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Dazzling Death of a Sunlike Star |
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Posted by Julia
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 натисни тук за информация на български
February 14, 2007
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Despite losing one of its most popular cameras last month, the Hubble Space
Telescope is still proving its worth, capturing a new round of awe-inspiring
images with its remaining camera (see related images
of Hubble's top discoveries).
On Tuesday NASA released this new shot of a dying star—a white dwarf shown as
a bright dot near the center of nebula NGC 2440—that was once similar to our
sun.
Low- to medium-size stars like our sun usually end their lives as white
dwarfs. Once most of a star's hydrogen has been converted to helium, the star
enters the red giant phase, eventually expelling its outer material to form a
nebula of stellar debris. The hot core left behind is a white dwarf.
Spied by the telescope's Wide Field and Planetary Camera 2, this white dwarf
is 4,000 light-years from Earth. It is also one of the hottest known, with a
surface temperature of nearly 400,000°F (200,000°C). Ultraviolet light from the
dying star is illuminating gaseous material being cast off from the star's core.
Our sun will also likely burn out and become a white dwarf surrounded by a
vivid nebula—but not for another five billion years.
—Victoria Gilman
news.nationalgeographic.com
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