The universe has given us new knowledge and led us to more unknown futures. How many galaxies are "around" after the boundary of the Milky Way has been explored? Can humans solve the mystery of the formation of supermassive black holes after the first detection of medium-mass black holes with gravitational waves?
Looking back on 2020, we will talk to the universe again with a journey through time and space.
Oxygen appears in extragalactic galaxies.
The abundance of oxygen in the universe is second only to hydrogen and helium. Previously, astronomers thought that oxygen molecules should be everywhere in the space between stars, but there has been no evidence that oxygen exists outside the Milky Way.
This "suspense" was answered in an article published in Astrophysics on February 1 this year. In the "Makaryan 23 1" galaxy, which is 560 million light years away from the earth, Chinese and foreign scientists have jointly discovered oxygen. It is reported that this is the first time that humans have discovered oxygen outside the Milky Way, and it is also the most detected oxygen outside the solar system so far.
"Makaryan 23 1" is located in Ursa Major. Previously, astronomers had detected oxygen in the Orion Nebula and Ophiuchus Nebula of the Milky Way. According to calculation, the proportion of oxygen in "Makarian 23 1" is 0/00 times that of Orion Nebula. Scientists speculate that "Makarian 23 1" experienced a stronger oxygen formation process than the Orion Nebula.
Astronomers say that the conditions for the existence of oxygen and water are found in the spectrum of extraterrestrial matter, so it cannot be asserted that there must be life in its environment; If you can't see these "markers", you may not have the possibility of life.
Wang Junzhi, the first author of the above-mentioned research paper and a researcher at the Shanghai Observatory of Chinese Academy of Sciences, said that the discovery of oxygen outside the Milky Way will help to further deepen the understanding of the composition of the universe and challenge the related theories such as the formation and consumption of oxygen in interstellar media.
"This study is the first time that scientists have discovered oxygen outside the Milky Way, but why the oxygen content in interstellar space is generally much lower than expected is still an unsolved mystery." Li Wei, chief scientist of the 500-meter spherical radio telescope (FAST), said.
The underground structure on the back of the moon was revealed for the first time.
The Von Kamen Crater is located in the Antarctic-aitken Basin on the back of the moon, which is one of the oldest craters in the solar system. It was formed 4 billion years ago, retaining the rocks of the original moon, and it is also the deepest basin known on the moon.
20 19 13, Chang' e-4 successfully landed at the bottom of the impact crater in Von Kamen. After that, the "Yutu II" lunar rover used panorama camera, infrared spectrometer, lunar radar and other advanced instruments to carry out scientific exploration and research on the back of the moon.
In the early morning of February 27th, 2020, the international scientific journal Science Progress published online the "CT" results of China "Yutu II" lunar rover crashing into Von Kamen.
The research team led by Li Chunlai and Su Yan, researchers from the National Astronomical Observatory of Chinese Academy of Sciences, used the lunar radar on the "Yutu II" lunar rover to reveal the layered structure 40 meters underground in the landing zone on the back of the moon for the first time, and found that the underground material consists of low-loss lunar soil material and a large number of stones of different sizes. This is the first time that mankind has unveiled the mystery of the underground structure on the back of the moon.
Specifically, the research team identified three stratigraphic units within 40 meters along the "Yutu II" 106 meter path.
Among them, the first unit is fine-grained lunar soil with a depth of 12 m from the lunar surface to the underground, in which a small amount of stones are embedded. The layer is formed on a sputtering material overlapped by a plurality of impact pits; The second unit is sputtering deposition from 12 meters to 24 meters underground, in which there are a lot of stones, even forming gravel layers and gravel piles; The third unit is 24 meters to 40 meters underground, which is the product of weathering of older sputtering deposits in different periods.
The researchers said that this study can help people understand the history of lunar impact and volcanic activity, and is expected to bring new enlightenment to the study of geological evolution on the back of the moon.
Find out the boundary of the galaxy
Astronomers have long known that the brightest part of the Milky Way is a pancake-shaped stellar disk, in which the sun is located, and its width is about 1 .200 million light years (1light year is about 946 billion kilometers). Outside the stellar disk is a gas disk. A huge halo of dark matter surrounds the two disks and goes far beyond their range. However, it is difficult for scientists to measure the diameter of the Milky Way galaxy because this dark halo does not emit light.
On March 23rd, the website of Science News reported a study by British scientists. Alice Dyson, an astrophysicist at Durham University in England, and her colleagues used the calculation of galaxies near the Milky Way to get that the exact diameter of the Milky Way is 6.5438+0.9 million light years, with an error of less than 400,000 light years.
In order to find the boundary of the Milky Way, Dixon's team used a computer to simulate the side-by-side appearance of the Milky Way and its nearby large galaxy Andromeda. The results show that the velocity of nearby small galaxies outside the edge of the dark halo of giant galaxies will decrease significantly.
Using existing telescopes, Dixon's team found that small galaxies near the Milky Way also experienced the same speed drop. This happened about 950,000 light-years away from the center of the Milky Way, which should be the boundary of the Milky Way. From this, they concluded that the Milky Way is about 65.438+0.9 billion light years wide.
Rosemary Wise, an astronomer at Johns Hopkins University in the United States, pointed out that the latest measurement results can help astronomers clarify other properties of the Milky Way. For example, the bigger the Milky Way, the heavier its "weight" and the more galaxies that should "dance together". So far, scientists have found about 60 "dancing partners" for the Milky Way, and more should be found in the future.
That summer solstice happened to meet the "Phnom Penh solar eclipse"
On June 2 1 day, when the sun was almost directly on the tropic of cancer, the northern hemisphere ushered in the longest day, which was the summer solstice. On the same day, Tianmu Theater also staged one of the most wonderful astronomical performances of the year-"Eclipse in Phnom Penh".
According to Hu, an engineer at Purple Mountain Observatory of China Academy of Sciences, this is the only total solar eclipse that can be observed in China in this century, and the time coincides with that in summer.
The size of an eclipse depends on the positional relationship between the sun, the earth and the moon. Shi Zhicheng, a member of the Chinese Astronomical Society and director of the Tianjin Astronomical Society, explained that the farther the sun is from the earth, the smaller its apparent diameter, while the closer the moon is to the earth, the larger its umbra, so when the sun is at apogee and the moon is at perigee, the maximum eclipse will be obtained.
More than 2000 years ago, the solar eclipse inspired mankind to understand the universe and discover the law of the earth's revolution. When the sun is blocked by the moon, it is easier for people to observe the corona activity, which is helpful to predict its future activity trend. As an astronomical phenomenon, solar eclipse has a certain influence on the ionosphere, which plays a key role in satellite-ground communication.
Different from previous annular eclipses, this annular eclipse is very close to the total lunar eclipse. More than 99% of the entire round surface of the sun is covered, and the remaining circle of Phnom Penh is very thin.
Some experts say that in the remaining 80 years of 2 1 century, there are only 10 annular eclipses in China, and five of them will occur in the extreme north or south. The annular eclipse zone is small, and the transit time of the moon shadow is short, which is not convenient for observation.
Up to now, the largest 3D map of the universe has been released.
The universe was born in the Big Bang about 654.38+03.8 billion years ago. Scientists know something about the early and recent days of the universe, but what changes the universe has experienced during 1 10 billion years has always been an unsolved mystery.
On July 20th, according to foreign media reports, after analyzing more than 4 million galaxies and superbright quasars with great energy, the international Sloan Digital Sky Survey Project (SDSS) released the largest three-dimensional map of the universe so far, telling the story of the expansion of the universe during the period of 65.438+0.65438+0 billion years, filling the gap in human exploration of the history of the universe.
This map was drawn by the Extended Baryon Oscillation Spectrum Survey (eBOSS) project, which is a part of SDSS. This achievement is based on the cooperation of hundreds of researchers from dozens of institutions around the world for more than 20 years.
Studies have shown that the filaments and gaps that make up the structure of the universe began when the universe was only 300 thousand years old. In addition, the expansion of the universe began to accelerate about 6 billion years ago and has been expanding ever since. This accelerated expansion seems to be driven by dark energy, which is consistent with Einstein's general theory of relativity.
In addition, the researchers pointed out that astrophysicists knew that the universe was expanding many years ago, but they have been unable to accurately measure the speed of the expansion of the universe-Hubble constant. The survey results of Ebbs and SDSS show that the current expansion speed of the universe does not match the expansion speed obtained by other previous studies, and it still needs further research and investigation by scientists.
Find an "impossible" medium-mass black hole
On September 2nd, official website, the American Laser Interferometric Gravitational Wave Observatory reported that the observatory and the Italian Virgo Gravitational Wave Observatory jointly detected a black hole with a mass of 1.42 times that of the sun, which is the first time that scientists have detected such a medium-mass black hole.
The researchers pointed out that previously observed black holes can be roughly divided into two categories: stellar-mass black holes and supermassive black holes. The former is several times to dozens of times the mass of the sun and is considered to be formed after the death of a massive star; The mass of the latter is about several hundred thousand to several billion times that of the sun. Medium-mass black holes are in between, and their mass is 100 to 1000 times that of the sun. Before receiving this signal, scientists did not find any evidence to prove their existence.
This black hole is formed by merging two black holes with the mass of about 85 times and 65 times that of the sun, respectively. The energy of 8 times the mass of the sun released by the merger permeates the universe in the form of gravitational waves and is captured by two detectors.
The researchers detected the gravitational wave signal GW 19052 1 on May 2 19, and the duration was less than 0. 1 second. Scientists speculate that GW 19052 1 is probably a signal generated by the merger of two black holes with special properties.
So far, almost all the gravitational wave signals that have been "recognized" come from the merger of two stars, including the merger of two black holes and the merger of two neutron stars.
Water molecules appear in the illumination area of the moon.
Is there water on the moon? Scientists never stop exploring. Previously, scientists speculated that ice might be hidden in the dark crater on the back of the moon. Now, the latest research confirms that there may be water on the illuminated surface of the moon.
10 year 10 On October 26th, Nature Astronomy published an article saying that NASA first detected water molecules on the surface of kravis crater illuminated by the moon in the southern hemisphere of the moon, relying on the stratospheric infrared observatory "Sophia".
This discovery shows that water may be distributed on the whole surface of the moon, not just on the dark back of the moon. In other words, water can exist on the surface of the moon even under solar radiation.
It is difficult for water molecules to stay on the surface of the moon exposed to sunlight. According to the survey data, water is trapped in the soil on the surface of the moon, with a concentration of 100-400 ppm, which is equivalent to 100-400 ml of water per kilogram of lunar soil, which is 100 times drier than the Sahara desert, but the exact water content needs further verification.
According to the paper, the detected water may be stored in glassy substances on the surface of the moon or between particles, which can protect water in harsh environment.
Without the protection of the atmosphere, can the water source on the solar irradiation surface of the moon still be used? "This also needs to understand the distribution range, burial depth and long-term preservation of water on the surface of the moon." Zhou Liyong, a professor at the School of Astronomy and Space Science of Nanjing University, believes that it is necessary to find out whether the water content is high enough, where it is enriched, whether it can be mined, what is the mechanism of water storage on the surface of the moon, and what kind of technology is needed to effectively collect water.
"These findings are really exciting and have great research and application prospects, but the cost is still unpredictable." Zhou Liyong said.
The "500-meter spherical radio telescope (FAST)" saw the source of the rapid radio burst.
Fast radio burst, a mysterious radio burst phenomenon in the universe. Its duration is as short as a few milliseconds, but in these milliseconds of "sudden inspiration", there is huge energy, which can completely release the power generation of tens of billions of years on the earth in the form of radio waves.
In recent ten years, astronomers have been exploring its source. What information does it contain?
Scientists published three research results on fast radio bursts in Nature. Using the 500-meter spherical radio telescope (FAST), they captured some clues about the origin of fast radio bursts.
Professor Peking University and researcher Li Kejia of the National Astronomical Observatory of Chinese Academy of Sciences used FAST to detect the fast radio burst source FRB 18030 1 15 bursts, and the intensity curve of each burst was different. This is the first time in the world that the radiation of this explosion source has very rich polarization characteristics. The polarization diversity observed by FAST clearly shows that the explosion source of fast radio bursts in the universe may come from physical processes in the magnetosphere of dense celestial bodies.
"Similar to the earth, magnetars also form magnetosphere. Our observation this time is the most direct evidence that fast radio bursts come from the magnetosphere. " Li Kejia said.
In addition, a joint research team composed of Dr. Lin Lin from Beijing Normal University, Dr. Zhang Chunfeng from Peking University and Dr. Wang Pei from the National Astronomical Observatory of Chinese Academy of Sciences made a multi-band joint observation on the repetitive source SGR 1935+2 145 of the Milky Way soft gamma-ray burst by using FAST. The observation results show that there is a weak correlation between fast radio bursts and soft γ -ray repeated bursts, and the fast radio bursts produced by magnetar bursts must depend on extremely special physical conditions.
Phosphine first appeared in the atmosphere of Venus.
On September 14, the journal Nature Astronomy published an article saying that in 20 17 and 20 19, a research team including Jane Grievous, a scientist from Cardiff University in England, used Maxwell Telescope (JCMT) and Atacama MM/MM Array Telescope (ALMA) to explore Venus.
This is the first time that scientists have detected phosphine in the atmosphere of Venus. Researchers believe that the detection of phosphine can not be used as strong evidence for the existence of microbial life, but it can indicate that unknown geological or chemical processes may occur on Venus.
Venus, in a harsh environment, gives people hope for life because of the clues of phosphine, but it doesn't last long and is questioned again.
65438126 October, a new study published in the journal Nature Astronomy pointed out that the spectral data previously considered as phosphine are actually very close to sulfur dioxide, which is very common in the atmosphere of Venus.
Another study led by Leiden University in the Netherlands shows that the spectral data obtained by ALMA can be explained by compounds other than phosphorus gas. On this basis, they concluded that "no statistically significant phosphine was detected" in the atmosphere of Venus.
However, the "hope" of life on Venus did not end there. After re-examining the initial data, the Grievous team released the conclusion that ALMA's data showed a spectral feature that could only be explained by phosphine compounds. According to the latest data, the content of phosphine is only 65,438+0/7 of the original published result.
Does phosphine really exist in the atmosphere of Venus? Where does phosphine come from? Do they bear the imprint of life? These are all worth looking forward to.
GECAM gravitational wave detector lifted off
65438+February 10 At 4 o'clock in xichang satellite launch center, the Long March 10 carrier rocket was successfully launched with the "Gravitational Wave Storm High Energy Electromagnetic Correspondence All-day Monitor" (GECAM) and entered the scheduled orbit.
Li Xinqiao, a satellite payload engineer, said that GECAM will be the astronomical satellite with the highest sensitivity in detecting gamma bursts in orbit in several years, and the satellite with the strongest comprehensive detection capability for magstar bursts, fast radio bursts and earth gamma flashes. It will monitor gravitational wave gamma bursts, high-energy radiation of fast radio bursts, special gamma bursts, magnetic starbursts and other high-energy celestial phenomena all day, and study dense celestial bodies such as neutron stars and black holes and their merging process. In addition, GECAM will also detect solar flares, earth gamma flashes, earth electron beams and other space high-energy radiation phenomena, providing scientific observation data for further revealing its physical mechanism.
Gravitational wave gamma burst is the most important scientific detection target of GECAM. For the detection of gravitational waves, the spatial positioning accuracy of ground equipment is not high. Therefore, scientists need a satellite-GECAM, which can give the location of gravitational wave explosion in time with high accuracy.
Li Xinqiao introduced: "GECAM can continuously and accurately observe the energy spectrum and light changes of the homologous gamma-ray bursts that occur almost at the same time as gravitational-wave gamma-rays, and at the same time, it can give the azimuth information of gravitational-wave events with high accuracy, narrowing the range of tens to hundreds of square degrees where the ground gravitational-wave detection equipment is located. This will help observation equipment in space and other bands on the ground to better determine their corresponding celestial sources and carry out follow-up observations. "