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Abstract: We present an observational study of the planetary nebula PN NGC 7354consisting of narrowband Halpha and NII6584 imaging as well as low- andhigh-dispersion long-slit spectroscopy and VLA-D radio continuum. According toour imaging and spectroscopic data, NGC 7354 has four main structures: a quiteround outer shell and an elliptical inner shell, a collection of low-excitationbright knots roughly concentrated on the equatorial region of the nebula, andtwo symmetrical jet-like features, not aligned either with the shells- axes, orwith each other. We have obtained physical parameters like electron temperatureand electron density as well as ionic and elemental abundances for thesedifferent structures. Electron temperature and electron density slightly varythroughout the nebula. The local extinction coefficient c Hbeta shows anincreasing gradient from south to north and a decreasing gradient from east towest consistent with the number of equatorial bright knots present in eachdirection. Abundance values show slight internal variations but most of themare within the estimated uncertainties. In general, abundance values are ingood agreement with the ones expected for PNe. Radio continuum data areconsistent with optically thin thermal emission. We have used the interactivethree-dimensional modeling tool SHAPE to reproduce the observed morphokinematicstructures in NGC 7354 with different geometrical components. Our SHAPE modelis in very good agreement with our imaging and spectroscopic observations.Finally, after modeling NGC 7354 with SHAPE, we suggest a possible scenario forthe formation of the nebula.



Autor: M.E. Contreras, R. Vázquez, L.F. Miranda, L.Olguín, S. Zavala, S. Ayala

Fuente: https://arxiv.org/



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