An article published in “The Astronomical Journal” reports the discovery of areas of remarkable star formation in the molecular clouds known as Digel Clouds, more than 58,000 light-years from the center of the Milky Way. A team of researchers used the James Webb Space Telescope to obtain the detail needed to recognize protostars, outflows and jets of material, and nebular structures. Star formation is more intense than what was visible in observations conducted with other instruments and is interesting also because the Digel Clouds are poor in elements heavier than hydrogen and helium, a characteristic that makes them similar to the primordial Milky Way.
The image (NASA, ESA, CSA, STScI, M. Ressler (NASA-JPL)) captured by the James Webb Space Telescope’s NIRCam and MIRI instruments shows the Digel Cloud 2S cluster in the near and mid-infrared.
Astronomers expect to find limited star formation in the region of the Milky Way known as the extreme outer Galaxy (EOG), the region more than 58,000 light-years from the center of the Milky Way, because it contains the least amount of gas. Various telescopes identified areas of star formation such as the molecular clouds known as Digel Clouds but couldn’t provide enough detail to study their properties. The James Webb Space Telescope has the power to detect details in these clouds.
The researchers used the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) instruments to capture images inside Digel Clouds 1 and 2 in four clusters designated 1A, 1B, 2N, and 2S. In the Digel Cloud 2S cluster, they found remarkable activity with protostars emitting extended jets of material from their poles, an activity typical during star formation. Previous observations suggested the presence of a subcluster, and the images taken by the James Webb Space Telescope confirmed it.
Astronomers are also interested in star formation in Digel Clouds because of their composition, which has fewer elements heavier than hydrogen and helium than the rest of the Milky Way. This makes the edges of the galaxy similar to the early Milky Way, before generations of stars generated heavy elements over billions of years.
This study is just the beginning of a new phase in research into star formation in Digel Clouds. Natsuko Izumi, a researcher at Gifu University and the National Astronomical Observatory of Japan, this study’s lead author, has been studying those outer areas of the Milky Way for years. She explained that by combining data from multiple observatories and telescopes, it’s possible to examine every stage of the process of protostar evolution. She added that she intends to investigate the circumstellar disks in that area to understand why they have a shorter lifespan than star-forming regions in the inner parts of the Milky Way.
So far, astronomers couldn’t obtain many details of the Milky Way’s peripheral area, but the James Webb Space Telescope is solving this problem. As in other cases, it offered some surprises and this too will allow for new follow-up studies of star formation and how the environment in that area influences its processes.
