How many new soles could arise in the future in the Milky Way? Chinese astronomers plan to use the Five-Hundred Spherical Aperture Telescope (FAST), by far the largest ever built, to look for new suns’ birth places and thereby better understand how stars are formed and the substances of life.
Recently, astronomers from the National Astronomical Observatories of the Chinese Academy of Sciences captured for the first time the birth of a dark molecular cloud using three telescopes from the United States and Europe.
The discovery was published in the journal Astrophysical Journal and was presented by the journal Nature as a milestone.
Li Di, chief scientist of FAST, said that hydrogen, the most abundant element in the universe and the main raw material for the formation of stars, exists mainly in the form of atoms in the universe. Only after the hydrogen atoms turn into hydrogen molecules can gravitational collapses and nuclear fusion reactions be triggered, igniting new stars, Li explained.
“The key step for the conversion of hydrogen atoms into hydrogen molecules occurs at the surface of the cosmic dust,” said Li.
The scientists found dark regions in the universe that are rich in atomic and molecular gases and in cosmic dust, known as dark interstellar clouds. These places are the “cradles” that cause the birth of new stars, new planets and possibly life. However, dark interstellar clouds have the lowest temperature in the Milky Way, about minus 263 degrees Celsius. It is difficult to identify hydrogen atoms and molecules in dark clouds at such a low temperature.
Chinese astronomers developed a new method of observation, called HI Narrow Self-absorption. Through this method and the radio telescopes at the Arecibo Observatory and the Radio Astronomical Observatory of Five Colleges in the United States, as well as the European Hershel Space Observatory, the Chinese research team discovered the dark cloud B227, which has a “carapace” exterior of atomic hydrogen, but a nucleus dominated by molecular hydrogen.
“Our analyzes showed that the dark cloud is about 6 million years old; It is still a baby. A new sun will be born within that cloud, “Li said.
“Tens of thousands of dark interstellar clouds have been found previously, but this was the first time we could observe a molecular cloud when it was born,” he added.
Scientists are still unclear how long it will take for atomic hydrogen to turn into molecular hydrogen in a dark cloud. It is estimated that it takes about 10 million years to form a Sun in a molecular cloud, according to the classical model.
But some scientists believe that it only takes a million years. “Our measurement this time supports the classical model,” Li said.
The discovery gave Li confidence in finding future places of birth of new suns with FAST.
“The high sensitivity of FAST and its advantage in sky coverage will allow us to study the molecular clouds in the Milky Way, as well as in the Andromeda Galaxy, adjacent to ours,” Li explained.
Only after the hydrogen molecules were formed in the universe did complete chemical processes take place, forming complex organic molecules. It seems that amino acids, the components of life, can easily form under astro-chemical conditions. It is possible that amino acids are found in space in the next few years, he said.
“We also plan to cooperate with the Image Mapping Project of the Milky Way Observatory of Purple Mountain, to capture the dark clouds at birth and study how many new suns will be born in our galaxy,” Li predicted.
FAST, the most sensitive radio telescope in the world, located in a naturally deep and round karst depression in the southwestern Chinese province of Guizhou, was completed in September 2016 and will begin operations in September this year. The performance of the telescope during the operation is beyond imagination, Li said. FAST will also be used for molecular observations related to the origin of life in space, he added.