An object in the sky brightens suddenly, but shows no hydrogen lines in its spectrum. It ismost likely a(n):
A)comet.
B)Type I supernova.
C)Type II supernova.
D)asteroid impact.
E)stellar collision.

Question

Quizplus · Accepted Answer

Type I supernovae do not show hydrogen lines in their spectra, and they are known for their sudden brightening in the sky. Comets, asteroid impacts, and stellar collisions would not produce a sudden brightening without also producing visible hydrogen lines. Type II supernovae also produce hydrogen lines in their spectra. Since the object shows no hydrogen lines in its spectrum, it is likely not a normal star. Type I supernovae, however, are known to have very weak or absent hydrogen lines. Additionally, Type I supernovae are known for their sudden and explosive brightening. Therefore, B) Type I supernova is the best choice.

An Object in the Sky Brightens Suddenly, but Shows No