Using thispicture ofnine gigapixelsobtained with the help of the VISTA infrared scanning telescope at the Paranal Observatory (Chile), an international team of astronomers has createdthe 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 previously. The image is so large that, if printed at book-size resolution, it would be 30 feet long and 25 feet high.
“By observing in detail 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 about that 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, which astronomers call a nucleus. Understanding the formation and evolution of the nucleus of the Milky Way is vital to understanding 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, a 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 points out. In fact, the data obtained by the VISTA infrared scanning telescope, which has a large mirror (4.1 meters in diameter), a wide field of vision and very sensitive infrared detectors, has been created, an immense image has been created in color of 108,200 by 81,500 pixels, that is, the largest catalog created to date of the concentration of stars in the central region of the Milky Way.
To assist in the analysis of this catalog,the brightness of each star has been plotted against its color for about 84 million stars to create a color-magnitude diagram. Color-magnitude diagrams are very valuable tools frequently used by astronomers to study the different physical properties of stars, such as their temperatures, masses, and ages. “Each star occupies a particular point on this diagram at any point in its life. Where it falls depends on how bright and hot it is. Since the new data gives us snapshots of all the stars at once, we can make a census of all the stars in this part of the Milky Way, “clarifies Dante Minniti.
