VLT/FORS1 spectrophotometry of the first planetary nebula discovered in the Phoenix dwarf galaxy

Abstract

Context: A planetary nebula (PN) candidate was discovered during FORS imaging of the Local Group dwarf galaxy Phoenix. Aims: Use this PN to complement abundances from red-giant stars. Methods: FORS spectroscopy was used to confirm the PN classification. Empirical methods and photoionization modeling were used to derive elemental abundances from the emission line fluxes and to characterize the central star. Results: For the elements deemed most reliable for measuring the metallicity of the interstellar medium (ISM) from which the PN formed, [O/H] ~ -0.46 and [Ar/H] ~ -1.03. [O/H] has lower measurement errors but greater uncertainties due to the unresolved issue of oxygen enrichment in the PN precursor star. Conclusions: Earlier than 2 Gyr ago (the lower limit of the derived age for the central star) the ISM had Z = 0.002--0.008, a range slightly more metal-rich than the one provided by stars. Comparing our PN-to-stellar values to surveys for other dwarf Local Group galaxies, Phoenix appears as an outlier.

12 pages, 5 figures, accepted by A&A

References in corpus (5)

• Hot Dust and PAH Emission at Low Metallicity: A Spitzer Survey of Local Group and Other Nearby Dwarf Galaxies
• The Planetary Nebula population of the Sagittarius Dwarf Spheroidal Galaxy
• The Progenitors of Planetary Nebulae in Dwarf Irregular Galaxies
• High-quality Spectrophotometry of the Planetary Nebula in the Fornax dSph
• The CO content of the Local Group dwarf irregular galaxies IC5152, UGCA438, and the Phoenix dwarf