Astronomy Picture of the Day

Discover the cosmos! Each day we feature a different image or photograph of our fascinating universe, along with a brief explanation written by a professional astronomer.

September 10, 1995
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White Dwarfs Cool
Credit: NASA, HST, WFPC 2, H. Richer (UBC)

Explanation: The circled stars in the above picture are from a class that is hard to see in the cosmos: white dwarfs. The entire photo covers a small region near the center of a globular cluster known as M4. Researchers using the Hubble Space Telescope discovered a large concentration of white dwarfs in M4. This was expected - low mass stars, including the Sun, are known to evolved to the white dwarf stage. White dwarfs do not usually evolve further, they just gradually cool down from their high temperatures. It is hoped that studying how these stars cool could lead to a better understanding of their ages, of the age of their parent globular cluster, and hopefully even the age of our universe!

Tomorrow's picture: Proplyds: Infant Solar Systems

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Astronomy Picture of the Day (TM) is created and copyrighted in 1995 by Robert Nemiroff and Jerry Bonnell who are solely responsible for its content.

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