The Sun in our solar system is considered a yellow dwarf star. The word "dwarf" might seem odd in relation to the Sun, especially with temperatures that can reach up to 6,000°C (11,000°F). The Solar Views website estimates that filling the Sun's interior would require more than 1 million Earths. Yet, the Sun is a dwarf all the same. There are other types of dwarf stars in the night sky and most of them are in the later phases of their star cycle. Brown dwarfs are stars that have failed to gain enough size and density to become main sequence stars. White dwarf stars have nearly burned all their hydrogen and helium, while the black dwarfs are non-luminous, dead stars. According to a BBC Science report, black and brown dwarf stars could possibly contribute to the universe's dark matter.
When two stars orbit closely around a central point of gravity, they are called binary stars. According to Cornell University's astronomy department, half the stars you see in the night sky are actually star pairs orbiting so close that they appear as one. There are different types of binary stars. Astronomers categorize them by their level of visibility and brightness along a light curve. In a visible binary system, both stars are clearly revealed through the telescope. However, these visible pairs only make up about five percent of the stars you see in the night sky. Their counterparts, the spectroscopic binaries, are paired so closely together that even telescopic views are unable to see the individual stars.
Giant stars are some of the largest and rarest stars in the night sky. According to the BBC Science website, giant stars are 1,000 times more luminous than the Sun. Some of the most recognizable stars such as Betelgeuse in the Orion constellation are massive super giant stars. The largest of these was found to be 10 million times brighter than the Sun. When the hydrogen fuel inside a star is exhausted, helium gas inside the core contracts. This reaction increases the temperature of the star to such a point that hydrogen fusion restarts in the core at even greater levels than before. Giant stars may be larger than other star types, but they burn out their energy at a much faster rate. Where dwarfs and binary stars exist for billions of years, the giant stars only last for a few million years.