The R136 star cluster dissected with Hubble Space Telescope/STIS. III. The most massive stars and their clumped winds

Abstract

Context: The star cluster R136 inside the LMC hosts a rich population of massive stars, including the most massive stars known. The strong stellar winds of these very luminous stars impact their evolution and the surrounding environment. We currently lack detailed knowledge of the wind structure that is needed to quantify this impact. Aims: To observationally constrain the stellar and wind properties of the massive stars in R136, in particular the parameters related to wind clumping. Methods: We simultaneously analyse optical and UV spectroscopy of 53 O-type and 3 WNh-stars using the FASTWIND model atmosphere code and a genetic algorithm. The models account for optically thick clumps and effects related to porosity and velocity-porosity, as well as a non-void interclump medium. Results: We obtain stellar parameters, surface abundances, mass-loss rates, terminal velocities and clumping characteristics and compare these to theoretical predictions and evolutionary models. The clumping properties include the density of the interclump medium and the velocity-porosity of the wind. For the first time, these characteristics are systematically measured for a wide range of effective temperatures and luminosities. Conclusions: We confirm a cluster age of 1.0-2.5 Myr and derive an initial stellar mass of $\ge 250{\mathrm{M}}_{\odot }$ for the most massive star in our sample, R136a1. The winds of our sample stars are highly clumped, with an average clumping factor of $f_{\mathrm{cl}}=29\pm 15$. We find tentative trends in the wind-structure parameters as a function of mass-loss rate, suggesting that the winds of stars with higher mass-loss rates are less clumped. We compare several theoretical predictions to the observed mass-loss rates and terminal velocities and find that none satisfactorily reproduces both quantities. The prescription of Krtička & Kubát (2018) matches best the observed mass-loss rates.

arXiv commentAccepted for publication in A&A; Appendix I will not be included in the published version

References in corpus (93)

• Mass-loss predictions for O and B stars as a function of metallicity
• Progenitors of core-collapse supernovae
• Pre-Supernova Evolution of Massive Single and Binary Stars
• Rotating Massive Main-Sequence Stars I: Grids of Evolutionary Models and Isochrones
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Mass loss from hot massive stars
• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
• Galaxy Zoo Green Peas: Discovery of A Class of Compact Extremely Star-Forming Galaxies
• One Hundred First Stars : Protostellar Evolution and the Final Masses
• Atmospheric NLTE-Models for the Spectroscopic Analysis of Blue Stars with Winds. II. Line-Blanketed Models
• The Discordance of Mass-Loss Estimates for Galactic O-Type Stars
• Primordial Star Formation under the Influence of Far Ultraviolet Radiation: 1540 Cosmological Halos and the Stellar Mass Distribution
• An upper limit to the masses of stars
• Quantitative Spectroscopy of O Stars at Low Metallicity. O Dwarfs in NGC 346
• The VLT-FLAMES Tarantula Survey I: Introduction and observational overview
• An excess of massive stars in the local 30 Doradus starburst
• 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
• Low mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
• The Formation and Destruction of Molecular Clouds and Galactic Star Formation
• Before the first supernova: combined effects of HII regions and winds on molecular clouds
• Evolution and fate of very massive stars
• The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of HeII 1640 in young star clusters
• The VLT-FLAMES Tarantula Survey XII. Rotational velocities of the single O-type stars
• The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution
• A Porosity-Length Formalism for Photon-Tiring-Limited Mass Loss from Stars Above the Eddington Limit
• Rotating Massive Main-Sequence Stars II: Simulating a Population of LMC early B-type Stars as a Test of Rotational Mixing
• Neglecting the porosity of hot-star winds can lead to underestimating mass-loss rates
• O stars with weak winds: the Galactic case
• Wind modelling of very massive stars up to 300 solar masses
• BONNSAI: a Bayesian tool for comparing stars with stellar evolution models
• The evolution of rotating very massive stars with LMC composition
• The VLT-FLAMES survey of massive stars: Mass loss and rotation of early-type stars in the SMC
• Properties of Galactic early-type O-supergiants: A combined FUV-UV and optical analysis
• The VLT-FLAMES survey of massive stars: Wind properties and evolution of hot massive stars in the LMC
• An XMM-Newton view of the young open cluster NGC 6231 -- II. The OB star population
• The VLT-FLAMES Tarantula Survey XVII. Physical and wind properties of massive stars at the top of the main sequence
• The VLT-FLAMES Tarantula Survey - XI. A census of the hot luminous stars and their feedback in 30 Doradus
• The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars
• Spectral analysis of early-type stars using a genetic algorithm based fitting method
• The Birth of a Massive First-Star Binary
• 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
• Mass loss from inhomogeneous hot star winds II. Constraints from a combined optical/UV study
• The porous atmosphere of eta Carinae
• Voigt Profile Fitting to Quasar Absorption Lines: An Analytic Approximation to the Voigt-Hjerting Function
• Global X-ray properties of the O and B stars in Carina
• Mass loss from inhomogeneous hot star winds I. Resonance line formation in 2D models
• Testing massive star evolution, star-formation history and feedback at low metallicity : Spectroscopic analysis of OB stars in the SMC Wing
• Transition of the initial mass function in the metal-poor environments
• The R136 star cluster dissected with Hubble Space Telescope/STIS. II. Physical properties of the most massive stars in R136
• Nitrogen line spectroscopy in O-stars -- II. Surface nitrogen abundances for O-stars in the Large Magellanic Cloud
• The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars
• The VLT-FLAMES Tarantula Survey. XXIX. Massive star formation in the local 30 Doradus starburst
• Evolution of surface CNO abundances in massive stars
• 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
• Metallicity-dependent wind parameter predictions for OB stars
• Star formation in 30 Doradus
• The VLT-FLAMES Tarantula Survey XXIV. Stellar properties of the O-type giants and supergiants in 30 Doradus
• The transition mass-loss rate: Calibrating the role of line-driven winds in massive star evolution
• Measuring mass-loss rates and constraining shock physics using X-ray line profiles of O stars from the Chandra archive
• 3-D radiative transfer in clumped hot star winds I. Influence of clumping on the resonance line formation
• The VLT-FLAMES Tarantula Survey. VII. A low velocity dispersion for the young massive cluster R136
• Atmospheric NLTE-models for the spectroscopic analysis of blue stars with winds. IV. Porosity in physical and velocity space
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars. I. Method and first results
• Grids of stellar models with rotation VI: Models from 0.8 to 120 $M_{\odot }$ at a metallicity Z = 0.006
• The IACOB project: A grid-based automatic tool for the quantitative spectroscopic analysis of O-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 VLT-FLAMES Tarantula Survey XXVI: Properties of the O-dwarf population in 30 Doradus
• Environmental Dependence of Type Ia Supernova Luminosities from a Sample without a Local-Global Difference in Host Star Formation
• The VLT-FLAMES Tarantula Survey XXV. Surface nitrogen abundances of O-type giants and supergiants
• X-ray emission from massive stars in Cyg OB2
• The impact of rotation on the line profiles of Wolf-Rayet stars
• Empirical mass-loss rates and clumping properties of Galactic early-type O supergiants
• Mass loss and the Eddington parameter: a new mass-loss recipe for hot and massive stars
• The properties of ten O-type stars in the low-metallicity galaxies IC 1613, WLM and NGC 3109
• 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
• Calibrating Interstellar Abundances using SNR Radiative Shocks
• VLT/SINFONI time-resolved spectroscopy of the central, luminous, H-rich WN stars of R136
• Stochastic Low Frequency Variability in 3-Dimensional Radiation Hydrodynamical Models of Massive Star Envelopes
• Theoretical wind clumping predictions of OB supergiants from line-driven instability simulations across the bi-stability jump
• Forming clusters within clusters: How 30 Doradus recollapsed and gave birth again
• Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds. V. Complete comoving frame transfer, and updated modeling of X-ray emission
• Constraining the Overcontact Phase in Massive Binary Evolution I. Mixing in V382 Cyg, VFTS 352, and OGLE SMC-SC10 108086
• Global hot-star wind models for stars from Magellanic Clouds
• Physics and evolution of the most massive stars in 30 Dor. Mass loss, envelope inflation, and a variable upper stellar mass limit
• Upper Mass-Loss Limits and Clumping in the Intermediate and Outer Wind Regions of OB stars
• Mass-loss rates of Very Massive Stars
• Probing the weak wind phenomenon in Galactic O-type giants
• Mapping the core of the Tarantula Nebula with VLT-MUSE II. The spectroscopic Hertzsprung-Russell diagram of OB stars in NGC 2070
• Uncrowding R 136 from VLT-SPHERE extreme adaptive optics
• High contrast and resolution near infrared photometry of the core of R136
• Giant Molecular Cloud Formation at the Interface of Colliding Supershells in the Large Magellanic Cloud