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Using ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA), astronomers have created an extensive infrared atlas of five nearby star nurseries by piecing together more than a million images. This large mosaic reveals young stars in the process of formation, embedded in thick clouds of dust. Thanks to these observations, astronomers have a unique tool to decipher the complex mystery of stellar birth.
says Stefan Mengast, an astronomer at the University of Vienna in Austria and lead author of the new study published today in Astronomy & Astrophysics. “This will allow us to understand the processes that turn gas and dust into stars.”
Stars form when clouds of gas and dust collapse under their own gravity, but the details of how this happens are not fully understood. How many stars are born from the cloud? How big is it? How many stars will also have planets?
To answer these questions, the Meingast team surveyed five nearby star-forming regions using the VISTA telescope at ESO’s Paranal Observatory in Chile. Using the VISTA infrared camera VIRCAM, the team captured the light coming from deep within the dust clouds. “Dust obscures these young stars from our view, making them almost invisible to our eyes. Only at infrared wavelengths can we look deeply into these clouds, studying stars under construction,” explains Alina Rotsteiner, also a doctoral student at the university. Vienna and co-author of the study.
The survey, called VISIONS, observed regions of star formation in the constellations Orion, Ophiuchus, Chamaeleon, Corona Australis, and Lupus. These regions are less than 1,500 light-years away and are so large that they span a vast area of the sky. VIRCAM’s field of view is three full moons in diameter, making it uniquely suited to mapping these extremely large regions.
The team acquired more than a million photos over a five-year period. The individual images were then stitched together into the large mosaic released here, revealing vast cosmic landscapes. These detailed panoramas feature dark patches of dust, glowing clouds, newborn stars, and distant background stars of the Milky Way.
Because the same regions have been observed over and over again, the VISIONS data will also allow astronomers to study how young stars move. “With VISIONS, we monitor these young stars over several years, which allows us to measure their motion and see how they leave their parent clouds,” explains João Alves, an astronomer at the University of Vienna and VISIONS’ principal investigator. This is no easy feat, as the apparent transformation of these stars as seen from Earth is as small as the width of a human hair seen from a distance of 10 km. Measurements of stellar motions complement those obtained by the European Space Agency’s Gaia mission at visible wavelengths, where young stars are hidden by thick veils of dust.
The VISIONS Atlas will keep astronomers busy for years to come. “There is tremendous long-term value to the astronomical community here, which is why ESO directs public surveys such as VISIONS,” says Monika Petr-Gotzens, an ESO astronomer in Garching, Germany, and co-author of this study. Furthermore, VISIONS will lay the foundation for future observations with other telescopes such as ESO’s Extremely Large Telescope (ELT), currently under construction in Chile and set to become operational later this decade. “ELT will allow us to zoom in on specific regions in unprecedented detail, giving us a never-before-seen close-up view of the individual stars currently forming there,” Meingast concludes.
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