Black holes are among the most mysterious objects in space. Now researchers have discovered a black hole in a very special way. The special find may help finally learn more about the origin of mysterious objects.
By means of a "strange star the astronomers found a black hole. The search method is new – and is likely to lead to many more discoveries, which should significantly advance research into black holes. Photo/graphic: Edo
Black hole- the name still does not do justice to the fascination that this space phenomenon has for science. Black holes are the phantoms of the universe, still we know only conditionally what exactly they are.
Now researchers at the European Southern Observatory Eso have made a discovery that should significantly advance the study of black holes.
What is a black hole??
For a long time, a black hole was nothing more than gray theory. The term was coined by the US physicist John Archibald Wheeler in 1967. While the existence of the phenomenon was considered likely, concrete observations did not occur until the 1980s and ’90s, such as studies of the supermassive black hole Sagittarius A* at the center of our galaxy. In 2019, astronomers were even able to produce a radio telescopic image of the black hole M87* at the center of the galaxy M87, 55 million light-years away. And in the spring of 2020, Eso researchers found a black hole that is closer to Earth than any previously observed black hole: Indirectly, it could even be observed with the naked eye in the sky via its two companion stars.
The first picture of a black hole: In the center of the galaxy M87 there is such an object with a mass of 6.5 billion solar masses.
Photo: Nasa/Event Horizon Telescope Collaboration
What is known: a black hole is an object whose mass is concentrated in an extremely small volume. This creates such a strong gravitation in the environment that even light can no longer penetrate to the outside or pass through the black hole.
Researchers find black hole with new method
Now, with the help of the Very Large Telescope (VLT), astronomers have found a small black hole outside the Milky Way galaxy. They achieved this by observing the influence of the black hole on the motion of a star in its immediate vicinity. This detection method was used for the first time to detect a black hole outside our galaxy. An important step in the study of mysterious objects. For the new method could be the key to discovering hidden black holes in the Milky Way and nearby galaxies, and significantly help answer the question: Where do black holes come from?? How they are formed? And how do they evolve over time?
Job search for engineers
The newly discovered black hole was spotted in NGC 1850. The acronym NGC stands for the New General Catalogue of Nebulae and Clusters of Stars, a catalog of star clusters and galaxies that has been in use since the 19th century. The method established as a standard work at the beginning of the twentieth century. NGC 1850 is a cluster of thousands of stars in the Large Magellanic Cloud that contains about 160.000 light-years away from our galaxy.
„ÄLike Sherlock Holmes tracking down a criminal organization by its deeds, we look at each star in this cluster with a magnifying glass in hand, trying to find evidence for the existence of black holes, but without seeing them directly.", says Sara Saracino of the Astrophysics Research Institute at Liverpool John Moores University in the United Kingdom.
Saracino led the research, the results of which have now been accepted for publication in the Monthly Notices of the Royal Astronomical Society. „The result shown here reveals only one of the delinquents we are looking for, but once you find one, you are well on your way to discovering many others in various clusters.“
Black hole is eleven times as massive as the sun
The first black hole the team detected in this way is about eleven times as massive as the Sun. The object betrayed itself by its gravitational influence a star orbiting it. Researchers have discovered such small black holes in other galaxies in the past by collecting the X-ray light emitted by the objects as they swallow up matter. Black holes have also been detected by observing gravitational waves generated by the collision of black holes with each other or with neutron stars.
But: Only the fewest black holes with stellar mass can be detected by X-rays or gravitational waves. „The great majority can only be unmasked on the basis of movements", Says Stefan Dreizler, a member of the team at the University of Gottingen in Germany. „When they form a system with a star, they affect its course in subtle but detectable ways, so we can find them with sophisticated instruments.“
New method should bring breakthrough
The method Saracino and her team are now using should ensure that many more black holes are found in the future. This puts science in a position to unlock its secrets. „Every single discovery we make will be important for our future understanding of star clusters and the black holes in them", says Mark Gieles of the University of Barcelona in Spain, co-author of the study.
The discovery marks the first time astronomers have found a black hole in a young star cluster. NGC 1850 is about 100 million years old- Only a brief moment on astronomical scales. For comparison, the Milky Way is 13.6 billion years old. By comparing these objects with more evolved black holes in older star clusters, researchers can understand how the objects grow, for example, when they engulf stars or merge with other black holes.
Team collects two years of black hole data
For two years, the team used data collected with the help of the Multi Unit Spectroscopic Explorer (Muse) at the Eso’s VLT in the Chilean Atacama Desert. „Muse allowed us to observe very densely populated areas, such as the innermost regions of star clusters, and analyzed the light from each nearby star. The result is information about thousands of stars at one go, at least ten times more than with any other instrument", says Sebastian Kamann of the Astrophysics Research Institute in Liverpool and co-author of the study. Finally, the researchers were able to locate the strange star, whose peculiar motion indicated the presence of a black hole. They confirmed their findings using data from the Optical Gravitational Lensing Experiment at the University of Warsaw and the Hubble Space Telescope operated by the space agencies Nasa and Esa.
In astronomy, bigger is sometimes better- or at least more accurately. In addition to the VLT, ESO’s Extremely Large Telescope (ELT) in Chile is scheduled to go into operation in the next few years. With this, astronomers will be able to find even more hidden black holes, it is hoped. „The ELT will definitely revolutionize this field", says in any case Sara Saracino. „It will allow us to observe much fainter stars in the same field of view and to search for black holes in globular clusters located at much greater distances.“