hubble deep field
Hubble eXtreme Deep Field "XDF" (2012) view — except for a few stars, every speck of light is an entire galaxy — some as old as 13.2 billion years. NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team

The universe may be much brighter than scientists previously believed as almost half of its stars may be “orphans” hidden in the space between galaxies, according to a paper published in the journal Science. The finding was based on data collected by a suborbital rocket launched by NASA as part of a project named Cosmic Infrared Background Experiment, or CIBER.

According to a statement issued by NASA, maps created using photographs snapped by CIBER rockets revealed a much brighter cosmic glow than previously observed. This background glow, called Extragalactic Background Light, or EBL, which falls under the infrared spectrum, appears to represent more light than that produced by known galaxies in the universe.

In order to explain this discrepancy, scientists reportedly came up with two hypotheses -- the light might be coming from very early, very distant galaxies, or it might be coming from orphan stars lying outside galactic boundaries.

“The light looks too bright and too blue to be coming from the first generation of galaxies,” James Bock, principal investigator of the CIBER project from the California Institute of Technology and NASA’s Jet Propulsion Laboratory, said, in the 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.”

Michael Zemcov, the lead author of the paper describing the results, said, in the statement, that although scientists have previously observed cases where stars had been stripped away from their parent galaxies, the new measurements implied that the phenomenon could be much more widespread.

“We think these stars are being scattered out into space during galaxy collisions,” Zemcov said.

Based on the amount and intensity of the EBL observed, scientists said that there could be just as many stars lying outside galaxies as there are inside them.

“Future experiments can test whether stray stars are indeed the source of the infrared cosmic glow,” the NASA statement said. “If the stars were tossed out from their parent galaxies, they should still be located in the same vicinity. The CIBER team is working on better measurements using more infrared colors to learn how stripping of stars happened over cosmic history.”