Astronomers using NASA's Hubble Space Telescope have assembled a
comprehensive picture of the evolving universe – among the most colorful deep
space images ever captured by the 24-year-old telescope.
Researchers say the image, in new study called the Ultraviolet Coverage of
the Hubble Ultra Deep Field, provides the missing link in star formation. The
Hubble Ultra Deep Field 2014 image is a composite of separate exposures taken in
2003 to 2012 with Hubble's Advanced Camera for Surveys and Wide Field Camera
3.
Astronomers previously studied the Hubble Ultra Deep Field (HUDF) in visible
and near-infrared light in a series of images captured from 2003 to 2009.
The
HUDF shows a small section of space in the southern-hemisphere constellation
Fornax. Now, using ultraviolet light, astronomers have combined the full range
of colors available to Hubble, stretching all the way from ultraviolet to
near-infrared light. The resulting image -- made from 841 orbits of telescope
viewing time -- contains approximately 10,000 galaxies, extending back in time
to within a few hundred million years of the big bang.
Prior to the Ultraviolet Coverage of the Hubble Ultra Deep Field study of the
universe, astronomers were in a curious position. Missions such as NASA's Galaxy
Evolution Explorer (GALEX) observatory, which operated from 2003 to 2013,
provided significant knowledge of star formation in nearby galaxies. Using
Hubble's near-infrared capability, researchers also studied star birth in the
most distant galaxies, which appear to us in their most primitive stages due to
the significant amount of time required for the light of distant stars to travel
into a visible range. But for the period in between, when most of the stars in
the universe were born -- a distance extending from about 5 to 10 billion
light-years -- they did not have enough data.
"The lack of information from ultraviolet light made studying galaxies in the
HUDF like trying to understand the history of families without knowing about the
grade-school children," said principal investigator Harry Teplitz of Caltech in
Pasadena, California. "The addition of the ultraviolet fills in this missing
range."
Ultraviolet light comes from the hottest, largest and youngest stars. By
observing at these wavelengths, researchers get a direct look at which galaxies
are forming stars and where the stars are forming within those galaxies.
Studying the ultraviolet images of galaxies in this intermediate time period
enables astronomers to understand how galaxies grew in size by forming small
collections of very hot stars. Because Earth's atmosphere filters most
ultraviolet light, this work can only be accomplished with a space-based
telescope.
"Ultraviolet surveys like this one using the unique capability of Hubble are
incredibly important in planning for NASA's James Webb Space Telescope," said
team member Dr. Rogier Windhorst of Arizona State University in Tempe. "Hubble
provides an invaluable ultraviolet light dataset that researchers will need to
combine with infrared data from Webb. This is the first really deep ultraviolet
image to show the power of that combination."
The Hubble Space Telescope is a project of international cooperation between
NASA and the European Space Agency. NASA's Goddard Space Flight Center in
Greenbelt, Maryland, manages the telescope.
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