Atmospheric models of these stars have two key parameters: a "transformed radius" that is proportional to the radius at which Rosseland optical depth equals twenty, and an e fective temperature that is computed iteratively while accounting for line blanketing. Local thermodynamic equilibrium and plane-parallel geometry are not valid assumptions for these stars' atmospheres. The centers of about ten percent of planetary nebulae contain one of these stars. So-called "slash" stars are spectroscopically intermediate between these stars and O-type stars. At low metallicity and high rotation rate, the inner core of one of these stars becomes a hypernova in the "collapsar" model of long-duration gamma-ray bursts. Broad emission lines of helium and either carbon or nitrogen characterize these stars, which evolve from luminous blue variables. For 10 points, identify these
Atmospheric models of these stars have two key parameters: a "transformed radius" that is proportional to the radius at which Rosseland optical depth equals twenty, and an e fective temperature that is computed iteratively while accounting for line blanketing. Local thermodynamic equilibrium and plane-parallel geometry are not valid assumptions for these stars' atmospheres. The centers of about ten percent of planetary nebulae contain one of these stars. So-called "slash" stars are spectroscopically intermediate between these stars and O-type stars. At low metallicity and high rotation rate, the inner core of one of these stars becomes a hypernova in the "collapsar" model of long-duration gamma-ray bursts. Broad emission lines of helium and either carbon or nitrogen characterize these stars, which evolve from luminous blue variables. For 10 points, identify these doubly-eponymous stars that have extremely high rates of mass loss.
Atmospheric models of these stars have two key parameters: a "transformed radius" that is proportional to the radius at which Rosseland optical depth equals twenty, and an e fective temperature that is computed iteratively while accounting for line blanketing.