X-Shooting ULLYSES: Massive stars at low metallicity. XIII. Putting the bi-stability jump to the test in the LMC

Abstract

We aim to investigate the theoretical bi-stability jump, which predicts an increase in mass-loss rates below 21 kK. We further aim to constrain the photospheric and wind parameters of a sample of 16 LMC late-O and B supergiants. We utilise the 1D, non-LTE radiative transfer model CMFGEN in a grid-based approach and subsequent fine-tuned spectroscopic fitting procedure to determine the stellar and wind parameters of each star. We apply this method to ultra-violet data from the ULLYSES programme and complementary optical data from the XShootU collaboration. We also utilise evolutionary models to obtain the evolutionary masses and compare them to our derived spectroscopic masses. We derive physical parameters and wind properties of 16 late-O and B supergiants that span a wide $T_{eff}$ range of 12-30 kK, surface gravity range $\log g/cm{s}^{-2}$ of 1.8-3.1, and a mass-loss rate range of $10^{-7.6}-10^{-5.7}{M}_{\odot }y{r}^{-1}$. We also compare our results to previous studies spectroscopic studies of LMC OB stars. We find that our derived photospheric and wind properties are consistent with multiple previous studies. For most of our sample, we find that the evolutionary masses and spectroscopic masses are consistent. Our results do not reproduce a bi-stability jump in any temperature range, but rather a monotonic decrease in mass-loss rate at lower temperatures. We obtain a terminal wind velocity-effective temperature relation for LMC supergiants. We find that our derived mass-loss rates do not agree with predictions from any of the numerical recipes. This is also the case for the ratio of the terminal wind velocity to the escape velocity $v_{\infty }/v_{esc}$, and we derive a $v_{\infty }/v_{esc}$-$T_{eff}$ relation. We find that wind properties are metallicity dependent from a comparison with a previous SMC study, and we obtain a new modified wind momentum-luminosity relation.

References in corpus (38)

• Pre-Supernova Evolution of Massive Single and Binary Stars
• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• Mass loss from hot massive stars
• The empirical metallicity dependence of the mass-loss rate of O- and early B-type stars
• The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution
• A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition
• BONNSAI: a Bayesian tool for comparing stars with stellar evolution models
• Quantitative Spectroscopy of 24 A supergiants in the Sculptor galaxy NGC 300: Flux weighted gravity luminosity relationship, metallicity and metallicity gradient
• The spectroscopic Hertzsprung-Russell diagram
• The VLT-FLAMES Tarantula Survey XVII. Physical and wind properties of massive stars at the top of the main sequence
• On the consistent treatment of the quasi-hydrostatic layers in hot star atmospheres
• Quantitative studies of the optical and UV spectra of Galactic early B supergiants I. Fundamental parameters
• 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. II. Physical properties of the most massive stars in R136
• Evolution of surface CNO abundances in massive stars
• Metallicity-dependent wind parameter predictions for OB stars
• 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
• X-Shooting ULLYSES: massive stars at low metallicity. I. Project Description
• LMC Blue Supergiant Stars and the Calibration of the Flux-weighted Gravity--Luminosity Relationship
• X-Shooting ULLYSES: Massive stars at low metallicity. III. Terminal wind speeds of ULLYSES massive stars
• Testing the predicted mass-loss bi-stability jump at radio wavelengths
• New mass-loss rates of B supergiants from global wind models
• The IACOB project XII. A new grid of northern standards for the spectral classification of B-type stars
• Clumping and X-Rays in cooler B supergiant stars
• The IACOB project X. Large-scale quantitative spectroscopic analysis of Galactic luminous blue stars
• Quantitative spectroscopy of B-type supergiants
• The IACOB project IX. Building a modern empirical database of Galactic O9-B9 supergiants: sample selection, description, and completeness
• X-Shooting ULLYSES: Massive Stars at low metallicity II. DR1: Advanced optical data products for the Magellanic Clouds
• X-Shooting ULLYSES: Massive Stars at low metallicity IX: Empirical constraints on mass-loss rates and clumping parameters for OB supergiants in the Large Magellanic Cloud
• The IACOB project XI. No increase of mass-loss rates over the bistability region
• Optical spectroscopy of the blue supergiant Sk-69 279 and its circumstellar shell with SALT
• X-Shooting ULLYSES: Massive stars at low metallicity. IV. Spectral analysis methods and exemplary results for O stars
• A modern guide to quantitative spectroscopy of massive OB stars
• The blue supergiant Sher 25 revisited in the Gaia era
• Bringing Stellar Evolution & Feedback Together: Summary of proposals from the Lorentz Center Workshop, 2022
• X-Shooting ULLYSES: Massive Stars at Low Metallicity: XI. Pipeline-determined Physical Properties of Magellanic Cloud OB Stars
• X-Shooting ULLYSES: massive stars at low metallicity: XII. The clumped winds of O-type (super)giants in the Large Magellanic Cloud

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