The spectacular new image of the Helix nebula shows infrared colors

According to new observations from the Spritzer Space Telescope for NASA, a group of comets is disgraceful collide and kicking up dust around a dead star. The star is at the center of the much-photographed Helix nebula (Helix), a bright cloud of gas with an uncanny resemblance to a giant eye.

"We were surprised to see so much dust around this star," said Dr. Kate Su of the University of Arizona in Tucson, lead author of the article written about the results. The work will appear in the March 1 issue of Astrophysical Journal Letters."The dust must be coming from comets that survived the death of their sun."

The spectacular new image of the Helix nebula, taken by the Spitzer Space Telescope shows infrared colors. The dusty dead star appears as a white dot in the red center of the nebula. The whole picture looks like the red pupil of the eye of a green monster.

The Helix nebula, located about 700 light years away in the constellation Aquarius, was formed when a star similar to our sun died and shed his skin, or outer layer. The radiation from the hot center of the white dwarf, as he calls the dead star, heats the expelled material, causing it to fluoresce brightly colored. This cosmic beauty, called a planetary nebula, will not last long. In about 10,000 years, its shiny clouds will fade, leaving the white dwarf and comets around it alone in the empty space.

Astronomers have studied the white dwarf in the center of the Helix nebula for long, but so far no one had detected any dust close to it. Spitzer, an infrared observatory in space, captured the glow of a dusty disk around the stellar corpse at a distance of 35 to 150 astronomical units, about (an astronomical unit is the distance between our Sun and Earth).

At first, his and the team were shocked to see the dust. According to astronomers, when the star died, expelling its outer layers all the dust in the system should have been expelled. The team then obtained more detailed data, which again indicated the presence of a dust disk.

Where does the dust? According to astronomers, is likely to have been created by collisions between comets in the outer margins of the white dwarf system. A few million years before the white dwarf was formed and when it was still a lively star like our sun, its comets and possibly planets were in stable orbits, harmoniously traveling around the star. But when the star died, any inner planets would have burned or been consumed as the star expanded. The outer planets, asteroids and comets were pushed and pulled against each other.

Our own solar systems have a similar transformation in about five billion years. Like the Helix nebula, a cosmic butterfly shine, and our sun, transformed into a white dwarf, surrounded by the group end of the outer planets to survive, and a frantic group of comets.

Similar evidence from comets that survived the death of the star had been seen previously with Spitzer. In January last year, astronomers reported using the observatory to find a dust disk around a white dwarf. In that case, the disk was closer to the star, at a distance of between 0.005 and 0.03 AU.

"Finding evidence for planetary activity around a white dwarf is a surprise," said Dr. George Rieke of the University of Arizona, a co-author of the article. "Finding it twice with such different properties is of great surprise!"

The Spitzer data will surely help to explain a mystery surrounding the white dwarf of the Helix nebula. Previous observations with the telescope Rsntgensatellit German X-ray Observatory and the Chandra X-ray NASA indicated that the white dwarf was emitting X-rays of very high energy. Although the white dwarf is hot, about 110,000 Kelvin (nearly 200,000 degrees Fahrenheit) is not hot enough to explain the X-ray energy Astronomers thought that perhaps the white dwarf was accreting matter from a companion star that cannot see.

But the Spitzer observations point to a different answer. As a member of his team, the Dra.You-Hua Chu of the University of Illinois at Urbana-Champaign, the material on the disc just found may be falling into the star, producing X-rays "The high energy X-rays were a mystery that had not been resolved," said Chu. "Now we may have found an answer in the infrared."

The Jet Propulsion Laboratory (Jet Propulsion Laboratory - JPL, for its acronym in English) in Pasadena, Calif. manages the Spitzer Space Telescope, a mission of the Science Mission Directorate at NASA Headquarters in Washington. Also in Pasadena, science operations are conducted at the Spitzer Science Center located at the California Institute of Technology (Caltech, for its abbreviation). Caltech manages JPL for NASA.