Skywatch

  • April 27, 2006

    Episode 33: The Birth of Brown Dwarfs

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    Shownotes

    How small can an object be and still be called a star? Or, how big can an object be and still be considered a planet? Stars form from large, swirling clouds of gas and dust that have so much mass that they collapse. As the star forms, its interior becomes so hot that fusion begins. The star shines with its own fuel. Planets seem to form around stars. They seem to coalesce from the clumps of the material left over from the star formation process. Planets shine by reflecting light from their parent star. Somewhere in between planets and stars are brown dwarfs. Astronomers are trying to find these objects to help them better understand how stars and planets form. Current theory suggests that brown dwarfs form like stars, but never obtain enough mass to ignite the fusion process. New observations of two brown dwarfs orbiting together allowed scientists to measure the masses of the objects. The observations confirm the theory that brown dwarfs start out as star-sized objects, but shrink and cool, becoming increasingly planet-sized as they age.