This graph, or spectrum, charts light from a faraway galaxy located 10 billion light years from Earth. It tracks mid-infrared light from an extremely luminous galaxy when the universe was only 1/4 of its current age.
Spectra are created when an instrument called a spectrograph spreads light out into its basic parts, like a prism turning sunlight into a rainbow. They reveal the signatures, or "fingerprints," of molecules that make up a galaxy and contribute to its light.
Spitzer's infrared spectrometer identified characteristic fingerprints of complex organic molecules called polycyclic aromatic hydrocarbons, illustrated in the artist's concept in the inset. These large molecules comprised of carbon and hydrogen, are considered among the building blocks of life.
Scientists determined it took 10 billion years for photons from this galaxy to reach Spitzer's infrared eyes. These complex carbon and hydrogen molecules are from a young galaxy which is undergoing intense star formation, at the time the universe was only 3.5 billion years old.
These distant galaxies with enormous amounts of gas being converted into young stars are some of the most luminous objects in the sky. Enshrouded by dust, they are only faint, inconspicuous little dots in optical images. They are as bright as 10 trillion suns put together and 10 times brighter than starburst galaxies seen in our local universe.
This prompts a fascinating question as to what physical process is driving such enormous energy production in these galaxies when the universe is so young. These data were taken by Spitzer's infrared spectrograph in August and September 2004.
Release: July 28, 2005
NASA's Spitzer Space Telescope has found the ingredients for life all the way back to a time when the universe was a mere youngster.
Using Spitzer, scientists have detected organic molecules in galaxies when our universe was one-fourth of its current age of about 14 billion years. These large molecules, known as polycyclic aromatic hydrocarbons, are comprised of carbon and hydrogen. The molecules are considered to be among the building blocks of life.
These complex molecules are very common on Earth. They form any time carbon-based materials are not burned completely. They can be found in sooty exhaust from cars and airplanes, and in charcoal broiled hamburgers and burnt toast.
The molecules, pervasive in galaxies like our own Milky Way, play a significant role in star and planet formation. Spitzer is the first telescope to see these molecules so far back in time.
"This is 10 billion years further back in time than we've seen them before," said Dr. Lin Yan of the Spitzer Science Center at the California Institute of Technology in Pasadena, Calif. Yan is lead author of a study to be published in the August 10 issue of the Astrophysical Journal. Previous missions -- the Infrared Astronomical Satellite and the Infrared Space Observatory -- detected these types of galaxies and molecules much closer to our own Milky Way galaxy. Spitzer's sensitivity is 100 times greater than these previous infrared telescope missions, enabling direct detection of organics so far away.
Since Earth is approximately four-and-a-half billion years old, these organic materials existed in the universe well before our planet and solar system were formed and may have even been the seeds of our solar system. Spitzer found the organic compounds in galaxies where intense star formation had taken place over a short period of time. These "flash in the pan" starburst galaxies are nearly invisible in optical images because they are very far away and contain large quantities of light-absorbing dust. But the same dust glows brightly in infrared light and is easily spotted by Spitzer.
Spitzer's infrared spectrometer split the galaxies' infrared light into distinct features that revealed the presence of organic components. These organic features gave scientists a milepost to gauge the distance of these galaxies. This is the first time scientists have been able to measure a distance as great as 10-billion light years away using the spectral fingerprints of polycyclic aromatic hydrocarbons.
"These complex compounds tell us that by the time we see these galaxies, several generations of stars have already been formed," said Dr. George Helou of the Spitzer Science Center, a co-author of the study. "Planets and life had very early opportunities to emerge in the universe."
Other co-authors include Ranga-Ram Chary, Lee Armus, Harry Tepliz, David Frayer, Dario Fadda, Jason Surace, and Philip Choi, all of the Spitzer Science Center.
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