84 million stars in a single image of the Milky Way

Using this nine gigapixel image obtained with the help of the VISTA infrared tracking telescope at the Paranal Observatory (Chile), an international team of astronomers has created the largest catalog to date of the center of the Milky Way, which includes 84 million stars , that is, ten times more than any portrait obtained before. The image is so large that, if it were printed at the resolution of a book, it would measure 9 meters long and 7 meters high.

"Looking in detail at the thousands of stars that surround the center of the Milky Way, we can learn much more about the formation and evolution, not only of our galaxy, but also of spiral galaxies in general," explains Roberto Saito, researcher main of this study.

Many spiral galaxies, including our host galaxy, the Milky Way, have a high concentration of old stars surrounding the center, what astronomers call the nucleus. Understanding the formation and evolution of the core of the Milky Way is vital for the knowledge of the galaxy as a whole. However, getting detailed observations of this region is not an easy task.

"Observing the core of the Milky Way is very difficult, as it is obscured by dust," adds Dante Minniti, co-author of the study. "To penetrate the heart of the galaxy, we need to observe in the infrared range of light, which is less affected by dust," he says. In fact, the data obtained by the VISTA infrared tracking telescope, which has a large mirror (4.1 meters in diameter), a wide field of view and very sensitive infrared detectors, has created an immense image in color of 108,200 by 81,500 pixels, that is, the largest catalog created until the time of the concentration of stars in the central region of the Milky Way.