Abstract
Early-B hypergiants belong to the most luminous stars in the Universe. They are characterized by high mass-loss rates (\(\dot M\)≈ 10−5 M⊙yr−1) and low terminal wind velocities (v ∞≈400 km s−1) implying very dense winds. They represent a short-lived evolutionary phase and are of particular interest for evolutionary theories of massive stars with mass loss. Due to their high luminosity they play a key role in connection with the “wind momentum — luminosity relation”. Among the main interesting characteristics of early-B hypergiants are the various kinds of photometric and spectroscopic variations. In several recent campaigns our group has performed extensive high dispersion spectroscopy of galactic early-B hypergiants with our fiber-fed echelle spectrograph Flash/Heros at the ESO-50 cm telescope. The main outcome was that their dense winds behave hydrodynamically differently to the less luminous supergiants of comparable spectral type. Outwardly accelerated propagating discrete absorption components of the P Cyg-type lines are the typical features rather than rotationally modulated line profile variations. These discrete absorptions could be traced in different spectral lines from photospheric velocities up to 75% of the terminal velocity. The stellar absorption lines show a pulsation-like radial velocity variability pattern lasting up to two weeks as the typical time scale. The radius variations connected with this pulsation-like motions are correlated with the emission height of the P Cyg-type profiles.
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© 1999 Springer-Verlag
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Wolf, B., Rivinius, T. (1999). Variable winds in early-B hypergiants. In: Wolf, B., Stahl, O., Fullerton, A.W. (eds) Variable and Non-spherical Stellar Winds in Luminous Hot Stars. Lecture Notes in Physics, vol 523. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0106381
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DOI: https://doi.org/10.1007/BFb0106381
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