What highly ionised elements are found in the spectrum of WR 102c?
Wolf–Rayet star Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of highly ionised helium and nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. Their surface temperatures range from 30,000 K to around 200,000 K, hotter than almost all other stars.
SN 2005gj SN 2005gj was a supernova located approximately 864 million light years (265 million parsecs) away from Earth. It was discovered on September 29, 2005, by the Sloan Digital Sky Survey and the Nearby Supernova Factory. 2005gj was noted because it had qualities of both type Ia and type IIn supernovae, and because hydrogen emission lines were found in its spectrum (see hydrogen spectral series). These hydrogen lines, which were found on the spectrum at redshift z=0.0613, are thought to be indicative of interactions with a circumstellar medium (CSM; a donut-shaped, nebula-like ring of matter around a star) by the supernova's ejected matter or white dwarf progenitor. Such emission lines are extremely rare in Type Ia supernovae – only one other Type Ia, SN 2002ic, has been observed to exhibit the same properties. However, 2005jg's CSM interaction was much stronger and more clearly observed than 2002ic's. The mass-loss history 2005gj's hydrogen lines suggest has been cited as evidence that Luminous Blue Variable (LBV) hypergiants can be progenitors of thermonuclear supernovae.