Previous models of cycltron-line features in the spectra of cosmic γ-ray bursts have assumed that the lines form in a thin, static atmosphere. Here we show that the observed absorption lines may in fact form in a radiation-diriven plasma wind expelled at relativistic velocities from the surface of a neutron star.

• Received 26 November 1990

DOI:https://doi.org/10.1103/PhysRevLett.66.1395