Properties of Galactic early-type O-supergiants: A combined FUV-UV and optical analysis

Abstract

We aim to constrain the properties and evolutionary status of early and mid-spectral type supergiants (from O4 to O7.5). These posses the highest mass-loss rates among the O stars, and exhibit conspicuous wind profiles. Using the non-LTE wind code CMFGEN, we simultaneously analyzed the FUV-UV and optical spectral range to determine the photospheric properties and wind parameters. We derived effective temperatures, luminosities, surface gravities, surface abundances, mass-loss rates, wind terminal velocities, and clumping filling factors. The supergiants define a very clear evolutionary sequence, in terms of ages and masses, from younger and more massive stars to older stars with lower initial masses. O4 supergiants cluster around the 3 Myr isochrone and are more massive than 60 Msun, while the O5 to O7.5 stars have masses in the range 50 - 40 Msun and are 4 +/- 0.3 Myr old. The surface chemical composition is typical of evolved O supergiants (nitrogen-rich, carbon- and oxygen-poor). While the observed ranges of carbon and nitrogen mass-fractions are compatible with those expected from evolutionary models for the measured stellar masses, the N/C ratios as a function of age are inconsistent with the theoretical predictions for the four earliest (O4 spectral type) stars of the sample. We question the efficiency of rotational mixing as a function of age for these stars and suggest that another mechanism may be needed to explain the observed abundance patterns. Mass-loss rates derived with clumped-models range within a factor of three of the theoretical mass-loss rates. The corresponding volume-filling factors associated with small-scale clumping are 0.05 +/- 0.02. Clumping is found to start close to the photosphere for all but three stars, two of which are fast rotators.

30 pages, 11 figures, accepted for publication in A&A 2012

References in corpus (21)

• The Supernova -- Gamma-Ray Burst Connection
• Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
• UBVJHK synthetic photometry of Galactic O stars
• Bright OB stars in the Galaxy - III. Constraints on the radial stratification of the clumping factor in hot star winds from a combined Halpha, IR and radio analysis
• The VLT-FLAMES survey of massive stars: constraints on stellar evolution from the chemical compositions of rapidly rotating Galactic and Magellanic Cloud B-type stars
• The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution
• The most massive stars in the Arches cluster
• A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition
• Neglecting the porosity of hot-star winds can lead to underestimating mass-loss rates
• Neon Abundances in B-Stars of the Orion Association: Solving the Solar Model Problem?
• On the origin of field O-type stars
• Adaptive Optics Photometry and Astrometry of Binary Stars. III. A Faint Companion Search of O-Star Systems
• On the sensitivity of HeI singlet lines to the FeIV model atom in O stars
• Early-type stars in the young open cluster IC1805. II. The probably single stars HD15570 and HD15629, and the massive binary/triple system HD15558
• On the Importance of the Interclump Medium for Superionization: O VI Formation in the Wind of Zeta Pup
• NLTE models of line-driven stellar winds III. Influence of X-ray radiation on wind structure of O stars
• Rotation and massive close binary evolution
• An XMM-Newton view of the young open cluster NGC 6231 III. Optically faint X-ray sources
• Mass fluxes for O stars
• The superimposed photospheric and stellar wind variability of the O-type supergiant alpha Cam
• Mixing of CNO-cycled matter in massive stars

Cited by in corpus (123)

• The IACOB project: I. Rotational velocities in Northern Galactic O and early B-type stars revisited. The impact of other sources of line-broadening
• A coordinated X-ray and Optical Campaign of the Nearest Massive Eclipsing Binary, $\delta$ Orionis Aa: IV. A multiwavelength, non-LTE spectroscopic analysis
• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• The evolution of rotating very massive stars with LMC composition
• The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars
• Towards a unified view of inhomogeneous stellar winds in isolated supergiant stars and supergiant high mass X-ray binaries
• A comparison of evolutionary tracks for single Galactic massive stars
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars II. A grid of O-type stars in the Galaxy and the Magellanic Clouds
• The R136 star cluster dissected with Hubble Space Telescope/STIS. III. The most massive stars and their clumped winds
• Magnetic massive stars as progenitors of "heavy" stellar-mass black holes
• Clumping in the inner winds of hot, massive stars from hydrodynamical line-driven instability simulations
• Wolf-Rayet stars in the Small Magellanic Cloud: II. Analysis of the binaries
• Coupling hydrodynamics with comoving frame radiative transfer: I. A unified approach for OB and WR stars
• The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars
• Massive stars at low metallicity: Evolution and surface abundances of O dwarfs in the SMC
• Evolution of surface CNO abundances in massive stars
• The Unusual Initial Mass Function of the Arches Cluster
• Macroclumping as solution of the discrepancy between Hα and P v mass loss diagnostics for O-type stars
• The IACOB project. V. Spectroscopic parameters of the O-type stars in the modern grid of standards for spectral classification
• Spectroscopic and physical parameters of Galactic O-type stars. III. Mass discrepancy and rotational mixing
• Measuring mass-loss rates and constraining shock physics using X-ray line profiles of O stars from the Chandra archive
• Lya escape from z~0.03 star-forming galaxies: the dominant role of outflows
• The surface nitrogen abundance of a massive star in relation to its oscillations, rotation, and magnetic field
• Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss
• BRITE-Constellation high-precision time-dependent photometry of the early-O-type supergiant $\zeta$ Puppis unveils the photospheric drivers of its small- and large-scale wind structures
• The Tarantula Massive Binary Monitoring: III. Atmosphere analysis of double-lined spectroscopic systems
• A Bake-Off Between CMFGEN and FASTWIND: Modeling the Physical Properties of SMC and LMC O-type Stars
• Mass loss from inhomogeneous hot star winds III. An effective-opacity formalism for line radiative transfer in accelerating, clumped two-component media, and first results on theory and diagnostics
• The Origin of Galactic Cosmic Rays as Revealed by their Composition
• On magnetic inhibition of photospheric macro-turbulence generated in the iron-bump opacity zone of O-stars
• No breakdown of the radiatively-driven wind theory in low-metallicity environments
• Modeling the early evolution of massive OB stars with an experimental wind routine
• The VLT-FLAMES Tarantula Survey XXV. Surface nitrogen abundances of O-type giants and supergiants
• The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMS
• Wind mass-loss rates of stripped stars inferred from Cygnus X-1
• Empirical mass-loss rates and clumping properties of Galactic early-type O supergiants
• A spectroscopic investigation of the O-type star population in four Cygnus OB associations. II. Determination of the fundamental parameters
• Simultaneous X-ray and optical spectroscopy of the Oef supergiant lambda Cep
• Spectroscopic evolution of massive stars on the main sequence
• Evidence for quasi-chemically homogeneous evolution of massive stars up to solar metallicity
• Spectroscopic evolution of very massive stars at Z = 1/2.5 Zsun
• A detailed X-ray investigation of ζ Puppis III. A spectral analysis of the whole RGS spectrum
• Spectroscopic and physical parameters of Galactic O-type stars. II. Observational constraints on projected rotational and extra broadening velocities as a function of fundamental parameters and stellar evolution
• Intensity interferometry of P Cygni in the H$\alpha$ emission line: towards distance calibration of LBV supergiant stars
• Constraints on porosity and mass loss in O-star winds from modeling of X-ray emission line profile shapes
• A Rare Encounter with Very Massive Stars in NGC 3125-A1
• Impact of clumping on core-collapse supernova radiation
• Massive stars in the Small Magellanic Cloud : Evolution, rotation and surface abundances
• On the formation of CIII 4647-50-51 and CIII 5696 in O star atmospheres
• Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds. V. Complete comoving frame transfer, and updated modeling of X-ray emission
• Global hot-star wind models for stars from Magellanic Clouds
• Far-Ultraviolet Observations of Outflows from IR-Luminous Galaxies
• New mass-loss rates of B supergiants from global wind models
• Critical angular velocity and anisotropic mass loss of rotating stars with radiation-driven winds
• Time-series photometry of the O4 I(n)fp star zeta Puppis
• A study of the effect of rotational mixing on massive stars evolution: surface abundances of Galactic O7-8 giant stars
• X-ray, UV and optical analysis of supergiants: $\epsilon$ Ori
• The X-ray catalog of spectroscopically identified Galactic O stars: Investigating the dependence of X-ray luminosity on stellar and wind parameters
• Observational properties of massive black hole binary progenitors
• Evidence for Very Massive Stars in extremely UV-bright star-forming galaxies at $z\sim 2.2-3.6$
• Measuring the shock-heating rate in the winds of O stars using X-ray line spectra
• Chemical abundances of fast-rotating massive stars. I. Description of the methods and individual results
• Investigating the origin of cyclical wind variability in hot, massive stars - I. On the dipolar magnetic field hypothesis
• The influence of rotation on optical emission profiles of O stars
• Clumping and X-Rays in cooler B supergiant stars
• Wind inhibition by X-ray irradiation in HMXBs: the influence of clumping and the final X-ray luminosity
• Warp and flare of the Galactic disc revealed with supergiants by Gaia EDR3
• MONOS.II. Orbit review and analysis for 35 single-lined spectroscopic binary systems and candidates
• A test for the theory of colliding winds: the periastron passage of 9 Sagittarii I. X-ray and optical spectroscopy
• Distances to Galactic OB-stars: Photometry vs. Parallax
• Chemical abundances of fast-rotating massive stars. II. Interpretation and comparison with evolutionary models
• The CHARA Array resolves the long-period Wolf-Rayet binaries WR 137 and WR 138
• A modern study of HD166734: a massive supergiant system
• Wind properties of Milky Way and SMC massive stars: empirical Z dependence from CMFGEN models
• The First Dynamical Mass Determination of a Nitrogen-rich Wolf-Rayet Star using a Combined Visual and Spectroscopic Orbit
• Probing the weak wind phenomenon in Galactic O-type giants
• New hydrodynamic solutions for line-driven winds of hot massive stars using Lambert $W$-function
• UV diagnostic of porosity-free mass-loss estimates in B stars
• Self-consistent solutions for line-driven winds of hot massive stars. The m-CAK procedure
• Evolution of massive stars with new hydrodynamic wind models
• A Faraday Rotation Study of the Stellar Bubble and HII Region Associated with the W4 Complex
• Effect of scattering on the transonic solution topology and intrinsic variability of line-driven stellar winds
• The origin of early-type runaway stars from open clusters
• Stellar wind models of central stars of planetary nebulae
• The Wolf-Rayet binaries of the nitrogen sequence in the Large Magellanic Cloud: spectroscopy, orbital analysis, formation, and evolution
• The distance, rotation, and physical parameters of zeta Pup
• X-ray and optical spectroscopy of the massive young open cluster IC1805
• On the origin of variable structures in the winds of hot luminous stars
• X-Shooting ULLYSES: Massive stars at low metallicity. IV. Spectral analysis methods and exemplary results for O stars
• Observational signatures of past mass-exchange episodes in massive binaries: The case of LSS 3074
• Candidate X-ray-Emitting OB Stars in the MYStIX Massive Star-Forming Regions
• Empirical mass-loss rates and clumping properties of O-type stars in the LMC
• Skymaps of observables of three-dimensional MHD astrosphere models
• Multiple short-lived stellar prominences on O stars: The O6.5I(n)fp star lambda Cephei
• A Deep Exposure in High Resolution X-Rays Reveals the Hottest Plasma in the $\zeta$Puppis Wind
• A modern guide to quantitative spectroscopy of massive OB stars
• Mid-infrared observations of O-type stars: spectral morphology
• Evolution of rotating massive stars with new hydrodynamic wind models
• Evolution of rotating massive stars adopting a newer, self-consistent wind prescription at SMC metallicity
• New self-consistent wind parameters fitting optical spectra of O-type stars observed with HERMES spectrograph
• Influence of X-ray radiation on the hot star wind ionization state and on the radiative force
• Improving 1D stellar atmosphere models with insights from multi-dimensional simulations I. 1D vs 2D stratifications and spectral comparison for O stars
• Similar but different: the varied landscape of Onfp/Oef stars variability
• The extreme O-type spectroscopic binary HD 93129A
• To clump or not to clump The impact of wind inhomogeneities on the optical and NIR spectroscopic analysis of massive OB stars
• UV Spectropolarimetry with Polstar: Massive Star Binary Colliding Winds
• The First Candidate Colliding-Wind Binary in M33
• Modelling O-star astrospheres with different relative speeds between the ISM and the star: 2D and 3D MHD model comparison
• The Effective Temperatures of O-type Stars from UV spectroscopy
• Moving inhomogeneous envelopes of stars
• X-ray irradiation of the stellar wind in HMXBs with B supergiants: Implications for ULXs
• New Luminous ON Spectra from the Galactic O-Star Spectroscopic Survey
• The IACOB project XV. Updated calibrations of fundamental parameters of Galactic O-type stars
• Unveiling the evolutionary state of three B supergiant stars: PU Gem, $\epsilon$ CMa and $\eta$ CMa
• X-Shooting ULLYSES: Massive Stars at Low Metallicity X. Physical Parameters and Feedback of Massive Stars in the LMC N11 B Star-Forming Region
• Helium-like X-ray line complexes show that the hottest plasma on the O supergiant zeta Puppis is in its wind
• Mixing due to internal gravity waves can explain the CNO surface abundances of B-type detached eclipsing binaries and single stars
• The Local Ultraviolet to Infrared Treasury I. Survey Overview of the Broadband Imaging
• The Emission and Suppression of Line Features in Luminous Transients
• Evolutionary models for the Very Massive Stars in the R136 cluster of 30 Doradus in the Large Magellanic Cloud
• Modeling and performance analysis of Implicit Electric Field Conjugation with two deformable mirrors applied to the Roman Coronagraph
• NLTE analysis of spectra: OBA stars
• Fe XVII $2p$-$3s$ line ratio diagnostic of shock formation radius in O stars