A serendipitous discovery by citizen scientists has provided a unique new window into the diverse environments that produce stars and star clusters, revealing the presence of “stellar nurseries” before infant stars emerge from their birth clouds, according to Planetary Science Institute Senior Scientist Grace Wolf-Chase.

“Yellowballs are small compact features that were identified in infrared images acquired by the Spitzer Space Telescope during online discussions on the Milky Way Project, an initiative on the online citizen science platform zooniverse.org, that asked citizen scientists to help identify features associated with young, massive stars greater than 10 solar masses,” said Wolf-Chase, lead author of “The Milky Way Project: Probing Star Formation with First Results on Yellowballs from DR2,” which appears in the Astrophysical Journal. “Early research suggested yellowballs are produced by young stars as they heat the surrounding gas and dust from which they were born.”

The yellowballs discovered by citizen scientists shed infrared light on a very early stage in the development of star clusters, when they are a ‘mere’ hundred thousand years old. “This is the point at which their presence is first revealed, but they remain embedded in their dusty birth cocoons,” Wolf-Chase said. “This allows us to link the properties of stars with their birth environments, as if a human were giving birth to a hundred or so infants at once.”