A mysterious object approaches the supermassive black hole of the Milky Way CREDITS: ANNA CIURLO/UCLA.

The structure is estimated to make its closest approach to Sagittarius A* around 2036, before spiraling out of existence, engulfed by the supermassive black hole.

Astronomers have observed for two decades a mysterious blob called X7, drifting around the supermassive black hole at the heart of the Milky Way, without knowing where it came from. Now a new analysis has uncovered a dramatic transformation in the X7’s shape, which has stretched to almost twice its initial length. That change in structure suggests that the strange blob is likely a cloud of interstellar dust and gas, created during a relatively recent collision between two stars: no other object in this region has shown such extreme evolution.

A team of scientists from the University of California at Los Angeles (UCLA) and the Keck Observatory in the United States has observed for 20 years the changes in the appearance, shape and behavior of a strange object that orbits around Sagittarius A*, the supermassive black hole that dominates the heart of the Milky Way. The structure, called X7, would be made up of remains from a merger between stars, which were part of a binary system.

Around Sagittarius A* Sagittarius A* is the supermassive black hole at the galactic center of the Milky Way: the nuclei of most spiral and elliptical galaxies are believed to contain such a black hole, with millions or tens of billions of solar masses. Part of an even larger structure, Sagittarius A* was first imaged on May 12, 2022 by the Event Horizon Telescope.

Now, the new study published in The Astrophysical Journal presents a comprehensive analysis of a strange object orbiting our galaxy’s supermassive black hole, describing an orbital path that would take around 170 years to complete. The structure has evolved spectacularly in a relatively short time, lengthening remarkably in the last 20 years until doubling its initial length. The group of researchers, led by Anna Ciurlo, has been observing changes in the enigmatic blob-shaped object over the past 20 years. “No other object in that region of the galaxy has shown such a radical evolution in such a short period of time,” Ciurlo said in a press release. “At first it showed the typical shape of a comet, so we thought it was the product of stellar winds or jets of particles from the black hole. But later we appreciated that X7 was getting longer and longer and that it had a particular orientation ”, he added.

The observations made it possible to define that X7 has a mass equivalent to 50 Earth masses and that it carries a specific orbit around Sagittarius A*. Although astronomers determined that it would complete that journey in 170 years, apparently it never will: specialists estimated that around 2036 it will make its closest approach to the supermassive black hole, to then spiral towards Sagittarius A* and vanish, being mercilessly swallowed. an irresistible attraction

Las enormes fuerzas de marea ejercidas por el agujero negro supermasivo finalmente destrozarán a X7 antes de que complete una órbita: caerá presa de la atracción gravitatoria de Sagitario A*, ya que las fuerzas de marea hacen que cualquier objeto que se acerque a un agujero negro caiga. estirar. El estiramiento se produce porque el lado de la estructura más cercano al agujero negro es atraído con mucha más fuerza que el extremo opuesto. X7 muestra unas propiedades similares a otros objetos que orbitan alrededor del agujero negro supermasivo de la Vía Láctea, que han sido clasificados como objetos G y presentan un comportamiento similar al de una estrella, aunque visualmente se aprecian como estructuras gaseosas. Sin embargo, la forma y la velocidad de X7 han cambiado más dramáticamente que lo observado para otros objetos G. En su aproximación a Sagittarius A*, X7 se mueve a velocidades de hasta unos 1.126 kilómetros por segundo

Reference The swan song of the galactic central source X7: an extreme example of tidal evolution near the supermassive black hole. Anna Ciurlo et al. The Astrophysical Journal (2023). DOI: https://doi.org/10.3847/1538-4357/acb344