Astronomers have just discovered a new secret of the Milky Way

Astronomers have developed a fairly advanced knowledge of the galaxies that litter our Universe. But ours, the Milky Way, still hides secrets. It has also just revealed a new one: a ring of metal-rich stars that surrounds the galactic bar.

When we look up at the sky at night, we rely on our own eyes to reveal to us the beauties of the Universe. The astronomers, they first imagined telescopes that opened up new horizons to them. Today, they even have instruments that allow them to see beyond the visible. In the field ofinfrared, for example. And thus to cross the barriers of dust which have long hidden the heart of our Milky Way.

Let us remember that our Earth sails somewhere in an arm of our spiral galaxy. In the plane of his disc. Difficult, under these conditions, to perceive the structure of the Milky Way. More so its internal structure. But, over the last decade, astronomers have taken advantage of a lot of new observational data to feed their simulations and build a model faithful to reality. That of a so-called barred galaxy. Which houses a band ofstars centers – a bar – which emerges from a bulge – the bulb.

Today, some Max Planck Institute researchers (Germany) bring new details to this description. Thanks to a study carried out in the wavelengths from near infrared on the database of the Apogee mission. This one studies in high resolution all stellar components of the Milky Way. By combining this data with that returned by the Gaia mission, which measures positions and movements of a billion stars, the researchers were almost there. All they needed were cutting-edge computer models to see beyond the galactic bulge and probe regions hitherto inaccessible. What to reveal in a new way the orbits of 30,000 stars located in the inner regions of the Milky Way.

Trace the history of the formation of the Milky Way

From there, astronomers have constructed maps of stellar density, metallicity and age of this region of the Milky Way. Maps that show, around the central bar of our galaxy, a ring structure richer in metals — understand, in elements heavier than thehydrogen and helium — and made up of younger stars, around 7 billion years old, concentrated towards the galactic plane.

Similar rings have already been observed inside other galaxies. But the researchers still wondered if there was one in ours. They now have the answer.

An answer that informs them a little more about the history of the formation of our Milky Way. Astronomers estimate that the galactic bar was formed at least 7 billion years ago. The stars that make up the newly observed ring must have continued to form from an influx of gas after the installation of this bar.

The question that remains unanswered is that of the possible link between the ring discovered by researchers at the Institut Max Plank and the spiral arms of the Milky Way. Is gas being piped into the interior of our galaxy to fuel star formation at the ring’s core as may be the case in other spiral galaxies? To answer this, astronomers will need not only additional data, but also more accurate models.