Source: NASA

Would you believe, bigger than an entire galaxy? At the January 2014 meeting of the American Astronomical Society, researchers revealed a patch of sky seen through a lens more than 500,000 light years wide.

The “lens” is actually a massive cluster of galaxies known as Abell 2744. As predicted by Einstein’s Theory of General Relativity, the mass of the cluster warps the fabric of space around it. Starlight passing by is bent and magnified, much like an ordinary lens except on a vastly larger scale.

Lately, the Hubble Space Telescope, along with the Spitzer Space Telescope and the Chandra X-ray Observatory, has been looking through this gravitational lens as part of a program called “Frontier Fields.” Auroras Underfoot (signup)

“Frontier Fields is an experiment to explore the first billion years of the Universe’s history,” says Matt Mountain from the Space Telescope Science Institute in Baltimore, Maryland. The question is, “Can we use Hubble’s exquisite image quality and Einstein’s theory of general relativity to search for the first galaxies?”

The answer seems to be “yes.” At the AAS meeting, an international team led by astronomers from the Instituto de Astrofísica de Canarias and La Laguna University discussed Hubble and Spitzer observations of the Abell 2744 cluster. Among the results was the discovery of one of the most distant galaxies ever seen—a star system 30 times smaller yet 10 times more active than our own Milky Way. Bursting with newborn stars, the firebrand is giving astronomers a rare glimpse of a galaxy born not long after the Big Bang itself.

Overall, the Hubble exposure of Abell2744 revealed almost 3,000 distant galaxies magnified as much as 10 to 20 times larger than they would normally appear. Without the boost of gravitational lensing, almost all of those background galaxies would be invisible.

Abell 2744 is just the beginning. Frontier Fields is targeting six galaxy clusters as gravitational lenses. Together, they form an array of mighty telescopes capable of probing the heavens as never before.

 
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"We can, for the first time, make long-exposure images that resolve objects just 0.02 arcseconds across – the equivalent of a dime viewed from more than a hundred miles away. At that resolution, you could see a baseball diamond on the moon."

The twofold improvement over past efforts rests on the fact that for the first time, a telescope with a large diameter primary mirror is being used for digital photography at its theoretical resolution limit in visible wavelengths – light that the human eye can see.

"As we move towards shorter wavelengths, image sharpness improves," said Jared Males, a NASA Sagan Fellow at the UA's department of astronomy. "Until now, large telescopes could make the theoretically sharpest photos only in infrared – or long wavelength – light, but our new camera can take photos that are twice as sharp in the visible light spectrum."

To overcome atmospheric turbulence, which plagues earth-based telescopes by causing the image to blur, Close's team developed a very powerful adaptive optics system that floats a thin (1/16th of an inch) curved glass mirror (2.8 feet across) on a magnetic field 30 feet above the telescope's primary mirror.

This so-called Adaptive Secondary Mirror (ASM) can change its shape at 585 points on its surface 1,000 times each second, counteracting the blurring effects of the atmosphere.

The new adaptive optics system, called MagAO for "Magellan Adaptive Optics," has already made some important scientific discoveries, published today in three scientific papers in the Astrophysical Journal. As the system was being tested and received what astronomers call "first light," the team pointed it to a famous and well-studied massive star that gives the Great Orion Nebula (Object M42) most of its UV light. The Orion Nebula, located just below Orion's Belt visible as smudge of light even with regular binoculars.

You can read whole article at phys.org

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