2010/07/16 by R. K. Prinja, Raman Prinja, D. Massa +1 · 66 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Computational physics #Geometry #Line (geometry) #Photosphere #Physics #Red supergiant #Spectral line #Stars #Stellar, planetary, and galactic studies #Supergiant #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/201015252
published in Astronomy and Astrophysics 521, L55 (EDP Sciences) · Accepted for publication in A&A Letters
arxiv created 2010/07/16 · openalex publication_date 2010/07/16 · arxiv updated 2015/05/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
<i>Aims. <i/>We seek to establish additional observational signatures of the effects of clumping in OB star winds. The action of clumping on strategic wind-formed spectral lines is tested to steer the development of models for clumped winds and thus improve the reliability of mass-loss determinations for massive stars.<i>Methods. <i/>The Siiv <i>λ<i/><i>λ<i/>1400 resonance line doublets of B0 to B5 supergiants are analysed using empirical line-synthesis models. The focus is on decoding information on wind clumping from measurements of ratios of the radial optical depths (<i>τ<i/><sub>rad<sub/>(<i>w<i/>)) of the red and blue components of the Siiv doublet. We exploit in particular the fact that the two doublet components are decoupled and formed independently for targets with relatively low wind terminal velocities.<i>Results. <i/>Line-synthesis analyses reveal that the mean ratio of <i>τ<i/><sub>rad<sub/>(<i>w<i/>) of the blue to red Siiv components are rarely close to the canonical value of ~2 (expected from atomic constants), and spread instead over a range of values between ~1 and 2. These results are interpreted in terms of a photosphere that is partially obscured by optically thick structures in the outflowing gas.<i>Conclusions. <i/>The spectroscopic signatures established in this study demonstrate the wide-spread existence of wind clumping in B supergiants. The additional information in unsaturated doublet profiles provides a means to quantify the porosity of the winds.