Rotten Egg Nebula a shocker in Hubble pic

The Calabash or Rotten Egg Nebula

By Richard Stenger
CNN

(CNN) -- Emitting intense bursts of energy and gas that give rise to colorful shock wave fronts, a nebula displays intricate configurations that scientists had speculated about but never seen with such clarity, until now.

The nebula, observed by the Hubble Space Telescope, contains a dying central star ejecting most of its gas in twin jets streaming in opposite directions.

The gas, seen in yellow, has reached incredible speeds, traveling as fast as 1,500,000 km/h. The twin locomotives slam into the surrounding gas, producing dual shock fronts, depicted in blue. A dusty ring in the center cloaks the central star from view.

Using special filters on the orbiting observatory, scientists have been able to discern the elaborate double-bubble frame created by the shock waves.

Computer models predicted such shock structures but astronomers have had trouble finding them in direct observations.

"This is the first time that these shock components have been seen in such a nebula," said Valentin Bujarrabal, a Hubble researcher from Spain.

"In the image we can see how the shocks have broken through the surrounding gas. We believe we can see both of the shock components that we expect, the forward and backward shock waves."

Common in the cosmos, such planetary nebulas form when dying stars cast off most of their material. Such a fate most likely awaits our own sun. They have nothing to do with planets, but early astronomers thought they looked liked planets and the name stuck.

This particular example, called the Rotten Egg Nebula because of its high concentration of sulfur compounds, which produce unpleasant odors on Earth, is a nebula in its early stages.

A sudden burst about 800 years ago stirred up much of the gas now flowing in the labyrinth. Within about 1,000 years, it will evolve into a full nebula, "like a butterfly emerging from its cocoon," said the European Space Agency, which released the image on Friday.

The structure, also known as the Calabash Nebula, is 1.4 light- years in length and resides in the constellation Puppis, some 5,000 light-years from Earth.