The 500-meter aperture spherical radio telescope (FAST), known as the "Chinese Heavenly Eye", has achieved a series of important scientific achievements in the field of astronomy in the past two years through national acceptance. On January 5, the Chinese Academy of Sciences held its first press conference of 2022 in Beijing to introduce these important achievements.
Open a new model for human understanding of star formation
On January 6, FAST's major progress in measuring interstellar magnetic fields by neutral hydrogen lines was officially published in the form of a cover article in the international academic journal Nature.
Magnetic field problems not only prevent physics test papers from getting high scores, but also hinder star formation.
For example, as a star, before the sun became the sun, it was just a molecular cloud in the universe, and it gathered very hard to try to increase the density and temperature in order to ignite the fire to "advance" to become a dazzling celestial body. But in this process, the magnetic field sets up a "barrier" - as the molecular cloud gathers to reach the state of dense cloud nuclei, the magnetic flux will increase, and the resistance caused by the magnetic field will also increase, and the resistance will hold up the interstellar matter and prevent it from continuing to contract.
But the sun has indeed formed, how did it do it?
"In the eyes of physicists, the magnetic field is as solid as a chair, and it doesn't disappear out of thin air." Li Jing, chief scientist of FAST and a researcher at the National Astronomical Observatories of the Chinese Academy of Sciences, said that the latest scientific research results published by his team have opened up a new model for human understanding of star formation.
Previously, the scientific community predicted that after the molecular cloud became dense, the magnetic flux increased against the trend was canceled out by a mechanism called bipolar dissipation. In the bipolar dissipation model, it takes about 10 million years for stars to form.
But Li's team observed the cold dark molecular cloud of Taurus through FAST and found that the magnetic flux had been canceled out before the molecular cloud contracted to a dense state, "which should have been dissipated by other means."
Li Said that this study overturned the prediction of the Bipolar Dissipative Standard Model and provided important observational evidence for solving the "magnetic flux problem", one of the classic problems of star formation. FAST observations reveal that there may be a more efficient magnetic field dissipation mechanism than the Standard Model, allowing star formation to occur earlier. This means that the time for star formation could be shortened from 10 million years to about 1 million years.
Capture samples of the largest rapid radio burst event to date
Fast radio bursts are currently the brightest explosive phenomena in the radio band of the known universe and one of the largest astronomical hotspot frontiers today.
From August to October 2019, FAST successfully captured samples of the largest rapid burst event to date, and the paper was published in the journal Nature on October 14, 2021. On January 5, the Chinese Academy of Sciences reviewed this achievement and presented sonic music based on the radio waveforms in this collection of rapid radio burst events.
This result was completed by an international cooperation team led by Li Jing, Wang Pei and Zhu Weiwei of the National Astronomical Observatory of the Chinese Academy of Sciences, which also revealed for the first time the complete energy spectrum of the rapid radio burst rate and its bimodal structure.
Wang Pei introduced that hundreds of rapid radio bursts have been detected, and only a few of them have shown repeated outbreaks. Fast radio burst 121102 is the first repeated burst known to mankind, FAST successfully captured its extreme activity period, the most intense period reached 122 outbreaks per hour, the cumulative acquisition of a total of 1652 high signal-to-noise ratio burst signals, becoming the largest collection of fast radio burst burst events, more than the sum of all previous articles published in the field, becoming a milestone in the systematic study of rapid radio burst repeat bursts.
Wang Pei humorously said that this result is equivalent to "a blind man touching an elephant and touching a leg" for the entire field of rapid radio burst research.
FAST plans to set aside 1% of the observation time to open to primary and secondary school students
At present, fast annual observation time is more than 5300 hours, which has far exceeded the work efficiency expected by international counterparts.
Wu Xiangping, an academician of the Chinese Academy of Sciences and a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, introduced at the meeting that FAST is preparing to take 1% of the observation time and open it to primary and secondary school students across the country, and scientists will cooperate with children to explore their own fantastic ideas.
Wu Xiangping said: "We plan to select the ideas of primary and secondary school students and let professionals help them realize their dreams. He said that this idea has a long history and plans to develop a relevant selection mechanism this year. 1% of the observation time means about 50 hours, which is very valuable for FAST.
It is reported that FAST has been open to global scientists to share, the machine time for "FAST drift scanning multi-scientific target simultaneous sky survey" and other 5 priority major projects. FAST also regularly solicits free observation applications from astronomers around the world. In addition, there is a small amount of time for maneuver observations, etc.
Source: China Youth Daily