Posted on 02/20/2003 3:02:38 PM PST by blam
Coldest place in the universe unveiled
Astronomers have released the first photograph of what is believed to be the coldest place in the universe.
The Boomerang Nebula, 5,000 light years from Earth, was discovered in 1979 and named in 1980 because ground-based telescopes could only detect a crooked elongated shape.
Its temperature is minus 272 C, about one degree above absolute cold, minus 273.15 degrees.
The Hubble Telescope took the picture for the European Space Agency and Nasa, who both control the satellite.
An ESA official said: "Even the minus 270 degrees C background glow from the Big Bang is warmer than this nebula. It is the only object found so far that has a temperature lower than the background radiation."
The Boomerang was chilled by a rapid escape of gas that has been under way for 1,500 years. The effect is familiar from a toy balloon that feels cold after the air has suddenly been released from it.
The nebula is only visible from the Southern Hemisphere.
Story filed: 15:23 Thursday 20th February 2003
Other nebulas have asked it not to come over to their house.
Don't know, a pyrometer?
The coolest place in space
By Dr David Whitehouse
BBC News Online science editor
Astronomers have identified the coldest place ever detected in space. It is the gas blown away from a star in the latter stages of its life-cycle.
The so-called Boomerang Nebula, one of the youngest of its kind, has been observed in minute detail by the Hubble Space Telescope (HST).
It seems that the central dying star has been expelling gas at such a rate that it has cooled as it expanded to such a degree that it is even colder than the cosmic background radiation that bathes all of space.
This HST image shows a young planetary nebula in the constellation of Centaurus, 5,000 light-years from Earth. Planetary nebulae form around a bright, central star when it expels gas in the last stages of its life.
Ghostly filaments
In 1995 astronomers revealed that it is the coldest place in the Universe found so far outside a terrestrial laboratory. With a temperature of -272 C, it is only one degree warmer than absolute zero.
Even the -270 C background radiation from the Big Bang that permeates the Cosmos is warmer than this nebula. It is the only object found so far that has a temperature lower than the background radiation.
The recent Hubble image shows faint arcs and ghostly filaments embedded within the diffuse gas of the nebula's lobes. It appears quite different from other observed planetary nebulae. Researchers speculate that the object is so young that it may not have had time to develop more familiar structures.
The remarkable coolness of the gas clouds may be the result of an unusual central star. The clouds appear to have been sculpted by a fierce 500,000 kilometre-per-hour wind blowing ultra-cold gas away from the dying central star.
The dying star has been losing as much as one-thousandth of a solar mass of material each year for perhaps a millennium. This is 10-100 times more than mass loss seen in other similar objects.
It is the rapid expansion, and subsequent cooling, of the gas cloud that has enabled it to become the coldest known region in the Universe.
IIRC, the light spectrum given off by an object uniquely indicates its temperature.
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