February 14, 2007—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.
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
Source of this blog : website of National Geographic.
No comments:
Post a Comment