One normal day, people are working in a space lab, and suddenly, P.A. system calls everyone into the main room. They walk in, and everybody sees a gigantic screen with a picture of a very dull looking sphere, almost like a star. The only problem is that itís not shining! So, what could this object possibly be, or is it an error in the system that found it?
What Are Brown Dwarfs?
What has less mass than a star, but more mass than a planet? Brown Dwarfs! Brown Dwarfs are failed stars. Brown Dwarfs wander around in space alone outside of our solar system like stars. Some will even be traveling among the cold and dark shadows of a great star.
How Are Stars Made?
Stars form when a gas cloud shrinks from gravity and gets hotter. When the temperature is high enough for the burning of hydrogen to occur in a starís core, it produces energy. Then the star starts shining. Hydrogen atoms are fused together to create helium in a starís core, making the star glow because the reactions release light and heat energy.
How Are Brown Dwarfs Made?
Brown dwarfs are formed when a star is forming. When the star doesnít get enough gas, it canít increase its temperature enough for atoms to combine to make hydrogen turn into helium. When a star doesnít get big enough, itís identified as a brown dwarf.
How Were Brown Dwarfs Named?
Brown dwarfs arenít really brown. Theyíre actually red. So why arenít they called red dwarfs? The name red dwarf was already used to describe a star with less than half of the Sunís mass. Apparently, red dwarfs were found first, and are also red, which is how they got their name. Until astrophysicist Jill C. Tarter suggested the name brown dwarf in 1975, failed stars did not have a name. They were referred to as black stars or infrared stars. Astronomers finally agreed on the name brown dwarf because brown dwarfs have brown line like streaks going around them.
How Are Brown Dwarfs Found?
For a long time, scientists believed brown dwarfs existed, but no one had ever found one. The search for brown dwarfs started in the mid 1980ís, and it was thought that brown dwarfs were very rare. It was really hard to find the first brown dwarf because theyíre not easily seen in outer space and because theyíre out of our solar system. Though stars are also outside of the solar system in the dim and dark skies of outer space, theyíre still pretty easy to find. Brown dwarfs are way harder to find than stars because stars shine with their own light, and brown dwarfs are dull and
donít shine at all. They could only be seen with telescopes and spectroscopes. Even when theyíre seen you canít just predict itís a brown dwarf because you have to know its history, how it originated, where it came from, and where it had been. These things need to be known because otherwise it could be any possible thing in space. When astronomers found out that brown dwarfs were more visible when they were closer to other stars, they found the first brown dwarf in 1995, proving they were real. After finding many of them, astronomers started wondering about their different sizes and whether they were all created in the same way. They did finally find all these answers. One is that brown dwarfs were created in a very similar way. The other one is there are many different sizes of brown dwarfs. The search for brown dwarfs wasnít over yet because astronomers still donít know exactly how many brown dwarfs there are in the universe. Astronomers believe there may be one hundred billion brown dwarfs in the whole universe.
What Are Problems With Brown Dwarfs?
A problem they have with finding brown dwarfs is when they find one, theyíre not actually always sure if itís a humongous planet or a tiny brown dwarf.
Why Are Brown Dwarfs Important?
Scientists have found and then explained that only ten percent of the universe has been found. Theyíre still trying to find out where the other ninety percent of the universe is. A theory is that itís all just brown dwarfs. If we know more about brown dwarfs, weíll understand our universe even better!
Brown Dwarfs. <http://astron.berkeley.edu/~basri/bdwarfs/ > Last visited: December 2001.
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Gibor Basri. The Discovery of Brown Dwarfs. <http://www.sciam.com/2000/0400issue/0400basri.html> Last visited: December 2001.
Space: Today, Tomorrow, and Always. </J0112188/brown_dwarfs.htm> Last visited: December 2001.
Space in the Spotlight Novi Meadows Elementary 2002
All pictures courtesy of NASA unless otherwise noted