2021/03/10 by Brian L. Flores, Brian L Flores, D. J. Hillier +1 · 10 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Filling factor #Galaxy #Interstellar medium #O-type star #Optics #Physics #Radiative transfer #Spectral line #Stars #Stellar, planetary, and galactic studies #Supergiant #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stab707
published in Monthly Notices of the Royal Astronomical Society 504(1), 311-325 (Oxford University Press) · Accepted for publication in MNRAS
openalex publication_date 2021/03/10 · arxiv created 2021/03/12 · arxiv updated 2021/03/24 · openalex created_date 2021/03/29 · openalex updated_date 2026/08/05
ABSTRACT Hot massive stars exhibit strong stellar winds that enrich the surrounding interstellar medium and affect the stars’ evolution. However, the winds are inhomogeneous (clumped) and are difficult to model in radiative transfer codes. To produce more realistic spectra, many codes use a volume-filling factor (VFF) approach to incorporate the effects of clumping. While this approach is convenient, it is simplistic. We introduce an alternative approach to incorporate clumping by assuming the wind is composed of dense spherical shells. Using this approach in the radiative transfer code cmfgen, we produce synthetic spectra for AzV83, an O7Iaf + supergiant located in the Small Magellanic Cloud. The spectrum of AzV83 is rich in both photospheric and wind features, making it an ideal candidate with which to investigate the physical characteristics of stellar winds. Synthetic spectra are compared to the star’s observed spectrum to better characterize the influence of clumped winds on spectral features, and to better understand the limitations of the VFF approach. The approach using spherical shells yields similar wind parameters to those obtained using the VFF approach although a slightly higher mass-loss rate is required to fit Hα. As expected, the interclump medium in the model with shells allows the high ionization resonance transitions of N v and O vi to be fitted using LX-ray/LBol ≈ 10−7, which is typically observed for O stars, and which is a factor of 10 lower than needed with the VFF approach.