Browsing Exact and Earth Sciences by Subject "Observações astronômicas no visível"

Now showing items 1-20 of 21

    • Anisotropic high-excitation emission and chemical abundances in the Seyfert 2 galaxy NGC 5643 

      Schmitt, Henrique Roberto; Storchi-Bergmann, Thaisa; Baldwin, Jack A. (1994) [Journal article]
      We present narrow-band images in the lines [O III] λ5007 and Hα(+ [N II] λλ6548, 6584 and long-slit spec­ troscopy along the bar of the Seyfert 2 galaxy NGC 5643. The continuum subtracted [O III] and Hα( images show that ...

    • Asteroseismology of the dov star PG 1159-035 with the Whole Earth Telescope 

      Winget, Donald Earl; Hansen, Carl J.; Fontaine, Gilles; Achilleos, Nicholas; Wickramasinghe, D.T.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; O'Donoghue, Darragh; Warner, B.; Kurtz, Donald W.; Buckley, David A.H.; Brickhill, J.; Vauclair, Gérard; Dolez, Noël; Chevreton, Michel; Barstow, Martin A.; Solheim, Jan-Eric; Kanaan Neto, Antonio Nemer; Hine, B.P.; Grauer, Albert D.; Frueh, M.L.; Claver, C.F.; Wood, Matthew A.; Bradley, Paul A.; Kleinman, Scot James; Provencal, Judith L.; Clemens, J. Christopher; Nather, R. Edward (1991) [Journal article]
      We report the results from 264.1 hr of nearly continuous time-series photometry on the pulsating pre-white dwarf star (DOV) PG 1159-035. The high-resolution power spectrum of this data set is dominated by power in the range ...

    • BV surface photometry of southern galaxies. I. NGC 4507 

      Storchi-Bergmann, Thaisa; Pastoriza, Miriani Griselda (1986) [Journal article]
      From B and V photographic surface photometry we have obtained photometric parameters, mean­ luminosity profiles, and B- V color indices for the barred spiral galaxy NGC 4507. The decomposition of the mean-luminosity B ...

    • A detection of the evolutionary time scale of the da white dwarf G117-B15A with the Whole Earth Telescope 

      Kepler, Souza Oliveira; Winget, Donald Earl; Nather, R. Edward; Bradley, Paul A.; Grauer, Albert D.; Fontaine, Gilles; Bergeron, Pierre; Vauclair, Gérard; Claver, C.F.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Mazeh, Tsevi; Leibowitz, Elia M.; Dolez, Noël; Chevreton, Michel; Barstow, Martin A.; Clemens, J. Christopher; Kleinman, Scot James; Sansom, A.E.; Tweedy, R.W.; Hine, B.P.; Provencal, Judith L.; Wesemael, F.; Wood, Matthew A.; Brassard, P.; Solheim, Jan-Eric; Emanuelsen, P.-I.; Kanaan Neto, Antonio Nemer; Kepler, Souza Oliveira (1991) [Journal article]
      We have detected the time rate of change for the main pulsation period of the 13,000 K DA white dwarf G117-B15A, using the Whole Earth Telescope (WET). The observed rate of period change, P = (12.0 ± 3.5) x 10- 15 s s - ...

    • Double-peaked broad line emission from the LINER nucleus of NGC 1097 

      Storchi-Bergmann, Thaisa; Baldwin, Jack A.; Wilson, Andrew S. (1993) [Journal article]
      We report the recent appearance of a very broad component in the Hα and Hβ emission lines of the weakly active nucleus of the Sersic-Pastoriza galaxy NGC 1097. Subtraction of the contribution of the stellar population from ...

    • Dust extinction of the stellar continua in Starburst galaxies : the ultraviolet and optical extinction law 

      Calzetti, Daniela; Kinney, Anne Louise; Storchi-Bergmann, Thaisa (1994) [Journal article]
      We analyze the IUE UV and the optical spectra of 39 starburst and blue compact galaxies in order to study the average properties of dust extinction in extended regions of galaxies. The optical spectra have been obtained ...

    • Field color magnitude diagram analysis along the bulge major axis 

      Ortolani, Sergio; Bica, Eduardo Luiz Damiani; Barbuy, Beatriz (1993) [Journal article]
      We analyze background fields along the bulge major axis away from the Galactic center by 2°.5, 13° and 31°. Our aim is to study the spatial distribution of different steiiar populations. A similar component of young disk ...

    • Galaxy properties in different environments. II. Star formation in bulges of late-type spirals 

      Bica, Eduardo Luiz Damiani; Maia, Marcio Antonio Geimba; Bonatto, Charles Jose; Dottori, Horacio Alberto; Pastoriza, Miriani Griselda (1994) [Journal article]
      The star formation history in the nucleus of late spiral galaxies is compared between a sample in a high galaxy density medium (HDS) and a control sample (CS) of isolated galaxies. We have observed 20 HDS and 18 CS galaxies ...

    • Hot degenerates in the MCT survey. I. MCT 130-1937, a new, color-selected PG 1159 object 

      Demers, Serge; Wesemael, F.; Irwin, Michael John; Fontaine, Gilles; Kepler, Souza Oliveira; Lamontagne, R.; Holberg, J.B. (1990) [Journal article]
      We report the discovery, in the course of a survey for high-latitude, ultraviolet-excess objects in the southern hemisphere, of a new white dwarf star belonging to the PG 1159 spectroscopic class. A variety of spectroscopic ...

    • A new luminous blue variable : R143 in 30 Doradus 

      Parker, Joel Wm.; Clayton, Geoffrey C.; Winge, Claudia; Conti, Peter S. (1993) [Journal article]
      We have discovered that R143 in the Large Magellanic Cloud is a luminous blue variable (LBV), the first and perhaps the lone LBV in the central cluster of 30 Doradus, and only the sixth known LMC LBV. Photo­ metric and ...

    • On the metal abundance of low-activity galactic nuclei 

      Storchi-Bergmann, Thaisa; Pastoriza, Miriani Griselda (1989) [Journal article]
      The characteristics of the nuclear spectrum of six Seyfert 2 and LINER nuclei with low activity and strong !ines of ionized nitrogen are investigated. From the equivalent widths of the absorption !ines, the age and metallicity ...

    • Optical spectroscopy and narrow-band images of the variable Seyfert 1 galaxy NGC 3783 

      Winge, Claudia; Pastoriza, Miriani Griselda; Storchi-Bergmann, Thaisa; Lipari, Sebastian (1992) [Journal article]
      We present narrow-band images centered on [O III] λ5007, Hα, and adjacent continua of the Seyfert 1 galaxy NGC 3783. The continuum images evidence that the bar emission is mainly due to old stars. The [O III] λ5007 image ...

    • Photographic photometry and the optical spectrum of the Seyfert galaxy IC 4329 A 

      Pastoriza, Miriani Griselda (1979) [Journal article]
      Spectrophotometric and photographic observations of IC 4329 A show that this Seyfert galaxy has reduced dimensions D x d = (13.6 x 7.6) kpc anda high luminosity Mph = -20.2. The nucleus is stratified in three zones: first, ...

    • SN 1992A : ultraviolet and optical studies based on HST, IUE and CTIO observations 

      Kirshner, Robert P.; Jeffery, David J.; Leibundgut, Bruno; Challis, Peter M.; Sonneborn, George; Phillips, M.M.; Suntzeff, N.B.; Smith, Robert Christopher; Winkler, P. Frank; Winge, Claudia; Hamuy, Mario; Hunter, Deidre A.; Roth, Katherine C.; Blades, J.C.; Branch, David; Chevalier, Roger A.; Fransson, Claes; Panagia, Nino; Wagoner, Robert V.; Wheeler, J. Craig; Harkness, Robert P. (1993) [Journal article]
      The Type Ia supernova SN 1992A in the SO galaxy NGC 1380 was observed as a target of opportunity by the International Ultraviolet Explorer (IUE) and with great alacrity by the Hubble Space Telescope (HST). Here we present ...

    • Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. VII. Variability of the optical spectrum of NGC 5548 over 4 years 

      Peterson, Bradley M.; Berlind, P.; Bertram, R.; Bochkarev, N.G.; Bond, D.; Brotherton, Mike; Busler, J.R.; Chuvaev, K.K.; Cohen, R.D.; Dietrich, Matthias; Elvis, Martin; Filippenko, Alexei V.; Foltz, C.B.; Garnavich, P.M.; Ho, Luis C.; Horine, E.; Horne, Keith; Huchra, John P.; Kollatschny, W.; Korista, Kirk T.; Malkan, M.A.; Matheson, T.; Mignoli, M.; Morris, S.L.; Nazarova, L.; Penfold, J.; Peters, J.; Pogge, Richard William; Pronik, V.I.; Rush, B.; Sergeev, S.G.; Shapovalova, A.I.; Shields, J.C.; Stirpe, Giovanna M.; Tokarz, S.; Wagner, R.M.; Weymann, R.J.; White, R.J.; Wilkes, B.J.; Wills, Derek; Wills, Beverley J.; Winge, Claudia; Younger, P.F. (1994) [Journal article]
      We report on the results of a continuation of a large monitoring program of optical spectroscopy of the Seyfert 1 galaxy NGC 5548. The new observations presented here were obtained between 1990 December and 1992 October, ...

    • Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. VI. Variability of NGC 3783 from ground-based data 

      Stirpe, Giovanna M.; Winge, Claudia; Altieri, B.; Alloin, Danielle Marie; Aguero, E.L.; Anupama, G.C.; Ashley, R.; Bertram, R.; Calderon, J.H.; Catchpole, R.M.; Corradi, R.L.M.; Covino, E.; Dottori, Horacio Alberto; Feast, M.W.; Ghosh, K.K.; Hutton, R. Gil; Glass, I.S.; Grebel, Eva K.; Jorda, L.; Koen, C.; Laney, C.D.; Maia, Marcio Antonio Geimba; Marang, Fred; Mayya, Y.D.; Morrell, Nidia; Nakada, Y.; Pastoriza, Miriani Griselda; Pati, A.K.; Pelat, D.; Peterson, Bradley M.; Prabhu, T.P.; Roberts, G.; Sagar, R.; Salamanca, I.; Sekiguchi, Kazuhiro; Storchi-Bergmann, Thaisa; Subramaniam, A.; Villada, M.; Wagner, R.M.; Whitelock, P.A.; Winkler, Hartmut; Clavel, J.; Dietrich, Matthias; Kollatschny, W.; Perola, G.C.; Van Winckel, H.; Van Wyk, Francois; O'Brien, P.T.; Recondo-Gonzalez, M.C.; Rodriguez-Pascual, P.M.; Santos-Lleo, M. (1994) [Journal article]
      The Seyfert 1 galaxy NGC 3783 was intensely monitored in several bands between 1991 December and 1992 August. This paper presents the results from the ground-based observations in the optical and near-IR bands, which ...

    • Study of the nuclei of NGC 3732 and IC 4662 

      Pastoriza, Miriani Griselda; Dottori, Horacio Alberto (1981) [Journal article]
      The nuclei of two galaxies which show intense [O III] emission lines, NGC 3732, an Sa, and IC 4662, an irregular with a very bright nucleus, are analyzed spectroscopically. The physical condition of the emitting gas and ...

    • The discovery of a new DAV star using IUE temperature determination 

      Kanaan Neto, Antonio Nemer; Kepler, Souza Oliveira; Giovannini Junior, Odilon; Diaz, M.P. (1992) [Journal article]
      We report the discovery of a new ZZ Ceti star observed on the assumption that most DA stars with temperature near 11,000 K are pulsators and on a temperature determination using lUE data. Even though BPM 37093 had already ...

    • The ionization cone, obscured nucleus, and gaseous outflow in NGC 3281 : a prototypical Seyfert 2 galaxy? 

      Storchi-Bergmann, Thaisa; Wilson, Andrew S.; Baldwin, Jack A. (1992) [Journal article]
      We present narrow-band images and long-slit spectroscopy of the central region of the highly inclined Seyfert galaxy NGC 3281. The image of the continuum-subtracted [O III] λ4959 emission line shows a very clear conical ...

    • The nuclear region of NGC 7469 

      Bonatto, Charles Jose; Pastoriza, Miriani Griselda (1990) [Journal article]
      We have made spectrophotometric observations of the nuclear and circumnuclear regions of the Seyfert 1 galaxy NGC 7469, and we analyze the dynamics and structure of the emission-line regions. In the nuclear region of NGC ...