This object keeps astronomers up at night. The mystery has finally been solved.

Known to researchers since 1966, Cygnus X-3 is a so-called microquasar. Located in our galaxy and part of the constellation Cygnus, it poses a major challenge to astronomers. As part of a recent effort to focus on its surprisingly high brightness, members of the research team used the capabilities of the IXPE observatory.

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The results of the analyzes performed are available at: Natural astronomyAs the authors of the publication explain, this very close binary system contains a massive star and most likely a black hole. Together they form a very powerful source of X-rays. And given the fact that we are talking about a microquasar, its high brightness has kept scientists awake at night.

Emissions from this system — about 24,000 light-years from Earth — were discovered in the 1970s. It was then that astronomers noticed very powerful jets, that is, streams of hot gas moving at close to the speed of light. Launched from Cygnus X-3, emissions continued for several days and then stopped for a period of time.

The object known as Cygnus X-3 is a so-called microquasar. It is about 24,000 light-years away.

The situation is made more difficult by the fact that this system cannot be observed in visible light. The desired progress only occurred with the development of technologies that allow infrared or X-ray observations. Astronomers realized that it was an X-ray binary system in which material was transferred from a massive star into a compact object orbiting its center of gravity.

According to the researchers, the second object is a neutron star or black hole with a mass of about five solar masses. In turn, its companion is one of the so-called Wolf-Rayet stars, which throw off huge amounts of material that feeds the accretion disk around the black hole. However, this still does not explain the surprisingly high brightness of Cygnus X-3. Representatives from the University of Turku decided to solve the mystery once and for all.

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As they explain, their research has shown that the compact object, probably a black hole, is surrounded by a shell of dense, opaque material. The observed light, responsible for the incredible brightness, is reflected off the inner walls of the funnel-shaped structure. These walls are made of gas, and astronomers compare the entire structure to a cup with a mirror-like interior.

Thanks to IXPE observations, astronomers have concluded that when Cygnus X-3 is exposed to the largest amounts of infalling material, the polarization index reaches 24.9%. When the situation changes, the polarization index drops to 10.4%. The conclusion? Apparently, the structure of the funnel changes in response to the infalling material in one way or another.