The deepest views of the cosmos from NASA’s Hubble Space
Telescope yield clues that the very first stars may have burst
into the universe as brilliantly and spectacularly as a fireworks
finale. In this case though the finale came first, long before
Earth, the Sun and the Milky Way Galaxy formed.
If this interpretation is correct, it offers a tantalizing
possibility that astronomers may behold this stellar blaze of
glory when they use NASA’s Next Generation Space Telescope and
other future space telescopes to probe even farther into the very
early universe.
Studies of Hubble’s deepest views of the heavens by Kenneth M.
Lanzetta of the State University of New York at Stony Brook and
colleagues lead to the preliminary conclusion that the universe
made a significant portion of its stars in a torrential firestorm
of star birth, which abruptly lit up the pitch-dark heavens just a
few hundred million years after the big bang. Though stars
continue to be born today in galaxies, the star birthrate could be
a trickle compared to the predicted gusher of stars in those
opulent early years.
This new idea of a continually escalating rate of star birth the
farther Hubble looks back in time offers a dramatic revision of
previous Hubble Deep Field studies that proposed that the star
birthrate in the early universe ramped up to a “baby boom” about
halfway back to the beginning of the universe.
“If this can be verified it will dramatically change our
understanding of the universe,” said Dr. Anne Kinney, director of
the Astronomy and Physics division at NASA Headquarters,
Washington. “Because stars are the building blocks of galaxies and
the birthplace of solar systems, proving that countless numbers of
stars began forming so early after the birth of the universe could
cause us to rethink a lot of our theories.”
Lanzetta bases his conclusion on a new analysis of galaxies in the
Hubble deep fields taken near the north and south celestial poles
(in 1995 and 1998 respectively). He reports in an upcoming issue
of the Astrophysical Journal that the farthest objects in the deep
fields are only the “tip of the iceberg” of an effervescent period
of star birth that is unlike anything the universe will ever see
again. Lanzetta concludes that 90 percent of the light from the
early universe is missing in the Hubble deep fields. “The previous
census of the deep fields missed most of the ultraviolet light in
the universe; most of it is invisible,” he says.
Based on an analysis of galaxy colors, Lanzetta concludes that the
farthest objects in the deep fields must be extremely intense,
unexpectedly bright knots of blue-white, hot newborn stars
embedded in primordial galaxies that are too faint to be seen even
by Hubble’s far vision. It’s like seeing only the lights on a
distant Christmas tree and inferring the presence of the whole
tree.
Likewise, Lanzetta deduced the total population of stars in the
early universe based on observing only the brightest stars with
the Hubble telescope. Because such far extrapolations are built on
certain assumptions, this conclusion will require further analysis
and observation.
Lanzetta next plans to use Hubble’s Advanced Camera for Surveys,
to be installed in early 2002, to look even deeper into the
universe to try to directly verify some portion of the missing
light. He will also look for very distant supernovae as an
alternate measure of star formation. “Because they are point
sources of light, supernovae are not subject to the same
cosmological brightness-dimming effects like galaxies (which are
extended sources of light),” says Lanzetta.
The Association of Universities for Research in Astronomy, Inc.
operates the Space Telescope Science Institute for NASA, under
contract with the Goddard Space Flight Center, Greenbelt, Md. The
Hubble Space Telescope is a project of international co-operation
between NASA and the European Space Agency.
Additional information is available on the Internet at:
http://oposite.stsci.edu/pubinfo/pr/2002/02
http://hubble.stsci.edu/go/news
http://oposite.stsci.edu/pubinfo/latest.html
http://oposite.stsci.edu/pubinfo/pictures.html
