The Light Element Abundance Distribution in NGC 5128 from Planetary Nebulae

Abstract

The light element abundance pattern from many planetary nebulae (PNe) covering the upper 4 mag. of the [O III] luminosity function was observed with ESO VLT FORS1 multi-slit. Spectra of 51 PNe over the wavelength range 3500-7500 Angstrom were obtained in three fields at 4, 8 and 17 kpc, for a distance of 3.8 Mpc. Emission line ratios are entirely typical of PN such as in the Milky Way. The temperature sensitive [O III]4363A line was weakly detected in 10 PNe, both [O II] and [O III] lines were detected in 30 PNe, and only the bright [O III]5007A line in 7 PN. Cloudy photoionization models were run to match the spectra by a spherical, constant density nebula ionized by a black body central star. He, N, O and Ne abundances with respect to H were determined and, for brighter PNe, S and Ar; central star luminosities and temperatures are also derived. For 40 PNe with Cloudy models, from the upper 2 mag. of the luminosity function, the most reliably estimated element, oxygen, has a mean 12+log(O/H) of 8.52. No obvious radial gradient is apparent in O/H over a range 2-20 kpc. Comparison of the PN abundances with the stellar population, from the spectra of the integrated starlight on the multi-slits and photometric studies, suggests [Fe/H]=-0.4 and [O/Fe]=0.25. The masses of the PN central stars in NGC 5128 from model tracks imply an epoch of formation more recent than for the minority young population from colour-magnitude studies. The PNe progenitors may belong to the young tail of a recent, minor, star formation episode or derive from other evolutionary channels.[Abridged]

28 pages, 12 tables, 11 figures. Accepted for publication in Astronomy & Astrophysics

References in corpus (13)

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• On the solar nickel and oxygen abundances
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• Chemical Abundance Evidence of Enduring High Star Formation Rates in an Early Type Galaxy: High [Ca/Fe] in NGC 5128 Globular Clusters
• Constraining black hole masses in low-accreting AGN using X-ray spectra
• An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A): Planetary nebulae catalogues
• Hubble Space Telescope Spectroscopy of a Planetary Nebula in an M31 Open Cluster: Hot-Bottom Burning at $3.4M_{\odot }$
• Blasting away a dwarf galaxy: The "tail" of ESO 324-G024
• MUSE crowded field 3D spectroscopy in NGC 300 : IV. Planetary nebula luminosity function