Sagittarius A is composed of Sagittarius A East Star（Supernova remnant）, Sagittarius A (spiral structure) andSagittarius A*(Dense radio wave source,Supermassive black hole）Three parts.These three parts overlap, of which Sagittarius A is the largest eastern star, West Star is located off center in the eastern star, and Sagittarius A * is located near the center of the western star.They look very similar in structureVenn diagram。The first picture of the supermassive black hole Sagittarius A * has been taken inBeijing TimeMay 12, 2022 byEvent horizon telescope(EHT) officially released by the cooperation organization.[7-10]
Sagittarius A East Star is about 25 light-years wide and hasSupernova remnantThe nature of theSupernovaThe explosion occurred about 35000-10000 years ago.But if we want to create such a huge structureExplosive energyThe explosion energy of supernovae is 50-100 times higher than that of ordinary supernovae.It is speculated that the eastern star Sagittarius A is located near the center of the black holeBlack hole gravityA supernova remnant exploding under compression.
Sagittarius A, Western Star
Surface luminosity and velocity of the interior of Sagittarius A
Sagittarius A West Star looks like a three armedHelical structureTherefore, it is also called "micro spiral structure".However, the name and appearance are misleading, because the three arms of Sagittarius A are not really spiral structures.It is made of several piecesCosmic dustEgyptGas cloudIt is composed of, surrounds and rushes at the speed of 1000km/sSagittarius A*。These cloudySurface layerHave beenionization。Ionization sources are widespreadHigh qualityStars (more than 100 stars have been identifiedOB star）They are distributed within the range of seconds from the center.
Sagittarius A, the western star, has a huge archAstrolabeSurrounded by.The star disk is composed of thicktorusMolecular gas composition.The north arm of Sagittarius A was originally in this arch, but it may fall due to some changes.These changes may be caused by the supernova explosion of East Sagittarius A.The north arm is very bright, stretching from the south to the north, even to the east.The north arm can be observed as weakZhanyuan。
The western arc can be seen as the inner layer of the ionization of the arcuate disk.The east arm and the stick are the other two huge clouds like the north arm, but their detours are different.They are estimated to be 20 times eachSolar mass。
On these large structures, there are also some smaller clouds and holes.The most obvious one is the small hole, which is estimated to be a giant starStellar windFoam blowing in the north arm.
Sagittarius A * is located inGalactic center, considered to be aSupermassive black hole。Orbits around stars in Sagittarius A *Speed ratioGalaxyThe speed of other stars inside is higher.One of the stars, called S2, orbits Sagittarius A * at a speed of about 5000 kilometers per second.[1]
G2 phagocytosis process
In 2014, it has long been regarded by astronomers asGas cloudThe mysterious object G2 has passed through Sagittarius A *, during which it did not disappear into theEvent horizonOn the contrary, it finally disintegrates, which indicates that G2 is different from the previous gasCloudinessCelestial body G1 may be a stellar remnant, and has a stronggravitational fieldInstead of gas clouds.[2]
In December 2008, astronomers confirmed thatSagittarius A*Quality andSolar massMultiple relationship of.It is found that there is a starS2Elliptical movement around Sagittarius A *Track semimajor axisIs 9.50 102Astronomical unit（Earth revolutionThe radius of the orbit is one astronomical unit), and Sagittarius A * is at the focus of the ellipse.The operating period of S2 is 15.2 years.
In this focus,Galactic centerThe mysterious celestial body Sagittarius A * also fell into the view of the mortal public from nine days away from the earth 26000 light years.It is said that it is a black hole.According to the American Science Daily, if people can seeRadio wave，Sagittarius A galaxyIt will be the largest and brightest star in the sky, and its brightness is 20 times that of the full moon.Recently, NASA FermiGamma raySpace telescopeThe latest observation results show that Sagittarius AGalaxyNestled in a pair of giant radio petal shaped gas smoke regions, each plume is nearly 100 light-years long, and these gases are formed bySupermassive black holeSprayed.US Naval Research LaboratoryTeddy Cheung, a member of the Fermi research group, said, "We have observed previously unseen scenes in the gamma ray range. We have not only seen the extended pinnate radio petal structure, but also found gamma rays in this areaOutputIt is 10 times more than its radio output.We can call it the 'gamma ray galaxy'. "
Sagittarius A galaxy is 26000 light years away from the Earth, which is the first galaxy withCosmic radioSource galaxy.French spaceRadiationJurgen Knodlseder of the Research Center said:“Radio galaxyIt should be that there is a huge double lobe radio gas jet structure aroundElliptical galaxy, andSagittarius A galaxyIt is a typical textbook example! "
Astronomers classify Sagittarius A as an "active galaxy", which applies to any galaxy with different ejections from its centerWavelength rangeA strong jet of material.
These magnetic properties released by black holesMaterial flowFlying at the speed close to the speed of light, after tens of millions of years of formation process, the magnetic field and energy particles gradually fill to form two petal jet flow structures.When light speed electrons spiral through the complex magnetic field of petal structure, radio waves are also gradually formed.
Observation history
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Sagittarius A * was first discovered in February 1974.Its observation mainly depends on the observation of light variation.[4]
Max Bronk AliensInstitute of Physics(Max Planck Institute for Extraterrestrial Physics) An international research team led by Rainer Sch ö del has observed the star S2 close to Sagittarius A * for ten years, and announced the evidence that Sagittarius A * is a massive compact body on October 16, 2002.Originally from S2Kepler orbitcalculation,Sagittarius A*The mass of is 2.6 ± 200000Solar massWith a radius of 120Astronomical unit。Subsequent observations estimated that the mass of Sagittarius A * should be 4.1 million solar masses with a volume radius of less than 45 astronomical units.[5]
In November 2004, astronomers found thatIntermediate-mass black hole GCIRS 13E, its orbit is about 3 light years away from Sagittarius A *.The mass of GCIRS 13E is 1300 solar mass, belonging to a star cluster with 7 stars,[5]This observation supportsSuperheavy black holeIt can absorb smaller black holes and stars around to grow.
After 16 years of observation of Sagittarius A *, it is believed that its mass is 4.31 million ± 0.38 millionSolar mass。researcherReinhard Genzel (Reinhard Genzel) thinks thatPrima facie evidenceProve the existence of superheavy black holes.[6]
