Young star cluster found near supermassive black hole, challenging theories

An international team, led by Dr. Florian Peißker at the University of Cologne’s Institute of Astrophysics, conducted a detailed analysis of a young star cluster near the supermassive black hole Sagittarius A* (Sgr A*) at the center of our galaxy. The cluster, known as IRS13, was discovered over two decades ago, but recent data from various telescopes has allowed scientists to determine that these stars are much younger than expected—only a few hundred thousand years old, in contrast to our sun’s age of approximately 5 billion years.

Surprisingly, the harsh conditions near the supermassive black hole, with high-energy radiation and tidal forces, make it improbable for such a cluster of young stars to exist there. The research, published in The Astrophysical Journal under the title “The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*, I. Detection of a Rich Population of Dusty Objects in the IRS13 Cluster,” utilized the James Webb Space Telescope (JWST) to observe a spectrum free from atmospheric interference, revealing the presence of water ice in the Galactic Center. This water ice is typically found in dusty disks around very young stars, further confirming the youth of these stars near the black hole.

In addition to the surprising discovery of young stars and water ice, the study led by Dr. Peißker suggests that IRS13 has a complex history of formation. It may have migrated toward the supermassive black hole through various processes, including friction with the interstellar medium, collisions with other star clusters, or internal mechanisms. Eventually, the black hole’s gravitational pull captured the cluster, possibly forming a bow shock at the front of the cluster due to surrounding dust, which then led to additional star formation.

Dr. Peißker remarked that this analysis sheds light on a long-standing mystery surrounding the youthful stars in the Galactic Center. Interestingly, there is another star cluster, the S-cluster, even closer to the black hole, also comprising young stars younger than expected by existing theories.

The findings related to IRS13 open up avenues for further research, potentially connecting the immediate vicinity of the black hole to regions several light years away. Dr. Michal Zajaček, the study’s second author, emphasized that IRS13 appears to be the key to understanding the origin of the dense star population at the galaxy’s center. This research provides substantial evidence that very young stars within the supermassive black hole’s reach may have formed in clusters like IRS13, marking the first identification of star populations of varying ages so close to the Milky Way’s core.

Source: University of Cologne

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