The SPIRE and PACS instruments, the "eyes" of the ESA Herschel telescope have discovered large numbers of stars of every age in a part of our galaxy that had, until 4 October, been believed to be cold and inactive. The images are so spectacular that staff in Paris decided to publish them immediately. "The emotional impact was exceptional," said Sergio Molinari, an Italian researcher with the IFSI (Institute for Interplanetary Space Physics, part of INAF) who plays an important role in this story. Molinari is in fact the principal investigator of the only Italian-led programme among the twenty key observational projects chosen by the ESA. The programme is called Hi-GAL (Herschel Infrared GALactic Plane Survey); it includes a decisive contribution from the Italian Space Agency, and is the programme which discovered these "pearls".
"To be able to see the entire lifecycle of material in the galaxy in a single real image, exactly as shown in theory, from diffuse to dense clouds and on until the final phases of stellar evolution was a truly remarkable experience," said Molinari. The "eyes" of Herschel were turned towards the Southern Cross constellation and the two instruments, SPIRE and PACS, were used contemporaneously for the first time. The structure of the area under investigation was shown with a resolution that had never been seen before and allowed scientists to gather a large quantity of data such as mass, temperature and composition of the material present. Molinari did not in fact call them "star necklaces" but more precisely "mazes of filaments with chains of embryonic stars in various evolutionary phases". The experiment has only just begun, but has already furnished solid evidence that our galaxy is continuously forging new generations of stars.