THE COLORFUL DEMISE OF A SUN-LIKE STAR
This image, taken by NASA's Hubble Space Telescope, shows the colorful "last hurrah"of a star like our Sun. The star is ending its life by casting off its outer layers
of gas, which formed a cocoon around the star's remaining core. Ultraviolet light
from the dying star makes the material glow. The burned-out star, called a white
dwarf, is the white dot in the center. Our Sun will eventually burn out and shroud
itself with stellar debris, but not for another 5 billion years.
Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae.
The objects have nothing to do with planets. Eighteenth- and nineteenth-century
astronomers called them the name because through small telescopes they resembled
the disks of the distant planets Uranus and Neptune. The planetary nebula in this
image is called NGC 2440. The white dwarf at the center of NGC 2440 is one of the
hottest known, with a surface temperature of nearly 400,000 degrees Fahrenheit
(200,000 degrees Celsius). The nebula's chaotic structure suggests that the star
shed its mass episodically. During each outburst, the star expelled material in a
different direction. This can be seen in the two bow tie-shaped lobes. The nebula
also is rich in clouds of dust, some of which form long, dark streaks pointing away
from the star. NGC 2440 lies about 4,000 light-years from Earth in the direction of
the constellation Puppis.
The image was taken Feb. 6, 2007, with Hubble's Wide Field Planetary Camera 2. The
colors correspond to material expelled by the star. Blue corresponds to helium;
blue-green to oxygen, and red to nitrogen and hydrogen.
Credit: NASA, ESA, and K. Noll (STScI)
Acknowledgment: The Hubble Heritage Team (STScI/AURA)