Phenomenon near the massive black hole called Sagittarius A*

Even now as we contemplate the stars above us, there is an immense amount of research taking place which helps to give us a greater understanding of our galaxy by studying the titanic movements in space. News brought from the astronomers from UCLA's Galactic Center Orbits Initiative has said that they have discovered a phenomenon near the massive black hole called Sagittarius A*. Their research can be read in the journal Nature.

These strange objects do not remain static and appear to be affected by the black hole as their orbits bring them closer, making them elongated the closer that they become. "These objects look like gas and behave like stars," said co-author Andrea Ghez, UCLA's Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and director of the UCLA Galactic Center Group.

A UCLA postdoctoral researcher and a leading author, Anna Ciurlo, has also observed that their orbits range from 100 to 1000 years.

Ghez's research group discovered one of the unusual objects at the centre of our galaxy in 2005, later named G1 whilst German astronomers named a further object found in the centre of the Milky way G2, which Ghez and her research team believe is an extremely large star created from the merging of two stars into one extremely large body cloaked in gas and dust.

The excitement over the unusual objects of which a further 4 have been observed and named G3, G4, G5 and G6 revolves around the affect that the black hole has over the bodies as it sweeps the gas from the objects and the resulting distortion of the unusual objects as their orbit takes them past the black hole.

“At the time of closest approach, G2 had a really strange signature," Ghez said. "We had seen it before, but it didn't look too peculiar until it got close to the black hole and became elongated, and much of its gas was torn apart. It went from being a pretty innocuous object when it was far from the black hole to one that was really stretched out and distorted at its closest approach and lost its outer shell, and now it's getting more compact again."

Co-author Mark Morris, UCLA professor of physics and astronomy, says "When that happens, it might be able to produce an impressive fireworks show since the material eaten by the black hole will heat up and emit copious radiation before it disappears across the event horizon."

Ghez believes that the merging of stars might be more common than previously thought and suggests that as time goes by there is more understanding about how galaxies and black holes evolve and that possibly many of the stars that watched today are a result of these mergers.

Ciurlo also noted another exciting element of G2's in that although its gaseous outer shell was stretched dramatically at its proximity to the black hole, the dust within the gas stayed fairly stable, indicating a possible stellar object contained inside G2.

Chez and her colleagues have gathered data for 20 years and made observations from the W.M. Keck Observatory in Hawaii contributing to the development of a powerful technology known as adaptive optics which corrects the distorting effects of the Earth's atmosphere in real-time. The contributions made by Ghez meant that they were able to conduct and update analysis of 13 years of their UCLA Galactic Center Orbits Initiative data.

In July 2019, Ghez's research team were able to report that they had made a comprehensive test of Einstein's iconic general theory of relativity near the black hole. They concluded that Einstein's theory passed the test and is correct until further research proves it otherwise.

Ghez and her team continue to watch the black hole. In September 2019,  they reported that the black hole was becoming more powerful but at this stage were unable to explain why although as Ghez noted the centre of the Milky Way compares dramatically to our much less hectic place in the universe.

"The Earth is in the suburbs compared to the center of the galaxy, which is some 26,000 light-years away," Ghez said. "The center of our galaxy has a density of stars 1 billion times higher than our part of the galaxy. The gravitational pull is so much stronger. The magnetic fields are more extreme. The center of the galaxy is where extreme astrophysics occurs -- the X-sports of astrophysics."

Ghez said this research would help to teach us what is happening in the majority of galaxies.

The research that Ghez leads is being funded by the National Science Foundation, W.M. Keck Foundation and Keck Visiting Scholars Program, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, Jim and Lori Keir, and Howard and Astrid Preston and is considered to be extremely important as it helps to teach us about what is happening in the majority of galaxies, which in turn will enable us to learn more about our own.