From the Hubble Space Telescope
This picture, taken with NASA's Hubble Space Telescope, reveals a small, bright nebula embedded in the center of the larger one . Astronomers have dubbed the entire nebula the "Southern Crab Nebula" (He2-104), because, from ground-based telescopes, it looks like the body and legs of a crab. The nebula is several light-years long located in the Southern Hemisphere constellation of Centaurus and is a few thousand light-years from Earth.
The possible creators of these shapes cannot be seen at all in this Wide Field and Planetary Camera 2 image. It's a pair of aging stars buried in the glow of the tiny, central nebula. One of them is a red giant, a bloated star that is exhausting its nuclear fuel and is shedding its outer layers in a powerful stellar wind. Its companion is a hot, white dwarf. This odd duo is called a symbiotic system. The red giant is also a Mira Variable, a pulsating red giant, that is far away from its partner. It could take as much as 100 years for the two to orbit around each other.
The interaction between these two stars may have sparked episodic outbursts of material, creating the gaseous bubbles that form the nebula. They interact by playing a celestial game of "catch": as the red giant throws off its bulk in a powerful stellar wind, the white dwarf catches some of it. As a result, an accretion disk of material forms around the white dwarf and spirals onto its hot surface. Gas continues to build up on the surface until it sparks an eruption, blowing material into space. This explosive event may have happened twice in the "Southern Crab." The hourglass-shaped nebulae may represent two separate outbursts that occurred several thousand years apart. The jets of material in the lower left and upper right corners may have been accelerated by the white dwarf's accretion disk and probably are part of the older eruption.
Image Title: Symbiotic Star Blows Bubbles into Space
based on press release for PHOTO NO.: STScI-PRC99-32a
Credits: Romano Corradi, Instituto de Astrofisica de Canarias, Tenerife, Spain; Mario Livio, Space Telescope Science Institute, Baltimore, Md.; Ulisse Munari, Osservatorio Astronomico di Padova-Asiago, Italy; Hugo Schwarz, Nordic Optical Telescope, Canarias, Spain; and NASA
Last Modified On: Sunday, December 17, 2000