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Since the use of high-resolution high signal-to-noise spectroscopy in the study of massive stars, it became clear that an ad-hoc velocity field at the stellar surface, termed macroturbulence, is needed to bring the observed shape of spectral lines into agreement with observations. We seek a physical explanation of this unknown broadening mechanism. We interprete the missing line broadening in terms of collective pulsational velocity broadening due to non-radial gravity-mode oscillations. We also point out that the rotational velocity can be seriously underestimated whenever the line profiles are fitted assuming a Gaussian macroturbulent velocity rather than an appropriate pulsational velocity expression.
We present results from the first extensive study of convection zones in the envelopes of hot massive stars, which are caused by opacity peaks associated with iron and helium ionization. These convective regions can be located very close to the stell
Are the kG-strength magnetic fields observed in young stars a fossil field left over from their formation or are they generated by a dynamo? We use radiation non-ideal magnetohydrodynamics simulations of the gravitational collapse of a rotating, magn
Ultrarelativistic heavy ion collisions produce a quark-gluon matter which lies in the future light cone originating from given points on the $t=z=0$ plane of the Minkowski spacetime manifold. We show that in a weak coupling regime the Minkowski vacuu
We present a new directly-observable statistic which uses sky position and proper motion of stars near the Galactic center massive black hole to identify populations with high orbital eccentricities. It is most useful for stars with large orbital per
We have derived relations between full-width-half-maxima and equivalent widths of metallic absorption lines in the spectra of RR~Lyrae stars to estimate new upper limits on the axial equatorial rotational velocities of RR~Lyrae and metal-poor red hor