Quantitative studies of the optical and UV spectra of Galactic early B supergiants I. Fundamental parameters

Abstract

We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0 - B5 supergiants of luminosity classes Ia, Ib, Iab and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made. These parameters are derived for individual stars using CMFGEN, the nLTE, line-blanketed model atmosphere code of Hillier et al., 1998. The B supergiant temperature scale derived here shows a reduction of 1000 - 3000 K compared to previous results obtained using unblanketed codes. Mass loss rate estimates are in good agreement with predicted theoretical values and all of the 20 B0 - B5 supergiants analysed show evidence for CNO processing. The observed WLR values calculated for B0 - B0.7 supergiants are larger than predicted values, whereas the reverse is true for B1 - B5 supergiants. This means that the discrepancy between observed and theoretical values cannot be resolved by adopting clumped (i.e., lower) mass loss rates, as for O stars. The most surprising result is that, although CMFGEN succeeds in reproducing the optical spectrum accurately, it fails to reproduce key UV diagnostics, such as NV and CIV P Cygni profiles, precisely. This problem arises because the models are not ionised enough and fail to reproduce the full extent of the observed absorption trough of the P Cygni profiles. These findings add further support to the need to revise the standard model of massive star winds.

arXiv commentA&A in press; 35 pages, 33 figures

References in corpus (24)

• A Hipparcos census of the nearby OB associations
• A new calibration of stellar parameters of Galactic O stars
• A Grid of NLTE Line-Blanketed Model Atmospheres of O-type Stars
• Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC
• The Discordance of Mass-Loss Estimates for Galactic O-Type Stars
• Physical Parameters and Wind Properties of Galactic Early B Supergiants
• Quantitative Spectroscopy of O Stars at Low Metallicity. O Dwarfs in NGC 346
• Hydrodynamical Simulations of Corotating Interaction Regions and Discrete Absorption Components in Rotating O-Star Winds
• Low mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. II. Analysis of 20 More Magellanic Cloud Stars, and Results from the Complete Sample
• Revised Stellar Temperatures for Magellanic Cloud O Supergiants from FUSE and VLT-UVES Spectroscopy
• A-type Supergiant Abundances in the SMC: Probes of Evolution
• Fundamental parameters of Galactic luminous OB stars VI. Temperatures, masses and WLR of Cyg OB2 supergiants
• Understanding B-type Supergiants in the Low Metallicity Environment of the SMC
• Understanding B-type supergiants in the low metallicity environment of the SMC II
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. I. A Sample of 20 Stars in the Magellanic Clouds
• Quantitative studies of the Far-UV, UV and optical spectra of late O and early B-type supergiants in the Magellanic Clouds
• B-type Supergiants in the SMC: Chemical compositions and comparison of static and unified models
• Constraints on the Ionization Balance of Hot-Star Winds from FUSE Observations of O Stars in the Large Magellanic Cloud
• C II abundances in early-type stars: solution to a notorious non-LTE problem
• Large-scale wind structures in OB supergiants: a search for rotationally modulated Hαvariability
• Terminal velocities of luminous, early-type SMC stars
• Multi-periodic photospheric pulsations and connected wind structures in HD64760
• The ionization structure of early-B supergiant winds

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• Semi-analytical formulas for the fundamental parameters of Galactic early B supergiants
• Mixing of CNO-cycled matter in massive stars
• Wind structure of late B supergiants I. Multi-line analyses of near-surface and wind structure in HD 199 478 (B8 Iae)