A recent rocket experiment conducted by NASA detected a previously unknown cosmic glow of infrared light between galaxies. Scientists later identified this glow as coming from orphaned stars.
According to NASA, the discovery is redefining how scientists think of galaxies.
Individually, these lonesome stars are too faint to detect. But together, they create a background of fluctuating near-infrared light. NASA thinks half of all stars could lie outside galaxies.
This is a time-lapse photograph of the Cosmic Infrared Background Experiment (CIBER) rocket launch, taken from NASA's Wallops Flight Facility in Virginia in 2013. The image is from the last of four launches.
(Caption and image credit: T. Arai/University of Tokyo via NASA)
"We think stars are being scattered out into space during galaxy collisions," Michael Zemcov, an astronomer at the California Institute of Technology and NASA's Jet Propulsion Laboratory, said in a statement. "While we have previously observed cases where stars are flung from galaxies in a tidal stream, our new measurement implies this process is widespread."
The light was spotted as part of the Cosmic Infrared Background Experiment, which uses suborbital rockets to take pictures at two infrared wavelengths.
This graphic illustrates how the Cosmic Infrared Background Experiment, or CIBER, team measures a diffuse glow of infrared light filling the spaces between galaxies. The glow does not come from any known stars and galaxies; instead, the CIBER data suggest it comes from stars flung out of galaxies. (Caption and image credit: NASA/JPL-Caltech)
“Sounding rockets are an important element in our balanced toolbox of missions from small to large," Mike Garcia, program scientist from NASA Headquarters, said of the technology.
The information that came back as part of the experiment, which was published in the journal Science, revealed the previously undetected stars between galaxies.
"The light looks too bright and too blue to be coming from the first generation of galaxies," James Bock, principal investigator of the CIBER, said in a statement. "The simplest explanation, which best explains the measurements, is that many stars have been ripped from their galactic birthplace, and that the stripped stars emit on average about as much light as the galaxies themselves."
Watch NASA's video about the discovery:
The Associated Press contributed to this report.