Navegação por Autor "Heckman, Timothy M."

Resultados 1-11 de 11

    • An atlas of H II regions in nearby Seyfert galaxies 

      Evans, I.N.; Koratkar, A.P.; Storchi-Bergmann, Thaisa; Kirkpatrick, H.; Heckman, Timothy M.; Wilson, Andrew S. (1996) [Artigo de periódico]
      Continuum-subtracted Hα images of 17 nearby Seyfert galaxies are presented. The images are calibrated astrometrically usmg the Hubble Space Telescope Guide Star Catalog reference frame. For each galaxy, an inventory of HII ...

    • An atlas of the circumnuclear regions of 75 Seyfert galaxies in the near-ultraviolet with the Hubble Space Telescope advanced camara for surveys 

      Muñoz Marín, Victor M.; González Delgado, Rosa M.; Schmitt, Henrique Roberto; Fernandes, Roberto Cid; Pérez Jiménez, Enrique; Storchi-Bergmann, Thaisa; Heckman, Timothy M.; Leitherer, Claus (2007) [Artigo de periódico]
      We present an atlas of the central regions of 75 Seyfert galaxies imaged in the near-UV with the Advanced Camera for Surveys of the Hubble Space Telescope at an average resolution of ~10 pc. These data complement archival ...

    • Circumnuclear stellar population, morphology, and environment of Seyfert 2 galaxies : an evolutionary scenario 

      Storchi-Bergmann, Thaisa; González Delgado, Rosa M.; Schmitt, Henrique Roberto; Fernandes Junior, Roberto Cid; Heckman, Timothy M. (2001) [Artigo de periódico]
      We investigate the relation between the characteristics of the circumnuclear stellar population and both the galaxy morphology and the presence of close companions for a sample of 35 Seyfert 2 nuclei. Fifteen galaxies ...

    • Empirical diagnostics of the starburst-AGN connection 

      Fernandes Junior, Roberto Cid; Heckman, Timothy M.; Schmitt, Henrique Roberto; González Delgado, Rosa M.; Storchi-Bergmann, Thaisa (2001) [Artigo de periódico]
      We examine a representative sample of 35 Seyfert 2 nuclei. Previous work has shown that nearly half (15) of these nuclei show the direct (but difficult to detect) spectroscopic signature at optical/near-UV wavelengths of ...

    • Gas metallicity distributions in SDSS-IV MaNGA galaxies : what drives gradients and local trends? 

      Boardman, Nicholas Fraser; Wild, Vivienne; Heckman, Timothy M.; Sánchez, Sebastián F.; Riffel, Rogério; Riffel, Rogemar André; Zasowski, G. (2023) [Artigo de periódico]
      The gas metallicity distributions across individual galaxies and across galaxy samples can teach us much about how galaxies evolve. Massive galaxies typically possess negative metallicity gradients, and mass and metallicity ...

    • Probing evolutionary population synthesis models in the near infrared with early-type galaxies 

      Hahn, Luis Gabriel Dahmer; Riffel, Rogério; Rodriguez-Ardila, Alberto; Martins, Lucimara Pires; Kehrig, Carolina; Heckman, Timothy M.; Pastoriza, Miriani Griselda; Dametto, Natacha Zanon (2018) [Artigo de periódico]
      We performed a near-infrared (NIR; ∼1.0 –2.4 μm) stellar population study in a sample of early-type galaxies. The synthesis was performed using five different evolutionary population synthesis libraries of models. Our main ...

    • Stellar population gradients in Seyfert 2 galaxies : northern sample 

      Raimann, Daniel Iunes; Storchi-Bergmann, Thaisa; González Delgado, Rosa M.; Fernandes Junior, Roberto Cid; Heckman, Timothy M.; Leitherer, Claus; Schmitt, Henrique Roberto (2003) [Artigo de periódico]
      We use high signal-to-noise ratio long-slit spectra in the λλ3600–4700 range of the 20 brightest northern Seyfert 2 galaxies to study the variation of the stellar population properties as a function of distance from the ...

    • The heating of dust in starburst galaxies : the contribution of the nonionizing radiation 

      Calzetti, Daniela; Bohlin, Ralph C.; Kinney, Anne Louise; Storchi-Bergmann, Thaisa; Heckman, Timothy M. (1995) [Artigo de periódico]
      The IUE UV and optical spectra and the far-infrared (FIR) IRAS flux densities of a sample of starburst and blue compact galaxies are used to investigate the relationship between dust obscuration and dust emission. The ...

    • The obscuring starburst of NGC 6221 and implications for the hard x-ray background 

      Levenson, Nancy A.; Fernandes Junior, Roberto Cid; Weaver, Kim A.; Heckman, Timothy M.; Storchi-Bergmann, Thaisa (2001) [Artigo de periódico]
      We present NGC 6221 as a case study of "X-ray-loud composite galaxies", which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC ...

    • The stellar populations of low-luminosity active galactic nuclei. I. Ground-based observations 

      Fernandes, Roberto Cid; González Delgado, Rosa M.; Schmitt, Henrique Roberto; Storchi-Bergmann, Thaisa; Martins, Lucimara Pires; Pérez Jiménez, Enrique; Heckman, Timothy M.; Leitherer, Claus; Schaerer, Daniel (2004) [Artigo de periódico]
      We present a spectroscopic study of the stellar populations of low-luminosity active galactic nuclei (LLAGNs). Our main goal is to determine whether the stars that live in the innermost (100 pc scale) regions of these ...

    • The stellar populations of low-luminosity active galactic nuclei. II. Space telescope imaging spectrograph observations 

      González Delgado, Rosa M.; Fernandes, Roberto Cid; Storchi-Bergmann, Thaisa; Martins, Lucimara Pires; Pérez Jiménez, Enrique; Heckman, Timothy M.; Leitherer, Claus; Schaerer, Daniel (2004) [Artigo de periódico]
      We present a study of the stellar populations of low-luminosity active galactic nuclei (LLAGNs). Our goal is to search for spectroscopic signatures of young and intermediate-age stars and to investigate their relationship ...