The Very Large Telescope (VLT) isEuropean Southern ObservatoryBuilt in ChileParina ObservatoryLargeOptical telescope, consisting of four telescopes with the same aperture of 8.2 meters.The four telescopes of VLT can be used alone or composedOptical interferometerConduct high-resolution observation.[1]When working as an interferometer, the VLT will have the light gathering ability of a telescope with an aperture of 16 meters and the angular resolution ability of a telescope with an aperture of 130 meters[2]。
VLT project started in 1986 and started to work in 2012, with a cost of more than 500 million dollars.Each primary mirror of VLT weighs about 22 tons. Each telescope weighs about 500 tons.The main scientific task of VLT is to search forplanet, ResearchNebulaThe birth and observation of inner stars are activeGalactic nucleusPossible hidden insideblack holeAnd exploring the edge of the universe.[1]
The Very Large Telescope (hereinafter referred to as VLT) consists of four identical 8.2 meter telescopes placed at the top of Sero Parana, 2632 meters above sea level.The main mirror weighs 22 tons, but its thickness is only 18 cm. It is located in the port city of ChileAntofagastaSero Parena, 130 kilometers to the south, stands outAtacama DesertChina is one of the driest regions on the earth, which is very suitable for astronomical observation.Organized by 8 European countriesEuropean Southern ObservatoryThe very large telescope built is worth 500 million US dollars. It was approved in 1987 and is the only one in the world built according to the expected plan and budget.
The four telescopes are named Antu, Kueyen, Melipal and Yepun in the local Putongo language, which means the sun, the moon, the Southern Cross and Sirius.These names were put forward by a Chilean female student in a competition sponsored by the European Southern Observatory.Antu was the first to be built. It began trial observation in the spring of 1998 and was delivered to astronomers in April 1999. It is equipped with sensitive infrared and optical band cameras andSpectrograph。Astronomers have used it to studycomet、Protoplanetary disk 、Planetary nebula、Super planetRelics and remotenessRadio galaxy。
The second telescope, Kueyen, was tested in March 1999 and delivered to astronomers in April 2000 after a year of debugging.Its main instruments are two large spectrographs, which are expected to be 500000 in the next 10 yearsStellar spectrum。In addition, Kueyen can also take visible light images.
The third telescope, Melipal, began trial observation and continued debugging in January 2000.Its first scientific instrument was the spectrograph, which was mainly designed to study the early universe and distant galaxies.The telescope will be equipped with compensation atmosphereTurbulenceOfadaptive optics System.Of the four telescopes, Melipal is the most suitable for cosmological research.
The fourth telescope Yepun began its trial observation in July 2000.Its mechanical structure was completed in May 1999, and the 8.2-meter main mirror reached Sero Parena in April 2000.It has the best optical mirror in the world with a surface precision of 8.5 nm.If the terrain of the United States is flat like the main mirror of Yepun, its highest peak will be less than 2.5 cm.[2-3]
In 2005 and 2006,European Southern ObservatoryFour auxiliary telescopes with a diameter of 1.8m have been successively built near the VLT, which together with four 8.2m telescopes form the VLTI.These auxiliary telescopes will not significantly increase the focus area of the interferometer, but can increase the number of baselines and improve the imaging quality.[4]
Main design parameters
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Structure Diagram of VLT Telescope
Since 1986, the European Southern Observatory (ESO) has developed a 16 m equivalent aperture telescope consisting of four 8 m telescopesOptical telescope。Four 8m telescopes are arranged in a straight line. The focal ratio of the main mirror of each 8m telescope is f/2. The optical system is an R-C system. There are two Nasmyth focal points, the focal ratio is f/15, the field of view is 0.5 °, and oneFocus of hinge。The main mirror of each very large telescope has an aperture of 8.2m, a focal ratio of f/2, a weight of 22t and a thickness of 18cm. The R-C optical system is used. The 470t frame floats on the 0.05mm thick oil film and can rotate flexibly.Direct drive is adopted, the motor diameter is 16m, and the steel strip code is used to measure the angle to achieve high accuracy.The telescope usesHorizon device, the main mirror adoptsActive optical systemYes, the active optical system with 150 actuators is installed below.Its pointing accuracy is 1 ″, tracking accuracy is 0.05 ″, the weight of the mirror cylinder is 100t, the weight of the fork arm is less than 120t, and the deformation error of the secondary mirror is 0.4mm when the wind speed is 100km/h.
The telescope is installed in theParina Observatory, 2632m above sea level, dry climate, desert type bare rock landform, 340 sunny nights in a year,Visual acuityIt reaches 0.5 ″, which is very conducive to astronomical observation.The VLT dome is equipped with refrigeration equipment, which cools in the dome during the day until the expected observation temperature at night. During observation, the temperature around the telescope can be quickly consistent with the outside temperature, maintaining a good dome visibility.There are eight small fans around the main mirror, which can be attached to the mirror when necessary to improve its visual acuity.All electric control cabinets are equipped with refrigerant to take away the heat generated.[5-7]
Characteristics of VLT
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Main mirror of VLT
First, VLT has strong adaptability. Its four telescopes can be used alone or combined in many ways;Secondly, VLT is equipped with 11 cameras, includingMid infraredIts observation plan is ambitious;Third, and most importantly, its four telescopes can be used asOptical interferometerTo work.When it works as an interferometer, its light gathering capacity is equivalent to that of a telescope with an aperture of 16 metersHaier telescope10 times higher thanKeck telescope2.5 times higher.Its angular resolution can reach 0.0005 angular secondsHubble Space Telescope50 times higher, which means that two front lights of a car 640000 kilometers away can be distinguished.In order to achieve such a high resolution, the European Southern Observatory has built three auxiliary telescopes with an aperture of 1.8 meters for VLT.The auxiliary telescope can be placed in different places nearby to increase the number of interferometer baselines and improve the resolution.[8]
Ounan Station
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In the 1950s, European astronomers were deeply impressed by the newly built Haier Telescope at Palomar Mountain in the United States with a diameter of 5.08 meters.In 1954, European physicists united to establish the European Particle Physics Laboratory, which enabled European researchers to build powerfulParticle accelerator。This fact greatly inspired European astronomers, who naturally thought that they should also work together to promote future large-scale telescope projects.
The famous Dutch astronomy JH. Ault and the German astronomer W. Budd worked hard to advocate this idea.After nearly a decade of diplomatic discussions, five European countries, Belgium, France, Germany, the Netherlands and Sweden, finally reached a consensus.On October 5, 1962, the five countries jointly formedEuropean Southern Observatory(referred to as Ounan TV Station for short) was finally established.The reason why it is called the European Southern Observatory is that European astronomers have noticed the lack of human knowledge of the Southern Celestial Bodies, and they are eager to establish an observatory with powerful instruments in the Southern Hemisphere to promote and organize the astronomical observation of the Southern Celestial.Later, Denmark, Italy and Switzerland successively joined the platform, bringing the number of members of the platform to eight.However, the United Kingdom will not participate in the activities of the European Southern Observatory because it has observation bases in Australia and South Africa in the southern hemisphere.
As early as before the establishment of the European Southern Observatory was announced, that is, since 1955, astronomers who participated in the preparation of the European Southern Observatory have carried out the work of selecting the best site.They once sent people to the Kalahadi Desert in Africa for investigation, but they did not find a very ideal site.In the early 1960s, the American team told them that they could find a better location in Chile, South America.So, in April 1964, scientists from the European Southern Observatory visited Chile.This time, they chose Lasia Mountain (meaning saddle mountain in Spanish) in Atacama Desert, 600 kilometers north of Santiago.The mountain is 2400 meters above sea level. The meteorological conditions on the top of the mountain are very suitable for astronomical observation, which is very satisfactory to the astronomers at the European Southern Observatory.
After a long time of land acquisition negotiation, Ounantai finally purchased an 800 square kilometers of land centered on the Mountain of La Cia from the Chilean government.Since then, the site of the European Southern Observatory has become the world's largest "enclave" (a foreign territory within the territory of a country).On March 25, 1969, the official ribbon cutting ceremony was held on the Mount Lasia. Since then, new instruments and equipment have been settled here almost every year.For example, in 1976, the largest long-awaited equipment of the European Southern Observatory - 3.6m diameter was installedReflecting telescope；In 1980, it was equipped with a 1.4-meter auxiliary telescope;In 1984, the 2.2 meter telescope from West Germany arrived here;In 1987, Sweden's 15m aperture submillimeter waveradio telescopeThis brings the total number of telescopes on Mount La Silla to 14;In 1989, one 3.5m diameterNew technology telescopeBroke the record again.The research field of the European Southern Observatory involves many aspects, such as stars, galaxies, interstellar matter, galaxy clusters and quasars. Therefore, the Mountain of Lacia has become another holy place for observation, which is almost comparable to the Mauna Kea Mountain in Hawaii.
The headquarters of Onan Radio is located in Jiaxing, the northern suburb of Munich. This is a generous gift from the German government to Onan Radio, where the technical and administrative parts of Onan Radio are concentrated.Many astronomers from Europe and around the world often meet here to discuss problems.What is exciting is that in July 1987, the European Southern Radio set up a permanent satellite communication line between Jiaxing and Lasia Mountain.This satellite line enables astronomers to control the pointing of the telescope on Mount La Silla in Jiaxing's office, use TV to see the images in the telescope's field of view, and also control the terminal equipment of the telescope,For example, in the process of negative film exposure, the guide star (a small telescope is attached to a large astronomical telescope, and in the process of tracking and photographing celestial objects with a large telescope, the small telescope monitors the tracking situation through the eyepiece at any time, corrects the deviation, and ensures the tracking accuracy, referred to as the guide star) receives the digital recording information of the spectrum or CCD image.The image processing software in the computer can process the observed data in a timely manner, so that the observer can know the quality of observation at any time so as to take corresponding measures in a timely manner.
At this point, astronomers can make observations by sitting in the office of Jiaxing instead of traveling to the Mount Lasia, so their observation time can vary from long to short;In addition, for several observation items proposed at the same time, you can select the most favorable items that are most suitable for the observation conditions of the night to observe, which not only brings great convenience to observers, but also can use the telescope more effectively.[8]
European Southern ObservatoryThe very large telescope (VLT) of the Orion Nebula has made the most in-depth observation of the center of the Orion Nebula so far.The research results challenge the previously widely accepted understanding of the formation and history of the Orion Nebula.
Orion is one of the constellations in the equatorial belt. The famous Orion Nebula is located in it. It spans about 24 light years and is a huge gas dust cloud that is producing new stars.These star forming regions contain a large amount of hydrogen atomic gas, young hot stars, protoplanetary disks and stellar jets that sweep material at a high speedOrion NebulaThe brightness is very high, even visible to the naked eye on the earth. For a long time, its ideal relative distance and observation conditions provide important conditions for people to explore the theory of star formation.
This time, astronomers from Chile and Germany usedEuropean Southern ObservatoryThe Very Large Telescope in ChileOrion nebula Launched the most comprehensive and profound analysis.The powerful HAWK-I infrared instrument equipped with the telescope not only presents people with spectacular and beautiful pictures, but also reveals ten times the number of brown dwarfs and independent objects with planetary mass known before.
The composition of brown dwarf stars is similar to that of stars, but the fusion reaction could not be ignited due to insufficient mass.Although they are called "failed stars", researchers said that finding the existence of such low-quality stars is an exciting thing in itself, because their form of existence depends on their environment, which is "unexpected wealth" for astronomers and can help better understand the history of star formation.[9]
European Southern ObservatoryThe Very Large Telescope Interferometer (VLTI) of ESO has revealed the secret of the largest supergiant Huang Te, which is now among the ten largest stars.According to VLTI measurement, its diameter is 1300 times larger than the sun, and it is the main star of the binary system.The observation lasted more than six years, and some data came from amateur astronomers, all of which showed that this pair of rare and extraordinary objects were in rapid change and were in a very short (rapid evolution) stage of their lives.
With the help of ESO's Very Large Telescope Interferometer (VLTI), an international cooperation team led by Olivier Chesneau of the Blue Coast Observatory in Nice, France, found that the super giant Huangte star HR 5171A was extremely huge - more than 1300 suns in diameter, far beyond expectations.This makes it the largest known yellow supergiant, and enough to rank among the ten largest stars - more than the famousRed supergiantBetelgeuse（Orion alpha）Its diameter is about 50% larger and its brightness is about one million times that of the sun.[10]
A new type of stellar explosion is observed
In 2022, an international team of astronomers used the very large telescope of the European Southern Observatory (ESO) for the first time to observe and confirm a new type of stellar explosion, whose intensity is about one millionth of that of a nova explosion, and is temporarily named as a micro nova.This new mechanism enriches and deepens people's understanding of stellar explosions.[11]
Found the "ashes" left by the explosion of the first batch of stars in the universe
May 2023In September, French and Italian scientists jointly used the European Space Agency's Very Large Telescope to discover the "ash" left by the first batch of star explosions in the universe for the first time: they detected three remote gas clouds whose chemical composition was in line with scientists' expectations for the first batch of star explosionsmatching[12]。
Decoding planetary nebulaeThe Secret of "Disappearance" of Sulfur Element
In 2024,Using high-precision spectral data from the Very Large Telescope in Parena, Chile, built by the European Southern Observatory, researchers studied about 130 planetary nebulae in the center of the Milky Way Galaxy.The results show that the anomaly of sulfur "missing" is related to the mass of the host star of the planetary nebula.[13]
