Remotest Galaxy Born In Dawn of Universe
Astronomers in Europe and the United States say they have spotted the farthest and oldest galaxy ever found, a star cluster 13.2 billion light years away.
With the combined power of NASA’s Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, 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. Source: NASA/JPL
Get The Edge On Star Formation In NGC 7090
When John Herschel first viewed this galaxy on October 4, 1834, you can bet he would have never imagined it as we see it today. Located about thirty million light-years away in the constellation of Indus, NGC 7090 displays its beautiful edge-on form and its active star-forming regions to the NASA/ESA Hubble Space Telescope. The image was taken using the Wide Field Channel of the Advanced Camera for Surveys aboard the Hubble Space Telescope and combines orange light (colored blue here), infrared (colored red) and emissions from glowing hydrogen gas (also in red).
While we aren’t able to see the spiral arms of this incredible galaxy due to its orientation, we can take a close look at the galaxy’s disc and thick nucleus region – home to a huge group of cool, old stars. However, there’s more here than just a pretty picture. Sprinkled over this image is a web of pink/red – clouds of hydrogen gas. Here is where new stars are actively being born. Cut across the image are dark dust lanes, showing filamentary structure. This blocks the light from the core of the galaxy and adds even more to its visual appeal.
As elegant as the dust may make the image appear, observational astronomers curse it for hiding details. However, at near-infrared wavelengths, the dust curtain is drawn back and we are able to see what is hiding behind it. What’s more, by observing in the radio wavelength, astronomers are able to study the structure of the dust itself and its relationship with star formation.
There’s more to the picture… Than meets the eye. Hey, hey… My, My.
Original Story Source: Hubble News/Photo Release.