The Cocoon Nebula and its ionizing star: do stellar and nebular abundances agree?

Abstract

(Abridged) Main sequence massive stars embedded in an HII region should have the same chemical abundances as the surrounding nebular gas+dust. The Cocoon nebula, a close-by Galactic HII region ionized by a narrow line B0.5 V single star (BD+46 3474), is an ideal target to perform a detailed comparison of nebular and stellar abundances in the same Galactic HII region. We investigate the chemical content of O, N and S in the Cocoon nebula from two different points of view: an empirical analysis of the nebular spectrum and a detailed spectroscopic analysis of its ionizing B-type star using state-of-the-art stellar atmosphere modeling. By comparing the stellar and nebular abundances, we aim to indirectly address the long-standing problem of the discrepancy found between abundances obtained from collisionally excited lines (CELs) and optical recombination lines in photoionized nebulae. We collect spatially resolved spectroscopy of the Cocoon nebula and a high resolution optical spectrum of its ionizing star. Standard nebular techniques are used to compute the physical conditions and gaseous abundances of O, N and S. We perform a self-consistent spectroscopic abundance analysis of BD+46 3474 based on the atmosphere code FASTWIND to determine the stellar parameters and Si, O, and N abundances. The Cocoon nebula and its ionizing star, located at a distance of 800+-80 pc, have a very similar chemical composition as the Orion nebula and other B-type stars in the solar vicinity. This result agrees with the high degree of homogeneity of the present-day composition of the solar neighbourhood as derived from the study of the local cold-gas ISM. The comparison of stellar and nebular CELs abundances in the Cocoon nebula indicates that O and N gas+dust nebular values are in better agreement with stellar ones assuming small temperature fluctuations, of the order of those found in the Orion nebula.

arXiv commentAccepted for publication in A&A. 13 pages, 7 tables and 6 figures

References in corpus (46)

• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Rotating Massive Main-Sequence Stars I: Grids of Evolutionary Models and Isochrones
• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
• Atmospheric NLTE-Models for the Spectroscopic Analysis of Blue Stars with Winds. II. Line-Blanketed Models
• On The Cosmic Origins Of Carbon And Nitrogen
• A reappraisal of the chemical composition of the Orion nebula based on VLT echelle spectrophotometry
• The IACOB project: I. Rotational velocities in Northern Galactic O and early B-type stars revisited. The impact of other sources of line-broadening
• Oxygen, Carbon and Nitrogen evolution in galaxies
• Extragalactic chemical abundances: do HII regions and young stars tell the same story? The case of the spiral galaxy NGC 300
• The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution
• Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons
• Eliminating Error in the Chemical Abundance Scale for Extragalactic HII Regions
• Keck HIRES Spectroscopy of Extragalactic HII Regions: C and O Abundances from Recombination Lines
• On the abundance discrepancy problem in HII regions
• The localized chemical pollution in NGC 5253 revisited: Results from deep echelle spectrophotometry
• Ionization Correction Factors for Planetary Nebulae: I- Using optical spectra
• Carbon and Oxygen Galactic Gradients: Observational Values from HII Region Recombination Lines
• The Chemical Composition of the 30 Doradus Nebula Derived from VLT Echelle Spectrophotometry
• Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars
• Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution
• Optical Recombination Lines of Heavy-elements in Giant Extragalactic HII Regions
• Measuring nebular temperatures: the effect of new collision strengths with equilibrium and kappa-distributed electron energies
• Carbon Nitrogen, and Oxygen Galactic Gradients: A Solution to the Carbon Enrichment Problem
• Properties of the ionized gas in HH202. II: Results from echelle spectrophotometry with UVES
• Nitrogen line spectroscopy in O-stars -- II. Surface nitrogen abundances for O-stars in the Large Magellanic Cloud
• The chemical composition of the Orion star-forming region. III. C, N, Ne, Mg and Fe abundances in B-type stars revisited
• The chemical composition of the Orion star forming region: I. Homogeneity of O and Si abundances in B-type stars
• The chemical composition of the Orion star-forming region: II. Stars, gas, and dust: the abundance discrepancy conundrum
• A photoionization modeling study of 30 Doradus: the case for small-scale chemical inhomogeneity
• [O II] line ratios
• Chemical composition of B-type supergiants in the OB8, OB10, OB48, OB78 associations of M31
• A New Distance to M33 Using Blue Supergiants and the FGLR Method
• NGC 2579 and the carbon and oxygen abundance gradients beyond the solar circle
• The IACOB project: A grid-based automatic tool for the quantitative spectroscopic analysis of O-stars
• Nitrogen line spectroscopy of O-stars -- I. Nitrogen III emission line formation revisited
• A new method for an objective, ${\chi }^2$-based spectroscopic analysis of early-type stars
• Enrichment of the ISM by metal-rich droplets and the abundance bias in HII regions
• Recalibration of Pagel's method for HII regions considering the thermal structure, the ionization structure, and the depletion of O into dust grains
• Fluorescent excitation of Balmer lines in gaseous nebulae: case D
• Sulfur Abundances in the Orion Association B Stars
• A global study of the HII region M43 and its ionizing star (I. Stellar parameters and nebular empirical analysis)
• Ionized gas diagnostics from protoplanetary discs in the Orion Nebula and the abundance discrepancy problem
• Densities, temperatures, pressures, and abundances derived from OII recombination lines in HII regions and their implications
• Properties of the ionized gas in HH202. I: Results from integral field spectroscopy with PMAS

Cited by in corpus (25)

• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• Understanding Galaxy Evolution through Emission Lines
• The MOSDEF Survey: Electron Density and Ionization Parameter at $z\sim 2.3$
• Young stars and ionized nebulae in M83: comparing chemical abundances at high metallicity
• The IACOB project. V. Spectroscopic parameters of the O-type stars in the modern grid of standards for spectral classification
• Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution
• The Galactic radial abundance gradients of C, N, O, Ne, S, Cl and Ar from deep spectra of H II regions
• Revisiting the radial abundance gradients of nitrogen and oxygen of the Milky Way
• Carbon and oxygen abundance gradients in NGC300 and M33 from optical recombination lines
• The radial abundance gradient of oxygen towards the Galactic anticentre
• Gradients of chemical abundances in the Milky Way from HII regions: distances derived from Gaia EDR3 parallaxes and temperature inhomogeneities
• A Characteristic Mass Scale in the Mass-Metallicity Relation of Galaxies
• Star Formation In Nearby Clouds (SFiNCs): X-ray And Infrared Source Catalogs And Membership
• Density biases and temperature relations for DESIRED HII regions
• On the radial abundance gradients of nitrogen and oxygen in the inner Galactic disc
• Radial abundance gradients in the outer Galactic disk as traced by main-sequence OB stars
• Bar effect on gas-phase abundance gradients. I. Data sample and chemical abundances
• Stars and gas in the most metal-poor galaxies I: COS and MUSE observations of SBS 0335-052E
• First Co-spatial Comparison of Stellar, Neutral-, and Ionized-gas Metallicities in a metal-rich galaxy: M83
• The last 5 Gyr of Galactic chemical evolution based on H II region abundances derived from a temperature independent method
• Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy II: HH204
• Open cluster Dolidze 25: Stellar parameters and the metallicity in the Galactic Anticentre
• Gas-phase Fe/O and Fe/N abundances in Star-Forming Regions. Relations between nucleosynthesis, metallicity and dust
• The Formation of Filaments and Dense cores in the Cocoon Nebula (IC~5146)
• The ADF and the t${}^2$ formalism in H II regions based on the upper mass limit of the IMF for the MW