Chuck Bednar for redOrbit.com – Your Universe Online
Citizen scientists scanning thousands of images from the Spitzer Space Telescope helped NASA scientists discover mysterious objects which have now been identified as a phase of massive star formation, officials at the US space agency announced on Tuesday.
The objects, which had been dubbed “yellowballs” due to their apparent colors in images, were first discovered about four years ago by an armchair astronomer using The Milky Way Project, a project that asks the general public for help analyzing Spitzer’s catalog of infrared images.
While looking at some of the telescope’s pictures, one volunteer noticed the yellowballs and took to a project message board to ask fellow citizen scientists what the “bright yellow fuzzy objects” he discovered were. The discussion continued as more than 900 were discovered and tagged, and now new research published by The Astrophysical Journal sheds new light on the matter.
“The volunteers started chatting about the yellow balls they kept seeing in the images of our galaxy, and this brought the features to our attention,” explained Grace Wolf-Chase of the Adler Planetarium in Chicago, one of the authors of that study.
“With prompting by the volunteers, we analyzed the yellow balls and figured out that they are a new way to detect the early stages of massive star formation,” added lead author Charles Kerton, an associate professor at Iowa State University and a member of The Milky Way Project science team. “The simple question of ‘Hmm, what’s that?’ led us to this discovery.”
The study authors found that these yellowballs are actually a phase of massive star formation, preceding the green bubbles with red centers that result from massive newborn stars blowing out cavities in their surroundings. Wolf-Chase called them the “missing link between the very young embryonic stars buried in dark filaments and newborn stars blowing the bubbles.”
Despite their name, these objects are not actually yellow – they only appear that way in the infrared, color-assigned images obtained by Spitzer. While they appear small in the 122-foot mosaic of the Milky Way at the Adler Planetarium, they are actually hundreds to thousands of times bigger than our solar system, the researchers noted.
The astronomers also studied the luminosity and physical sizes of 138 of the unusual objects. They found that the majority of these yellowballs were in regions of the galaxy that contained dense gas, and that their luminosity was consistent with that expected from a collection of newly formed massive stars. Finally, they concluded that there was an early “yellowball stage” in the formation of stars that are 10 to 40 times as massive as our sun.
“All massive stars probably go through this yellowball stage,” Kerton explained in a statement. “The most massive stars go through this stage very early and quickly. Less massive stars go through this stage more slowly.”
He and his colleagues also explained that additional analysis of yellowballs in future studies may help shed new light on how regions of massive star formation grow from early compact stages to more evolved and bubble-like structures.
“These results attest to the importance of citizen scientist programs,” said Wolf-Chase. Kerton added that the discovery is “a nice example of people looking at something in the universe and saying, ‘That’s different,’ and then passing it on to professional astronomers.”
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