Browsing Exact and Earth Sciences by Author "Valerdi, Mabel"

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    • Chemical abundances in Seyfert galaxies : IX. Helium abundance estimates 

      Dors Júnior, Oli Luiz; Valerdi, Mabel; Freitas-Lemes, Priscila; Krabbe, Angela Cristina; Riffel, Rogemar André; Amôres, Eduardo Brescansin de; Riffel, Rogério; Armah, Mark; Santos, Adriano Francisco Monteiro dos; Oliveira Junior, Celso Benedito de (2022) [Journal article]
      For the first time, the helium abundance relative to hydrogen (He/H), which relied on direct measurements of the electron temperature, has been derived in the narrow line regions (NLRs) from a local sample of Seyfert 2 ...

    • Chemical abundances in Seyfert galaxies : X. sulphur abundance estimates 

      Dors Júnior, Oli Luiz; Valerdi, Mabel; Riffel, Rogemar André; Riffel, Rogério; Cardaci, Mónica V.; Hägelle, Guillermo Federico; Armah, Mark; Revalski, Mitchell; Flury, Sophia; Freitas-Lemes, Priscila; Amôres, Eduardo Brescansin de; Krabbe, Angela Cristina; Binette, Luc; Feltre, Anna; Storchi-Bergmann, Thaisa (2023) [Journal article]
      For the first time, the sulphur abundance relative to hydrogen (S/H) in the narrow-line regions of a sample of Seyfert 2 nuclei (Sy 2s) has been derived via direct estimation of the electron temperature. Narrow emission-line ...

    • Oxygen abundances in the narrow line regions of Seyfert galaxies and the metallicity–luminosity relation 

      Armah, Mark; Riffel, Rogério; Dors Júnior, Oli Luiz; Oh, Kyuseok; Koss, Michael; Ricci, Claudio; Trakhtenbrot, Benny; Valerdi, Mabel; Riffel, Rogemar André; Krabbe, Angela Cristina (2023) [Journal article]
      We present oxygen abundances relative to hydrogen (O/H) in the narrow line regions (NLRs) gas phases of Seyferts 1 (Sy 1s) and Seyferts 2 (Sy 2s) active galactic nuclei (AGNs). We used fluxes of the optical narrow emission ...