(ORDO NEWS) — Scientists from the Max Planck Institute for Extraterrestrial Physics, based on APOGEE data, built the most accurate model of the central region of the Milky Way to date and discovered a new structure there – a ring of metal-rich stars.
Studying the structure of our Galaxy has always been a difficult task, because we have to look at it from the inside. The solar system is located near one of the arms of the galactic disk.
From this vantage point, many stars in the Galaxy are hidden from us by dense clouds of gas and dust. It is especially difficult to see the central region. Therefore, scientists are actively studying other galaxies, paying more attention to those that are similar to the Milky Way.
The Milky Way is a barred spiral galaxy. In other galaxies with this structure, scientists have repeatedly noticed a ring of forming stars in the central region. The question arose: does the Milky Way have such a ring?
For ten years now, scientists from the Max Planck Institute for Extraterrestrial Physics (Germany) have been collecting data from astronomical observations and building computer models of our Galaxy. In their new study, they worked with the results of the APOGEE survey and Gaia observations.
Astronomers compared the parameters of more than 30 thousand stars and built a computer model of their movement. The result is the most accurate map of the central region of the galaxy. With its help, it was possible for the first time to see a slowly rotating bar ( slow bar ) and a curved bulge, shaped like a peanut.
The APOGEE survey is a large-scale project for a spectroscopic survey of the sky. It was organized as part of the Sloan Digital Sky Survey (SDSS). Observations were made in the near infrared range. This range allows you to see through dense clouds of gas and dust.
From APOGEE, the authors of the new work received information about the composition, position, Doppler shift, and approximate age of stars in the central region of the Milky Way, and from the Gaia project, the exact coordinates, direction, and speed of movement.
By combining the data, the scientists were able to calculate the complete orbits of the stars in the central region. This made it possible to simulate a region of the Galaxy hidden by the bulge.
Thanks to the accuracy and completeness of the data of the new model, a coveted ring of younger and more metal-rich stars has been revealed around the central bar. And most importantly, near the galactic plane, their concentration was higher.
This means that active star formation in the ring continued after the formation of the bar, so their age can be used to analyze the evolution of the central structures of the Milky Way. According to the authors of the study, the average age of the stars in the ring suggests that the galactic bar formed at least seven billion years ago.
It is not yet known whether there is a connection between this ring of stars and the spiral arms of the Milky Way, and whether gas flows feed the thin ring, as happens in other spiral galaxies.
Let’s hope that astronomers will be able to answer these questions after the launch of the next generation of telescopes. New devices will allow scientists to conduct more accurate observations. Based on these data, it will be possible to develop more complex computer models. Our galaxy still has many secrets to uncover.
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