The colorfully named Crescent nebula and Thor's Helmet nebula both surround these types of objects, while one of these in Sagittarius is surrounded by a pinwheel nebula.  Edward Pickering discovered a namesake series of spectral lines in these objects that were later attributed to helium.  They exhibit broad emission bands, and they may be divided into three categories: carbon-rich, nitrogen-rich, and the rare oxygen-rich variety.  A popular model for long-duration GRB's involves the collapse of these objects, a so-called "collapsar," and these objects are believed to evolve immediately from luminous blue variables, while the best-known example of them is Gamma Velorum.  For 10 points, name these massive stars possessing strong stellar winds, which eject their mass at a rate of 10-5 solar 
The colorfully named Crescent nebula and Thor's Helmet nebula both surround these types of objects, while one of these in Sagittarius is surrounded by a pinwheel nebula.  Edward Pickering discovered a namesake series of spectral lines in these objects that were later attributed to helium.  They exhibit broad emission bands, and they may be divided into three categories: carbon-rich, nitrogen-rich, and the rare oxygen-rich variety.  A popular model for long-duration GRB's involves the collapse of these objects, a so-called "collapsar," and these objects are believed to evolve immediately from luminous blue variables, while the best-known example of them is Gamma Velorum.  For 10 points, name these massive stars possessing strong stellar winds, which eject their mass at a rate of 10-5 solar masses per year, and are named after their two discoverers.
The colorfully named Crescent nebula and Thor's Helmet nebula both surround these types of objects, while one of these in Sagittarius is surrounded by a pinwheel nebula.  
Wolf-Rayet stars