First stars formed much earlier than thought

Artist's view of stars forming in early universe

By Richard Stenger
CNN Sci-Tech

(CNN) -- The original generation of stars exploded into life more brilliantly and much sooner than previously estimated, according to an investigation of the deepest and oldest pictures of the universe.

A spectacular torrent of stellar births lit up the dark cosmos only several hundred million years after the Big Bang, producing a substantial number of the stars in the heavens, astronomers announced Tuesday.

The idea that a sudden burst produced many stars soon after the beginning of the universe revises an earlier theory that the star birth rate gradually increased during the infancy of the cosmos.

Although star births continue in galaxies today, the rate could be "a trickle compared to the predicted gusher in the early years," the team of scientists said.

The group made the conclusion after examining images taken by the Hubble Space Telescope of some of the deepest observable galaxies.

Revised timeline pushes star birth peak much closer to Big Bang

The term "deep," in an astronomical sense, refers to the faintest and most distant objects in the universe. Because the objects are among the oldest, Hubble can work as "time machine" by taking snapshots of the early universe.

The ancient star groups in the Hubble image date back more than 10 billion years, much closer to the beginning of the universe. The further back the scientists looked in time, the higher the birth rate of stars.

Astronomer Ken Lanzetta of the State University of New York at Stony Brook, who with colleagues presented the findings at a NASA press conference, described the tantalizing pictures as "the tip of the iceberg."

Beyond the technological limits of Hubble's vision, in uncharted recesses that more advanced space observatories could render visible within years, lie patches of intensely hot and bright blue-white infant stars in primordial galaxies, speculated Lanzetta after studying the colors of the furthest galaxies.

Hubble deep field image

"The previous census of the deep fields missed most of the ultraviolet light in the universe," which likely accounts for a significant portion of early cosmic energy, Lanzetta said.

According to astronomers, the Big Bang ignited the universe into existence about 14 billion years ago. The original generation of stars began to shine about 100 million years later. Galaxies have been identified whose light left them when the universe was about 1 billion years old.

Lanzetta and colleagues pinpointed the projected peak of star births in the cosmos to between 500 million and 1 billion years after the Big Bang. The earlier estimate was between 4 billion and 5 billion years after the cosmic genesis, or shortly after our Milky Way Galaxy formed.