X-Shooting ULLYSES: Massive stars at low metallicity. III. Terminal wind speeds of ULLYSES massive stars

Abstract

The winds of massive stars have an impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed, is a global wind parameter and an essential input for models of stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a legacy UV spectroscopic survey with HST, we have the opportunity to quantify the wind speeds of massive stars at sub-solar metallicity (in the Large and Small Magellanic Clouds, 0.5Z and 0.2Z) at an unprecedented scale. We empirically quantify the wind speeds of a large sample of OB stars, including supergiants, giants, and dwarfs at sub-solar metallicity. Using these measurements, we investigate trends of terminal wind speed with a number of fundamental stellar parameters, namely effective temperature, metallicity, and surface escape velocity. We empirically determined the terminal wind speed for a sample of 149 OB stars in the Magellanic Clouds either by directly measuring the maximum velocity shift of the absorption component of the Civ 1548-1550 line profile, or by fitting synthetic spectra produced using the Sobolev with exact integration method. Stellar parameters were either collected from the literature, obtained using spectral-type calibrations, or predicted from evolutionary models. We find strong trends of terminal wind speed with effective temperature and surface escape speed when the wind is strong enough to cause a saturated P Cygni profile in Civ 1548-1550. We find evidence for a metallicity dependence on the terminal wind speed proportional to Z^0.22+-0.03 when we compared our results to previous Galactic studies. Our results suggest that effective temperature rather than surface escape speed should be used as a straightforward empirical prediction of terminal wind speed and that the observed metallicity dependence is steeper than suggested by earlier works.

arXiv comment21 pages, 16 figures, 8 tables. Accepted in A&A

References in corpus (72)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• The observed properties of dwarf galaxies in and around the Local Group
• Mass-loss predictions for O and B stars as a function of metallicity
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• A new calibration of stellar parameters of Galactic O stars
• Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars
• Pre-Supernova Evolution of Massive Single and Binary Stars
• Rotating Massive Main-Sequence Stars I: Grids of Evolutionary Models and Isochrones
• Mass loss from hot massive stars
• The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars
• The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500
• Physical Parameters and Wind Properties of Galactic Early B Supergiants
• The empirical metallicity dependence of the mass-loss rate of O- and early B-type stars
• Massive stars in massive clusters II: Disruption of bound clusters by photoionization
• The IACOB project: I. Rotational velocities in Northern Galactic O and early B-type stars revisited. The impact of other sources of line-broadening
• The VLT-FLAMES survey of massive stars: Evolution of surface N abundances and effective temperature scales in the Galaxy and Magellanic Clouds
• The VLT-FLAMES survey of massive stars: Surface chemical compositions of B-type stars in the Magellanic Clouds
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. II. Analysis of 20 More Magellanic Cloud Stars, and Results from the Complete Sample
• Revised Stellar Temperatures for Magellanic Cloud O Supergiants from FUSE and VLT-UVES Spectroscopy
• The Wolf-Rayet stars in the Large Magellanic Cloud: A comprehensive analysis of the WN class
• BONNSAI: a Bayesian tool for comparing stars with stellar evolution models
• Predictions for mass-loss rates and terminal wind velocities of massive O-type stars
• Bright OB stars in the Galaxy IV. Stellar and wind parameters of early to late B supergiants
• The Galactic O-Star Spectroscopic Survey (GOSSS). III. 142 additional O-type systems
• The evolution of rotating very massive stars with LMC composition
• Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties
• The VLT-FLAMES Tarantula Survey XVII. Physical and wind properties of massive stars at the top of the main sequence
• Understanding B-type Supergiants in the Low Metallicity Environment of the SMC
• The VLT-FLAMES Survey of Massive Stars: Stellar parameters and rotational velocities in NGC3293, NGC4755 and NGC6611
• 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
• Fundamental Properties of O-Type Stars
• Testing massive star evolution, star-formation history and feedback at low metallicity : Spectroscopic analysis of OB stars in the SMC Wing
• Theory and Diagnostics of Hot Star Mass Loss
• Understanding B-type supergiants in the low metallicity environment of the SMC II
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. I. A Sample of 20 Stars in the Magellanic Clouds
• Nitrogen line spectroscopy in O-stars -- II. Surface nitrogen abundances for O-stars in the Large Magellanic Cloud
• Massive stars at low metallicity: Evolution and surface abundances of O dwarfs in the SMC
• Metallicity-dependent wind parameter predictions for OB stars
• B-type Supergiants in the SMC: Chemical compositions and comparison of static and unified models
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. III. More Results from the Magellanic Clouds
• The VLT-FLAMES Tarantula Survey XXIV. Stellar properties of the O-type giants and supergiants in 30 Doradus
• The VLT-FLAMES Tarantula Survey XIX. B-type Supergiants - Atmospheric parameters and nitrogen abundances to investigate the role of binarity and the width of the main sequence
• A consistent solution for the velocity field and mass-loss rate of massive stars
• The Tarantula Massive Binary Monitoring: III. Atmosphere analysis of double-lined spectroscopic systems
• Stellar population of the superbubble N206 in the LMC II. Parameters of the OB and WR stars, and the total massive star feedback
• A Bake-Off Between CMFGEN and FASTWIND: Modeling the Physical Properties of SMC and LMC O-type Stars
• A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
• 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
• X-Shooting ULLYSES: massive stars at low metallicity. I. Project Description
• Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC1613
• A census of massive stars in NGC 346. Stellar parameters and rotational velocities
• No breakdown of the radiatively-driven wind theory in low-metallicity environments
• The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMS
• LMC Blue Supergiant Stars and the Calibration of the Flux-weighted Gravity--Luminosity Relationship
• How Significant is Radiation Pressure in the Dynamics of the Gas Around Young Stellar Clusters?
• Empirical mass-loss rates and clumping properties of Galactic early-type O supergiants
• The spectroscopic Hertzsprung-Russell diagram of hot massive stars in the SMC
• On the Importance of the Interclump Medium for Superionization: O VI Formation in the Wind of Zeta Pup
• Terminal velocities of luminous, early-type SMC stars
• NLTE models of line-driven stellar winds II. O stars in SMC
• Theoretical wind clumping predictions of OB supergiants from line-driven instability simulations across the bi-stability jump
• Massive stars in the Small Magellanic Cloud : Evolution, rotation and surface abundances
• Global hot-star wind models for stars from Magellanic Clouds
• New massive members of Cygnus OB2
• New mass-loss rates of B supergiants from global wind models
• A non-LTE analysis of the spectra of two narrow lined main sequence stars in the SMC
• Coronal winds powered by radiative driving
• The earliest O-type eclipsing binary in the Small Magellanic Cloud, AzV 476: A comprehensive analysis reveals surprisingly low stellar masses
• Wind properties of Milky Way and SMC massive stars: empirical Z dependence from CMFGEN models
• Shock-heated radiation-driven outflows as a solution to the weak-wind problem of late O-type stars
• Optical spectroscopy of the blue supergiant Sk-69 279 and its circumstellar shell with SALT
• Bottling the Champagne: Dynamics and Radiation Trapping of Wind-Driven Bubbles around Massive Stars

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