Black holesThey are among the most mysterious and incredible objects in the known Universe. These gravitational behemoths are formed when massive stars suffer gravitational collapse at end of their lives and lose their outer layers in massive explosions (a supernova).
The star remnant is so dense, that its curvature of spacetime becomes infinity within its vicinity and its gravity so intense, that nothing (not even sunlight) can escape from its surface. These objects are impossible to see with conventional optical telescopes, which study objects in visible lighting.
Astronomers are trained to look for black holes using non-visible wavelengths and observe their effect on objects within their immediate vicinity.
After consulting the Gaia Data Release 3(DR3), a team of amateur astronomers that was recently led by University of Alabama Huntsville. A black hole was observedOur cosmic backyard. They describe this monster in their study. Black holeIt is approximately twelve times larger than the Sun’s mass and lies around 1,550 light years from Earth.
This black hole is a great opportunity for astrophysicists because of its mass, relative proximity, and potential for fusion.
Dr. Sukanyachakrabarti was the Pei-Ling Chan Endowed chair in the Department of Physics of UAH. She was joined by astronomers representing the Observatories of Carnegie Institution for Science and the Rochester Institute of Technology.
Their recent findings are described in this paper Published onlineThe following is currently being reviewed Astrophysical Journal.
Astronomers find black holes of particular interest because they provide opportunities to study laws of physics under extreme conditions. Some black holes, such as the supermassive dark holes (SMBH), that are located at the center most massive galaxies play a crucial role in galaxy formation.
There are many unanswered questions about the role of non-interacting black holes in galactic evolution. These binary systems include a star and black hole. However, the star does not draw material from the black hole. Said Dr. Chakrabari in a UAH Press release:
“It is still not clear how these non-interacting blackholes affect galactic dynamics within the Milky Way. If there are many of them, it may affect the formation and internal dynamics of our galaxy. We looked for objects with large companion masses, but whose brightness could have been attributed to one visible star. This gives you a reason to believe that the companion is dark.
Dr. Chakrabarti’s team analysed data from Gaia DR3, which contained information about nearly 200,000 binary stars as observed by European Space Agency (ESA). Gaia Observatory. The team reviewed spectrographic measurements made by other telescopes such as the Lick Observatory’s Automated Planet Finder, Giant Magellan Telescopes (GMT), or the W.M. Keck Observatory in Hawaii.
These measurements indicated that the main sequence star was subject to a strong gravitational force. As Dr. Chakrabari Explained:
These spectroscopic measurements can determine the pull of the black holes on the Sun-like star. They also give us a Doppler shift line-of-sight velocity. By analyzing the line-of-sight velocities of the visible star – and this visible star is akin to our own Sun – we can infer how massive the black hole companion is, as well as the period of rotation, and how eccentric the orbit is. These spectroscopic measurements confirmed the Gaia solution. They also showed that this binary system was composed of a visible Star that orbits a massive object.
Because they orbit in tighter orbits, and pull material from their stellar partners, interacting black holes can be easier to see in visible light. This material forms a torus-shaped disk around the black holes that accelerates to relativistic velocities (closer to the speed of light), becoming extremely energetic, and emitting Xray radiation.
Non-interacting black hole orbits are wider and they do not form these disks. Therefore, it is possible to infer their presence by studying the motions of visible stars. Said Dr. Chakrabarti:
“The majority of black holes in binary systems are in X-ray binaries – in other words, they are bright in X-rays due to some interaction with the black hole, often due to the black hole devouring the other star. The X-rays are visible as the gravitational potential of the other star’s material falls down. This is a black hole that’s massive. However, it orbits for 185 days or half a year. It is very far away from the visible star, and it hasn’t made any significant progress toward it.
Dr. Chakrabarti, along with her colleagues, could uncover many more non-interacting systems using the techniques they used.
According to current estimates there may be one million stars visible in our galaxy with black hole companions. This is only a small fraction of the galaxy’s stellar population (100 million stars), but Gaia Observatory has made precise measurements that have helped narrow this search. To date, Gaia has obtained data on the positions and proper motions of over 1 billion astronomical objects – including stars, galaxies,
Astronomers will be able to learn more from further studies of this population, including the formation pathway for black holes. As Dr. Chakrabarti Summary:
While there are many possible routes, non-interacting black hole around luminous stars is a completely new population. So, it will likely take us some time to understand their demographics, and how they form, and how these channels are different – or if they’re similar – to the more well-known population of interacting, merging black holes.”
This article was first published by Universe Today. Read Original article.
