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Astronomers have combined a natural gravitational lens and a sophisticated telescope array to get the sharpest view ever of "star factories" in a galaxy more than 10 billion light-years from Earth. They found that the distant galaxy, known as SMM J2135-0102, is making new stars 250 times faster than our Milky Way Galaxy.
They also pinpointed four discrete star-forming regions within the galaxy, each more than 100 times brighter than locations (like the Orion Nebula) where stars form in our galaxy. This is the first time that astronomers have been able to study properties of individual star-forming regions within a galaxy so far from Earth.
"To a layperson, our images appear fuzzy, but to us, they show the exquisite detail of a Faberge egg," said Steven Longmore of the Harvard-Smithsonian Center for Astrophysics (CfA). Longmore is an author of the paper describing these findings, which was published in the March 21 Nature online.
Due to the time it takes light to travel to us, we see the galaxy as it existed just 3 billion years after the Big Bang. It was Milky Way-sized at the time. If we could see it today, 10 billion years later, it would have grown into a giant elliptical galaxy much more massive than our own.
"This galaxy is like a teenager going through a growth spurt," said Mark Swinbank of Durham University, lead author on the paper. "If you could see it today as an 'adult,' you'd find the galactic equivalent of Yao Ming the basketball player."
From our point of view, SMM J2135-0102 is located behind a massive cluster of nearby galaxies. The cluster's gravity acts as a lens to magnify the more distant galaxy by a factor of 16 in both apparent size and brightness, bringing otherwise imperceptible details to light.
The galaxy, while heavily obscured by dust at visible wavelengths, emits prodigious amounts of light at submillimeter wavelengths (close to the radio region of the spectrum). Indeed, it is the brightest known submillimeter galaxy, making it a natural target for the Submillimeter Array (SMA).
The SMA is an 8-element interferometer operating in the wavelength range of 0.3 to 2 millimeters, located atop Mauna Kea in Hawaii. Combined with the natural magnification of the gravitational lens, the array provided extremely high-resolution observations — equivalent to using a telescope in Boston to spot a dime in Washington, D.C. This yielded a level of detail for a galaxy 10 billion light-years away comparable to the best observations of nearby starburst galaxies (which also show high rates of star formation).