older. Methods. We determined costs from invoices or we estimated costs. We obtained vaccination data from the Citywide Immunization Registry and reports from the community points of dispensing. Results. The school campaign delivered approximately 202,089 vaccines for $17.9 million and $88 per dose. The community campaign delivered 49,986 vaccines for $7.6 million and $151 per dose. At projected capacity, the school campaign could have delivered 371,827 doses at $53 each or $13 each when we excluded the value of in-kind resources. The community points of dispensing could have administered 174,000 doses at $51 each or $24 each when we excluded the value of in-kind resources. Conclusions. The school campaign delivered vaccines at a lower cost per dose than did the community campaign. Had demand been higher, both campaigns may have delivered vaccine at lower, more comparable cost per dose.

  7. Peering Through the Dust. II. XMM-Newton  Observations of Two Additional FIRST-2MASS Red Quasars

    Science.gov (United States)

    Glikman, Eilat; LaMassa, Stephanie; Piconcelli, Enrico; Urry, Meg; Lacy, Mark

    2017-10-01

    We obtained XMM-Newton observations of two highly luminous dust-reddened quasars, F2M1113+1244 and F2M1656+3821, that appear to be in the early, transitional phase predicted by merger-driven models of quasar/galaxy co-evolution. These sources have been well studied at optical through mid-infrared wavelengths and are growing relatively rapidly, with Eddington ratios > 30 % . Their black hole masses are relatively small compared to their host galaxies, placing them below the {M}{BH}{--}{L}{bulge} relation. We find that for both sources, an absorbed power-law model with 1%–3% of the intrinsic continuum scattered or leaked back into the line of sight best fits their X-ray spectra. We measure the absorbing column density (N H ) and constrain the dust-to-gas ratios in these systems, finding that they lie well below the Galactic value. This, combined with the presence of broad emission lines in their optical and near-infrared spectra, suggests that the dust absorption occurs far from the nucleus and in the host galaxy, while the X-rays are mostly absorbed in the nuclear, dust-free region within the sublimation radius. We also compare the quasars’ absorption-corrected, rest-frame X-ray luminosities (2–10 keV) to their rest-frame infrared luminosities (6 μm) and find that red quasars, similar to other populations of luminous obscured quasars, are either underluminous in X-rays or overluminous in the infrared.

  8. LOW-MASS TERTIARY COMPANIONS TO SPECTROSCOPIC BINARIES. I. COMMON PROPER MOTION SURVEY FOR WIDE COMPANIONS USING 2MASS

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Peter R. [Department of Physics and Astronomy, P.O. Box 3003, Franklin and Marshall College, Lancaster, PA 17604 (United States); Burgasser, Adam J. [Department of Physics, University of California, San Diego, CA 92093 (United States); Faherty, Jacqueline K. [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10034 (United States); Kirkpatrick, J. Davy, E-mail: peter.allen@fandm.edu [IPAC, California Institute of Technology, Pasadena, CA 91125 (United States)

    2012-08-15

    We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the Two Micron All Sky Survey Point Source Catalog and follow-up observations with the KPNO and CTIO 4 m telescopes. Note that this sample is not volume complete but volume limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200 AU to 10,000 AU ({approx}10'' {yields} {approx} 10'). From 77 sources followed-up to date, we recover 11 previously known tertiaries, 3 previously known candidate tertiaries, of which 2 are spectroscopically confirmed and 1 rejected, and 3 new candidates, of which 2 are confirmed and 1 rejected. This yields an estimated wide tertiary fraction of 19.5{sup +5.2}{sub -3.7}%. This observed fraction is consistent with predictions set out in star formation simulations where the fraction of wide, low-mass companions to spectroscopic binaries is >10%.

  9. A refined protocol for calculating air flow rate of naturally-ventilated broiler barns based on co2 mass balance

    Directory of Open Access Journals (Sweden)

    Luciano Barreto-Mendes

    2014-01-01

    Full Text Available Este estudio se realizó para evaluar protocolos relativamente simples para el monitoreo de la tasa de ventilación (TV en instalaciones pecuarias con ventilación natural (ENV. Los protocolos de ensayo se aplicaron primero a una instalación de pollos de engorde mecánicamente ventilada (EMV, donde TV se estimó con mayor precisión y luego se utilizaron para calcular la TV en la ENV. Las concentraciones de CO2 se midieron con dos esquemas de muestreo diferentes: (S1 la media de las mediciones al interior y a lo largo de la longitud de la instalación a dos alturas de 0,5 m y 1,5 m del suelo; y (S2 igual que la anterior pero con las mediciones de concentración fueron realizadas únicamente a 0,5 m del suelo. La tasa de producción de CO2 metabólico dinámico de las aves se predijo con dos algoritmos diferentes: (A1 el mantenimiento constante durante los periodos de luz y oscuridad, y (A2 que varía con la actividad de los animales sobre una base horaria. Los resultados demostraron que la combinación de S2 con A1 o A2 presentó la mejor estimación de TV en el ENV.

  10. Peering through the dust: NuSTAR observations of two first-2MASS red quasars

    DEFF Research Database (Denmark)

    LaMassa, Stephanie M.; Ricarte, Angelo; Glikman, Eilat

    2016-01-01

    Some reddened quasars appear to be transitional objects in the paradigm of merger-induced black hole growth/galaxy evolution, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer...

  11. The Solar Neighborhood. XXXIII. Parallax Results from the CTIOPI 0.9m Program: Trigonometric Parallaxes of Nearby Low-Mass Active and Young Systems

    CERN Document Server

    Riedel, Adric R; Henry, Todd J; Subasavage, John P; Jao, Wei-Chun; Malo, Lison; Rodriguez, David R; White, Russel J; Gies, Douglas R; Dieterich, Sergio B; Winters, Jennifer G; Davison, Cassy L; Nelan, Edmund P; Blunt, Sarah C; Cruz, Kelle L; Rice, Emily L; Ianna, Philip A

    2014-01-01

    We present basic observational data and association membership analysis for 45 young and active low-mass stellar systems from the ongoing RECONS photometry and astrometry program at the Cerro Tololo Inter-American Observatory. Most of these systems have saturated X-ray emission (log(Lx/Lbol) > -3.5) based on X-ray fluxes from the ROSAT All-Sky Survey, and many are significantly more luminous than main-sequence stars of comparable color. We present parallaxes and proper motions, Johnson-Kron-Cousins VRI photometry, and multiplicity observations from the CTIOPI program on the CTIO 0.9m telescope. To this we add low-resolution optical spectroscopy and line measurements from the CTIO 1.5m telescope, and interferometric binary measurements from the Hubble Space Telescope Fine Guidance Sensors. We also incorporate data from published sources: JHKs photometry from the 2MASS point source catalog; X-ray data from the ROSAT All-Sky Survey; and radial velocities from literature sources. Within the sample of 45 systems, ...

  12. VizieR Online Data Catalog: Early-type galaxies at z<0.04 star formation rates (Vaddi+, 2016)

    Science.gov (United States)

    Vaddi, S.; O'Dea, C. P.; Baum, S. A.; Whitmore, S.; Ahmed, R.; Pierce, K.; Leary, S.

    2016-05-01

    The nearby galaxy sample was selected from the Two Micron All Sky Survey (2MASS; Jarrett et al. 2003AJ....125..525J) that has an apparent Ks band (2.2um) magnitude of 13.5 and brighter and whose positions correlate with the Chandra archive of ACIS-I and ACIS-S observations (C. Jones 2015, private communication). We examine observations in multiple wavelengths for this study, namely, radio, IR, and UV. IR observations were collected from the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010AJ....140.1868W) and 2MASS (Jarrett et al. 2003AJ....125..525J). Rather than use the existing cataloged values, we chose to perform photometry on 2MASS Ks band images and WISE band images (see section 3.1). Radio data for our sample are drawn from several resources: the NRAO VLA Sky Survey (NVSS; Condon et al. 1998, VIII/65), Faint Images of the Radio Sky at Twenty-centimeters (FIRST; Becker et al. 1995ApJ...450..559B, see VIII/92), and the Sydney University Molonglo Sky Survey (SUMSS; Mauch et al. 2003, VIII/81). Far-UV (FUV) and near-UV (NUV) magnitudes are collected from the Galaxy Evolution Survey (GALEX) GR6 release. (2 data files).

  13. Long-term Multiwavelength Observations of Polars

    Science.gov (United States)

    Santana, Joshua; Mason, Paul A.

    2016-06-01

    Polars are cataclysmic variables with the highest magnetic field strengths (10-250 MG). Matter is accreted after being funneled by the strong magnetic field of the white dwarf. We perform a meta-study of multi-wavelength data of polars. Many polars have been observed in surveys, such as SDSS, 2MASS, ROSAT, just to name a few. Some polars have now been detected by the JVLA, part of an expanding class of radio CVs. A large subset of polars have long-term optical light curves from CRTS and AAVSO. We suggest that the long term light curves of polars display a variety of signature behaviors and may be grouped accordingly. Additional characteristics such a binary period, magnetic field strengths, X-ray properties, and distance estimates are examined in context with long-term observations.

  14. XMM-Newton Observation of the {\\alpha} Persei Cluster

    CERN Document Server

    Pillitteri, Ignazio; Wolk, Scott J; Syal, Megan Bruck

    2013-01-01

    We report on the analysis of an archival observation of part of the {\\alpha} Persei cluster obtained with XMM-Newton. We detected 102 X-ray sources in the band 0.3-8.0 keV, of which 39 of them are associated with the cluster as evidenced by appropriate magnitudes and colors from 2MASS photometry. We extend the X-ray Luminosity Distribution (XLD) for M dwarfs, to add to the XLD found for hotter dwarfs from spatially extensive surveys of the whole cluster by ROSAT. Some of the hotter stars are identified as a background, possible slightly older group of stars at a distance of approximately 500 pc.

  15. Swift follow-up of 1RXS J194211.9+255552

    DEFF Research Database (Denmark)

    Sidoli, L.; Fiocchi, M.; Bird, A. J.

    2011-01-01

    Following the INTEGRAL/JEM-X detection of the unidentified source 1RXS J194211.9+255552 (ATel #3816) on December 18, we asked for a Swift/XRT follow-up observation. Swift observed the source field on December 21, 2011 at 06:10:09.7 (UTC), with a net exposure of 1756 s. Within the ROSAT error circle......MASS All-Sky Catalog of Point Sources, 19421116+2556056 (J=13.479, H=12.834, K=12.793 mag; although we note that the 2MASS image indicates a blend of two stars, the brighter more consistent with the XRT position), as well as a single star in the USNO-B1.0 catalog, 1159-0412038, at 1.62 arcsec offset...

  16. Liquid chromatography/negative electrospray ionization ion trap MS(2) mass spectrometry application for the determination of microcystins occurrence in Southern Portugal water reservoirs.

    Science.gov (United States)

    Rodrigues, M A; Reis, M P; Mateus, M C

    2013-11-01

    Microcystins (MCs) are toxins produced by cyanobacteria which are common organisms in the phytoplankton of eutrophic lakes, rivers and freshwater reservoirs. In the present work, a novel method of liquid chromatography-electrospray ion trap tandem mass spectrometry (LC/ESI/Ion trap-MS/MS), operated in the negative ionization mode, was developed for the analysis of these cyanotoxins. The method was applied to determine the amounts of total microcystins-LR, -YR and -RR in two water reservoirs in Southern Portugal, namely Alqueva and Beliche. A total of 30 water samples were analysed along 2011. Solid phase extraction (SPE) was used for sample cleaning-up and analyte enrichment. The extracted toxins were separated on a C18 column with a gradient of acetonitrile/water with 0.1% formic acid. Detection of microcystins was carried out using multiple reaction monitoring (MRM) in the negative polarity mode, as this method gave a higher selectivity. The MC-RR, YR and LR quantification limits were 17.9, 31.7 and 15.8 ng/L, respectively; quite below the limits recommended by WHO guidelines for drinking water (1 μg/L). Total MC highest concentrations were found in the warm months of June, July and September in Alqueva sampling sites, with concentrations of MC LR and RR ranging 17-344 and 25-212 ng/L, respectively, showing comparable results for MC-RR and LR and slightly lower concentration of MC-YR. Detected values for Beliche reservoir were below quantification limits.

  17. Simultaneous Multiwavelength Observations of Magnetic Activity in Ultracool Dwarfs. IV. The Active, Young Binary NLTT 33370 AB (=2MASS J13142039+1320011)

    CERN Document Server

    Williams, P K G; Irwin, J; Berta-Thompson, Z K; Charbonneau, D

    2014-01-01

    We present multi-epoch simultaneous radio, optical, H{\\alpha}, UV, and X-ray observations of the active, young, low-mass binary NLTT 33370 AB (blended spectral type M7e). This system is remarkable for its extreme levels of magnetic activity: it is the most radio-luminous ultracool dwarf (UCD) known, and here we show that it is also one of the most X-ray luminous UCDs known. We detect the system in all bands and find a complex phenomenology of both flaring and periodic variability. Analysis of the optical light curve reveals the simultaneous presence of two periodicities, 3.7859 $\\pm$ 0.0001 and 3.7130 $\\pm$ 0.0002 hr. While these differ by only ~2%, studies of differential rotation in the UCD regime suggest that it cannot be responsible for the two signals. The system's radio emission consists of at least three components: rapid 100% polarized flares, bright emission modulating periodically in phase with the optical emission, and an additional periodic component that appears only in the 2013 observational cam...

  18. Cosmic ray antiproton measurements in the 4-19 GeV energy range using the NMSU/WiZard-matter antimatter superconducting spectrometer 2 (MASS2)

    Energy Technology Data Exchange (ETDEWEB)

    Basini, G.; Bongiorno, F. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Brunetti, M.T.; Codini, A.; Grimani, C. [Perugia Univ. (Italy)]|[INFN, Perugia (Italy); De Pascale, M.P. [Rome Univ. `Tor Vergata` (Italy)]|[INFN, Rome (Italy); Hof, M. [Siegen Univ. (Germany). Fachbereich Physik; Golden, R.L.; Stochaj, S.J. [New Mexico State Univ., Las Cruces, NM (United States). Particle Astrophysics Lab.; Brancaccio, F.M. [Florence Univ. (Italy)]|[INFN, Florence (Italy)

    1995-09-01

    The p/p-ratio from 4 to 19 GeV has been measured using the NMSU/WiZard balloon borne matter antimatter superconducting spectrometer (MASS2) instrument. This is the first confirmation of the cosmic ray antiproton component made in this energy range since their discovery in 1979. The MASS2 instrument is an updated version of the instrument flown in 1979. The p/p- ratio is 1.52x10{sup -}4.

  19. Alteration of hyaloclastites in the HSDP 2 Phase 1 Drill Core: 2. Mass balance of the conversion of sideromelane to palagonite and chabazite

    Science.gov (United States)

    Walton, Anthony W.; Schiffman, Peter; MacPherson, G. L.

    2005-09-01

    The Hawaii Scientific Drilling Project 2 Phase 1 core permits study of each stage of alteration of basalt glass during burial because stages of the process are separated vertically. Previous work has shown that alteration of hyaloclastite occurs progressively. The latest stage observed in the Phase 1 core involves marginal replacement of sideromelane in shards with palagonite while simultaneously forming chabazite in pores. The basic reaction at this stage is sideromelane + components from pore waters = palagonite + chabazite + components to pore waters. Mass balance calculations show that Fe was virtually immobile in this process, being retained in palagonite. Na, Ca, Ba, P, Al, and Si were lost during palagonitization and not fully consumed in making chabazite. Mg was lost during palagonitization but retained elsewhere in smectite. K, Rb, and Sr were extracted from pore waters and enriched in the sum of the alteration products. The amount of enrichment depended upon the amount of chabazite present, which depended upon the porosity when chabazite formed. Ti, Y, U, Zr, Nb, REE, and Th were enriched in palagonite, compared to sideromelane, but were absent in chabazite. Mass balance of all phases for the entire alteration process (including earlier stages) was not possible because poorly consolidated samples do not yield accurate modal values of phases, trace element analysis of smectite was not possible, and exchange with lavas and intrusions in the succession cannot be evaluated. Calculations indicate that too little of major oxides, except Na2O, was released during palagonitization to account for the amount of smectite observed in hyaloclastites. The results of this study, and several others published in the literature, indicate that under various circumstances palagonitization will consume particular elements from pore fluid or release them to it. Such mobility implies that the hydrology of the particular system and the composition of the dissolved solids in the pore water will control whether palagonitization is a source or sink of elements. The potential exists that palagonitization of basalt glass is an important source or sink of elements for seawater and fluids circulating in the ocean crust.

  20. Weak-lensing-inferred scaling relations of galaxy clusters in the RCS2: mass-richness, mass-concentration, mass-bias and more

    CERN Document Server

    van Uitert, Edo; Hoekstra, Henk; Semboloni, Elisabetta; Gladders, Michael D; Yee, H K C

    2016-01-01

    We study a sample of ~10^4 galaxy clusters in the redshift range 0.2 5x10^13 h_70^-1 M_sun, discovered in the second Red-sequence Cluster Survey (RCS2). The depth and excellent image quality of the RCS2 enable us to detect the cluster-mass cross-correlation up to z~0.7. To obtain cluster masses, concentrations and halo biases, we fit a cluster halo model simultaneously to the lensing signal and to the projected density profile of red-sequence cluster members, as the latter provides tight constraints on the cluster miscentring distribution. We parametrise the mass-richness relation as M_200 = A x (N_200/20)^alpha, and find A = (16.7 +- 1.2) x 10^13 h_70^-1 M_sun and alpha = 0.73 +- 0.09 at low redshift (0.2

  1. Evolution of the NASA/IPAC Extragalactic Database (NED) into a Data Mining Discovery Engine

    Science.gov (United States)

    Mazzarella, Joseph M.; NED Team

    2017-06-01

    We review recent advances and ongoing work in evolving the NASA/IPAC Extragalactic Database (NED) beyond an object reference database into a data mining discovery engine. Updates to the infrastructure and data integration techniques are enabling more than a 10-fold expansion; NED will soon contain over a billion objects with their fundamental attributes fused across the spectrum via cross-identifications among the largest sky surveys (e.g., GALEX, SDSS, 2MASS, AllWISE, EMU), and over 100,000 smaller but scientifically important catalogs and journal articles. The recent discovery of super-luminous spiral galaxies exemplifies the opportunities for data mining and science discovery directly from NED's rich data synthesis. Enhancements to the user interface, including new APIs, VO protocols, and queries involving derived physical quantities, are opening new pathways for panchromatic studies of large galaxy samples. Examples are shown of graphics characterizing the content of NED, as well as initial steps in exploring the database via interactive statistical visualizations.

  2. Broad-band spectral energy distribution of 3000 Angstroem break quasars from the Sloan Digital Sky Survey

    CERN Document Server

    Meusinger, H; Mirhosseini, A; Pertermann, F

    2016-01-01

    The Sloan Digital Sky Survey (SDSS) discovered a few unusual quasars with a characteristic break in the continuum around 3000 A that neither shows the typical structure of broad absorption line (BAL) troughs nor is explained by typical intrinsic dust reddening. We used the method of Kohonen self-organising maps for a systematical search for quasars with such properties in the SDSS spectra archive. We constructed a sample of 23 quasars classified as 3000 A break quasars and two comparison samples of quasars with similar properties, to some extent, but also showing typical BAL features. We computed ensemble-averaged broad-band SEDs based on archival data from SDSS, GALEX, 2MASS, UKIDSS, and WISE. The SEDs were corrected for intrinsic dust absorption by the comparison with the average SED of normal quasars. The de-reddened arithmetic median composite SED of the 3000 A break quasars is found to be indistinguishable from that of the unusual BAL quasars. We conclude that 3000 A break quasars are most likely extreme...

  3. A search for new hot subdwarfs stars by means of Virtual Observatory tools.

    Science.gov (United States)

    Solano, E.; Pérez-Fernández, E.; Ulla, A.; Oreiro, R.; Rodrigo, C.

    2017-03-01

    We present here a selection strategy to find new, uncatalogued hot subdwarfs making use of Virtual Observatory (VO) tools. We used large area catalogues (GALEX, SDSS, Super-Cosmos, 2MASS) to retrieve photometric and astrometric information of stellar objects. To these objects, we applied colour and proper motion filters, together with an effective temperature cut-off, aimed at separating hot subdwarfs from other blue objects such as white dwarfs, cataclysmic variables or main sequence OB stars. As a result, we obtained 437 new, uncatalogued hot subdwarf candidates, which represents an increase of 17% in the census of known hot subdwarfs. Visual inspection of the 68 candidates with SDSS specrum showed that 65 can be classified as hot subdwarfs: 5 sdOs, 25 sdOBs and 35 sdBs. This success rate above 95 per cent proves the robustness and efficiency of our methodology. Taking advantage of the VOSA capabilities, we built the Spectral Energy Distribution (SED) of our candidates. 45 per cent of the SEDs showed infrared excesses, a signature of their probable binary nature. The stellar companions of the binary systems so detected are expected to be late-type main sequence stars. A more detailed description of the methodology, the analysis and results can be found at Pérez-Fernández et al. (2016)

  4. SOURCE EXPLORER: Towards Web Browser Based Tools for Astronomical Source Visualization and Analysis

    Science.gov (United States)

    Young, M. D.; Hayashi, S.; Gopu, A.

    2014-05-01

    As a new generation of large format, high-resolution imagers come online (ODI, DECAM, LSST, etc.) we are faced with the daunting prospect of astronomical images containing upwards of hundreds of thousands of identifiable sources. Visualizing and interacting with such large datasets using traditional astronomical tools appears to be unfeasible, and a new approach is required. We present here a method for the display and analysis of arbitrarily large source datasets using dynamically scaling levels of detail, enabling scientists to rapidly move from large-scale spatial overviews down to the level of individual sources and everything in-between. Based on the recognized standards of HTML5+JavaScript, we enable observers and archival users to interact with their images and sources from any modern computer without having to install specialized software. We demonstrate the ability to produce large-scale source lists from the images themselves, as well as overlaying data from publicly available source ( 2MASS, GALEX, SDSS, etc.) or user provided source lists. A high-availability cluster of computational nodes allows us to produce these source maps on demand and customized based on user input. User-generated source lists and maps are persistent across sessions and are available for further plotting, analysis, refinement, and culling.

  5. Galaxy And Mass Assembly (GAMA): Panchromatic Data Release (far-UV --- far-IR) and the low-z energy budget

    CERN Document Server

    Driver, Simon P; Andrews, Stephen K; Davies, Luke J; Kafle, Prajwal R; Lange, Rebecca; Moffett, Amanda J; Mannering, Elizabeth; Robotham, Aaron S G; Vinsen, Kevin; Alpaslan, Mehmet; Andrae, Ellen; Baldry, Ivan K; Bauer, Amanda E; Bamford, Steven P; Bland-Hawthorn, Joss; Bourne, Nathan; Brough, Sarah; Brown, Michael J I; Cluver, Michelle E; Croom, Scott; Colless, Matthew; Conselice, Christopher J; da Cunha, Elisabete; De Propris, Roberto; Drinkwater, Michael; Dunne, Loretta; Eales, Steve; Edge, Alastair; Frenk, Carlos; Graham, Alister W; Grootes, Meiert; Holwerda, Benne W; Hopkins, Andrew M; Ibar, Edo; van Kampen, Eelco; Kelvin, Lee S; Jarrett, Tom; Jones, D Heath; Lara-Lopez, Maritza A; Lopez-Sanchez, Angel R; Liske, Jochen; Loveday, Jon; Maddox, Steve J; Madore, Barry; Meyer, Martin; Norberg, Peder; Penny, Samantha J; Phillipps, Stephen; Popescu, Cristina; Tuffs, Richard J; Peacock, John A; Pimbblet, Kevin A; Rowlands, Kate; Sansom, Anne E; Seibert, Mark; Smith, Matthew W L; Sutherland, Will J; Taylor, Edward N; Valiante, Elisabetta; Wang, Lingyu; Wilkins, Stephen M; Williams, Richard

    2015-01-01

    We present the GAMA Panchromatic Data Release (PDR) constituting over 230deg$^2$ of imaging with photometry in 21 bands extending from the far-UV to the far-IR. These data complement our spectroscopic campaign of over 300k galaxies, and are compiled from observations with a variety of facilities including: GALEX, SDSS, VISTA, WISE, and Herschel, with the GAMA regions currently being surveyed by VST and scheduled for observations by ASKAP. These data are processed to a common astrometric solution, from which photometry is derived for 221,373 galaxies with r<19.8 mag. Online tools are provided to access and download data cutouts, or the full mosaics of the GAMA regions in each band. We focus, in particular, on the reduction and analysis of the VISTA VIKING data, and compare to earlier datasets (i.e., 2MASS and UKIDSS) before combining the data and examining its integrity. Having derived the 21-band photometric catalogue we proceed to fit the data using the energy balance code MAGPHYS. These measurements are ...

  6. The Effects of Close Companions (and Rotation) on the Magnetic Activity of M Dwarfs

    CERN Document Server

    Morgan, Dylan P; Garcés, Ane; Catalán, Silvia; Dhital, Saurav; Fuchs, Miriam; Silvestri, Nicole M

    2012-01-01

    We present a study of close white dwarf and M dwarf (WD+dM) binary systems and examine the effect that a close companion has on the magnetic field generation in M dwarfs. We use a base sample of 1602 white dwarf -- main sequence binaries from Rebassa et al. to develop a set of color cuts in GALEX, SDSS, UKIDSS, and 2MASS color space to construct a sample of 1756 WD+dM high-quality pairs from the SDSS DR8 spectroscopic database. We separate the individual WD and dM from each spectrum using an iterative technique that compares the WD and dM components to best-fit templates. Using the absolute height above the Galactic plane as a proxy for age, and the H{\\alpha} emission line as an indicator for magnetic activity, we investigate the age-activity relation for our sample for spectral types \\leqM7. Our results show that early-type M dwarfs (\\leqM4) in close binary systems are more likely to be active and have longer activity lifetimes compared to their field counterparts. However, at a spectral type of M5 (just pas...

  7. Discovery of superstrong, fading, iron line emission and double-peaked Balmer lines of the galaxy SDSSJ0952+2143 - the light echo of a huge flare

    CERN Document Server

    Komossa, S; Wang, T; Ajello, M; Ge, J; Greiner, J; Lü, H; Salvato, M; Saxton, R; Shan, H; Xu, D; Yuan, W

    2008-01-01

    We report the discovery of superstrong, fading, high-ionization iron line emission in the galaxy SDSSJ095209.56+214313.3 (SDSSJ0952+2143 hereafter), which must have been caused by an X-ray outburst of large amplitude. SDSSJ0952+2143 is unique in its strong multiwavelength variability; such a broadband emission-line and continuum response has not been observed before. The strong iron line emission is accompanied by unusual Balmer line emission with a broad base, narrow core and double-peaked narrow horns, and strong HeII emission. These lines, while strong in the SDSS spectrum taken in 2005, have faded away significantly in new spectra taken in December 2007. Comparison of SDSS, 2MASS, GALEX and follow-up GROND photometry reveals variability in the NUV, optical and NIR band. Taken together, these unusual observations can be explained by a giant outburst in the EUV--X-ray band, detected even in the optical and NIR. The intense and variable iron, Helium and Balmer lines represent the ``light echo'' of the flare,...

  8. Multi-wavelength study of 14000 star-forming galaxies from the Sloan Digital Sky Survey

    CERN Document Server

    Izotov, Y I; Fricke, K J; Henkel, C

    2013-01-01

    (abridged) We studied a large sample of ~14000 dwarf star-forming galaxies with strong emission lines selected from the Sloan Digital Sky Survey (SDSS) and distributed in the redshift range of z~0-0.6. We modelled spectral energy distributions (SED) of all galaxies which were based on the SDSS spectra in the visible range of 0.38-0.92 micron and included both the stellar and ionised gas emission. These SEDs were extrapolated to the UV and mid-infrared ranges to cover the wavelength range of 0.1-22 micron. The SDSS spectroscopic data were supplemented by photometric data from the GALEX, SDSS, 2MASS, WISE, IRAS, and NVSS all-sky surveys. We derived global characteristics of the galaxies, such as their element abundances, luminosities, and stellar masses. The luminosities and stellar masses range within the sample over ~5 orders of magnitude, thereby linking low-mass and low-luminosity blue compact dwarf (BCD) galaxies to luminous galaxies, which are similar to high-redshift Lyman-break galaxies (LBGs). The lumi...

  9. Dust emission in star-forming dwarf galaxies: General properties and the nature of the sub-mm excess

    CERN Document Server

    Izotov, Y I; Fricke, K J; Krugel, E; Henkel, C

    2014-01-01

    We studied the global characteristics of dust emission in a large sample of emission-line star-forming galaxies. The sample consists of two subsamples. One subsample (SDSS sample) includes ~4000 compact star-forming galaxies from the SDSS, which were also detected in all four bands at 3.4, 4.6, 12, and 22 mum of the WISE all-sky survey. The second subsample (Herschel sample) is a sample of 28 compact star-forming galaxies observed with Herschel in the FIR range. Data of the Herschel sample were supplemented by the photometric data from the Spitzer observations, GALEX, SDSS, WISE, 2MASS, NVSS, and FIRST surveys, as well as optical and Spitzer spectra and data in sub-mm and radio ranges. It is found that warm dust luminosities of galaxies from the SDSS sample and cold and warm dust luminosities of galaxies from the Herschel sample are strongly correlated with Hbeta luminosities, which implies that one of the main sources of dust heating in star-forming galaxies is ionising UV radiation of young stars. Using the...

  10. Star-formation histories of local luminous infrared galaxies

    CERN Document Server

    Pereira-Santaella, Miguel; Colina, Luis; Miralles-Caballero, Daniel; Pérez-González, Pablo G; Arribas, Santiago; Bellocchi, Enrica; Cazzoli, Sara; Díaz-Santos, Tanio; López, Javier Piqueras

    2015-01-01

    We present the analysis of the integrated spectral energy distribution (SED) from the ultraviolet (UV) to the far-infrared and H$\\alpha$ of a sample of 29 local systems and individual galaxies with infrared (IR) luminosities between 10^11 Lsun and 10^11.8 Lsun. We have combined new narrow-band H$\\alpha$+[NII] and broad-band g, r optical imaging taken with the Nordic Optical Telescope (NOT), with archival GALEX, 2MASS, Spitzer, and Herschel data. The SEDs (photometry and integrated H$\\alpha$ flux) have been fitted with a modified version of the MAGPHYS code using stellar population synthesis models for the UV-near-IR range and thermal emission models for the IR emission taking into account the energy balance between the absorbed and re-emitted radiation. From the SED fits we derive the star-formation histories (SFH) of these galaxies. For nearly half of them the star-formation rate appears to be approximately constant during the last few Gyrs. In the other half, the current star-formation rate seems to be enha...

  11. Far-UV to mid-IR properties of nearby radio galaxies

    CERN Document Server

    de Ruiter, Hans R; Fanti, Roberto; Fanti, Carla

    2015-01-01

    We investigate whether the far-UV continuum of nearby radio galaxies reveals evidence for the presence of star forming or non-stellar components. If a UV excess due to an extra radiation component exists we compare this with other properties such as radio power, optical spectral type and the strength of the emission lines. We also discuss the possible correlation between the ultra-violet flux, IR properties and central black hole mass. We use two sampes of low luminosity radio galaxies with comparable redshifts ($z < 0.2$). Spectral Energy Distributions are constructed using a number of on-line databases: GALEX, SDSS, 2MASS, and WISE. The parameter $XUV$ is introduced, which measures the excess slope of the UV continuum between 4500 and 2000 \\AA, with respect to the UV radiation produced by the underlying old galaxy component. We find that the UV excess is usually small or absent in low luminosity sources, but sets in abruptly at the transition radio power above which we find mostly FRII sources. $XUV$ beh...

  12. The impact of interactions, bars, bulges, and AGN on star formation efficiency in local massive galaxies

    CERN Document Server

    Saintonge, A; Fabello, S; Wang, J; Catinella, B; Genzel, R; Gracia-Carpio, J; Kramer, C; Moran, S; Heckman, T M; Schiminovich, D; Schuster, K; Wuyts, S

    2012-01-01

    Using observations from the GASS and COLD GASS surveys and complementary data from SDSS and GALEX, we investigate the nature of variations in gas depletion time observed across the local massive galaxy population. The large and unbiased COLD GASS sample allows us to assess the relative importance of galaxy interactions, bar instabilities, morphologies and the presence of AGN in regulating star formation efficiency. Both the H2 mass fraction and depletion time vary as a function of the distance of a galaxy from the main sequence in the SFR-M* plane. The longest gas depletion times are found in below-main sequence bulge-dominated galaxies that are either gas-poor, or else on average less efficient than disk-dominated galaxy at converting into stars any cold gas they may have. We find no link between AGN and these long depletion times. The galaxies undergoing mergers or showing signs of morphological disruptions have the shortest molecular gas depletion times, while those hosting strong stellar bars have only ma...

  13. Updated 34-band Photometry for the Sings/KINGFISH Samples of Nearby Galaxies

    Science.gov (United States)

    Dale, D. A.; Cook, D. O.; Roussel, H.; Turner, J. A.; Armus, L.; Bolatto, A. D.; Boquien, M.; Brown, M. J. I.; Calzetti, D.; De Looze, I.; Galametz, M.; Gordon, K. D.; Groves, B. A.; Jarrett, T. H.; Helou, G.; Herrera-Camus, R.; Hinz, J. L.; Hunt, L. K.; Kennicutt, R. C.; Murphy, E. J.; Rest, A.; Sandstrom, K. M.; Smith, J.-D. T.; Tabatabaei, F. S.; Wilson, C. D.

    2017-03-01

    We present an update to the ultraviolet-to-radio database of global broadband photometry for the 79 nearby galaxies that comprise the union of the KINGFISH (Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel) and SINGS (Spitzer Infrared Nearby Galaxies Survey) samples. The 34-band data set presented here includes contributions from observational work carried out with a variety of facilities including GALEX, SDSS, Pan-STARRS1, NOAO, 2MASS, Wide-Field Infrared Survey Explorer, Spitzer, Herschel, Planck, JCMT, and the VLA. Improvements of note include recalibrations of previously published SINGS BVR C I C and KINGFISH far-infrared/submillimeter photometry. Similar to previous results in the literature, an excess of submillimeter emission above model predictions is seen primarily for low-metallicity dwarf or irregular galaxies. This 33-band photometric data set for the combined KINGFISH+SINGS sample serves as an important multiwavelength reference for the variety of galaxies observed at low redshift. A thorough analysis of the observed spectral energy distributions is carried out in a companion paper.

  14. Searching for Distant Galaxy Clusters: Utilizing the Virtual Observatory for Multiwavelength Images and Survey Cross-correlation

    Science.gov (United States)

    Van Duyne, J.; Lucas, R.; Tamura, T.; Rohde, D.

    2004-12-01

    Through the tools and technology made available via the Virtual Observatory, we have explored the multiwavelength properties, survey coverage, and environments of a sample of 71 steep (-1.0 < α < 0.5) spectrum radio sources taken from the Texas Interferometer Radio catalog (Douglas et al. 1996). Through the VLA proposal by Lucas & Chambers (1989), these radio sources were observed with the A-array configuration at 20 cm and 1485 MHz and with 1 full Schmidt SRC-J, high-latitude sky survey plate ( ˜ 6 sq deg) down to J ˜ 22 with the purpose of finding optical counterparts of mid-to-high z galaxy clusters. With the knowledge that this field had been imaged via the Sloan Digital Sky Survey (SDSS DR2, r=22.2), we submitted the coordinates of the Lucas & Chambers survey sources to the VO image access protocol (SIAP) to quickly and efficiently explore the SDSS ugriz 5-band color images of these sources, specifically looking for u-band drop-outs. Additionally, we used this same technique to explore the multiwavelength coverage of this field with all surveys registered with the VO (2MASS, ROSAT, VLA FIRST/NVSS, Chandra, XMM) via ˜ 1 arcminute snapshots. This revealed a multitude of interesting objects, such as double-lobed radio galaxies with bent jets, implying intercluster medium interactions, extremely faint optical sources with point source 2MASS/J-band detections, and the re-discovery of 3C 273. Finally, as a proof of concept, we utilized the VO tool Topcat to cross-correlate the radio and X-ray positions of known galaxy clusters via the RBSC-NVSS Sample (Bauer et al. 2000) and ROSAT Brightest Cluster Sample (Ebeling et al. 1998), resulting in 17 clusters matched at < 15 arcsec separation. These results demonstrate the simple, yet highly effective utility of the Virtual Observatory on a sample data set to reveal scientifically interesting objects on a short timescale. We would like to acknowledge the National Virtual Observatory Summer School for supplying the

  15. Cross Correlations of X-ray and Optically Selected Clusters With Near Infrared and Optical Galaxies

    CERN Document Server

    Sánchez, A G; Böhringer, H; Schücker, P; Sanchez, Ariel G.; Lambas, Diego G.; Boehringer, Hans; Schuecker, Peter

    2005-01-01

    We compute the real-space cluster-galaxy cross-correlation xi_cg(r) using the ROSAT-ESO Flux Limited X-ray (REFLEX) cluster survey, a group catalogue constructed from the final version of the 2dFGRS, and galaxies extracted from 2MASS and APM surveys. This first detailed calculation of the cross-correlation for X-ray clusters and groups, is consistent with previous works and shows that xi_cg(r) can not be described by a single power law. We analyse the clustering dependence on the cluster X-ray luminosity L_X and virial mass M_vir thresholds as well as on the galaxy limiting magnitude. We also make a comparison of our results with those obtained for the halo-mass cross-correlation function in a LambdaCDM N-body simulation to infer the scale dependence of galaxy bias around clusters. Our results indicate that the distribution of galaxies shows a significant anti-bias at highly non-linear small cluster-centric distances (b_cg(r) ~ 0.7), irrespective of the group/cluster virial mass or X-ray luminosity and galaxy...

  16. Swift follow-up of 1RXS J194211.9+255552

    DEFF Research Database (Denmark)

    Sidoli, L.; Fiocchi, M.; Bird, A. J.;

    2011-01-01

    Following the INTEGRAL/JEM-X detection of the unidentified source 1RXS J194211.9+255552 (ATel #3816) on December 18, we asked for a Swift/XRT follow-up observation. Swift observed the source field on December 21, 2011 at 06:10:09.7 (UTC), with a net exposure of 1756 s. Within the ROSAT error circle...... there is only one pointlike source, at the following position (J2000): RA(hh mm ss.s) = 19h42m11.13s, Dec(dd mm ss.s) = +25:56:07.32 (3.6 arcsec error radius). The source light curve is variable on time scale of about 1000 s (similar to the Jem-X light curve). A fit to the XRT spectrum (1-10 keV) with a power......MASS All-Sky Catalog of Point Sources, 19421116+2556056 (J=13.479, H=12.834, K=12.793 mag; although we note that the 2MASS image indicates a blend of two stars, the brighter more consistent with the XRT position), as well as a single star in the USNO-B1.0 catalog, 1159-0412038, at 1.62 arcsec offset...

  17. Compact X-ray Sources in Nearby Galaxy Nuclei

    CERN Document Server

    Colbert, E J M

    1998-01-01

    We have found compact, near-nuclear X-ray sources in 21 (54\\%) of a complete sample of 39 nearby face-on spiral and elliptical galaxies with available ROSAT HRI data. ROSAT X-ray luminosities (0.2 $-$ 2.4 keV) of these compact X-ray sources are $\\sim$10$^{37}

  18. Constraints on Dark Energy, Observable-mass Scaling Relations, Neutrino Properties and Gravity from Galaxy Clusters

    DEFF Research Database (Denmark)

    Rapetti Serra, David Angelo

    Using a data set of 238 cluster detections drawn from the ROSAT All-Sky Survey and X-ray follow-up observations from the Chandra X-ray Observatory and/or ROSAT for 94 of those clusters we obtain tight constraints on dark energy, both luminosity-mass and temperature-mass scaling relations, neutrin...

  19. Updated Models for the Creation of a Low-z QSO Absorber by a Dwarf Galaxy Wind

    CERN Document Server

    Keeney, Brian A; Stocke, John T; Danforth, Charles W; Levesque, Emily M

    2014-01-01

    We present new GALEX images and optical spectroscopy of J1229+02, a dwarf post-starburst galaxy located 81 kpc from the 1585 km/s absorber in the 3C 273 sight line. The absence of H\\alpha\\ emission and the faint GALEX UV fluxes confirm that the galaxy's recent star formation rate is $1$R_{vir}$ are likely intergalactic systems and cannot be identified unambiguously as the circumgalactic material of any one individual galaxy.

  20. Simvastatin but not bezafibrate decreases plasma lipoprotein-associated phospholipase A(2) mass in type 2 diabetes mellitus : Relevance of high sensitive C-reactive protein, lipoprotein profile and low-density lipoprotein (LDL) electronegativity

    NARCIS (Netherlands)

    Constantinides, Alexander; de Vries, Rindert; van Leeuwen, Jeroen J. J.; Gautier, Thomas; van Pelt, L. Joost; Tselepis, Alexandros D.; Lagrost, Laurent; Dullaart, Robin P. F.

    2012-01-01

    Objective: Plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) levels predict incident cardiovascular disease, impacting Lp-PLA(2) as an emerging therapeutic target. We determined Lp-PLA(2) responses to statin and fibrate administration in type 2 diabetes mellitus, and assessed relationship

  1. Long-term, Multiwavelength Light Curves of Ultra-cool Dwarfs: I. An Interplay of Starspots & Clouds Likely Drive the Variability of the L3.5 dwarf 2MASS 0036+18

    CERN Document Server

    Croll, Bryce; Han, Eunkyu; Dalba, Paul A; Radigan, Jacqueline; Morley, Caroline V; Lazarevic, Marko; Taylor, Brian

    2016-01-01

    We present multi-telescope, ground-based, multiwavelength optical and near-infrared photometry of the variable L3.5 ultra-cool dwarf 2MASSW J0036159+182110. We present 22 nights of photometry of 2MASSW J0036159+182110, including 7 nights of simultaneous, multiwavelength photometry, spread over ~120 days allowing us to determine the rotation period of this ultra-cool dwarf to be 3.080 +/- 0.001 hr. Our many nights of multiwavelength photometry allow us to observe the evolution, or more specifically the lack thereof, of the light curve over a great many rotation periods. The lack of discernible phase shifts in our multiwavelength photometry, and that the amplitude of variability generally decreases as one moves to longer wavelengths for 2MASSW J0036159+182110, is generally consistent with starspots driving the variability on this ultra-cool dwarf, with starspots that are ~100 degrees K hotter or cooler than the ~1700 K photosphere. Also, reasonably thick clouds are required to fit the spectra of 2MASSW J0036159...

  2. Simvastatin but not bezafibrate decreases plasma lipoprotein-associated phospholipase A(2) mass in type 2 diabetes mellitus : Relevance of high sensitive C-reactive protein, lipoprotein profile and low-density lipoprotein (LDL) electronegativity

    NARCIS (Netherlands)

    Constantinides, Alexander; de Vries, Rindert; van Leeuwen, Jeroen J. J.; Gautier, Thomas; van Pelt, L. Joost; Tselepis, Alexandros D.; Lagrost, Laurent; Dullaart, Robin P. F.

    2012-01-01

    Objective: Plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) levels predict incident cardiovascular disease, impacting Lp-PLA(2) as an emerging therapeutic target. We determined Lp-PLA(2) responses to statin and fibrate administration in type 2 diabetes mellitus, and assessed

  3. Seismic response of a high-rise isolation structure 2-mass model with pure mass method%高层隔震结构双质点模型的地震响应单纯质点法研究

    Institute of Scientific and Technical Information of China (English)

    刘阳; 刘文光; 何文福; 杨巧荣

    2013-01-01

    Aiming at a two-mass simplified model of a high-rise isolated structure, the pure mass method ( PMM) utilized to calculate quickly earthquake responses of high-rise isolated structures was proposed here. Firstly, the conversion relation between the two-mass simplified model and the archetype was established and the parameters of the two-mass model were determined according to the equivalent criteria for base shear force and energy. And then, two key parameters of stiffness conversion coefficient and mass ratio were obtained to determine seismic responses. The envelope response calculation formulas of the simplified model were proposed based on the energy balance method. The energy balance method and the model conversion relation were used to predict the seismic response envelope values of every layer of the archetype. An engineering example of 22-story high-rise isolated structure was converted into a two-mass simplified model. Then, the effectiveness and analysis accuracy of the pure mass model method were verified. It was shown that computational results of the new method are similar to those with multi-mass model time history analysis method; the calculation time of the proposed method is less, and the model parameters determination is clear and convenient; the new method can be applied to analyze the earthquake responses of high-rise isolated structures.%针对高层隔震结构的双质点简化模型提出了可快速计算其地震响应的单纯质点法,该方法基于基底剪力及能量等效原则来建立简化两质点分析模型与原结构模型之间的转换关系及简化模型的参数取值,推导得到了确定地震反应的两个关键参数:刚度转换系数和质量比.研究基于能量平衡方法提出了高层隔震结构简化分析模型包络反应的计算式,并通过利用能量平衡原理及模型参数转换关系来预测原高层隔震结构的各层地震反应包络值.对22层高层隔震结构工程实例首先进行了双质点模型的转化,其后验证了单纯质点法的有效性和分析精度,分析结果表明新方法计算结果与多质点模型时程分析法计算结果相近,且能包络上部结构各层地震响应.该方法计算量少,参数取值简便,可用于高层隔震结构地震响应的初步分析.

  4. CO2充注量对跨临界轿车空调系统性能的影响%Impact of CO2 mass charge on trans-critical automotive air conditioning system

    Institute of Scientific and Technical Information of China (English)

    刘洪胜; 陈江平; 陈芝久

    2005-01-01

    试验研究了CO2充注量对跨临界轿车空调系统性能的影响.研究表明:CO2充注量对跨临界制冷系统的性能影响很大,存在一个最佳的CO2充注量,此时COP最大;CO2充注量不足,会导致制冷量和COP降低,CO2充注量过多,会导致压缩机耗功大幅度上升;制冷循环随CO2充注量的不同,具有6个特征明显的工作循环.根据这些表现特征,提出了用4个参数作为判断CO2充注量是否合适的特征参数.为确定跨临界制冷系统的最佳充注量、对系统进行优化设计和高效运行控制提供了参考.

  5. VizieR Online Data Catalog: Star Formation Reference Survey (SFRS) (Ashby+, 2011)

    Science.gov (United States)

    Ashby, M. L.; Mahajan, S.; Smith, H. A.; Willner, S. P.; Fazio, G. G.; Raychaudhury, S.; Zezas, A.; Barmby, P.; Bonfini, P.; Cao, C.; Gonzalez-Alfonso, C.; Ishihara, D.; Kaneda, H.; Lyttle, V.; Madden, S.; Papovich, C.; Sturm, E.; Surace, J.; Wu, H.; Zhu, Y. N.

    2013-01-01

    Star formation is arguably the most important physical process in the cosmos. It is a fundamental driver of galaxy evolution and the ultimate source of most of the energy emitted by galaxies. A correct interpretation of star formation rate (SFR) measures is therefore essential to our understanding of galaxy formation and evolution. Unfortunately, however, no single SFR estimator is universally available or even applicable in all circumstances: the numerous galaxies found in deep surveys are often too faint (or too distant) to yield significant detections with most standard SFR measures, and until now there have been no global, multi-band observations of nearby galaxies that span all the conditions under which star-formation is taking place. To address this need in a systematic way, we have undertaken a multi-band survey of all types of star-forming galaxies in the local Universe. This project, the Star Formation Reference Survey (SFRS), is based on a statistically valid sample of 369 nearby galaxies that span all existing combinations of dust temperature, SFR, and specific SFR. Furthermore, because the SFRS is blind with respect to AGN fraction and environment it serves as a means to assess the influence of these factors on SFR. Our panchromatic global flux measurements (including GALEX FUV+NUV, SDSS ugriz, 2MASS JHKs, Spitzer 3-8um, and others) furnish uniform SFR measures and the context in which their reliability can be assessed. This paper describes the SFRS survey strategy, defines the sample, and presents the multi-band photometry collected to date. (7 data files).

  6. NED in the Era of Very Large Extragalactic Surveys

    Science.gov (United States)

    Fadda, Dario; Mazzarella, J. M.; Ogle, P. M.; Madore, B. F.; Ebert, R.; Baker, K.; Chan, H.; Chen, X.; Frayer, C.; Helou, G.; Jacobson, J. D.; LaGue, C.; Lo, T. M.; Pevunova, O.; Schmitz, M.; Terek, S.; Steer, I.

    2014-01-01

    The NASA/IPAC Extragalactic Database (NED) is in the process of rapid expansion both from the growth of the astrophysics literature and from very large sky surveys containing hundreds of millions of objects. Over the last year alone, over 3 million objects from more than 5 thousand journal articles have been folded into NED. In the same time period, approximately 60 million UV sources from the GALEX All-Sky Survey and Medium Imaging Survey catalogs have been fully integrated into the database. A new data processing approach has been developed to fold in very large catalogs. Firstly, a new NED layer is created to contain the entries from a catalog. Subsequently, the new entries are cross-matched with existent NED objects following a rule-based statistical approach. This new layer currently contains approximately 500 million near-infrared sources from the 2MASS Point Source Catalog. In future releases, we expect to fully integrate this catalog while loading a new layer of hundreds of millions of sources from the new All-WISE survey. To make accessible this wealth of new data, NED is undergoing a major user interface upgrade. As a result of a "near-position" search, the new interface is able to display sources from very large catalogs which have not yet been cross-matched with other NED objects. Navigation and searches have been simplified and enriched. For instance, the "by-parameters" search has been completely revamped and long searches are now queued and executed in the background. The latest release includes a new tool to explore galaxy environments and a guide for authors documenting the best practices to publish data in the major astrophysical journals. Researchers are encouraged to visit the NED exhibit for a demonstration of these and other new capabilities.

  7. Old stellar population synthesis: new age and mass estimates for Mayall Ⅱ = G1

    Institute of Scientific and Technical Information of China (English)

    Jun Ma; Richard de Grijs; Zhou Fan; Soo-Chang Rey; Zhen-Yu Wu; Xu Zhou; Jiang-Hua Wu; Zhao-Ji Jiang; Jian-Sheng Chen; Kyungsook Lee; Sangmo Tony Sohn

    2009-01-01

    Mayall Ⅱ = G1 is one of the most luminous globular clusters (GCs) in M31. Here, we determine its age and mass by comparing multicolor photometry with theo-retical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBV RI, and infrared JHK8 2MASS data, we construct the most extensive spectral energy distribution of G1 to date, spanning the wavelength range from 1538 to 20000A. A quantitative comparison with a variety of simple stellar pop-ulation (SSP) models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ~1.7Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates (of order 107M⊙) indicate that G1 is one of the most massive GCs in the Local Group. However, we speculate that the cluster's exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, (1.65±0.63) × 102L⊙ far-ultraviolet-bright, hot, extreme horizontal-branch stars, depend-ing on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar pho-tometry, provided that some of the free parameters can be constrained independently.

  8. A search for new hot subdwarf stars by means of virtual observatory tools II

    Science.gov (United States)

    Pérez-Fernández, E.; Ulla, A.; Solano, E.; Oreiro, R.; Rodrigo, C.

    2016-04-01

    Recent massive sky surveys in different bandwidths are providing new opportunities to modern astronomy. The Virtual Observatory (VO) represents the adequate framework to handle the huge amount of information available and filter out data according to specific requirements. In this work, we applied a selection strategy to find new, uncatalogued hot subdwarfs making use of VO tools. We used large area catalogues like GALEX, Sloan Digital Sky Survey (SDSS), SuperCosmos and Two Micron All Sky Survey (2MASS) to retrieve photometric and astrometric information of stellar objects. To these objects, we applied colour and proper motion filters, together with an effective temperature cutoff, aimed at separating hot subdwarfs from other blue objects such as white dwarfs, cataclysmic variables or main-sequence OB stars. As a result, we obtained 437 new, uncatalogued hot subdwarf candidates. Based on previous results, we expect our procedure to have an overall efficiency of at least 80 per cent. Visual inspection of the 68 candidates with SDSS spectrum showed that 65 can be classified as hot subdwarfs: 5 sdOs, 25 sdOBs and 35 sdBs. This success rate above 95 per cent proves the robustness and efficiency of our methodology. The spectral energy distribution of 45 per cent of the subdwarf candidates showed infrared excesses, a signature of their probable binary nature. The stellar companions of the binary systems so detected are expected to be late-type main-sequence stars. A detailed determination of temperatures and spectral classification of the cool companions will be presented in a forthcoming work.

  9. The Origin of Isolated Early-Type Galaxies: A Multiwavelength Study of Three Systems

    Science.gov (United States)

    Fanelli, Michael N.; Marcum, Pamela M.; Ashley, Trisha L.; Fuse, Christopher R.; O'Toole Appleby, Heather

    2017-01-01

    One major approach to understanding the zero-redshift galaxy population is to distinguish the processes driving passive (internal) evolution of stellar systems from interaction-induced changes. The study of the structure and star formation history of highly isolated systems defines the baseline for quiescent evolution. Isolated early-type galaxies (ETGs) are an especially interesting population, since most ETGs are found in cluster environments. Possible evolutionary paths for isolated ETGs are merged (formerly) compact groups or direct collapse early in cosmic time.As part of our long-term program to identify and explore highly isolated ETGs, we present panchromatic observations of the stars, neutral gas and dust in three highly isolated systems: Mrk 150, KIG 824 and SDSS J235021+141343, a subset of our initial isolated ETG sample. Our goal is to understand the evolutionary paths for these systems, in terms of their merger history, gas fueling and star formation rates. Each system presents diverse properties: Mrk 150 is optically blue and currently forming stars, while KIG 824 is red with no evidence for ongoing star formation; all possess neutral gas. Mrk 150 fits the class of luminous blue compact galaxies [M(V) = -19.2, B-V = 0.47] and possibly represents a link in the evolutionary chain leading to isolated, red and dead systems.We combine GALEX UV photometry, optical images and spectra from the Sloan Survey, IR photometry from 2MASS, WISE and IRAS along with neutral hydrogen observations from the GBT. These data permit us to describe their morphology, quantify the current high-mass star formation rate, and determine the gas and dust content. Derived properties help constrain the evolution of these particular systems in the larger context of ETGs evolving in void-like regions.

  10. Spectral Analysis, Synthesis, & Energy Distributions of Nearby E+A Galaxies Using SDSS-IV MaNGA

    Science.gov (United States)

    Weaver, Olivia A.; Anderson, Miguel Ricardo; Wally, Muhammad; James, Olivia; Falcone, Julia; Liu, Allen; Wallack, Nicole; Liu, Charles; SDSS Collaboration

    2017-01-01

    Utilizing data from the Mapping Nearby Galaxies at APO (MaNGA) Survey (MaNGA Product Launch-4, or MPL-4), of the latest generation of the Sloan Digital Sky Survey (SDSS-IV), we identified nine post-starburst (E+A) systems that lie within the Green Valley transition zone. We identify the E+A galaxies by their SDSS single fiber spectrum and u-r color, then confirmed their classification as post-starburst by coding/plotting methods and spectral synthesis codes (FIREFLY and PIPE3D), as well as with their Spectral Energy Distributions (SEDs) from 0.15 µm to 22 µm, using GALEX, SDSS, 2MASS, and WISE data. We produced maps of gaussian-fitted fluxes, equivalent widths, stellar velocities, metallicities and age. We also produced spectral line ratio diagrams to classify regions of stellar populations of the galaxies. We found that our sample of E+As retain their post-starburst properties across the entire galaxy, not just at their center. We detected matching a trend line in the ultraviolet and optical bands, consistent with the expected SEDs for an E+A galaxy, and also through the J, H and Ks bands, except for one object. We classified one of the nine galaxies as a luminous infrared galaxy, unusual for a post-starburst object. Our group seeks to further study stellar population properties, spectral energy distributions and quenching properties in E+A galaxies, and investigate their role in galaxy evolution as a whole. This work was supported by the Alfred P. Sloan Foundation via the SDSS-IV Faculty and Student Team (FAST) initiative, ARC Agreement #SSP483 to the CUNY College of Staten Island. This work was also supported by grants to The American Museum of Natural History, and the CUNY College of Staten Island through from National Science Foundation.

  11. Beyond The Prime Directive: The MAST Discovery Portal and High Level Science Products

    Science.gov (United States)

    Fleming, Scott W.; Abney, Faith; Donaldson, Tom; Dower, Theresa; Fraquelli, Dorothy A.; Koekemoer, Anton M.; Levay, Karen; Matuskey, Jacob; McLean, Brian; Quick, Lee; Rogers, Anthony; Shiao, Bernie; Thompson, Randy; Tseng, Shui-Ay; Wallace, Geoff; White, Richard L.

    2015-01-01

    The Mikulski Archive for Space Telescopes (MAST) is a NASA-funded archive for a wide range of astronomical missions, primarily supporting space-based UV and optical telescopes. What is less well-known is that MAST provides much more than just a final resting place for primary data products and documentation from these missions. The MAST Discovery Portal is our new search interface that integrates all the missions that MAST supports into a single interface, allowing users to discover (and retrieve) data from other missions that overlap with your targets of interest. In addition to searching MAST, the Portal allows users to search the Virtual Observatory, granting access to data from thousands of collections registered with the VO, including large missions spanning the electromagnetic spectrum (e.g., Chandra, SDSS, Spitzer, 2MASS, WISE). The Portal features table import/export, coordinate-based cross-matching, dynamic chart plotting, and the AstroView sky viewer with footprint overlays. We highlight some of these capabilities with science-driven examples. MAST also accepts High Level Science Products (HLSPs) from the community. These HLSPs are user-generated data products that can be related to a MAST-supported mission. MAST provides a permanent archive for these data with linked references, and integrates it within MAST infrastructure and services. We highlight some of the most recent HLSPs MAST has released, including the HST Frontier Fields, GALEX All-Sky Diffuse Radiation Mapping, a survey of the intergalactic medium with HST-COS, and one of the most complete line lists ever derived for a white dwarf using FUSE AND HST-STIS. These HLSPs generate substantial interest from the community, and are an excellent way to increase visibility and ensure the longevity of your data.

  12. Unravelling the Nature of HD 81032 – A New RS CVn Binary

    Indian Academy of Sciences (India)

    J. C. Pandey; K. P. Singh; S. A. Drake; R. Sagar

    2005-12-01

    BVR photometric and quasi-simultaneous optical spectroscopic observations of the star HD 81032 have been carried out during the years 2000–2004. A photometric period of 18.802 ± 0.07d has been detected for this star. A large group of spots with a migration period of 7.43 ± 0.07 years is inferred from the first three years of the data. H and CaII H and K emissions from the star indicate high chromospheric activity. The available photometry in the BVRIJHK bands is consistent with the spectral type of K0IV previously found for this star.We have also examined the spectral energy distribution of HD 81032 for the presence of an infrared colour excess using the 2MASS JHK and IRAS photometry, but found no significant excess in any band above the normal values expected for a star with this spectral type. We have also analyzed the X-ray emission properties of this star using data obtained by the ROSAT X-ray observatory during its All-Sky Survey phase. An X-ray flare of about 12 hours duration was detected during the two days of X-ray coverage obtained for this star. Its X-ray spectrum, while only containing 345 counts, is inconsistent with a single-temperature component solar-abundance coronal plasma model, but implies either the presence of two or more plasma components, non-solar abundances, or a combination of both of these properties. All of the above properties of HD 81032 suggest that it is a newly identified, evolved RS CVn binary.

  13. Near-UV Sources in the Hubble Ultra Deep Field: The Catalog

    CERN Document Server

    Voyer, Elysse N; Siana, Brian; Gardner, Jonathan P; Quirk, Cori; Teplitz, Harry I

    2009-01-01

    The catalog from the first high resolution U-band image of the Hubble Ultra Deep Field, taken with Hubble's Wide Field Planetary Camera 2 through the F300W filter, is presented. We detect 96 U-band objects and compare and combine this catalog with a Great Observatories Origins Deep Survey (GOODS) B-selected catalog that provides B, V, i, and z photometry, spectral types, and photometric redshifts. We have also obtained Far-Ultraviolet (FUV, 1614 \\AA) data with Hubble's Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) and with Galaxy Evolution Explorer (GALEX). We detected 31 sources with ACS/SBC, 28 with GALEX/FUV, and 45 with GALEX/NUV. The methods of observations, image processing, object identification, catalog preparation, and catalog matching are presented.

  14. Dwarf Detachment and Globular Cluster Formation in Arp 305

    CERN Document Server

    Hancock, M; Struck, C; Giroux, M L; Hurlock, S

    2009-01-01

    Tidal Dwarf Galaxies (TDG), concentrations of interstellar gas and stars in the tidal features of interacting galaxies, have been the subject of much scrutiny. The `smoking gun' that will prove the TDG hypothesis is the discovery of independent dwarf galaxies that are detached from other galaxies, but have clear tidal histories. As part of a search for TDGs we are using GALEX to conduct a large UV imaging survey of interacting galaxies selected from the Arp Atlas. As part of that study, we present a GALEX UV and SDSS and SARA optical study of the gas-rich interacting galaxy pair Arp 305. The GALEX UV data reveal much extended diffuse UV emission and star formation outside the disks including a candidate TDG between the two galaxies. We have used a smooth particle hydrodynamics code to model the interaction and determine the fate of the candidate TDG.

  15. Tidal Dwarf Galaxies, Accretion Tails, and `Beads on a String' in the `Spirals, Bridges, and Tails' Interacting Galaxy Survey

    CERN Document Server

    Smith, Beverly J; Struck, Curtis; Hancock, Mark; Hurlock, Sabrina

    2009-01-01

    We have used the GALEX ultraviolet telescope to study stellar populations and star formation morphology in a well-defined sample of more than three dozen nearby optically-selected pre-merger interacting galaxy pairs. We have combined the GALEX NUV and FUV images with broadband optical maps from the Sloan Digitized Sky Survey to investigate the ages and extinctions of the tidal features and the disks. We have identified a few new candidate tidal dwarf galaxies in this sample, as well as other interesting morphologies such as accretion tails, `beads on a string', and `hinge clumps'. In only a few cases are strong tidal features seen in HI maps but not in GALEX.

  16. Near-UV Sources in the Hubble Ultra Deep Field: The Catalog

    Science.gov (United States)

    Gardner, Jonathan P.; Voyrer, Elysse; de Mello, Duilia F.; Siana, Brian; Quirk, Cori; Teplitz, Harry I.

    2009-01-01

    The catalog from the first high resolution U-band image of the Hubble Ultra Deep Field, taken with Hubble s Wide Field Planetary Camera 2 through the F300W filter, is presented. We detect 96 U-band objects and compare and combine this catalog with a Great Observatories Origins Deep Survey (GOODS) B-selected catalog that provides B, V, i, and z photometry, spectral types, and photometric redshifts. We have also obtained Far-Ultraviolet (FUV, 1614 Angstroms) data with Hubble s Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) and with Galaxy Evolution Explorer (GALEX). We detected 31 sources with ACS/SBC, 28 with GALEX/FUV, and 45 with GALEX/NUV. The methods of observations, image processing, object identification, catalog preparation, and catalog matching are presented.

  17. A Citizen-Science-enabled Comprehensive Search for XUV-disk Galaxies

    Science.gov (United States)

    Thilker, David A.

    2017-03-01

    Initial efforts to identify extended UV disk (XUV-disk) galaxies were confined to nearby targets using image products from early in the GALEX mission. We developed a beta Zooniverse-based citizen science project to address this issue, specifically (1) allowing a dramatically larger galaxy sample by crowd-sourcing blink comparison UV-optical image inspection to volunteers, and (2) incorporating all archived GALEX data for each target considered. We aim to widely deploy this project to the public within the upcoming year.

  18. The Planetary Archive

    Science.gov (United States)

    Penteado, Paulo F.; Trilling, David; Szalay, Alexander; Budavári, Tamás; Fuentes, César

    2014-11-01

    We are building the first system that will allow efficient data mining in the astronomical archives for observations of Solar System Bodies. While the Virtual Observatory has enabled data-intensive research making use of large collections of observations across multiple archives, Planetary Science has largely been denied this opportunity: most astronomical data services are built based on sky positions, and moving objects are often filtered out.To identify serendipitous observations of Solar System objects, we ingest the archive metadata. The coverage of each image in an archive is a volume in a 3D space (RA,Dec,time), which we can represent efficiently through a hierarchical triangular mesh (HTM) for the spatial dimensions, plus a contiguous time interval. In this space, an asteroid occupies a curve, which we determine integrating its orbit into the past. Thus when an asteroid trajectory intercepts the volume of an archived image, we have a possible observation of that body. Our pipeline then looks in the archive's catalog for a source with the corresponding coordinates, to retrieve its photometry. All these matches are stored into a database, which can be queried by object identifier.This database consists of archived observations of known Solar System objects. This means that it grows not only from the ingestion of new images, but also from the growth in the number of known objects. As new bodies are discovered, our pipeline can find archived observations where they could have been recorded, providing colors for these newly-found objects. This growth becomes more relevant with the new generation of wide-field surveys, particularly LSST.We also present one use case of our prototype archive: after ingesting the metadata for SDSS, 2MASS and GALEX, we were able to identify serendipitous observations of Solar System bodies in these 3 archives. Cross-matching these occurrences provided us with colors from the UV to the IR, a much wider spectral range than that

  19. Explosive Growth and Advancement of the NASA/IPAC Extragalactic Database (NED)

    Science.gov (United States)

    Mazzarella, Joseph M.; Ogle, P. M.; Fadda, D.; Madore, B. F.; Ebert, R.; Baker, K.; Chan, H.; Chen, X.; Frayer, C.; Helou, G.; Jacobson, J. D.; LaGue, C.; Lo, T. M.; Pevunova, O.; Schmitz, M.; Terek, S.; Steer, I.

    2014-01-01

    The NASA/IPAC Extragalactic Database (NED) is continuing to evolve in lock-step with the explosive growth of astronomical data and advancements in information technology. A new methodology is being used to fuse data from very large surveys. Selected parameters are first loaded into a new database layer and made available in areal searches before they are cross-matched with prior NED objects. Then a programmed, rule-based statistical approach is used to identify new objects and compute cross-identifications with existing objects where possible; otherwise associations between objects are derived based on positional uncertainties or spatial resolution differences. Approximately 62 million UV sources from the GALEX All-Sky Survey and Medium Imaging Survey catalogs have been integrated into NED using this new process. The December 2013 release also contains nearly half a billion sources from the 2MASS Point Source Catalog accessible in cone searches, while the large scale cross-matching is in progress. Forthcoming updates will fuse data from All-WISE, SDSS DR12, and other very large catalogs. This work is progressing in parallel with the equally important integration of data from the literature, which is also growing rapidly. Recent updates have also included H I and CO channel maps (data cubes), as well as substantial growth in redshifts, classifications, photometry, spectra and redshift-independent distances. The By Parameters search engine now incorporates a simplified form for entry of constraints, and support for long-running queries with machine-readable output. A new tool for exploring the environments of galaxies with measured radial velocities includes informative graphics and a method to assess the incompleteness of redshift measurements. The NED user interface is also undergoing a major transformation, providing more streamlined navigation and searching, and a modern development framework for future enhancements. For further information, please visit our

  20. Recent Advances and Coming Attractions in the NASA/IPAC Extragalactic Database

    Science.gov (United States)

    Mazzarella, Joseph M.; Baker, Kay; Pan Chan, Hiu; Chen, Xi; Ebert, Rick; Frayer, Cren; Helou, George; Jacobson, Jeffery D.; Lo, Tak M.; Madore, Barry; Ogle, Patrick M.; Pevunova, Olga; Steer, Ian; Schmitz, Marion; Terek, Scott

    2017-01-01

    We review highlights of recent advances and developments underway at the NASA/IPAC Extragalactic Database (NED). Extensive updates have been made to the infrastructure and processes essential for scaling NED for the next steps in its evolution. A major overhaul of the data integration pipeline provides greater modularity and parallelization to increase the rate of source cross-matching and data integration. The new pipeline was used recently to fold in data for nearly 300,000 sources published in over 900 recent journal articles, as well as fundamental parameters for 42 million sources in the Spitzer Enhanced Imaging Products Source List. The latter has added over 360 million photometric measurements at 3.6, 4.5, 5.8. 8.0 (IRAC) and 24 microns (MIPS) to the spectral energy distributions of affected objects in NED. The recent discovery of super-luminous spiral galaxies (Ogle et al. 2016) exemplifies the opportunities for science discovery and data mining available directly from NED’s unique data synthesis, spanning the spectrum from gamma ray through radio frequencies. The number of references in NED has surpassed 103,000. In the coming year, cross-identifications of sources in the 2MASS Point Source Catalog and in the AllWISE Source Catalog with prior objects in the database (including GALEX) will increase the holdings to over a billion distinct objects, providing a rich resource for multi-wavelength analysis. Information about a recent surge in growth of redshift-independent distances in NED is presented at this meeting by Steer et al. (2017). Website updates include a ’simple search’ to perform common queries in a single entry field, an interface to query the image repository with options to sort and filter the initial results, connectivity to the IRSA Finder Chart service, as well as a program interface to query images using the international virtual observatory Simple Image Access protocol. Graphical characterizations of NED content and completeness are

  1. THE PANCHROMATIC STARBURST IRREGULAR DWARF SURVEY (STARBIRDS): OBSERVATIONS AND DATA ARCHIVE

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W.; Mitchell, Noah P.; Skillman, Evan D., E-mail: kmcquinn@astro.umn.edu [Institute for Astrophysics, University of Minnesota, 116 Church Street, S.E., Minneapolis, MN 55455 (United States)

    2015-06-22

    Understanding star formation in resolved low mass systems requires the integration of information obtained from observations at different wavelengths. We have combined new and archival multi-wavelength observations on a set of 20 nearby starburst and post-starburst dwarf galaxies to create a data archive of calibrated, homogeneously reduced images. Named the panchromatic “STARBurst IRregular Dwarf Survey” archive, the data are publicly accessible through the Mikulski Archive for Space Telescopes. This first release of the archive includes images from the Galaxy Evolution Explorer Telescope (GALEX), the Hubble Space Telescope (HST), and the Spitzer Space Telescope (Spitzer) Multiband Imaging Photometer instrument. The data sets include flux calibrated, background subtracted images, that are registered to the same world coordinate system. Additionally, a set of images are available that are all cropped to match the HST field of view. The GALEX and Spitzer images are available with foreground and background contamination masked. Larger GALEX images extending to 4 times the optical extent of the galaxies are also available. Finally, HST images convolved with a 5″ point spread function and rebinned to the larger pixel scale of the GALEX and Spitzer 24 μm images are provided. Future additions are planned that will include data at other wavelengths such as Spitzer IRAC, ground-based Hα, Chandra X-ray, and Green Bank Telescope H i imaging.

  2. Star-forming regions in NGC 2903 bar (Popping+, 2010)

    NARCIS (Netherlands)

    Popping, G.; Perez, I.; Zurita, A.

    2012-01-01

    To investigate the extinction and the star-formation in the bar of NGC 2903 we used the Spitzer 24um observations from the Multiband Imaging Photometer (MIPS) instrument. To analyse the UV emission and its distribution in NGC 2903, we used GALEX mission data. Ground-based optical images from the Slo

  3. The SAURON project - XVIII. The integrated UV-line-strength relations of early-type galaxies

    NARCIS (Netherlands)

    Bureau, Martin; Jeong, Hyunjin; Yi, Sukyoung K.; Schawinski, Kevin; Houghton, Ryan C. W.; Davies, Roger L.; Bacon, Roland; Cappellari, Michele; de Zeeuw, P. Tim; Emsellem, Eric; Falcón-Barroso, Jesús; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc; Sohn, Young-Jong; Thomas, Daniel; van den Bosch, Remco C. E.; van de Ven, Glenn

    2011-01-01

    Using far-ultraviolet (FUV) and near-ultraviolet (NUV) photometry from guest investigator programmes on the Galaxy Evolution Explorer (GALEX) satellite, optical photometry from the MDM Observatory and optical integral-field spectroscopy from SAURON, we explore the UV-line-strength relations of the 4

  4. The SAURON project : XVIII. The integrated UV-line-strength relations of early-type galaxies

    NARCIS (Netherlands)

    Bureau, Martin; Jeong, Hyunjin; Yi, Sukyoung K.; Schawinski, Kevin; Houghton, Ryan C. W.; Davies, Roger L.; Bacon, Roland; Cappellari, Michele; de Zeeuw, P. Tim; Emsellem, Eric; Falcon-Barroso, Jesus; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc; Sohn, Young-Jong; Thomas, Daniel; van den Bosch, Remco C. E.; van de Ven, Glenn

    2011-01-01

    Using far-ultraviolet (FUV) and near-ultraviolet (NUV) photometry from guest investigator programmes on the Galaxy Evolution Explorer (GALEX) satellite, optical photometry from the MDM Observatory and optical integral-field spectroscopy from SAURON, we explore the UV-line-strength relations of the 4

  5. The Radio Continuum-Star Formation Rate Relation in WSRT SINGS Galaxies

    NARCIS (Netherlands)

    Heesen, Volker; Brinks, Elias; Leroy, Adam K.; Heald, George; Braun, Robert; Bigiel, Frank; Beck, Rainer

    We present a study of the spatially resolved radio continuum-star formation rate (RC-SFR) relation using state-of-the-art star formation tracers in a sample of 17 THINGS galaxies. We use SFR surface density (ΣSFR) maps created by a linear combination of GALEX far-UV (FUV) and Spitzer 24 μm maps. We

  6. The Radio Continuum-Star Formation Rate Relation in WSRT SINGS Galaxies

    NARCIS (Netherlands)

    Heesen, Volker; Brinks, Elias; Leroy, Adam K.; Heald, George; Braun, Robert; Bigiel, Frank; Beck, Rainer

    2014-01-01

    We present a study of the spatially resolved radio continuum-star formation rate (RC-SFR) relation using state-of-the-art star formation tracers in a sample of 17 THINGS galaxies. We use SFR surface density (ΣSFR) maps created by a linear combination of GALEX far-UV (FUV) and Spitzer 24 μm maps. We

  7. VizieR Online Data Catalog: Malin 1 images at 6 wavelengths (Boissier+, 2016)

    Science.gov (United States)

    Boissier, S.; Boselli, A.; Ferrarese, L.; Cote, P.; Roehlly, Y.; Gwyn, S. D. J.; Cuillandre, J.-C.; Roediger, J.; Koda, J.; Munos Mateos, J. C.; Gil de, Paz A.; Madore, B. F.

    2016-10-01

    Six images of Malin 1 are provided in fits format, using the same pixel scale. The original data are taken from the GUViCS and NGVS surveys. Units and calibration are kept as in the standard products from these survey (i.e. GALEX FUV and NUV, and CFHT MegaCam u, g, i z. (2 data files).

  8. The Extreme Hosts of Extreme Supernovae

    CERN Document Server

    Neill, James D; Gal-Yam, Avishay; Quimby, Robert; Ofek, Eran; Wyder, Ted K; Howell, D Andrew; Nugent, Peter; Seibert, Mark; Martin, D Christopher; Overzier, Roderik; Barlow, Tom A; Foster, Karl; Friedman, Peter G; Morrissey, Patrick; Neff, Susan G; Schiminovich, David; Bianchi, Luciana; Donas, José; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Rich, R Michael; Szalay, Alex S

    2010-01-01

    We use GALEX ultraviolet (UV) and optical integrated photometry of the hosts of seventeen luminous supernovae (LSNe, having peak M_V 100 M_sun), by appearing in low-SFR hosts, are potential tests for theories of the initial mass function that limit the maximum mass of a star based on the S FR.

  9. VizieR Online Data Catalog: Intermediate-luminosity X-ray objects catalog (Colbert+, 2002)

    Science.gov (United States)

    Colbert, E. J. M.; Ptak, A. F.

    2002-11-01

    ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray point sources in galaxies other than our own. X-ray observations of normal galaxies with ROSAT and Chandra have revealed that off-nuclear, compact, intermediate-luminosity (LX[2-10keV]>=1039erg/s) X-ray objects (IXOs, a.k.a. ULXs [ultraluminous X-ray sources]) are quite common. Here we present a catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the ROSAT HRI imaging data for galaxies with cz<=5000km/s from the Third Reference Catalog of Bright Galaxies. (2 data files).

  10. X-Ray Surveys

    CERN Document Server

    Giommi, P; Perri, M

    1998-01-01

    A review of recent developments in the field of X-ray surveys, especially in the hard (2-10 and 5-10 keV) bands, is given. A new detailed comparison between the measurements in the hard band and extrapolations from ROSAT counts, that takes into proper account the observed distribution of spectral slopes, is presented. Direct comparisons between deep ROSAT and BeppoSAX images show that most hard X-ray sources are also detected at soft X-ray energies. This may indicate that heavily cutoff sources, that should not be detectable in the ROSAT band but are expected in large numbers from unified AGN schemes, are in fact detected because of the emerging of either non-nuclear components, or of reflected, or partially transmitted nuclear X-rays. These soft components may complicate the estimation of the soft X-ray luminosity function and cosmological evolution of AGN.

  11. The BeppoSAX High Energy Large Area Survey. IV. On the soft X-ray properties of the hard X-ray-selected HELLAS sources

    CERN Document Server

    Vignali, C; Fiore, F; La Franca, F

    2001-01-01

    We present a comprehensive study of the soft X-ray properties of the BeppoSAX High-Energy Large Area Survey (HELLAS) sources. A large fraction (about 2/3) of the hard X-ray selected sources is detected by ROSAT. The soft X-ray colors for many of these objects, along with the 0.5-2 keV flux upper limits for those undetected in the ROSAT band, do imply the presence of absorption. The comparison with the ROSAT Deep Survey sources indicates that a larger fraction of absorbed objects among the HELLAS sources is present, in agreement with their hard X-ray selection and the predictions of the X-ray background synthesis models. Another striking result is the presence of a soft (additional) X-ray component in a significant fraction of absorbed objects.

  12. Particular boundary condition ensures that a fermion in d=1+5, compactified on a finite disk, manifests d=1+3 as a massless spinor with a charge 1/2, mass protected and chirally coupled to the gauge field

    DEFF Research Database (Denmark)

    Borstnik, N. M.; Nielsen, Holger Frits Bech

    2008-01-01

    The genuine Kaluza-Klein-like theories-with no fields in addition to gravity-have difficulties with the existence of massless spinors after the compactification of some space dimensions [E. Witten, Nucl. Phys. B 186 (1981) 412; E. Witten, Fermion quantum numbers in Kaluza-Klein theories, Princeton...... Technical Rep. PRINT-83-1056, October 1983]. We proposed in [N.S. Mankoc Borštnik, H.B. Nielsen, Phys. Lett. B 633 (2006) 771, hep-th/0509101; N.S. Mankoc Borštnik, H.B. Nielsen, hep-th/0311037] a boundary condition for spinors in (1+5) compactified on a flat disk that ensures masslessness of spinors (with...... all positive half integer charges) in d=(1+3) as well as their chiral coupling to the corresponding background gauge gravitational field. In this Letter we study the same toy model, proposing a boundary condition allowing a massless spinor of one handedness and only one charge (1/2) and infinitely...

  13. Particular boundary condition ensures that a fermion in d=1+5, compactified on a finite disk, manifests in d=1+3 as massless spinor with a charge 1/2, mass protected and chirally coupled to the gauge field

    CERN Document Server

    Borstnik, Norma Susana Mankoc

    2008-01-01

    The genuine Kaluza-Klein-like theories--with no fields in addition to gravity--have difficulties with the existence of massless spinors after the compactification of some space dimensions \\cite{witten}. We proposed in previous paper a boundary condition for spinors in d=(1+5) compactified on a flat disk that ensures masslessness of spinors (with all positive half integer charges) in d=(1+3) as well as their chiral coupling to the corresponding background gauge gravitational field. In this paper we study the same toy model, proposing a boundary condition allowing a massless spinor of one handedness and only one charge (1/2) and infinitely many massive spinors of the same charge, allowing disc to be curved. We define the operator of momentum to be Hermitean on the vector space of spinor states--the solutions on a disc with the boundary.

  14. Simulations applied to the bright SHARC XCLF Results and implications

    CERN Document Server

    Ulmer, M P; Pildis, R A; Romer, A K; Nichol, R C; Holden, B P

    1999-01-01

    We have performed simulations of the effectiveness of the Serendipitous High-redshift Archival ROSAT Cluster (SHARC) survey for various model universes. We find, in agreement with work based on a preliminary set of simulations no statistically significant evolution of the luminosity function out to z = 0.8.

  15. X-RAY AND OPTICAL EMISSION-LINE FILAMENTS IN THE COOLING FLOW CLUSTER 2A 0335+096

    NARCIS (Netherlands)

    SARAZIN, CL; OCONNELL, RW; MCNAMARA, BR

    1992-01-01

    We present a new high-resolution X-ray image of the 2A 0335 + 096 cluster of galaxies obtained with the High Resolution Imager (HRI) aboard the ROSAT satellite. The presence of dense gas having a very short cooling time in the central regions confirms its earlier identification as a cooling flow. Th

  16. X-RAY EMITTING FILAMENTS IN THE COOLING FLOW CLUSTER-A2029

    NARCIS (Netherlands)

    SARAZIN, CL; OCONNELL, RW; MCNAMARA, BR

    1992-01-01

    We present high-resolution X-ray observations of the cluster A2029 with the ROSAT HRI which confirm the presence of a cooling flow, despite the lack of optical line emission or evidence for recent star formation. The cooling rate and radius are M(c) almost-equal-to 370 M. yr-1 and r(c) almost-equal-

  17. Stellar X-ray Sources in the Rosette Nebula

    Institute of Scientific and Technical Information of China (English)

    W. P. Chen; P. S. Chiang; J. Z. Li

    2004-01-01

    We present optical photometric and spectroscopic studies of ROSAT X-ray stellar sources in the Rosette Nebula star-forming region. The brightest Xray sources are either massive stars or active T Tauri stars associated with the open cluster NGC 2244, or are foreground stars. Some of the spectra of the young stars newly identified in the region are presented.

  18. The faint neutron star soft X-ray transient SAX J1810.8-2609 in quiescence

    NARCIS (Netherlands)

    Jonker, P.G.; Wijnands, R.A.D.; van der Klis, M.

    2004-01-01

    We present the analysis of a 35-ksec-long Chandra observation of the neutron star soft X-ray transient (SXT) SAX J1810.8-2609. We detect three sources in the field of view. The position of one of them is consistent with the location of the ROSAT error circle of SAX J1810.8-2609. The accurate Chandra

  19. X-ray Emission from the Radio Jet in 3C 120

    DEFF Research Database (Denmark)

    Harris, D. E.; Hjorth, J.; Sadun, A. C.;

    1999-01-01

    We report the discovery of X-ray emission from a radio knot at a projected distance of 25" from the nucleus of the Seyfert galaxy, 3C 120. The data were obtained with the ROSAT High Resolution Imager (HRI). Optical upper limits for the knot preclude a simple power law extension of the radio spect...

  20. X-RAY AND OPTICAL EMISSION-LINE FILAMENTS IN THE COOLING FLOW CLUSTER 2A 0335+096

    NARCIS (Netherlands)

    SARAZIN, CL; OCONNELL, RW; MCNAMARA, BR

    1992-01-01

    We present a new high-resolution X-ray image of the 2A 0335 + 096 cluster of galaxies obtained with the High Resolution Imager (HRI) aboard the ROSAT satellite. The presence of dense gas having a very short cooling time in the central regions confirms its earlier identification as a cooling flow. Th

  1. A deep X-ray spectroscopic survey of the ESO imaging survey fields

    DEFF Research Database (Denmark)

    Nørgaard-Nielsen, Hans Ulrik; Jørgensen, H.E.; Hansen, Lene

    1998-01-01

    behaviour, known from bright archetypes of these classes, the faint ROSAT sources will, due to the hardness of the DXRB spectrum, only give an insignificant contribution at say 10 keV. By exploiting the excellent capability of the SODART telescopes to obtain broad band X-ray spectroscopy at energies > 2 ke...

  2. Rotational periods of solar-mass young stars in Orion

    NARCIS (Netherlands)

    Marilli, E.; Frasca, A.; Covino, E.; Alcalá, J.M.; Catalano, S.; Fernández, M.; Arellano Ferro, A.; Rubio Herrera, E.A.; Spezzi, L.

    2007-01-01

    Context: The evolution of the angular momentum in young low-mass stars is still a debated issue. The stars presented here were discovered as X-ray sources in the ROSAT All-Sky Survey (RASS) of the Orion complex and subsequently optically identified thanks to both low and high resolution spectroscopy

  3. Chandra Cluster Cosmology Project. II. Samples and X-Ray Data Reduction

    DEFF Research Database (Denmark)

    Vikhlinin, A.; Burenin, R. A.; Ebeling, H.;

    2009-01-01

    We discuss the measurements of the galaxy cluster mass functions at z ≈ 0.05 and z ≈ 0.5 using high-quality Chandra observations of samples derived from the ROSAT PSPC All-Sky and 400 deg2 surveys. We provide a full reference for the data analysis procedures, present updated calibration of relati...

  4. X-RAY EMITTING FILAMENTS IN THE COOLING FLOW CLUSTER-A2029

    NARCIS (Netherlands)

    SARAZIN, CL; OCONNELL, RW; MCNAMARA, BR

    1992-01-01

    We present high-resolution X-ray observations of the cluster A2029 with the ROSAT HRI which confirm the presence of a cooling flow, despite the lack of optical line emission or evidence for recent star formation. The cooling rate and radius are M(c) almost-equal-to 370 M. yr-1 and r(c) almost-equal-

  5. X-ray overluminous elliptical galaxies: A new class of mass concentrations in the universe?

    DEFF Research Database (Denmark)

    Vikhlinin, A.; McNamara, B.R.; Hornstrup, Allan;

    1999-01-01

    We detect four isolated, X-ray overluminous [L-x > 2 x 10(43) (h/0.5)(-2) ergs s(-1)] elliptical galaxies (OLEGs) in our 160 deg(2) ROSAT PSPC survey. The extent of their X-ray emission, total X-ray luminosity, total mass, and mass of the hot gas in these systems corresponds to poor clusters, and...

  6. Massive star formation in a gravitationally-lensed H II galaxy at z=3.357

    Science.gov (United States)

    Rauch, G.; Stanford, M.; Holden, S. A.; Stern, B. P.; Rosati, D.; Lombardi, P.; Humphrey, M.; Villar-Martin, A.; Hook, M.; Fosbury, R. N.; Squires, R. A. E.

    2003-01-01

    The Lynx arc, with a redshift of 3.357, was discovered during spectroscopic follow-up of the z=0.570 cluster RX J0848+4456 from the ROSAT Deep Cluster Survey. The arc is characterized by a very red R - K color and strong, narrow emission lines.

  7. Calibrating UV Star Formation Rates for Dwarf Galaxies from STARBIRDS

    CERN Document Server

    McQuinn, Kristen B W; Dolphin, Andrew E; Mitchell, Noah P

    2015-01-01

    Integrating our knowledge of star formation traced by observations at different wavelengths is essential for correctly interpreting and comparing star formation activity in a variety of systems and environments. This study compares extinction corrected integrated ultraviolet (UV) emission from resolved galaxies with color-magnitude diagram (CMD) based star formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The datasets are from the panchromatic STARBurst IRregular Dwarf Survey (STARBIRDS) and include deep legacy GALEX UV imaging, HST optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near UV fluxes predicted from the CMD-based SFRs - using four different models - agree with the measured, extinction corrected, integrated near UV fluxes from GALEX images, but the far UV predicted fluxes do not. Further, we find a systematic deviation between the SFRs based on integrated far U...

  8. The Panchromatic STARBurst IRregular Dwarf Survey (STARBIRDS) Data

    CERN Document Server

    McQuinn, Kristen B W; Skillman, Evan D

    2016-01-01

    Understanding star formation in resolved low mass systems requires the integration of information obtained from observations at different wavelengths. We have combined new and archival multi-wavelength observations on a set of 20 nearby starburst and post-starburst dwarf galaxies to create a data archive of calibrated, homogeneously reduced images. Named the panchromatic "STARBurst IRregular Dwarf Survey" (STARBIRDS) archive, the data are publicly accessible through the Mikulski Archive for Space Telescopes (MAST). This first release of the archive includes images from the Galaxy Evolution Explorer Telescope (GALEX), the Hubble Space Telescope (HST), and the Spitzer Space Telescope (Spitzer) MIPS instrument. The datasets include flux calibrated, background subtracted images, that are registered to the same world coordinate system. Additionally, a set of images are available which are all cropped to match the HST field of view. The GALEX and Spitzer images are available with foreground and background contamina...

  9. VizieR Online Data Catalog: COSMOS/UltraVISTA Ks-selected catalogs v4.1 (Muzzin+, 2013)

    Science.gov (United States)

    Muzzin, A.; Marchesini, D.; Stefanon, M.; Franx, M.; Milvang-Jensen, B.; Dunlop, J. S.; Fynbo, J. P. U.; Brammer, G.; Labbe, I.; van Dokkum, P.

    2016-07-01

    The current catalog release, v4.1 is a Ks-selected catalog of the COSMOS field based on the imaging from the DR1 UltraVISTA release (see McCracken+, 2012, J/A+A/544/A156). The catalog covers a total area of 1.62deg2, and has photometry in 30 bands including the GALEX, Subaru, CFHT, UltraVISTA, and Spitzer imaging. The 90% completeness limit of the survey is Ks,tot=23.4 AB. Photometry has been determined in a color aperture by PSF matching all bands, including additional source-fitting for the large-PSF space-based imaging such as GALEX and IRAC/MIPS. (6 data files).

  10. POSSIBLE SOURCES OF UV RADIATION IN ELLIPTICAL GALAXIES

    Directory of Open Access Journals (Sweden)

    F. C. Hernández

    2009-01-01

    Full Text Available We have compiled a sample of 519 nearby (z < 0:13 elliptical galaxies, selected by matching the Galaxy Evolution Explorer (GALEX Medium Imaging Survey (MIS with the Sloan Digital Sky Survey (SDSS Fourth Data Release (DR4. Our galaxies are bright, with r < 16:8 and have FUV (far ultraviolet an NUV (near ultraviolet emission. We build a UV Color Magnitude Relation (CMR using GALEX and SDSS photometric bands, and analyze the evolution of this CMR for these galaxies using stellar population synthesis models. We nd that these galaxies may have su ered a small amount of recent residual star formation (1{2% of the galaxy mass. Extreme Horizontal Branch (EHB stars can explain galaxies with 4 < NUV- r < 5:4.

  11. VizieR Online Data Catalog: UV and IR properties for galaxies (Mao+, 2014)

    Science.gov (United States)

    Mao, Y.-W.; Kong, X.; Lin, L.

    2017-03-01

    Broadband FUV and NUV imaging data were obtained from GALEX observations and downloaded from the Multimission Archive at Space Telescope Science Institute (MAST) Web site (http://galex.stsci.edu/); 8um (dust-only) and 24um images were observed by the Spitzer Space Telescope (Spitzer) and retrieved from the SINGS data distribution service (http://irsa.ipac.caltech.edu/data/SPITZER/SINGS/). Hα narrowband imaging data are also employed in this work. The Hα narrowband image for NGC 3031 was observed by the 60/90 cm Schmidt telescope at Xing-Long station of the National Astronomical Observatories of China with the filter of transmission profile FWHM~120Å. (2 data files).

  12. UV-IR color profiles of the outer regions of 2K nearby S4G galaxies

    Science.gov (United States)

    Bouquin, Alexandre Y. K.; Gil de Paz, Armando

    2017-03-01

    We present our new, spatially-resolved, photometry in FUV and NUV from images obtained by GALEX, and IRAC1 (3.6 μm) photometry obtained by the Spitzer Space Telescope. We analyzed the surface brightness profiles μFUV, μNUV, μ[3.6], as well as the radial evolution of the (FUV-NUV), (FUV - [3.6]), and (NUV - [3.6]) colors in the Spitzer Survey of Stellar Structures in Galaxies (S4G) galaxies (d populated by late-type star forming galaxies and quiescent early-type galaxies respectively. While most disk becomes radially bluer for GBS galaxies, and stay constant for GRS galaxies, a large fraction ( > 50%) of intermediary GALEX Green Valley (GGV) galaxies' outer disks are becoming redder. An outside-in quenching mechanism such as environmentally-related mechanisms such as starvation or ram-pressure-stripping could explain our results.

  13. Stochastic 2-D Models of Galaxy Disk Evolution. The Galaxy M33

    CERN Document Server

    Mineikis, Tadas

    2015-01-01

    We have developed a fast numerical 2-D model of galaxy disk evolution (resolved along the galaxy radius and azimuth) by adopting a scheme of parameterized stochastic self-propagating star formation. We explore the parameter space of the model and demonstrate its capability to reproduce 1-D radial profiles of the galaxy M33: gas surface density, surface brightness in the i and GALEX FUV passbands, and metallicity.

  14. Deep UV Luminosity Functions at the Infall Region of the Coma Cluster

    Science.gov (United States)

    Hammer, D. M.; Hornschemeier, A. E.; Salim, S.; Smith, R.; Jenkins, L.; Mobasher, B.; Miller, N.; Ferguson, H.

    2011-01-01

    We have used deep GALEX observations at the infall region of the Coma cluster to measure the faintest UV luminosity functions (LFs) presented for a rich galaxy cluster thus far. The Coma UV LFs are measured to M(sub uv) = -10.5 in the GALEX FUV and NUV bands, or 3.5 mag fainter than previous studies, and reach the dwarf early-type galaxy population in Coma for the first time. The Schechter faint-end slopes (alpha approximately equal to -1.39 in both GALEX bands) are shallower than reported in previous Coma UV LF studies owing to a flatter LF at faint magnitudes. A Gaussian-plus-Schechter model provides a slightly better parametrization of the UV LFs resulting in a faint-end slope of alpha approximately equal to -1.15 in both GALEX bands. The two-component model gives faint-end slopes shallower than alpha = -1 (a turnover) for the LFs constructed separately for passive and star forming galaxies. The UV LFs for star forming galaxies show a turnover at M(sub UV) approximately equal to -14 owing to a deficit of dwarf star forming galaxies in Coma with stellar masses below M(sub *) = 10(sup 8) solar mass. A similar turnover is identified in recent UV LFs measured for the Virgo cluster suggesting this may be a common feature of local galaxy clusters, whereas the field UV LFs continue to rise at faint magnitudes. We did not identify an excess of passive galaxies as would be expected if the missing dwarf star forming galaxies were quenched inside the cluster. In fact, the LFs for both dwarf passive and star forming galaxies show the same turnover at faint magnitudes. We discuss the possible origin of the missing dwarf star forming galaxies in Coma and their expected properties based on comparisons to local field galaxies.

  15. Environments and Morphologies of Red Sequence Galaxies with Residual Star Formation in Massive Clusters

    OpenAIRE

    Crossett, Jacob P.; Pimbblet, Kevin A.; Stott, John P; Jones, D. Heath

    2013-01-01

    We present a photometric investigation into recent star formation in galaxy clusters at z ~ 0.1. We use spectral energy distribution templates to quantify recent star formation in large X-ray selected clusters from the LARCS survey using matched GALEX NUV photometry. These clusters all have signs of red sequence galaxy recent star formation (as indicated by blue NUV-R colour), regardless of cluster morphology and size. A trend in environment is found for these galaxies, such that they prefer ...

  16. The Bright Symbiotic Mira EF Aquilae

    CERN Document Server

    Margon, Bruce; Tejos, Nicolas; Monroe, TalaWanda

    2016-01-01

    An incidental spectrum of the poorly studied long period variable EF Aquilae shows [O III] emission indicative of a symbiotic star. Strong GALEX detections in the UV reinforce this classification, providing overt evidence for the presence of the hot subluminous companion. Recent compilations of the photometric behavior strongly suggest that the cool component is a Mira variable. Thus EF Aql appears to be a member of the rare symbiotic Mira subgroup.

  17. Ultraviolet emission from main-sequence companions of AGB stars

    CERN Document Server

    Ortiz, Roberto

    2016-01-01

    Although the majority of known binary Asymptotic Giant Branch (AGB) stars are symbiotic systems (i.e. with a WD as a secondary star), main-sequence companions of AGB stars can be more numerous, even though they are more difficult to find because the primary high luminosity hampers the detection of the companion at visual wavelengths. However, in the ultraviolet the flux emitted by a secondary with T eff > 5500 ~ 6000 K may prevail over that of the primary, and then it can be used to search for candidates to binary AGB stars. In this work, theoretical atmosphere models are used to calculate the UV excess in the GALEX near- and far-UV bands due to a main-sequence companion. After analysing a sample of confirmed binary AGB stars, we propose as a criterium for binarity: (1) the detection of the AGB star in the GALEX far-UV band and/or (2) a GALEX near-UV observed-to-predicted flux ratio > 20. These criteria have been applied to a volume-limited sample of AGB stars within 500 pc of the Sun; 34 out of the sample of...

  18. The Evolution of the Visible and Hidden Star Formation in the Universe: Implication from the Luminosity Functions at FUV and FIR

    CERN Document Server

    Takeuchi, T T; Burgarella, D; Takeuchi, Tsutomu T.; Buat, Veronique; Burgarella, Denis

    2006-01-01

    Based on GALEX and IRAS/Spitzer datasets, we have found that both FUV and FIR luminosity functions (LFs) show a strong evolution from z=0 to z=1, but the FIR LF evolves much stronger than the FUV one. Consequently, the FIR/FUV luminosity density ratio increases from 4 (z=0) to 15 (z=1). It means that more than 80% of the star-forming activity in the Universe is hidden by dust at z=1. To explore this issue further, we have performed a combined analysis of the galaxy sample in FUV and FIR. For the Local Universe we used GALEX-IRAS sample, whereas at z=1 we used the Lyman-break galaxy sample selected by GALEX bands constructed by Burgarella et al. (2005), which is known to be representative of visible (i.e., non-obscured) star-forming galaxies at z=1. From these datasets, we constructed the LFs of the FUV-selected galaxies by the survival analysis to, take into account the upper-limit data properly. We discovered that the FIR LF of the Lyman-break galaxies show a significant evolution comparing with the local FI...

  19. THE NEAR-ULTRAVIOLET LUMINOSITY FUNCTION OF YOUNG, EARLY M-TYPE DWARF STARS

    Energy Technology Data Exchange (ETDEWEB)

    Ansdell, Megan; Baranec, Christoph [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Gaidos, Eric [Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822 (United States); Mann, Andrew W. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Lépine, Sebastien [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302 (United States); James, David [Cerro Tololo Inter-American Observatory, Casilla 603 La Serena (Chile); Buccino, Andrea; Mauas, Pablo; Petrucci, Romina [Instituto de Astronomía y Física del Espacio, C1428EHA Buenos Aires (Argentina); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Riddle, Reed [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-01-01

    Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lépine and Gaidos catalog of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Å) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5σ) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these ''false positives'' (FPs) as ∼16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.

  20. The Arecibo Legacy Fast ALFA Survey: The Galaxy Population Detected by ALFALFA

    CERN Document Server

    Huang, Shan; Giovanelli, Riccardo; Brinchmann, Jarle

    2012-01-01

    Making use of HI 21 cm line measurements from the ALFALFA survey (alpha.40) and photometry from the Sloan Digital Sky Survey (SDSS) and GALEX, we investigate the global scaling relations and fundamental planes linking stars and gas for a sample of 9417 common galaxies: the alpha.40-SDSS-GALEX sample. In addition to their HI properties derived from the ALFALFA dataset, stellar masses (M_*) and star formation rates (SFRs) are derived from fitting the UV-optical spectral energy distributions. 96% of the alpha.40-SDSS-GALEX galaxies belong to the blue cloud, with the average gas fraction f_HI = M_HI/M_* ~ 1.5. A transition in SF properties is found whereby below M_* ~ 10^9.5 M_sun, the slope of the star forming sequence changes, the dispersion in the specific star formation rate (SSFR) distribution increases and the star formation efficiency (SFE) mildly increases with M_*. The evolutionary track in the SSFR-M_* diagram, as well as that in the color magnitude diagram are linked to the HI content; below this trans...

  1. Extreme UV QSOs

    CERN Document Server

    Bianchi, Luciana; Efremova, Boryana; Herald, James E; Bressan, Alessandro; Martin, Cristopher

    2009-01-01

    We present a sample of spectroscopically confirmed QSOs with FUV-NUV color (as measured by GALEX photometry) bluer than canonical QSO templates and than the majority of known QSOs. We analyze their FUV to NIR colors, luminosities and optical spectra. The sample includes a group of 150 objects at low redshift (z $<$ 0.5), and a group of 21 objects with redshift 1.7$<$z$<$2.6. For the low redshift objects, the "blue" FUV-NUV color may be caused by enhanced Ly$\\alpha$ emission, since Ly$\\alpha$ transits the GALEX FUV band from z=0.1 to z=0.47. Synthetic QSO templates constructed with Ly$\\alpha$ up to 3 times stronger than in standard templates match the observed UV colors of our low redshift sample. The H$\\alpha$ emission increases, and the optical spectra become bluer, with increasing absolute UV luminosity. The UV-blue QSOs at redshift about 2, where the GALEX bands sample restframe about 450-590A (FUV) and about 590-940A(NUV), are fainter than the average of UV-normal QSOs at similar redshift in NUV,...

  2. Chandra Cluster Cosmology Project III: Cosmological Parameter Constraints

    DEFF Research Database (Denmark)

    Vikhlinin, A.; Kravtsov, A. V.; Burenin, R. A.

    2009-01-01

    , and nearly a factor of 2 improvement in systematics compared with constraints that can be obtained without clusters. The joint analysis of these four data sets puts a conservative upper limit on the masses of light neutrinos ∑m ν ...Chandra observations of large samples of galaxy clusters detected in X-rays by ROSAT provide a new, robust determination of the cluster mass functions at low and high redshifts. Statistical and systematic errors are now sufficiently small, and the redshift leverage sufficiently large for the mass...... function evolution to be used as a useful growth of a structure-based dark energy probe. In this paper, we present cosmological parameter constraints obtained from Chandra observations of 37 clusters with langzrang = 0.55 derived from 400 deg2 ROSAT serendipitous survey and 49 brightest z ≈ 0.05 clusters...

  3. The x ray population in globular clusters and three crab-like SNR in the large Magellanic cloud

    Science.gov (United States)

    Helfand, David J.

    1993-01-01

    This document is to serve as the requisite Final Technical Report on grant NAG5-1557 which was awarded under the NASA ROSAT Guest Investigator Program to Columbia University. In response to the NASA Research Anouncement describing the first round of Guest Investigations to be carried out under the U.S.-German ROSAT Program (AO-1), the PI submitted several proposals, three of which were accepted in part: (1) the x-ray population of globular clusters; (2) three crab-like SNR in the Large Magellanic Cloud; and (3) x rays from nearby radio pulsars. The status of these three programs as of 31 May 1993, the termination date of the grant, is reported.

  4. Machine learning etudes in astrophysics: selection functions for mock cluster catalogs

    Energy Technology Data Exchange (ETDEWEB)

    Hajian, Amir; Alvarez, Marcelo A.; Bond, J. Richard, E-mail: ahajian@cita.utoronto.ca, E-mail: malvarez@cita.utoronto.ca, E-mail: bond@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada)

    2015-01-01

    Making mock simulated catalogs is an important component of astrophysical data analysis. Selection criteria for observed astronomical objects are often too complicated to be derived from first principles. However the existence of an observed group of objects is a well-suited problem for machine learning classification. In this paper we use one-class classifiers to learn the properties of an observed catalog of clusters of galaxies from ROSAT and to pick clusters from mock simulations that resemble the observed ROSAT catalog. We show how this method can be used to study the cross-correlations of thermal Sunya'ev-Zeldovich signals with number density maps of X-ray selected cluster catalogs. The method reduces the bias due to hand-tuning the selection function and is readily scalable to large catalogs with a high-dimensional space of astrophysical features.

  5. Soft X-ray emission of nearby galaxy M81

    Institute of Scientific and Technical Information of China (English)

    苏旸; 毕红光; 李启斌

    1997-01-01

    The pointed observations of NGC3077 are analyzed by position sensitive proportional counter (PSPC) on board the ROSAT satellite on 1991-04-18, 1991, finding out that the X-ray emission range of M81 galaxy has, in the softer and more sensitive ROSAT PSPC band (0. 2-2. 4 keV), extended by 40% larger than ever observed by image proportional counter (IPC) on board the Einstein satellite, which shows that M81 galaxy has a larger X-ray corona. And by the aid of the timing analysis, it is concluded that M81 nucleus has no variabilities on time scale of a few minutes; hence the possibility of M81 nucleus having the marginal variability over time scale of about 2 min that Fabbiano (1988) found from the Einstein IPC observation is ruled out.

  6. Discovery of a large gravitational arc in the x-ray cluster A2280

    CERN Document Server

    Gioia, I M; Luppino, G A; Clowe, D I; Böhringer, H; Briel, U G; Voges, W; Huchra, J P; MacGillivray, H T

    1995-01-01

    This Letter presents the serendipitous discovery of a large arc in an X-ray selected cluster detected in the Rosat North Ecliptic Pole (NEP) survey. The cluster, associated with Abell 2280, is identified as the optical counterpart of the X-ray source RXJ 1743.5+6341. This object is a medium--distant z=0.326 and luminous (L_(0.5-2 kev) = 5.06x10**44 erg/s) cluster dominated by a central bright galaxy. The arc is located ~ 14 arcsec to the North-West of the cD and it is detected in the R and I bands but not in the B band. Photometric and spectroscopic observations of the cluster and of the arc are presented. Other similar discoveries in the course of imaging and spectroscopic surveys of Rosat are expected in the future.

  7. The intragroup medium in loose groups of galaxies

    OpenAIRE

    Helsdon, S. F.; Ponman, T.J.

    2000-01-01

    We have used the ROSAT PSPC to study the properties of a sample of 24 X-ray bright galaxy groups, representing the largest sample examined in detail to date. Hot plasma models are fitted to the spectral data to derive temperatures, and modified King models are used to characterise the surface brightness profiles. In agreement with previous work, we find evidence for the presence of two components in the surface brightness profiles. The extended component is generally found to be much flatter ...

  8. Optical Identifications of X-ray Selected AGNs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    For investigating the statistical properties of X-ray selected Active Galactic Nuclei (AGNs), we have carried out a program of optical identification of a selection of X-ray sources from ROSAT All Sky Survey Bright Source Catalogue (RASS-BSC) using the 2.16 m telescope of Beijing Astronomical Observatory (BAO). In the preliminary observations, 23 new AGNs were discovered, of which 9 are quasars, and 14 are Seyfert galaxies.

  9. Establishing Benchmarks For Minimum Competence With Dry Lab Robotic Surgery Drills.

    Science.gov (United States)

    Siddiqui, Nazema Y; Tarr, Megan E; Geller, Elizabeth J; Advincula, Arnold P; Galloway, Michael L; Green, Isabel C; Hur, Hye-Chun; Pitter, Michael C; Burke, Emily E; Martino, Martin A

    2016-01-01

    The Robotic Objective Structured Assessment of Technical Skills (R-OSATS) is a previously validated assessment tool that is used to assess 5 standardized inanimate robotic surgery drills. R-OSATS is used to evaluate performance on surgical drills, with scores of 0 to 20 for each drill. Our objective was to establish the minimum threshold score that denotes competence on these drills. Thus, we performed a standard setting study using data from surgeons and trainees in 8 academic medical centers. Cutoff scores for the minimal level of competence using R-OSATS were established using 2 techniques: the modified Angoff and the contrasting groups methods. For the modified Angoff method, 8 content experts met and, in an iterative process, derived the scores that a minimally competent trainee should receive. After 2 iterative rounds of scoring and discussion with the modified Angoff method, we established a minimum competence score per drill with high agreement (rWG range, 0.92-0.98). There was unanimous consensus that a trainee needs to achieve competence on each independent drill. A second method, the contrasting groups method, was used to verify our results. In this method, we compared R-OSATS scores from "inexperienced" (34 postgraduate year 1 and 2 trainees) with "experienced" (22 faculty and fellow) robotic surgeons. The distributions of scores from both groups were plotted, and a cutoff score for each drill was determined from the intersection of the 2 curves. Using this method, the minimum score for competence would be 14 per drill, which is slightly more stringent but confirms the results obtained from the modified Angoff approach. In conclusion, using 2 well-described standard setting techniques, we have established minimum benchmarks designating trainee competence for 5 dry lab robotic surgery drills.

  10. Soft X-ray Properties of Ultraluminous IRAS Galaxies

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We report on the results of cross-correlation of a sample of 903 Ultra luminous IRAS galaxies (ULIRGs) with the ROSAT-All Sky Survey Bright Source Catalogue and the ROSAT archived pointing observations. The sample of ULIRGs has been compiled from the recently released PSCz redshift survey. In total, 35 ULIRGs are securely detected by the ROSAT All-Sky Survey and pointing observa tions, five of which are blazars. The statistical properties of these sources in the soft X-ray band are determined and compared with their properties in other wavebands. We find that the ratio of the soft X-ray to the far-infrared flux spans about five orders of magnitude and reaches values of about unity. This ratio is a good indi cator of the main energy source of ULIRGs. Those with soft X-ray to far-infrared flux exceeding 0.01 are probably powered by accretion onto central supermassive black holes while those with ratios smaller than 0.001 are probably powered by starbursts or other heating processes, or are Compton thick sources. Some ULIRGs have energy contributions from both. This ratio is low for most ULIRGs and hy perluminous infrared galaxies, which explains their low detection rate by ROSAT and ASCA. We also find that some ULIRGs have a similar soft X-ray luminosity vs. temperature relation to that for groups of galaxies and elliptical galaxies, suggest ing a common origin of these systems. Our study also reveals a tight correlation between the hardness ratio and the soft X-ray luminosity for Seyfert ls/QSOs.

  11. The Hamburg/RASS optical identification project

    CERN Document Server

    Zickgraf, F J; Hagen, H J; Reimers, D

    2003-01-01

    We use digitized Schmidt direct and prism plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) to obtain optical identifications for all high galactic latitude X-ray sources in the ROSAT Bright Source Catalogue (RASS-BSC) at |b|>=30 deg and DEC >= 0deg. In this part of the sky the RASS-BSC contains about 5300 X-ray sources. Presently, identifications exist for about 4100 RASS-BSC sources in this galactic latitude range.

  12. Cosmological constraints from the evolution of the cluster baryon mass function at z similar to 0.5

    DEFF Research Database (Denmark)

    Vikhlinin, A.; Voevodkin, A.; Mullis, C.R.

    2003-01-01

    We present a new method for deriving cosmological constraints based on the evolution of the baryon mass function of galaxy clusters and implement it using 17 distant clusters from our 160 deg(2) ROSAT survey. The method uses the cluster baryon mass as a proxy for the total mass, thereby avoiding...... the cosmic microwave background and Type Ia supernovae near Omega(m) = 0.3 and Lambda = 0.7....

  13. SPIDERS: selection of spectroscopic targets using AGN candidates detected in all-sky X-ray surveys

    Science.gov (United States)

    Dwelly, T.; Salvato, M.; Merloni, A.; Brusa, M.; Buchner, J.; Anderson, S. F.; Boller, Th.; Brandt, W. N.; Budavári, T.; Clerc, N.; Coffey, D.; Del Moro, A.; Georgakakis, A.; Green, P. J.; Jin, C.; Menzel, M.-L.; Myers, A. D.; Nandra, K.; Nichol, R. C.; Ridl, J.; Schwope, A. D.; Simm, T.

    2017-07-01

    SPIDERS (SPectroscopic IDentification of eROSITA Sources) is a Sloan Digital Sky Survey IV (SDSS-IV) survey running in parallel to the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) cosmology project. SPIDERS will obtain optical spectroscopy for large numbers of X-ray-selected active galactic nuclei (AGN) and galaxy cluster members detected in wide-area eROSITA, XMM-Newton and ROSAT surveys. We describe the methods used to choose spectroscopic targets for two sub-programmes of SPIDERS X-ray selected AGN candidates detected in the ROSAT All Sky and the XMM-Newton Slew surveys. We have exploited a Bayesian cross-matching algorithm, guided by priors based on mid-IR colour-magnitude information from the Wide-field Infrared Survey Explorer survey, to select the most probable optical counterpart to each X-ray detection. We empirically demonstrate the high fidelity of our counterpart selection method using a reference sample of bright well-localized X-ray sources collated from XMM-Newton, Chandra and Swift-XRT serendipitous catalogues, and also by examining blank-sky locations. We describe the down-selection steps which resulted in the final set of SPIDERS-AGN targets put forward for spectroscopy within the eBOSS/TDSS/SPIDERS survey, and present catalogues of these targets. We also present catalogues of ˜12 000 ROSAT and ˜1500 XMM-Newton Slew survey sources that have existing optical spectroscopy from SDSS-DR12, including the results of our visual inspections. On completion of the SPIDERS programme, we expect to have collected homogeneous spectroscopic redshift information over a footprint of ˜7500 deg2 for >85 per cent of the ROSAT and XMM-Newton Slew survey sources having optical counterparts in the magnitude range 17 < r < 22.5, producing a large and highly complete sample of bright X-ray-selected AGN suitable for statistical studies of AGN evolution and clustering.

  14. ASCA Observation of the polar RX J1802.1+1804

    CERN Document Server

    Ishida, M; Remillard, R A; Motch, C

    1998-01-01

    We present X-ray data of RX J1802.1+1804 obtained by ASCA. Although it shows a clear orbital intensity modulation with an amplitude of nearly 100% below 0.5 keV in ROSAT data, the ASCA light curves are nearly flat except for a possible dip lasting about one-tenth of the orbital period. We discuss this within the model assumption of a stream-eclipsing geometry as derived from the ROSAT observations. The ASCA X-ray spectrum can be represented by a two temperature optically thin thermal plasma emission model with temperatures of ~1keV and >7 keV, suggesting postshock cooling as observed in EX Hya. A remarkable feature of the spectrum is the strong iron K_alpha emission line whose equivalent width is ~4 keV. To account for this, an iron abundance of greater than at least 1.3 times Solar is required. A combined spectral analysis of the ROSAT PSPC and ASCA data indicates that the N_H-corrected flux ratio of the soft blackbody (0.1-2.4 keV) to the hard optically thin thermal plasma emission (2-10 keV) is as large as...

  15. Long-Term Time Variability in the X-Ray Pulse Shape of the Crab Nebula Pulsar

    Science.gov (United States)

    Fazio, Giovanni G.

    2000-01-01

    This is the final performance report for our grant 'Long-Term Time Variability in the X-Ray Pulse Shape of the Crab Nebula Pulsar.' In the first year of this grant, we received the 50,000-second ROSAT (German acronym for X-ray satellite) High Resolution Images (HRI) observation of the Crab Nebula pulsar. We used the data to create a 65-ms-resolution pulse profile and compared it to a similar pulse profile obtained in 1991. No statistically significant differences were found. These results were presented at the January 1998 meeting of the American Astronomical Society. Since then, we have performed more sensitive analyses to search for potential changes in the pulse profile shape between the two data sets. Again, no significant variability was found. In order to augment this long (six-year) baseline data set, we have analyzed archival observations of the Crab Nebula pulsar with the Rossi X-Ray Timing Explorer (RXTE). While these observations have shorter time baselines than the ROSAT data set, their higher signal-to-noise offers similar sensitivity to long-term variability. Again, no significant variations have been found, confirming our ROSAT results. This work was done in collaboration with Prof. Stephen Eikenberry, Cornell University. These analyses will be included in Cornell University graduate student Dae-Sik Moon's doctoral thesis.

  16. A Catalog of Intermediate-luminosity X-ray Objects

    CERN Document Server

    Colbert, E

    2002-01-01

    ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray point sources in galaxies other than our own. X-ray observations of normal galaxies with ROSAT and Chandra have revealed that off-nuclear, compact, Intermediate-luminosity (Lx 2-10 keV >= 1e39 erg/s) X-ray Objects (IXOs, a.k.a. ULXs) are quite common. Here we present a catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the ROSAT HRI imaging data for galaxies with cz <= 5000 km/s from the Third Reference Catalog of Bright Galaxies (RC3). We have defined the cutoff Lx for IXOs so that it is well above the Eddington luminosity of a 1.4 Msol black hole (10^{38.3} erg/s), so as not to confuse IXOs with ``normal'' black hole X-ray binaries. This catalog is intended to provide a baseline for follow-up work with Chandra, and with space- and ground-based survey work at wavelengths other than X-ray. We demonstrate that elliptical galaxies with IXOs have a larger number of IXOs per galaxy than non-elliptical galaxies with...

  17. The Statistical Properties of Galaxies Containing ULXs

    CERN Document Server

    Ptak, A

    2004-01-01

    We present a statistical analysis of the properties of galaxies containing ultraluminous X-ray objects (ULXs). Our primary goal is to establish the fraction of galaxies containing a ULX as a function of ULX luminosity. Our sample is based on ROSAT HRI observations of galaxies. We find that ~ 12% of galaxies contain at least one ULX with L_X > 10^39 erg/s and ~ 1% of galaxies contain at least one ULX with L_X > 10^40 erg/s. These ULX frequencies are lower limits since ROSAT HRI observation would miss absorbed ULXs (i.e., with N_H >~ 10^21 cm^-2) and those within ~ 10" of the nucleus (due to the positional error circle of the ROSAT HRI). The Hubble type distribution of galaxies with a ULX differs significantly from the distribution of types for nearby RC3 galaxies, but does not differ significantly from the galaxy type distribution of galaxies observed by the HRI in general. We find no increase in the mean FIR luminosity or FIR / K band luminosity ratio for galaxies with a ULX relative to galaxies observed by t...

  18. CHANDRA Observations of V407 Vul: Confirmation of the Spin-up

    CERN Document Server

    Strohmayer, T E

    2004-01-01

    V407 Vul is a candidate double-degenerate binary with a putative 1.756 mHz (9.5 min) orbital frequency. In a previous timing study using archival ROSAT and ASCA data we reported evidence for an increase of this frequency at a rate consistent with expectations for gravitational radiation from a detached ultracompact binary system. Here we report the results of new CHANDRA timing observations which confirm the previous indications of spin-up of the X-ray frequency, and provide much tighter constraints on the frequency derivative. We obtained with CHANDRA a total of 90 ksec of exposure in two epochs separated in time by 11.5 months. The total time span of the archival ROSAT, ASCA and new CHANDRA data is now 10.5 years. This more than doubles the interval spanned by the ROSAT and ASCA data alone, providing much greater sensitivity to a frequency derivative. With the addition of the CHANDRA data an increasing frequency is unavoidable, with a value df/dt = 7.0 x 10-18 Hz/s. Although a long-term spin-up trend is con...

  19. X-ray emission from the local hot bubble and solar wind charge exchange

    Science.gov (United States)

    Uprety, Youaraj

    DXL (Diffuse X-rays from the Local galaxy) is a sounding rocket mission to quantify the Solar Wind Charge Exchange (SWCX) X-ray emission in the interplanetary medium, and separate its contribution from the Local Hot Bubble (LHB) emission. The first launch of DXL took place in December 2012. This thesis will describe the DXL instrumentation and calibrations, and discuss the results obtained. The mission uses two large area proportional counters to scan through the Helium Focusing Cone (HFC), a high helium density region in the solar system emitting excess X-rays due to SWCX. Using well determined models of the interplanetary neutral distribution and comparing the DXL results with data from the same region obtained by the ROSAT satellite away from the cone, we calculated that SWCX contributes at most 36% to the ¼ keV ROSAT band and 13% to the ¾ keV ROSAT band, in the galactic plane. This provides a firm proof for existence of a LHB which dominates the Diffuse X-ray Background (DXB) at ¼ keV, while raising new questions on the origin of the ¾ keV emission.

  20. A Broadband X-Ray Study of the Supernova Remnant 3C 397

    CERN Document Server

    Safi-Harb, S; Arnaud, K A; Keohane, J W; Borkowski, K J; Dyer, K K; Reynolds, S P; Hughes, J P

    2000-01-01

    We present an X-ray study of the radio bright supernova remnant (SNR) 3C 397 with ROSAT, ASCA, and RXTE. A central X-ray spot seen with the ROSAT High-Resolution Imager hints at the presence of a pulsar-powered component, and gives this SNR a composite X-ray morphology. Combined ROSAT and ASCA imaging show that the remnant is highly asymmetric, with its hard X-ray emission peaking at the western lobe. The spectrum of 3C 397 is heavily absorbed, and dominated by thermal emission with emission lines evident from Mg, Si, S, Ar and Fe. Single-component models fail to describe the spectrum, and at least two components are required. We use a set of non-equilibrium ionization (NEI) models (Borkowski et al. in preparation). The temperatures from the soft and hard components are 0.2 keV and 1.6 keV respectively. The corresponding ionization time-scales $n_0 t$ ($n_0$ being the pre-shock hydrogen density) are 6 $\\times 10^{12}$ cm$^{-3}$ s and 6 $\\times$ 10$^{10}$ cm$^{-3}$ s, respectively. The spectrum obtained with t...