Astronomers have found a giant interstellar cloud surprisingly near the earth.
Hiding around 300 light years from our solar system, this huge cloud of gas and dust is closest to its kind never found at the ground, beating the previous record holder of around 90 light years. Despite being about 5,500 times more massive than the sun, the cloud has gone unnoticed – so far.
Indeed, the cloud does not contain much carbon monoxide, molecules astronomers often use to probe these clouds, called molecular clouds. Astronomers have found this cloud while sweeping the sky for ultraviolet light from the main constituent of a molecular cloud, hydrogen molecules. The results, published on April 28 in Nature Astronomy, reveal a crescent -shaped cloud which, if visible, will appear to viewers on earth as the largest unique structure in the night sky – about 40 full moons.
« [It’s] An important observation because we want to find where the next generation of young stars will be formed near the sun, ”explains astronomer Blakesley Burkhart from Rutgers University in New Brunswick, NJ
The cloud, nicknamed EOS after the Greek goddess of dawn, is a fresh and dense drop of dust and gas – a type known to host stellar nurses often. However, an additional analysis of the team, reported in a document submitted on April 24 in Arxiv.org, suggests that the EOS did not have significant stellar births during the recent millennia.
-Although molecular hydrogen constitutes the major part of a mass of molecular cloud, it does not emit light when it is cold, which makes almost impossible to see in the clouds. However, when fueled by the light of the stars along the limits of the cloud, hydrogen emits light to very ultraviolet wavelengths. Using newly published data from the South Korean STSAT-1 satellite, which operated in the early 2000s, Burkhart and his team found the large hidden structure at sight. These data allow astronomers to estimate the size and distance of the cloud.
EOS offers a rare opportunity to study closely the formation and dissipation of molecular clouds. It also helps to reveal the amount of interstellar material available near our sun to form stars and planets.
“Each star, including our sun, was born in a molecular cloud,” explains Gregory Green, astronomer of the Max Plank Institute for Astronomy in Heidelberg, Germany, which was not involved in research. However, he notes, the researchers “note in fact that the EOS is probably not dense enough to collapse gravitally under its own weight, which suggests that it will not form stars”.
Although the cloud has just been found, it will not remain forever. Burkhart and his colleagues believe that the EOS will disappear slowly in the 6 million years. If the cloud was visible to us, it could be seen towards the constellation of Corona Borealis in the northern hemisphere, extending roughly the size of two hands stretched in the Shaka, or “suspend” the sign.
