TORONTO – Astronomers have just spotted a star in orbit of a black hole, about 2.5 times the equivalent of the distance between the Earth and the Moon, and it only takes half an hour for the star To complete a complete orbit. This corresponds to a speed equivalent to 1% of the speed of light!
In order to imagine what this represents, you must know that the Moon takes about 28 days to complete a full circle around our planet at a speed of about 3683 kilometers per hour … This means that the star in question moves At an incredibly high speed.
Using the data collected by a series of space telescopes, a team of astronomers managed to measure X-rays from a binary stellar system called 47 Tuc X9, which is in a cluster of stars At about 14,800 light years from Earth.
Astronomers already knew the two stars of the binary system, identified for the first time in 1989, but now astronomers know what happens at the heart of the system. ” For a long time, we thought X9 was a white dwarf, attracting the material of a star of low mass similar to the Sun ,” researcher Arash Bahramian said.
When a white dwarf attracts matter from another star, the system is described as a cataclysmic variable star . But in 2015, astronomers discovered that one of these two objects was most likely a black hole, calling the first hypothesis into question. Data from the Chandra Space Telescope confirmed the presence of large quantities of oxygen in the system environment (commonly associated with white dwarfs). But, instead of a white dwarf literally ripping another star, it would be a huge black hole, stripping the gases of a white dwarf.
White dwarfs are very dense stellar objects: imagine, for example, an object possessing the mass of the Sun, but making the size of the Earth. So, for something to attract and tear material off its surface, an impressive gravitational force would be needed. ” We believe that the star has been able to lose gas for the benefit of the black hole for tens of millions of years and has now lost most of its mass, ” says researcher James Miller-Jones. University of Curtin and the International Center for Radio Astronomy Research.
But one of the most important information about this discovery is that regular changes in the intensity of X-rays suggest that this white dwarf takes only 28 minutes to complete a complete orbit around the black hole! ” Before this discovery, the nearest star located around any black hole, was a system known as MAXI J1659-152, which is in orbit of the supposed black hole, with a period of revolution of 2.4 hours . If it turns out that these two supposed black holes in both systems have similar masses, this would imply an orbit three times larger in size than we found for X9, “says Miller-Jones.
To put this in perspective, the two objects located in X9 are about 1 million kilometers, equivalent to 2.5 times the Earth-Moon distance. Basically , a single orbit represents a journey of about 6.3 million kilometers in just half an hour, giving us a speed of about 12,600,000 kilometers per hour, about 1% of the speed of light !
” It is important to discover these rare black holes, because they are not just the end of the massive stars … they also continue to play a role in the evolution of other stars after their death, ” explains Geraint Lewis of The University of Sydney. For a black hole to overcome the intense gravitational force of a white dwarf, both bodies must be nearby. ” There may be so much material torn from the white dwarf that it could end up having the mass of a planet. If the white dwarf continues to lose its mass, it could totally evaporate , “said researcher Craig Heinke.
Although the current technology used by LIGO (the Observatory of gravitational waves by laser interferometry) is not yet capable of detecting the slow pulses emitted by X9, it is not excluded that progress in this area will make it possible in the future Close to detecting even lower frequency waves, to the delight of all scientists who wish to study gravitational waves!
At present, the study, which has been pre-published on arXiv.org, has yet to be peer-reviewed and is awaiting comments from the astrophysics community.