Sixty-nine young dwarf galaxies brimming with star formation were recently uncovered by NASA's Hubble Telescope.

The discoveries were part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), an ambitious three-year study to analyze the most distant galaxies in the universe. The CANDELS team uncovered the 69 young dwarf galaxies in near-infrared images taken with Hubble's Wide Field Camera 3 and Advanced Camera for Surveys.

"The galaxies have been there all along, but up until recently astronomers have been able only to survey tiny patches of sky at the sensitivities necessary to detect them," said Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany.

The observations suggest that such youthful galaxies were very common 9 billion years ago. Why the newly found dwarf galaxies were making batches of stars at such a high rate, however, remains a mystery.

"While these theoretical predictions may provide hints to explain the star formation in these newly discovered galaxies, the observed bursts are much more intense than what the simulations can reproduce," van der Wel said.

The answer could come from the discoveries that will be made using the James Webb Space Telescope, an infrared observatory scheduled to launch later this decade. This telescope will be able to probe these faint galaxies at an even earlier era to see the glow of their stars, reveal their chemical composition, and offer better details on their formation.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.