They discovered the smallest and heaviest star ever found near the black hole at the center of our galaxy

configuration properties stars They are well defined and require environments with a sufficiently low temperature (<20 K) and high gas densities. An international team of researchers led by Florian Pesker of the Institute for Astrophysics at the University of Cologne has discovered a very young star in its formation near the Sagittarius A* (Sgr A*) supermassive black hole in the center of the planet. milky way.

The star is only a few tens of thousands of years old, which makes it younger than humans. What’s special about young star X3a is that, in theory, it shouldn’t be very close to the supermassive black hole in the first place.

However, the team believes they formed in a cloud of dust orbiting the Earth. Black hole It sank into its current orbit only after it was formed. The study has just been published in Astrophysical Journal.

The region of the black hole at the center of our galaxy is generally a region characterized by highly dynamic processes and intense ultraviolet and X-ray radiation. These exact conditions work against the formation of stars like ours sun. Therefore, scientists have long hypothesized that over periods of billions of years, only very old and evolved stars can be stabilized by dynamic friction in the region of a supermassive black hole.

Surprisingly, however, very young stars were found near Sgr A* twenty years ago. It is still not clear how they got there or where they formed. The appearance of very young stars very close to a supermassive black hole has been called “The paradox of youth”.

the star X3a baby, which is ten times more massive and fifteen times heavier than our Sun, can now bridge the gap between star formation and young stars near Sgr A*. X3a needs special conditions to form near a black hole. First author Florian Bisker explained: “There is a region at a distance of a few light years from the black hole that meets the conditions for star formation. This region, which is a ring of gas and dust, is cool enough and protected from destructive radiation.”

the Low temperatures and the high densities They create an environment in which clouds of hundreds of solar masses can form. In principle, these clouds can move very quickly in the direction of the black hole because the collision and scattering of the clouds cancel out the angular momentum. In addition, very hot clumps formed near the young star which could then be accreted by X3a. These clusters could also have contributed to the X3a reaching such a high mass in the first place.

However, these groups are only part of the story of the X3a’s formation. Scientists still do not fully explain his birth. Specialists assumed that a temporary scenario is possible: protected from the gravitational influence of Sgr A * and from radiation Dense, could be a sufficiently dense cloud that may have formed in the outer ring of gas and dust around the galactic center. The mass of this cloud was about a hundred suns, and it collapsed under the influence of its gravity to turn into one or more stars.

This alleged decay time roughly corresponds to the age of X3a. Observations have shown that there are many such clouds that can interact with each other. Therefore, it is likely that the cloud will fall towards the black hole from time to time.”

This scenario would also be consistent with the stage of stellar evolution for X3a, which is currently a mature star. Therefore, it is quite plausible that the gas ring And dust is the birthplace of young stars in the center of our galaxy. “With its massive mass of about ten times that of the Sun, X3a is an interstellar giant, and these giants are evolving very rapidly towards maturity,” explained Michal Zajek of Masaryk University in Brno, Czech Republic, a co-author of the study. We were fortunate to discover the massive star in “The mid-oceanic envelope is shaped like a comet. Later, we identified key features associated with a young age, such as the compact envelope it orbits.”

Since similar rings of dust and gas can be found in other galaxies, the mechanism described can be applied there as well. Therefore, many galaxies can harbor very young stars in their centers. Planned observations using the space telescope NASA James Webb Or the European Southern Observatory’s Very Large Telescope in Chile will test this model of star formation for our galaxy and others.

Nadine B. participated in this research. Sabha, Masato Tsuboi, Jehan Moltaka, Lucas Labadie, Andreas Eckart, Vladimir Karas, Lucas Steinger, Matthias Subroit, Anjana Suresh, Maria Melamed and Jan Clint.

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