On October 6, Beijing time, an important astronomical research paper on the real identity of lithium rich giant stars, which was completed by researchers from China, Japan, France, the Netherlands, the United States, Australia and other countries, was published in the international academic journal Nature astronomy. Zhao Gang and Shi Jianrong, researchers of the National Astronomical Observatory of the Chinese Academy of Sciences, are co corresponding authors of the paper. Yan Hongliang, associate researcher of the National Astronomical Observatory of the Chinese Academy of Sciences, and Zhou Yutao, PhD, are co first authors of the paper. < / P > < p > what is the real identity of lithium rich giant stars in the universe, and how their lithium content is thousands of times higher than the theoretical value of stellar evolution. What is the latest understanding that this “big case” concerning the origin and evolution of the universe, which attracts the attention of the astronomical community, will bring? The reporter contacted Chinese experts for the first time and asked them to tell the story behind the discovery of this “big case” in the universe. < / P > < p > when it comes to lithium, modern people are no stranger. Whether it’s smart phones, tablet computers, UAVs or electric vehicles, they are all powered by lithium batteries. Little known is that this “new” element, which has only entered the public view in recent 10 years, is almost as old as the universe. According to Zhao Gang, lithium is one of the earliest elements in the universe. With the big bang 13.7 billion years ago, lithium appeared within 20 minutes of the birth of the universe. As one of the basic elements of today’s material universe, lithium can be said to connect the past and present of the universe. < / P > < p > a strange phenomenon is that the content of lithium in the universe for many days is quite different from the theory, which has been puzzling astronomers. The lithium rich giant is a typical example of this contradiction. Zhao Gang said that “giant stars” are the names of stars at the late stage of their life, because they have experienced a process of “fattening”, and they are much larger than young stars. < / P > < p > as the name suggests, the lithium content of “lithium rich giant” is far higher than that of “giant” of similar celestial bodies. They account for only 1% of the late low mass stars, but their atmospheres contain more lithium than the other 99%. < / P > < p > for example, tyc429-2097-1, a lithium rich giant star previously discovered by Guo Shoujing telescope in China, has more than 3000 times the lithium content of the sun and is the star with the highest Lithium Abundance known to mankind. If all the cars on the earth (about 1.4 billion) are replaced by electric cars, and the lithium on this star is used to make batteries to power them, then these 1.4 billion electric cars can be driven to any star you can see in the night sky at the same time, “for a walk on walk interstellar crossing.”. < / P > < p > in the view of the scientific research team, due to the unknown source of huge amounts of lithium in lithium rich giant stars, which may involve challenges to stellar evolution theory and standard stellar models, astronomers have been trying to uncover the mystery of these “minority groups” and find out where a large number of lithium came from, especially considering that the origin and evolution of lithium is also closely related to various aspects of the universe They are closely related to celestial bodies of similar scale. < / P > < p > according to Shi Jianrong, in order to solve the mystery of the origin of lithium in these late small mass stars, it is necessary to know when a large amount of lithium appeared. The gradual aging process of stars is called evolution in astronomy. If we can know the evolution stage of lithium rich giant stars, we will know the formation time of lithium and deduce their origin. < / P > < p > there are many opinions about the evolution stage of lithium rich giant stars in the scientific community. Traditionally, it is generally believed that most of the small mass lithium rich giant stars are “red giant”. There are two main reasons for this cognition: first, from the appearance of stars, their temperature and brightness really conform to the characteristics of “red giant”; second, in the process of evolution towards red giant, special convection with a speed of 10 times that of ordinary convection may occur inside stars, which is conducive to the formation of lithium, in line with the expectation of producing lithium rich giant. < / P > < p > as stars continue to evolve, more and more helium will be accumulated in the center of red giant stars, and the pressure and temperature will be higher and higher. Finally, in a moment, the helium nucleus was ignited, a new heart of stable combustion appeared, and the stars entered a new stage – “red cluster stars”. Compared with the stars just entering the “red giant”, the two stars with a difference of ages of millions of years look almost identical on the surface. < p > < p > most of them are considered to be “lithium rich” stars. According to Shi Jianrong, although they are similar in appearance, the “hearts” of these two kinds of stars are completely different. The newly published research is realized by monitoring the “heartbeat” of a large group of lithium rich giant stars found in the spectrum of Guo Shoujing’s telescope. < / P > < p > in the study, astronomers used a technology called “astroseismology” to measure the beating law of the heart of lithium rich giant stars, just like making “ECG” for each star. < / P > < p > it doesn’t matter if we don’t check, but we find that more than 80% of the original lithium rich stars are not “red giants” previously thought by academic circles, and their real identities are older “red cluster stars”. Further research by astronomers also found that different types of lithium rich giant stars are significantly different from traditional cognition in many aspects, such as lithium content and star mass. These findings are difficult to explain with current theories. < / P > < p > Zhao Gang said that for decades, most of the relevant theories have been put forward based on the premise of “red giant”, and even up to this year, many relevant theoretical studies are still discussing various mechanisms within the red giant. However, due to the completely different internal physical environment, the original theory is obviously not applicable to “red cluster stars”. < / P > < p > according to Yan Hongliang, the “heartbeat” of a star actually comes from the vibration of the star – starquake. So, how does the heart beat of a star, and how does astroseismology know the truth through the heart beat of a star? < / P > < p > researchers take the sun as an example, which “whispers” on thousands of frequencies all the time. Although scientists can’t really “hear” the sound of the sun, these noises make the brightness of the sun change slightly. So as long as we record the change of its brightness, we can know how the sun vibrates. Just like people’s heartbeat, the vibration of a star represents the internal information of its body, which can not be obtained by other conventional methods, while the method of starquake is like a doctor’s stethoscope listening to the “heartbeat” of the star. < p > < p > Yan Hongliang said that due to different fuel and energy transmission forms, the heart beat of “red giant” and “red cluster star” has a very significant difference: Generally speaking, the heart rate of “red giant” is faster, while the heart rate of older “red cluster star” is slower. < p > < p > this time, Kepler satellite, a space telescope launched by NASA in 2009 to search for earth like planets, is shouldering the function of measuring “ECG”. Its continuous photometric observation for four years has successfully applied astroseismology technology to the research of lithium rich giant stars. < / P > < p > Zhao Gang and his team members said that over the years, the identity of lithium rich giant stars has been confusing people. The latest research work of international scientific research team led by Chinese astronomers has solved the mystery of the true identity of lithium rich giant stars by auscultating the “heartbeat” of stars through “astroseismology”. The research results have promoted the perfection of stellar evolution theory and will deepen people’s understanding of the evolution of stars The understanding of the formation of cosmic matter. Global Tech

By ibmwl