Chandra found near supermassive black hole, the surviving core of a red giant

Supermassive black hole in the galaxy GSN 069 captured by its gravity red giant and pulled his outer layers, but the core of the star is a white dwarf — is left to spin in orbit around the black hole. To such conclusion astrophysicist Andrew king, analyzing data x-ray Observatory “Chandra”. Article published in Monthly Notices of the Royal Astronomical Society.

In 2019 x-ray Observatory “Chandra” and XMM-Newton X-ray recorded a powerful flash of x-ray radiation from the black hole, which is located in the center of the galaxy GSN 069 at a distance of 250 million light years from the Solar system. The mass of the black hole of 400 thousand times the mass of the Sun is the lower limit of mass for supermassive black holes. The flash lasted about an hour and was repeated every nine hours. The brightness of the flashes and their short duration it was difficult to explain by a simple transfer of mass onto the black hole. Then the scientists assumedthat the mass is flowing into the black hole from a star that is on an elliptical orbit and cause instability in the accretion disk during each passage of the pericenter.

Andrew king (Andrew King) from the University of Leicester calculated that the mass of the star, which rotates around the black hole for nine hours is 0.21 mass of the Sun. It is a white dwarf that was once the core of a red giant with a radius of at least 12 solar or even more, if we assume that a significant portion of the original mass of the white dwarf has already flowed into the black hole. Such a system may occur when the tidal destruction of stars — a common scenario in interaction with a black hole.

According to the calculations of the king, more likely another scenario — a close passage of a star near a black hole. In this scenario, a black hole captures a red giant to the orbit, where he loses ground only in the periapsis — exactly the same as it is now it makes the rest of his white dwarf. The mass transfer ends as soon as the star-giant loses its envelope. However, the emission of gravitational waves causes a white dwarf to fill the Roche lobe in a relatively short time due to the fact that its orbit is strongly elongated.

Thus the black hole will gradually absorb the star. It is expected that in about a trillion years the mass of the star will fall to the mass of Jupiter.

Find survivors near supermassive black holes star is not easy. Objects more massive than the black hole at the center of the galaxy GSN 069, can destroy stars before they’re on orbit, which will lose mass periodically, as does the recently discovered white dwarf. So look for these stars have near similar mass objects.

Follow-up of the star the black hole in the galaxy GSN 069 will help you understand its composition. If this is indeed the core of a red giant star falling into the black hole, the matter must be helium rich. However, it is possible that some amount of hydrogen from the shell of the red giant is still on the surface of the star. In addition, because of the proximity to the black hole, the effects of General relativity should affect the precession of the orbit of the star — it must have a period of two days. Long-term observations can confirm this assumption.

Supermassive black holes can not only eat stars, but to separate stellar pair caught in this black hole at the center of our milky Way galaxy. In addition, such objects influence on the chemical evolution of molecules in the environment.

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