AZA young proto-planetary nebula located 5,000 light years from the Earth has been identified as the current coldest region in space known to Scientists. The Boomerang Nebula, also known as the Bow Tie Nebula, has kept its frigid secret for more than twenty years, but now, scientists want answers. What makes it so cold? The truth might surprise you.
First observed in 1995, the Boomerang Nebula resides in the Centaurus constellation and was measured to span more than three trillion kilometers (more than 21,000 times the distance between the Earth and Sun). The Boomerang Nebula formed from the explosion of a dying star known as a red giant, a phase our own Sun will one day enter. As the red giant expands, it envelopes surrounding stars and debris before eventually collapsing into a cloud of gas.
As astronomers searched for the reason behind low temperature, they recorded data such as comparisons of the nebula’s radiation to the surrounding area of space and the rate at which gas and dust were ejected from the nebula. Their observations revealed that the Boomerang Nebula appeared to be absorbing light from the Cosmic Microwave Background(CMB), the leftover energy from the Big Bang.The Boomerang Nebula was colder than the radiation left over from the CMB.
At first, scientists couldn’t figure out why the Boomerang Nebula was so cold. When compared to other proto-planetary nebulae, the temperature alone was shocking. Cooling at a rate they’d never seen before, scientists discovered the Boomerang Nebula’s temperature was -458 degrees Fahrenheit, more than 490 degrees below the freezing point of water (32 degrees Fahrenheit). But why was the temperature drop this staggering?
According to astronomers who used ALMA, the Atacama Large Millimeter/submillimeter Array, when the red giant expanded and cooled, another star became lodged inside it, resulting in not one but two expanding and cooling stars. The star trapped inside the belly of the Boomerang Nebula ejected gas and dust in opposite directions, partially creating the bow-shaped appearance but this didn’t explain the temperature. Or does it?
When a gas expands, it rapidly cools. Proto-planetary nebulae enter a period of intense cooling and eject gases from its center. In the case of the Boomerang Nebula, the amount of gas and dust ejected was doubled, exploding at a rate of 164 km/s through two narrow points. As a result, gas was expelled and cooled much faster than normal, unable to gather in one place for warmth. A perfect example is to exhale naturally on your hand. You’ll notice your breath is warm. Now, purse your lips to create a narrow escape and blow. Feels cold, doesn’t it?