|
|
|
|
|
Hubble shows demise in ice and fire NASA NEWS RELEASE Posted: April 29, 2004
Most planetary nebulae are distinctive, but few are as extreme as NGC 6302, also known as the Bug Nebula. The fiery, dying star at its centre is shrouded by a blanket of icy hailstones. Robert Frost's 1920 poem "Fire and Ice" could have been written for this object: Some say the world will end in fire, This image of the Bug Nebula, taken with the NASA/ESA Hubble Space Telescope, shows impressive walls of compressed gas, laced with trailing strands and bubbling outflows. A dark, dusty torus surrounds the inner nebula (seen at the upper right). At the heart of the turmoil is one of the hottest stars known. Despite a sizzling temperature of at least 250,000 degrees C, the star itself has never been seen, as it is hidden by the blanket of dust and shines most brightly in the ultraviolet, making it hard to observe. Chemically, the composition of the Bug Nebula also makes it one of the more interesting objects known. Earlier observations with the European Space Agency's Infrared Space Observatory, ISO, have shown that the dusty torus contains hydrocarbons, carbonates such as calcite, as well as water ice and iron. The presence of carbonates is interesting. In the solar system, their presence is taken as evidence for liquid water in the past, because carbonates form when carbon dioxide dissolves in liquid water and forms sediments. But its detection in nebulae such as the Bug Nebula, where no liquid water has existed, shows that other formation processes cannot be excluded. Albert Zijlstra from UMIST in Manchester, UK, who leads a team of astronomers probing the secrets of this extreme object, says: "What caught our interest in NGC 6302 was the mixture of minerals and crystalline ice - hailstones frozen onto small dust grains. Very few objects have such a mixed composition." The dense dark dust torus around the central star contains the bulk of the measured dust mass and is something of an enigma to astronomers. They believe the nebula was expelled around 10,000 years ago, but do not quite understand how it formed and how long the dust torus can survive evaporation by the now very hot central star. The Hubble Space Telescope is a project of international cooperation between ESA and NASA. |
|
|
|
 |
|||||||||||||||||||||||||||||||||||||||||
Activities of the two Mars Exploration Rovers and new images are discussed in this briefing from April 28. (41min 08sec file)
The five crew members aboard the International Space Station answer questions from reporters in the U.S. and Europe during this in-flight news conference. (20min 26sec file)
The Boeing Delta 2 rocket launches with NASA's Gravity Probe-B spacecraft from Vandenberg Air Force Base, California. (4min 16sec file)
The Lockheed Martin Atlas 2AS rocket launches the Japanese Superbird 6 communications spacecraft from Cape Canaveral, Florida. (3min 09sec file)