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A Black Hole Nearest to the EarthHuman beings unveil an event horizon
Lee Soo-hyun, Editor | 승인 2020.07.02 01:24

 

 The ESO (European Southern Observatory) reported in the journal “Astronomy & Astrophysics” on May 6 that it found a black hole just 1,000 light years away from the 
Earth. “It is found with a star visible at night in the southern hemisphere of the Earth,” scientists clarified. The research team used an MPG /ESO 2.2-meter telescope to track down two stars moving together at the La Silla Observatory of ESO in Chile, and found evidence of an invisible object. They later found out that it was a black hole. ESO scientist Thomas Rivinius said the discovery is just a tip of an iceberg. This is because more similar black holes could be found. Located within the constellation of Telescopium, the HR 6819 stellar system can be seen with naked eyes in the southern hemisphere at dark and clear 
nights without binoculars or telescopes. The celestial system contains the black hole closest to the Earth than any known black hole so far.

 The research team originally observed to study celestial bodies with two stars. However, as the team analyzed the observational data, they surprisingly found the third object, a black hole, which had not been previously observed in HR 6819. They used the MPG/ESO 2.2-meter telescope with FEROS spectrometers in La Silla. It must be observed for months to determine the revolution cycle of 40 days. The service was provided, with which ESO staff observes on behalf of scientists. They eventually found out that one of the two stars orbits an invisible object every 40 days, while the second star was quite far from the first star.

 Almost all of these black holes indicate the existence of themselves by emitting powerful X-rays in the process of strongly interacting with the surroundingenvironment. Nonetheless, the hidden black hole of HR 6819 is one of the stellar-mass black holes that appear to be real black, because it does not interact violently with the surrounding 
environment. A stellar-mass black hole is created by a gravitational collapse in the last life of a heavy star. By studying the orbits of two stars in the celestial system, the team was able to discover black holes and calculate its mass. Rivinius concluded that an invisible object with at least four times the mass of the Sun must be a black hole. Astronomers have so far found dozens of black holes in our galaxy. However, scientists estimate that more stars in our galaxy collapsed into black holes, as they ended their lives. The discovery of quiet, invisible black holes like that in HR 6819 provides clues as to where many of the black holes hidden in our galaxy might be.

 Rivinius said, “There must be hundreds of millions of black holes in our galaxy, and we know very few. Cognizing what to look for would put us in a better position to find black holes.” Astronomers already estimate that any other black holes exist. Moreover, the discovery could help solve the mysteries of the universe about the formation and evolution of stars. 

 

Lee Soo-hyun, Editor  sylvie8@konkuk.ac.kr

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