The population of planetary nebulae and HII regions in M81. A study of radial metallicity gradients and chemical evolution

Abstract

We analyze the chemical abundances of planetary nebulae and HII regions in the M81 disk for insight on galactic evolution, and compare it with that of other galaxies, including the Milky Way. We acquired Hectospec/MMT spectra of 39 PNe and 20 HII regions, with 33 spectra viable for temperature and abundance analysis. Our PN observations represent the first PN spectra in M81 ever published, while several HII region spectra have been published before, although without a direct electron temperature determination. We determine elemental abundances of helium, nitrogen, oxygen, neon, sulfur, and argon in PNe and HII regions, and determine their averages and radial gradients. The average O/H ratio of PNe compared to that of the HII regions indicates a general oxygen enrichment in M81 in the last ~10 Gyr. The PN metallicity gradient in the disk of M81 is -0.055+-0.02 dex/kpc. Neon and sulfur in PNe have a radial distribution similar to that of oxygen, with similar gradient slopes. If we combine our HII sample with the one in the literature we find a possible mild evolution of the gradient slope, with results consistent with gradient steepening with time. Additional spectroscopy is needed to confirm this trend. There are no Type I PNe in our M81 sample, consistently with the observation of only the brightest bins of the PNLF, the galaxy metallicity, and the evolution of post-AGB shells. Both the young and the old populations of M81 disclose shallow but detectable negative radial metallicity gradient, which could be slightly steeper for the young population, thus not excluding a mild gradients steepening with the time since galaxy formation. During its evolution M81 has been producing oxygen; its total oxygen enrichment exceeds that of other nearby galaxies.

A&A, in press

References in corpus (6)

• Stellar Models and Yields of Asymptotic Giant Branch Stars
• The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale
• The Recent Star Formation Histories of M81 Group Dwarf Irregular Galaxies
• Planetary Nebula Abundances and Morphology: Probing the Chemical Evolution of the Milky Way
• The building up of the disk galaxy M33 and the evolution of the metallicity gradient
• Holmberg Ix: The Nearest Young Galaxy

Cited by in corpus (35)

• The Mass-Metallicity Relation with the Direct Method on Stacked Spectra of SDSS Galaxies
• The Abundance Properties of Nearby Late-Type Galaxies.I. The Data
• Fuel Efficient Galaxies: Sustaining Star Formation with Stellar Mass Loss
• "Counterpart" method for abundance determinations in HII regions
• Quantitative Spectroscopy of Blue Supergiant Stars in the Disk of M81: Metallicity, Metallicity Gradient and Distance
• The KLEVER Survey: Spatially resolved metallicity maps and gradients in a sample of 1.2 < z < 2.5 lensed galaxies
• The physics of gas phase metallicity gradients in galaxies
• The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies
• Radial Metallicity Distribution Breaks at Corotation Radius in Spiral Galaxies
• Planetary Nebulae: Sources of Enlightenment
• Analyzing derived metallicities and ionization parameters from model-based determinations in ionized gaseous nebulae
• Galactic planetary nebulae as probes of radial metallicity gradients and other abundance patterns
• Revisiting the abundance gradient in the maser host galaxy NGC 4258
• Metallicity gradients in Local Universe galaxies: time evolution and effects of radial migration
• The Te[N II]-Te[O III] temperature relation in H II regions and the reliability of strong-line methods
• Polycyclic aromatic hydrocarbons in spatially resolved extragalactic star forming complexes
• Bar effect on gas-phase abundance gradients. I. Data sample and chemical abundances
• Metal-Rich PNe in the Outer Reaches of M31
• An Oxygen Abundance Gradient into the Outer Disk of M81
• Distinguishing between symbiotic stars and planetary nebulae
• The radial metallicity gradient and the history of elemental enrichment in M81 through emission-line probes
• The oxygen abundance gradient in M81 and the robustness of abundance determinations in H II regions
• Characterisation of the Galactic thin disc with Corot targets
• Chemical Abundances of Planetary Nebulae in the Substructures of M31
• Optical Spectroscopy of Supernova Remnants in M81 and M82
• Mild evolution of the stellar metallicity gradients of disc galaxies
• Radiation fields by intermediate-age stellar populations with binaries as ionizing sources of H II regions
• Chemical and photometric evolution models for disk, irregular and low mass galaxies
• A study of extragalactic planetary nebulae populations based on spectroscopy. I. Data compilation and first findings
• Three-dimensional modeling of ionized gas. II. Spectral energy distributions of massive and very massive stars in stationary and time-dependent modeling of the ionization of metals in HII regions
• Extragalactic Planetary Nebulae: tracers of the chemical evolution of nearby galaxies
• Cumulative Oxygen Abundances of Spiral Galaxies
• 3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations
• Catalogue of central stars of extragalactic planetary nebulae
• Chemical abundances in Seyfert galaxies -- VII. Direct abundance determination of neon based on optical and infrared emission lines