New self-consistent wind parameters fitting optical spectra of O-type stars observed with HERMES spectrograph

Abstract

We perform spectral fitting for a set of O-type stars based on self-consistent wind solutions, which provide mass-loss rate and velocity profiles directly derived from the initial stellar parameters. The great advantage of this self-consistent spectral fitting is therefore the reduction of the number of free parameters to be tuned. Self-consistent values for the line-force parameters (k,alpha,delta) and subsequently for the mass-loss rate and terminal velocity are provided by the m-CAK prescription introduced in Paper I, updated in this work with improvements such as a temperature structure for the wind, self-consistently evaluated from the line-acceleration. Synthetic spectra are calculated using the radiative transfer code FASTWIND, replacing the classical beta-law for our new calculated velocity profiles. We found that self-consistent m-CAK solutions provide values for theoretical mass-loss rates on the order of the most recent predictions of other studies. From here, we generate synthetic spectra with self-consistent hydrodynamics to fit and obtain a new set of stellar and wind parameters for our sample of O-type stars whose spectra was taken with the high resolution echelle spectrograph HERMES (R=85000). We find a satisfactory global fit for our observations, with good accuracy for photospheric He I and He II lines and a quite acceptable fit for H lines. Although this self-consistent spectral analysis is currently constrained in the optical wavelength range only, this is an important step towards the determination of stellar and wind parameters without using a beta-law. Given these results, we expect that the values introduced here should be helpful for future studies about the stars constituting this sample, together with the prospective that the m-CAK self-consistent prescription be extended to numerous studies about massive stars in future.

Accepted for publication in Astronomy & Astrophysics, in 17 February 2022 In this updated version, we corrected information about funding data in Acknowledgements section

References in corpus (14)

• Mass loss from hot massive 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 MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• The VLT-FLAMES survey of massive stars: Mass loss and rotation of early-type stars in the SMC
• Variable accretion and emission from the stellar winds in the Galactic centre
• The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars. I. Method and first results
• MONOS: Multiplicity Of Northern O-type Spectroscopic systems. I. Project description and spectral classifications and visual multiplicity of previously known objects
• Radial dependence of line profile variability in seven O9--B0.5 stars
• An Updated Formalism For Line-Driven Radiative Acceleration and Implications for Stellar Mass Loss
• Self-consistent solutions for line-driven winds of hot massive stars. The m-CAK procedure
• Mid-infrared observations of O-type stars: spectral morphology
• $\Omega$-Slow Solutions and Be Star Disks
• Spectroscopic study of the O-type runaway supergiant HD 195592

Cited by in corpus (1)

• Evolution of massive stars with new hydrodynamic wind models