Free Astronomy Magazine November-December 2024

52 NOVEMBER-DECEMBER 2024 ASTRO PUBLISHING T his image shows the regions of the Milky Way mapped by the VISTA Variables in the Vía Láctea (VVV) survey and its companion project, the VVV eXtended survey (VVVX). The total area covered is equivalent to 8,600 full moons. The Milky Way comprises a central bulge — a dense, bright and puffed-up conglomeration of stars — and a flat disc around it. Red squares mark the central areas of our galaxy originally covered by VVV and later re-observed by VVVX: most of the bulge and part of the disc at one side of it. The other squares indicate regions observed only as part of the extended VVVX survey: even more regions of the disc at both sides (yellow and green), areas of the disc above and below the plane of the galaxy (dark blue) and above and below the bulge (light blue). The numbers indicate the galactic longitude and latitude, which as- tronomers use to chart objects in our galaxy. The names of various constellations are also shown. [ESO/VVVX survey] ing infrared light means VISTA can also spot very cold objects, which glow at these wavelengths, like brown dwarfs (‘failed’ stars that do not have sustained nuclear fusion) or free-floating planets that don’t orbit a star. The observations began in 2010 and ended in the first half of 2023, span- ning a total of 420 nights. By observing each patch of the sky many times, the team was able to not only determine the loca- tions of these ob- jects, but also track how they move and whether their bright- ness changes. They charted stars whose luminosity changes periodically that can be used as cosmic rulers for measuring distances. This has given us an accurate 3D view of the inner regions of the Milky Way, which were pre- viously hidden by dust. The researchers also tracked hyperve- locity stars — fast-moving stars cat- apulted from the central region of the Milky Way after a close en- counter with the supermassive black hole lurking there. The new map contains data gath- ered as part of the VISTA Variables in the Vía Láctea (VVV) survey and its companion project, the VVV eX- tended (VVVX) survey. “The project was a monumental effort, made possible because we were sur- rounded by a great team,” says Roberto Saito, an astrophysicist at the Universidade Federal de Santa Catarina in Brazil and lead author of the paper published in Astronomy & Astrophysics on the completion of the project. The VVV and VVVX surveys have already led to more than 300 scientific arti- cles. With the surveys now complete, the sci- entific exploration of the gathered data will continue for decades to come. Meanwhile, ESO’s Paranal Observa- tory is being prepared for the future: VISTA will be updated with its new instrument 4MOST and ESO’s Very Large Telescope (VLT) will receive its MOONS instrument. Together, they will provide spec- tra of millions of the objects surveyed here, with countless discov- eries to be expected. T his video sequence compares infrared and visible light views of the Lobster Nebula (NGC 6357). The visible light image created from the Digitized Sky Survey 2 and, for the central part, the ESO VLT. The new infrared image was taken with the VISTA telescope at the Paranal Observatory in Chile. In the infrared, the dust that obscures many stars becomes nearly transparent, revealing a whole host of new stars that are otherwise invisible. [ESO/VVV Survey/Digitized Sky Survey 2/D. Minniti. Acknowledgement: Ignacio Toledo. Music: movetwo] !