Clumping and X-rays in cooler B supergiant stars

Context. B supergiants (BSGs) are evolved stars with effective temperatures between ~10 to ~30 kK. Knowing the properties of these objects is important understand massive star evolution. Located on cool end line-driven wind regime, study their atmospheres can help us physics winds and phenomena such as bi-stability jump. Aims. Despite being well-studied stars, key UV features spectra have so far not been reproduced by atmosphere models for spectral types later than B1. In this study, we aim remedy situation performing quantitative analyzes that account effects X-rays clumping in wind. addition, also briefly investigate evolutionary status our sample based stellar parameters obtained. Methods. We determined photospheric via spectroscopy using computed CMFGEN PoWR. These were compared high-resolution optical four BSGs: HD206165, HD198478, HD53138, HD164353. further employed GENEC MESA tracks sample. Results. When including both X-rays, obtained a good agreement synthetic observed stars. For first time, lines UV, where previous studies unsuccessful. To model spectra, require moderately clumped ( f V∞ ≳ 0.5). infer relative X-ray luminosity about 10 −7.5 −8 , which lower typical ratio −7 . Moreover, find possible mismatch mass predictions derived spectroscopic masses, deserves deeper investigation might relate mass-discrepancy problem present other OB Conclusions. Our results provide direct evidence need be taken into describe BSGs. However, seem much less structured earlier OB-type findings line observational constraints well recent hydrodynamical simulations. The BSGs seems diverse some potentially post-red or merger products. moderate increase mass-loss rate around