1. Hubble Spies Dazzling Death of a Sunlike Star
(originally posted February 14, 2007)

Even though one of its most popular cameras broke in January, the Hubble Space Telescope was still proving its worth this year, capturing a new round of awe-inspiring images with its remaining camera (see related images of Hubble's top discoveries).

On February 13 NASA released this shot of a dying stara white dwarf shown as a bright dot near the center of nebula NGC 2440that 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 400,0000F (200,0000C). 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 nebulabut not for another five billion years.

Victoria Gilman

(Top space pictures determined by number of times viewed.)

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