The spectrum of a hot blue-white dwarf star like Vega or Sirius is dominated by very strong hydrogen lines. These stars are of spectral type A and have surface temperatures of
about 10,000 K.
COOLER
The spectrum of a yellow Sun-like star such as Capella may display a weaker H Beta line and fine metal lines clumped in the blue-green and orange. These type G stars have surface
temperatures around 6,000 K.
COOLEST
The spectrum of a cool red supergiant like Betelgeuse or Antares displays broad molecular bands of titanium oxide and many fine lines from such elements as sodium, iron, calcium
and magnesium. These stars are of spectral type M and have surface temperatures of about 3,000 K.
