An international group of astronomers reported the discovery of a previously unknown large molecular cloud. This is one of the closest such structures to Earth.
Molecular clouds are also stellar cradles. They are composed of gas and dust, among which the most abundant molecule is hydrogen, the fundamental building block needed to form stars and exoplanets. But they also contain other molecules, such as carbon monoxide (CO). Our Sun was also once formed by the gravitational collapse of one of the molecular clouds.
Astronomers usually detect molecular clouds using radio and infrared observations, which easily pick up the chemical signatures of carbon monoxide. However, the newly found cloud was discovered using a different method — by directly searching for the ultraviolet glow emitted by hydrogen molecules. For this purpose, astronomers involved the FIMS-SPEAR far-ultraviolet spectrograph, which worked on the Korean satellite STSAT-1.
The structure found was named Eos — after a Greek goddess from mythology who personified the dawn. The gas cloud is crescent-shaped and is about 300 light-years away from Earth, making it one of the closest known similar structures. It is dominated by molecular hydrogen gas, but is mostly “CO-dark”, meaning it does not contain much matter and does not emit characteristic signatures. This explains why it took so long to identify Eos using standard methods.
Eos is at the edge of the Local Bubble, an irregularly shaped region of rarefied hot gas inside the Orion arm that spans the solar system. Scientists estimate that the cloud has a huge size in projection on the sky — about 40 moons, and its mass is about 3,400 times the mass of the Sun. Model results suggest that Eos will evaporate in about 6 million years.
According to the researchers, Eos poses no threat to Earth. But because of its relative proximity, the gas cloud provides a unique opportunity to study the properties of its structure and how the gas and dust will begin to turn into stars. And the far-UV fluorescence emission technique used to detect Eos could rewrite our understanding of the interstellar medium, revealing hidden clouds throughout our galaxy and even beyond.
Earlier we reported on how astronomers found a huge molecular cloud at the center of the Milky Way.
According to Phys.org
