Hubble

Hubble Ultra Deep Field updated … with ultraviolet

James Guilford , , , ,
Photo: Hubble Ultra Deep Field 2014
The Hubble Ultra Deep Field 2014 image is a composite of separate exposures taken from 2003 to 2012 with Hubble’s Advanced Camera for Surveys and Wide Field Camera 3. Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

Astronomers using the Hubble Space Telescope have captured the most comprehensive picture ever assembled of the evolving Universe — and one of the most colorful. The study is called the Ultraviolet Coverage of the Hubble Ultra Deep Field (UVUDF) project.

Prior to this survey, astronomers were in a curious position. They knew a lot about star formation occurring in nearby galaxies thanks to UV telescope facilities such as NASA’s Galex observatory, which operated from 2003 to 2013. And, thanks to Hubble’s near-infrared and visible capability, they had also studied star birth in the most distant galaxies. We see these distant galaxies in their most primitive stages due to the vast amount of time it takes their light to reach us.

However, between five and 10 billion light-years away from us — corresponding to a time period when most of the stars in the Universe were born — there was a lack of the data needed to fully understand star formation. The hottest, most massive and youngest stars, which emit light in the ultraviolet, were often neglected as subjects of direct observation, leaving a significant gap in our knowledge of the cosmic timeline.

The addition of ultraviolet data to the Hubble Ultra Deep Field using Hubble’s Wide Field Camera 3 gives astronomers access to direct observations of regions of unobscured star formation and may help us to fully understand how stars formed. By observing at these wavelengths, researchers get a direct look at which galaxies are forming stars and, just as importantly, where the stars are forming. This enables astronomers to understand how galaxies like the Milky Way grew in size from small collections of very hot stars to the massive structures they are today.

The patch of sky in this image has been previously studied by astronomers in a series of visible and near-infrared exposures taken from 2004 to 2009: the Hubble Ultra Deep Field. Now, with the addition of ultraviolet light, they 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 to within a few hundred million years of the Big Bang.

Since the Earth’s atmosphere filters most ultraviolet light, this work can only be accomplished with a space-based telescope like Hubble. Ultraviolet surveys like this are incredibly important in planning for the James Webb Space Telescope (JWST) as Hubble is the only telescope currently able to obtain the ultraviolet data that researchers will need to combine with infrared data from JWST.

Planck mission results shake cosmology’s basics

James Guilford , , , , , ,
Image: Artist's concept: Planck spacecraft. Credit: ESA/NASA
Artist’s concept: Planck spacecraft. Credit: ESA/NASA

WASHINGTON — The Planck space mission has released the most accurate and detailed map ever made of the oldest light in the universe, revealing new information about its age, contents and origins.

The map results suggest the universe is expanding more slowly than scientists thought, and is 13.8 billion years old, 100 million years older than previous estimates. The data also show there is less dark energy and more matter, both normal and dark matter, in the universe than previously known. Dark matter is an invisible substance that only can be seen through the effects of its gravity, while dark energy is pushing our universe apart. The nature of both remains mysterious.

The map, based on the mission’s first 15.5 months of all-sky observations, reveals tiny temperature fluctuations in the cosmic microwave background, ancient light that has traveled for billions of years from the very early universe to reach us. The patterns of light represent the seeds of galaxies and clusters of galaxies we see around us today.

The findings also test theories describing inflation, a dramatic expansion of the universe that occurred immediately after its birth. In far less time than it takes to blink an eye, the universe blew up by 100 trillion trillion times in size. The new map, by showing that matter seems to be distributed randomly, suggests that random processes were at play in the very early universe on minute “quantum” scales. This allows scientists to rule out many complex inflation theories in favor of simple ones.

The newly-estimated expansion rate of the universe, known as Hubble’s constant, is 67.15 plus or minus 1.2 kilometers/second/megaparsec. A megaparsec is roughly 3 million light-years. This is less than prior estimates derived from space telescopes, such as NASA’s Spitzer and Hubble, using a different technique. The new estimate of dark matter content in the universe is 26.8 percent, up from 24 percent, while dark energy falls to 68.3 percent, down from 71.4 percent. Normal matter now is 4.9 percent, up from 4.6 percent.

Planck launched in 2009 and has been scanning the skies ever since, mapping the cosmic microwave background, the afterglow of the theorized big bang that created our universe. Complete results from Planck, which still is scanning the skies, will be released in 2014.

For more information about Planck, visit: http://www.nasa.gov/planck

From a NASA/JPL News Release, 3/21/2013