Navegando por Autor "Hernandez-Jimenez, José Andrés"

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    Análise de estruturas de galáxias espirais grand design via Séries e Transformadas de Fourier
    (2023-02-28) Oliveira Filho, Irapuan Rodrigues de; Oliveira, Virgínia Klausner de; Hernandez-Jimenez, José Andrés; Puerari, Ivânio; Vera-Villamizar, Nelson; Costa, Stella Faria; Caritá, Lucas Antonio; São José dos Campos
    Utilizando imagens do DESI Legacy Imaging Survey nas bandas g, r e z, foi realizada uma análise das estruturas espirais das galáxias IC 4566, NGC 768 e IC 1256. O objetivo deste trabalho é aplicar as Transformadas de Fourier unidimensional e bidimensional para análise das estruturas presentes em galáxias espirais grand design. Para isso, foram criados programas em P YTHON para implementação dos métodos, realizados testes com espirais teóricas e galáxias estudadas em outros trabalhos e assim, feita a aplicação nas três galáxias. Primeiramente, aplicamos a Série e a Transformada de Fourier bidimensional para determinação das componentes pmq dominantes em cada uma das estruturas espirais, além da medição do pitch angle a de cada modo. Em seguida, foi implementada a Transformada de Fourier unidimensional para determinação da ressonância de corrotação. Como resultado, IC 1256 apresentou como modo dominante m ? 3 e |a| « 21.8 , e as galáxias IC 4566 e NGC 768, m ? 2 com |a| « 16.9 e |a| « 18.9 , respectivamente. Com relação à ressonância de corrotação, para IC 4566 determinamos que o caráter do padrão espiral é trailing com raio de corrotação em 7.8 kpc e leading em 16 kpc; para NGC 768 o caráter do padrão é trailing e o raio de corrotação está em 15 kpc . Os métodos apresentam boa caracterização das estruturas espirais de galáxias grand design e os valores obtidos para o pitch angle aproximam-se de valores apresentados em outros estudos e técnicas.
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    Chemical abundances of LINER galaxies – nitrogen abundance estimations
    (Royal Astronomical Society) Oliveira Junior, Celso Benedito de ; Krabbe, Angela Cristina; Dors Junior, Oli Luiz; Zinchenko, Igor; Hernandez-Jimenez, José Andrés; Cardaci, Mónica Viviana; Hägele, Guilhermo Frederico; Ilha, Gabriele da Silva
    In this work, we investigated the nitrogen and oxygen abundances in a sample of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their nucleus. Optical spectroscopic data (3600 – 10 000 Å) of 40 LINERs from the Mapping Nearby Galaxies (MaNGAs) survey were considered. Only objects classified as retired galaxies, that is, whose main ionization sources are post-Asymptotic Giant Branch (pAGB) stars, were selected. The abundance estimates were obtained through detailed photoionization models built with the CLOUDY code to reproduce a set of observational emission line intensities ratios of the sample. Our results show that LINERs have oxygen and nitrogen abundances in the ranges of 8.0 􏰀 12 + log(O/H) 􏰀 9.0 (mean value 8.74 ± 0.27) and 7.6 􏰀 12 + log(N/H) 􏰀 8.5 (mean value 8.05 ± 0.25), respectively. About 70 per cent of the sample have oversolar O/H and N/H abundances. Our abundance estimates are in consonance with those for Seyfert 2 nuclei and H II regions with the highest metallicity, indicating that these distinct object classes show similar enrichment of the interstellar medium (ISM). The LINERs in our sample are located in the higher N/O region of the N/O versus O/H diagram, showing an unexpected negative correlation between these two parameters. These results suggest that these LINERs mainly exhibit a secondary nitrogen production and could be acting some other mechanisms that deviate them from the usual theoretical secondary nitrogen production curve and the H II regions observations. However, we did not find any evidence in our data able to support the literature suggested mechanisms. Alternatively, our results show that LINERs do not present any correlation between the N/O abundances and the stellar masses of the hosting galaxies.
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    Diagnostic diagrams for ram pressure stripped candidates
    (Royal Astronomical Society) Krabbe, Angela Cristina; Hernandez-Jimenez, José Andrés; Oliveira, Claudia Mendes de; Jaffe, Yara L.; Oliveira Junior, Celso Benedito de; Cardoso, Nathalia Machado; Castelli, Analía V Smith; Dors Junior, Oli Luiz; Cortesi, Arianna; Crossett, Jacob P.
    This paper presents a method for finding ram pressure stripped (RPS) galaxy candidates by performing a morphological analysis of galaxy images obtained from the Legacy survey. We consider a sample of about 600 galaxies located in different environments such as groups and clusters, tidally interacting pairs and the field. The sample includes 160 RPS previously classified in the literature into classes from J1 to J5, based on the increasing level of disturbances. Our morphological analysis was done using the ASTROMORPHLIB software followed by the inspection of diagnostic diagrams involving combinations of different parameters like the asymmetry (A), concentration (C), Sersic ´ index (n), and bulge strength parameters F(G, M20). We found that some of those diagrams display a distinct region in which galaxies classified as J3, J4, and J5 decouples from isolated galaxies. We call this region as the morphological transition zone and we also found that tidally interacting galaxies in pairs are predominant within this zone. Nevertheless, after visually inspecting the objects in the morphological transition zone to discard obvious contaminants, we ended up with 33 bona fide new RPS candidates in the studied nearby groups and clusters (Hydra, Fornax, and CLoGS sample), of which one-third show clear evidence of unwinding arms. Future works may potentially further increase significantly the samples of known RPS using such method.