This image reveals 18 tiny galaxies uncovered by NASA's Hubble Space Telescope. The puny galaxies, shown in the postage stamp-sized images, existed 9 billion years ago and are brimming with star birth. PHOTO: NASA

NASA's Hubble Space Telescope has discovered 18 dwarf galaxies showing unusually rapid stellar formations, which astronomers say may change the understanding of the ways in which galaxies form.

The observations were part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), a three-year study to analyze the most distant galaxies in the universe.

The high rate of star-birth in these frail galaxies has baffled astronomers. Earlier studies showed that star formation was a relatively slow process, stretching out over billions of years but newly-found galaxies suggest extraordinary results, NASA said on Thursday.

The CANDELS finding that there were galaxies of roughly the same size forming stars at very rapid rates at early times is forcing us to re-examine what we thought we knew about dwarf galaxy evolution, said Harry Ferguson of the Space Telescope Science Institute (STScI) in Baltimore, Md., co-leader of the CANDELS survey.

According to astronomers, the observed bursts are much more intense than those that a star formation can produce.

While scientists remain puzzled by the mystery of rapid stellar development, the James Webb Space Telescope, scheduled to launch later this decade, will be able to reveal detailed observations on their formation, said the space agency.

In addition to the faster star-birth observations, the Hubble telescope (which turned 21 this year) detected oxygen in the gas surrounding a few galaxies.

The oxygen shone like a neon sign, due to radiation from bursting stars, imparting unusual colors to the galaxies and making them stand out explained Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany, who is also the lead author of a paper on the results. The paper is being published online on Nov. 14 in The Astrophysical Journal.

van der Wel further said that the galaxies were discovered accidentally and because of their strange colors. The team was not looking specifically for these.