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High-resolution spectroscopy of the blue compact dwarf galaxy Haro 15 – II. Chemodynamics

Authors

  • Guillermo F. Hägele,

    Corresponding author
    1. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de la La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
    2. IALP-Conicet, Paseo del Bosque s/n, 1900 La Plata, Argentina
    3. Departamento de Física Teórica, C-XI, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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  • Verónica Firpo,

    1. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de la La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
    2. IALP-Conicet, Paseo del Bosque s/n, 1900 La Plata, Argentina
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  • Guillermo Bosch,

    1. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de la La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
    2. IALP-Conicet, Paseo del Bosque s/n, 1900 La Plata, Argentina
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  • Ángeles I. Díaz,

    1. Departamento de Física Teórica, C-XI, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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  • Nidia Morrell

    1. Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena, Chile
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E-mail: ghagele@fcaglp.unlp.edu.ar

ABSTRACT

We present a detailed study of the physical properties of the nebular material in four star-forming knots of the blue compact dwarf galaxy Haro 15. Using long-slit and echelle spectroscopy obtained at Las Campanas Observatory, we study the physical conditions (electron density and temperatures), ionic and total chemical abundances of several atoms, reddening and ionization structure, for the global flux and for the different kinematical components. The latter was derived by comparing the oxygen and sulphur ionic ratios to their corresponding observed emission-line ratios (the η and η′ plots) in different regions of the galaxy. Applying the direct method or empirical relationships for abundance determination, we perform a comparative analysis between these regions. The similarities found in the ionization structure of the different kinematical components imply that the effective temperatures of the ionizing radiation fields are very similar in spite of some small differences in the ionization state of the different elements. Therefore, the different gaseous kinematical components identified in each star-forming knot are probably ionized by the same star cluster. However, the difference in the ionizing structure of the two knots with knot A showing a lower effective temperature than knot B suggests a different evolutionary stage for them consistent with the presence of an older and more evolved stellar population in the first.

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