NASA Telescopes Spy Ultra-Distant Galaxy Amidst Cosmic 'Dark Ages'

J.D. Harrington

Headquarters, Washington

202-358-5241

j.d.harrington@nasa.gov

 

Whitney Clavin

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-4673

whitney.clavin@jpl.nasa.gov

WASHINGTON -- With the combined power of NASA's Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, astronomers have spotted what could be the most distant galaxy ever seen. Light from the young galaxy captured by the orbiting observatories first shone when our 13.7-billion-year-old universe was just 500 million years old.

The far-off galaxy existed within an important era when the universe began to transit from the so-called cosmic dark ages. During this period, the universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, remotest epochs of cosmic history.

"This galaxy is the most distant object we have ever observed with high confidence," said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore and lead author of a new paper appearing in Nature. "Future work involving this galaxy, as well as others like it that we hope to find, will allow us to study the universe's earliest objects and how the dark ages ended."

Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes. In other words, the starlight snagged by Hubble and Spitzer left the galaxy when the universe was just 3.6 percent of its present age. Technically speaking, the galaxy has a redshift, or "z," of 9.6. The term redshift refers to how much an object's light has shifted into longer wavelengths as a result of the expansion of the universe. Astronomers use redshift to describe cosmic distances.

Unlike previous detections of galaxy candidates in this age range, which were only glimpsed in a single color, or waveband, this newfound galaxy has been seen in five different wavebands. As part of the Cluster Lensing And Supernova Survey with Hubble Program, the Hubble Space Telescope registered the newly described, far-flung galaxy in four visible and infrared wavelength bands. Spitzer measured it in a fifth, longer-wavelength infrared band, placing the discovery on firmer ground.

Objects at these extreme distances are mostly beyond the detection sensitivity of today's largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on gravitational lensing. In this phenomenon, predicted by Albert Einstein a century ago, the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and the newfound galaxy magnified the newfound galaxy's light, brightening the remote object some 15 times and bringing it into view.

Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Way's mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

These first galaxies likely played the dominant role in the epoch of reionization, the event that signaled the demise of the universe's dark ages. This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron, a state that the gas has remained in since that time.

"In essence, during the epoch of reionization, the lights came on in the universe," said paper co-author Leonidas Moustakas, a research scientist at NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif.

Astronomers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Hubble and Spitzer, NASA's James Webb Telescope, which is scheduled for launch in 2018. The newly described distant galaxy likely will be a prime target.

For more information about Spitzer, visit http://www.nasa.gov/spitzer.

For more information about Hubble, visit\ http://www.nasa.gov/hubble.

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Hubble Watches Star Clusters on a Collision Course

Astronomers using data from NASA's Hubble Space Telescope caught two clusters full of massive stars that may be in the early stages of merging. The 30 Doradus Nebula is 170,000 light-years from Earth. What at first was thought to be only one cluster in the core of the massive star-forming region 30 Doradus has been found to be a composite of two clusters that differ in age by about one million years.

The entire 30 Doradus complex has been an active star-forming region for 25 million years, and it is currently unknown how much longer this region can continue creating new stars. Smaller systems that merge into larger ones could help to explain the origin of some of the largest known star clusters. The Hubble observations, made with the Wide Field Camera 3, were taken Oct. 20-27, 2009. The blue color is light from the hottest, most massive stars; the green from the glow of oxygen; and the red from fluorescing hydrogen.

Image Credit: NASA, ESA, and E. Sabbi (ESA/STScI)

A Change in the Air

An international team of astronomers using data from NASA's Hubble Space Telescope made an unparalleled observation, detecting significant changes in the atmosphere of a planet located beyond our solar system.

Exoplanet HD 189733b lies so near its star that it completes an orbit every 2.2 days. In late 2011, NASA's Hubble Space Telescope found that the planet's upper atmosphere was streaming away at speeds exceeding 300,000 mph. Just before the Hubble observation, NASA's Swift detected the star blasting out a strong X-ray flare, one powerful enough to blow away part of the planet's atmosphere.

The exoplanet is a gas giant similar to Jupiter, but about 14 percent larger and more massive. The planet circles its star at a distance of only 3 million miles, or about 30 times closer than Earth's distance from the sun. Its star, named HD 189733A, is about 80 percent the size and mass of our sun.

This artist's rendering illustrates the evaporation of HD 189733b's atmosphere in response to a powerful eruption from its host star.

Image Credit: NASA

Hubble Sees Red Giant Blow a Bubble

Camelopardalis, or U Cam for short, is a star nearing the end of its life. As stars run low on fuel, they become unstable. Every few thousand years, U Cam coughs out a nearly spherical shell of gas as a layer of helium around its core begins to fuse. The gas ejected in the star’s latest eruption is clearly visible in this picture as a faint bubble of gas surrounding the star.

U Cam is an example of a carbon star, a rare type of star with an atmosphere that contains more carbon than oxygen. Due to its low surface gravity, typically as much as half of the total mass of a carbon star may be lost by way of powerful stellar winds. Located in the constellation of Camelopardalis (The Giraffe), near the North Celestial Pole, U Cam itself is much smaller than it appears in this Hubble image. In fact, the star would easily fit within a single pixel at the center of the image. Its brightness, however, is enough to saturate the camera's receptors, making the star look much larger than it is.

The shell of gas, which is both much larger and much fainter than its parent star, is visible in intricate detail in Hubble’s portrait. This phenomenon is often quite irregular and unstable, but the shell of gas expelled from U Cam is almost perfectly spherical.

Image Credit: ESA/NASA

Hubble Sees a Vapor of Stars

Relatively few galaxies possess the sweeping, luminous spiral arms or brightly glowing center of our home galaxy the Milky Way. In fact, most galaxies look like small, amorphous clouds of vapor. One of these galaxies is DDO 82, captured by the Hubble Space Telescope. Though tiny compared to the Milky Way, such dwarf galaxies may contain between a few million and a few billion stars.

DDO 82, also known by the designation UGC 5692, is not without a hint of structure, however. Astronomers classify it as an "Sm galaxy," or Magellanic spiral galaxy, named after the Large Magellanic Cloud, a dwarf galaxy that orbits the Milky Way. That galaxy, like DDO 82, is said to have one spiral arm.

DDO 82 can be found in the constellation of Ursa Major (the Great Bear) approximately 13 million light-years away. The object is considered part of the M81 Group of around three dozen galaxies. DDO 82 gets its name from its entry number in the David Dunlap Observatory Catalogue. Canadian astronomer Sidney van den Bergh originally compiled this list of dwarf galaxies in 1959.

The image is made up of exposures taken in visible and infrared light by Hubble’s Advanced Camera for Surveys.

Image Credit: ESA/NASA

Hubble, Swift Detect First-Ever Changes In An Exoplanet Atmosphere

J. D. Harrington

Headquarters, Washington

202-358-5241

j.d.harrington@nasa.gov

 

Lynn Chandler

NASA Goddard Space Flight Center, Greenbelt, Md.

301-286-2806

lynn.chandler-1@nasa.gov

WASHINGTON -- An international team of astronomers using data from NASA's Hubble Space Telescope has made an unparalleled observation, detecting significant changes in the atmosphere of a planet located beyond our solar system.

The scientists conclude the atmospheric variations occurred in response to a powerful eruption on the planet's host star, an event observed by NASA's Swift satellite.

"The multiwavelength coverage by Hubble and Swift has given us an unprecedented view of the interaction between a flare on an active star and the atmosphere of a giant planet," said lead researcher Alain Lecavelier des Etangs at the Paris Institute of Astrophysics (IAP), part of the French National Scientific Research Center located at Pierre and Marie Curie University in Paris.

The exoplanet is HD 189733b, a gas giant similar to Jupiter, but about 14 percent larger and more massive. The planet circles its star at a distance of only 3 million miles, or about 30 times closer than Earth's distance from the sun, and completes an orbit every 2.2 days. Its star, named HD 189733A, is about 80 percent the size and mass of our sun.

Astronomers classify the planet as a "hot Jupiter." Previous Hubble observations show that the planet's deep atmosphere reaches a temperature of about 1,900 degrees Fahrenheit (1,030 C).

HD 189733b periodically passes across, or transits, its parent star, and these events give astronomers an opportunity to probe its atmosphere and environment. In a previous study, a group led by Lecavelier des Etangs used Hubble to show that hydrogen gas was escaping from the planet's upper atmosphere. The finding made HD 189733b only the second-known "evaporating" exoplanet at the time.

The system is just 63 light-years away, so close that its star can be seen with binoculars near the famous Dumbbell Nebula. This makes HD 189733b an ideal target for studying the processes that drive atmospheric escape.

"Astronomers have been debating the details of atmospheric evaporation for years, and studying HD 189733b is our best opportunity for understanding the process," said Vincent Bourrier, a doctoral student at IAP and a team member on the new study.

When HD 189733b transits its star, some of the star's light passes through the planet's atmosphere. This interaction imprints information on the composition and motion of the planet's atmosphere into the star's light.

In April 2010, the researchers observed a single transit using Hubble's Space Telescope Imaging Spectrograph (STIS), but they detected no trace of the planet's atmosphere. Follow-up STIS observations in September 2011 showed a surprising reversal, with striking evidence that a plume of gas was streaming away from the exoplanet.

The researchers determined that at least 1,000 tons of gas was leaving the planet's atmosphere every second. The hydrogen atoms were racing away at speeds greater than 300,000 mph. The findings will appear in an upcoming issue of the journal Astronomy & Astrophysics.

Because X-rays and extreme ultraviolet starlight heat the planet's atmosphere and likely drive its escape, the team also monitored the star with Swift's X-ray Telescope (XRT). On Sept. 7, 2011, just eight hours before Hubble was scheduled to observe the transit, Swift was monitoring the star when it unleashed a powerful flare. It brightened by 3.6 times in X-rays, a spike occurring atop emission levels that already were greater than the sun's.

"The planet's close proximity to the star means it was struck by a blast of X-rays tens of thousands of times stronger than the Earth suffers even during an X-class solar flare, the strongest category," said co-author Peter Wheatley, a physicist at the University of Warwick in England.

After accounting for the planet's enormous size, the team notes that HD 189733b encountered about 3 million times as many X-rays as Earth receives from a solar flare at the threshold of the X class.

Hubble is a project of international cooperation between NASA and the European Space Agency. Swift is operated in collaboration with several U.S. institutions and partners in the United Kingdom, Italy, Germany and Japan. NASA's Goddard Space Flight Center in Greenbelt, Md., manages both missions.

For images and video related to this finding, visit http://go.nasa.gov/Osbvfi.

For more information about Swift, visit http://www.nasa.gov/swift.

 

For more information about Hubble, visit http://www.nasa.gov/hubble.

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