Astronomy Fundamentals: The Astronomer & the Seven Dwarfs

Dwarf stars are the most plentiful in our sky. But as their name suggests, they are smaller in mass and thus less intrinsically bright. Our August fundamentals will focus on some white and red dwarf stars. Although each of these stars are dwarf stars, they are more different to each other than just their color. Red dwarfs are part of the main sequence stars, and are among the most plentiful in the universe. In addition, a good percentage of the stars nearest our solar system are also red dwarfs. Proxima Centauri, our nearest star is a red dwarf. Also not as easy to see is Barnard’s Star, a red dwarf star about six light years away. Main sequence stars are burning their main fuel of hydrogen, and red dwarfs have a long lifespan as the star undergoes fusion in its core.

White dwarfs on the other hand are bright, because they are the hot dense cores of sun-like stars that have burned through the main sequence and ended up as just the carbon core of a star. White dwarfs are also commonly found with planetary nebulae, since those outer layers puff off as the star cycles from hydrogen to helium and onto heavier elements as the life of the star progresses. These white dwarfs are about the mass of our sun but compacted to a diameter of Earth. Although they are very hot, they are also intrinsically faint. Fortunately, there are about 5 white dwarfs within about 16 light years of Earth. 40 Eridani B is about 4.4 magnitude and easily visible in a small scope. Interested in taking a tour of these mighty, yet smaller mass stars? Make sure to catch our August Fundamentals meeting with our presenter, NAA member Jim Hopkins.