#astronomical_studies.

[phonemantra-blog]

Perhaps astronomers have finally figured out the reason for the Milky Way's misalignment. It turns out that this is due to the halo of dark matter surrounding our galaxy Previously, we imagined our galaxy as a flat disk. However, when studying the shape of the Milky Way in more detail, scientists discovered that its disk was distorted. These features have long remained a mystery, but now astronomers at the Center for Astrophysics at Harvard and the Smithsonian Institution have conducted calculations that indicate that the dark matter halo surrounding the Milky Way may be “curved,” causing the edge to widen and the shape of the galaxy to bend. [caption id="attachment_70302" align="aligncenter" width="780"] dark side of the galaxy[/caption] Studying dark matter is challenging for scientists because it doesn't interact with light, making it "invisible." However, this substance makes up about 85% of all matter in the Universe, while ordinary matter makes up only about 15%. The only way to establish the presence of dark matter is its effect on gravity and its interaction with ordinary matter and light. Thus, it was discovered that galaxies rotate so quickly that in some cases the gravitational influence of the visible matter inside them would not be enough to prevent them from flying apart - dark matter is the “gravitational glue” that holds galaxies together. The “dark side of the galaxy” has skewed the Milky Way Thus, the researchers hypothesize that most, if not all, galaxies are wrapped in dark matter halos. In the case of the Milky Way, a halo of dark matter is thought to extend beyond the halo of stars surrounding its disk and core. Last year, the same Harvard team performed calculations that showed that the Milky Way's stellar halo has an elliptical shape, tilted relative to the galaxy's disk. Then scientists assumed that the shape of this dark matter halo would be similar to a stellar halo, but noticeably larger. Now the team has taken the study further, using computer models to calculate how the orbits of stars relate to the tilted halo of dark matter. The simulation showed an almost perfect match to the galaxy, its extended edge and distorted shape. “The tilted dark halo appears quite often in simulations, but no one has examined its effect on the Milky Way,” said Charlie Conroy, team member and professor of astronomy. The results of the study also support the assumption that the Milky Way “grew” as a result of collisions with other galaxies. “The tilted halo indicates that our galaxy experienced a collision and merger with another galaxy,” said Chiwon Jesse Han, leader of the study team. Calculating the shape of the dark matter halo around the Milky Way could reveal not only the history of the evolution of our galaxy but also help us understand the nature of dark matter and reveal some of the properties of the particles that make it up. The findings could also help astronomers study free-floating “blobs” of dark matter that drift between galaxies.

[phonemantra-blog]

Astrophysicists have discovered that the young star cluster IRS13 near the supermassive black hole Sagittarius A* is much younger than expected. The IRS13 cluster migrated to the black hole due to friction with the interstellar medium and collisions with other clusters An international team led by Dr. Florian Peisskei from the Institute of Astrophysics at the University of Cologne has studied in detail a young star cluster near the supermassive black hole Sagittarius A* (Sgr A*) at the center of our galaxy and found that it is much younger than previously estimated. This cluster, known as IRS13, was discovered more than twenty years ago, but only now has it been possible to identify its components in detail by combining a wealth of data collected using different telescopes over several decades. The stars inside the cluster are several hundred thousand years old—they are extremely young by the standards of stellar life. For comparison, our Sun is about 5 billion years old. The galaxy's high-energy radiation and tidal forces make it surprising to have so many young stars near a supermassive black hole. [caption id="attachment_65577" align="aligncenter" width="453"] IRS13 star[/caption] Young stars near a black hole: the mystery of the IRS13 star cluster near Sagittarius A* The study used observations from the James Webb Space Telescope (JWST) to record a spectrum free from interference from the galactic center. This spectrum reveals the presence of water ice in the galactic center. This water ice, which is often found in dusty disks around very young stars, was another independent indicator of the youth of some stars near the black hole. In addition to JWST's unexpected discovery of young stars and water ice, the researchers also discovered that IRS13 has a turbulent formation history. The results of the study suggest that IRS13 migrated to the supermassive black hole under the influence of friction with the interstellar medium, collisions with other star clusters, or internal processes. And then this star cluster was attracted by the gravity of the black hole. The process also created a compacted formation at the “top” of the cluster due to the dust surrounding the cluster. The increase in dust density stimulated further star formation. This explains why young stars are found mostly at the "top" or front of the cluster. “The analysis of IRS13 and interpretation of the history of this cluster is the first attempt to resolve a decades-old mystery about unexpectedly young stars at the galactic center. In addition to IRS13, there is another star cluster - the so-called S-cluster, which is even closer to the black hole and also consists of young stars. They are also much younger than is possible according to accepted theories,” says Dr. Paisskea. The results obtained about the IRS13 star cluster provide an open opportunity for further studies of the relationship between proximity to the black hole and regions several light years away. The second author of the study, Dr Mišal Zajaček from Masaryk University in Brno (Czech Republic), added: “The IRS13 star cluster appears to hold the key to the origin of the dense stellar population at the center of our galaxy. We have collected extensive evidence that very young stars within the range of a supermassive black hole could form in star clusters such as IRS13. This is also the first time we have been able to identify stellar populations of different ages - hot main sequence stars and young embryonic stars in a cluster so close to the center of the Milky Way."