Qwiz5 Quizbowl Essentials – Stellar Dwarfs

What sets dwarf stars apart from other stars is a difference in magnitude: dwarf stars are stars with smaller luminosity, mass, and size. The term “dwarf star” was first coined by Ejnar Hertzsprung, who used the term to refer to stars that were less bright than the sun. Over time the “dwarf” label has come to apply to objects other than stars. Read on to learn more about some of these dwarves and remember: size isn’t everything (check out our Qwiz5 on Neutron Stars to see why!)

By analyzing questions, you can see patterns emerge, patterns that will help you answer questions. Qwiz5 is all about those patterns. In each installment of Qwiz5, we take an answer line and look at its five most common clues. Here we explore five clues that will help you answer a tossup on astronomical dwarfs

WHITE DWARF

A white dwarf is an ancient star. These incredibly dense stellar remnants are the most common final stage in the life of low and medium-mass stars. Smaller stars eventually become white dwarfs after they have exhausted their hydrogen and helium fuel. In certain cases, when white dwarfs gain mass, they may be able to fuse carbon in their core and produce a Type Ia Supernova, a process known as carbon detonation.

RED DWARF

Red dwarfs are the most common type of star in the universe. Known as M-type stars, they are the smallest form of hydrogen-burning star. Proxima Centauri, the closest star to the sun, is a notable example of a red dwarf. Other famous red dwarfs include Barnard’s Star, and TRAPPIST-1, an ancient red dwarf approximately 40 light years from the sun.

BROWN DWARF

Not every star can be a star. A brown dwarf is considered a “failed star.” Brown dwarfs are stellar objects with a mass greater than Jupiter but smaller than that of a small star. Brown dwarfs are not dense enough to fuse hydrogen into helium, but they are dense enough to fuse lithium into other elements. Thus, the presence of lithium can in some cases identify a brown dwarf. Gliese 229B was the first brown dwarf to be identified by astronomers.

BLACK DWARF

Black dwarfs are a special kind of dwarf: a theoretical one. Black dwarfs are the hypothetical end stage of stellar evolution for many stars. Astronomers hypothesize that black dwarfs are what remains after a white dwarf has radiated away all its remaining heat. From what we know of the universe it is still too young to have any black dwarfs in it. Even if there were any, they would be extremely difficult to detect as they would emit neither light nor heat.

YELLOW DWARF

A yellow dwarf is another type of main-sequence Star. The stars are larger than red dwarfs, but still not massive enough to be considered a giant star. Yellow dwarfs are also referred to as G-type main sequence stars. You don’t have to travel far to find an example of a yellow dwarf; our sun is one. Other examples that can be seen from Earth by the naked eye include Alpha Centauri and Tau Ceti.

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Quizbowl is about learning, not rote memorization, so we encourage you to use this as a springboard for further reading rather than as an endpoint. Here are a few things to check out:

• Can planets orbiting a red dwarf star support life? Explore the question here.
  

• Brown dwarfs may be failed stars, but they haven’t failed to provide us with valuable information.
  

• White dwarfs normally don’t go full supernova, but when they do the results are spectacular!
  

• We are very fortunate that it will take a long time before our sun becomes a black dwarf.

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