Because they have very short lifespans - millions instead of billions of years, and thus they have been and gone.
the super giant stars are red
Some of the SUPER GIANT stars are Sirius,Sun,Rigel,Betelgeuse,and procyon.
the word super massive stars is the category name for the biggest stars in the galaxy
super giants are much cooler.
Neutron (smallest) Dwarf Medium Giant Super Giant (largest)
because giant and supergiant stage is very short
the super giant stars are red
Some of the SUPER GIANT stars are Sirius,Sun,Rigel,Betelgeuse,and procyon.
betelgeuse
Hot.
KY Cyngnii
Hot.
They are big stars.
the word super massive stars is the category name for the biggest stars in the galaxy
super giants are much cooler.
Big huge stars
Upper right