The star at the center of the oddly-shaped object PGC 3074547, variously called the Boomerang Nebula or Bow Tie Nebula, has been shedding gas as it dies. "The gas is cooling as it flows away from the white dwarf star in a process similar to how refrigerators stay cold by using expanding gas," writes Elizabeth Howell for SPACE.com.
The result is a nebula just barely warmer than absolute zero—the lowest possible temperature where all atomic motion ceases. It’s minus 458 degrees Fahrenheit or 1 degree Kelvin. Mika McKinnon for io9 reports:
"While we can get incredibly close to absolute zero in lab experiments, nothing we've done lasts nearly long enough to be a "place" instead of a brief, chilly moment in time. The Boomerang Nebula is so cold, the only way to measure the temperature is by watching how it absorbed the cosmic microwave background radiation, which is a relatively almost-toasty 2.8 Kelvin."
The entire nebula is only visible because starlight reflects off its floating dust grains.
But Boomerang will soon lose its "coldest place in the universe" designation. In 2016, NASA plans to launch the Cold Atom Lab, which io9 reports will be able to plunge down to 1/10 billionth of a degree above absolute zero. "One of the primary goals of this facility will be to explore a previously inaccessible regime of extremely low temperatures where interesting and novel quantum phenomena can be expected," NASA writes.
source: smithsonian.com By Marissa Fessenden