How Cold Can a Star Be?

Using data from an infrared satellite telescope called the Wide-Field Infrared Survey Explorer, NASA announced in 2011 that it had identified six heavenly bodies known as “Y-dwarfs.” Y-dwarfs are the coldest stars of the brown dwarf variety, which makes them the coolest of all stars -- cooler than the human body, even. Brown dwarfs and Y-dwarfs lack the mass needed to keep burning for extended periods of time. They tend to gradually cool and fade, until the only light they emit is a faint glow discernible only at infrared wavelengths, and invisible to the human eye.

Bodies lacking star power:

  • Scientists have determined that the coldest Y-dwarf, known as WISE 1828+2650, is colder than 80 degrees Fahrenheit (25 degrees C).

  • In comparison, the Sun in our solar system has a core temperature as high as 27 million degrees Fahrenheit. It will continue to burn for at least a few billion years.

  • These dwarf stars are commonly referred to as “failed stars” -- too puny to force atoms to fuse and release nuclear energy with the intensity typical of other stars.

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More Info: NASA

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