At the heart of our Milky Way, stars orbiting the central supermassive black hole appear strangely young. However, this apparent youth conceals a much darker reality.
Orbits of stars very close to Sagittarius A*, the supermassive black hole at the heart of the Milky Way.
Credit: ESO / L. Calçada / Spaceengine.org
Researchers from Northwestern University have recently discovered why some stars near Sagittarius A* (Sgr A*), the black hole at the center of our galaxy, have such a youthful appearance: they have literally absorbed their neighbors. In a region where star density reaches peak levels, stellar collisions are common. Thanks to computer simulations, the team was able to track the violent fate of a thousand fictional stars, revealing various outcomes for these brutal encounters.
In the midst of this turmoil, some stars lose mass during collisions, transforming into low-mass stars, while others merge, accumulating enough matter to appear massive and rejuvenated.
This discovery, presented at the American Physical Society's April meeting in California, offers insights into the complex dynamics governing the heart of the Milky Way. By exploring the consequences of these stellar encounters, the team identified the distance to the supermassive black hole as a key factor in a star's fate. Near Sgr A*, stars, propelled at dizzying speeds can merge after a collision, gorging on hydrogen and displaying deceptive youthfulness.
This study also sheds light on the history of our galaxy and on cosmic processes often obscured by the difficulty of directly observing these regions. Through these simulations, the researchers aim to understand how the galactic center was formed, offering a contrasting perspective with our own more benign stellar environment.
These efforts have been published in
The Astrophysical Journal Letters in March 2024 and
The Astrophysical Journal in September 2023, contributing to our understanding of the extreme phenomena governing the cores of galaxies.