(Clearwisdom.net)
Astronomers have numerous technical terms and numbering systems for
describing the universe, but one type of mysterious object has yet to be
classified. For now, these oddities are named for their strange appearance. They
are called blobs.
At the 205th annual meeting of the American Astronomical Society
in San Diego, Calif., astronomers presented new evidence in the case of the
giant galactic blobs. These blobs are huge clouds of intensely glowing material
that envelop faraway galaxies. Using NASA's Spitzer Space Telescope and its
powerful infrared vision, the astronomers caught a glimpse of the galaxies
tucked inside the blobs. Their observations reveal monstrously bright galaxies
and suggest that blobs might surround not one, but multiple galaxies in the
process of merging together.
"It is possible that extremely bright galactic mergers lie at the center of
all the mysterious blobs, but we still don't know how they fuel the blobs
themselves," said Dr. Harry Teplitz, Spitzer Science Center, California
Institute of Technology, Pasadena, Calif., co- author of the new research.
"It's like seeing smoke in the distance and now discovering that it's a
forest fire, not a house or car fire, but still not knowing whether it was
caused by lightning or arson."
The findings will ultimately provide a better understanding of how galaxies,
including ones like our own Milky Way, form.
Blobs were first discovered about five years ago with visible-light telescopes.
They are located billions of light-years away in ancient galactic structures or
filaments, where thousands of young galaxies are clustered together. These
large, fuzzy galactic halos are made up of hot hydrogen gas and are about 10
times as large as the galaxies they encompass. Astronomers can see glowing
blobs, but they don't know what provides the energy to light them up.
"To figure out what's going on, we need to better characterize the galaxies
at the center of the blobs," said Dr. James Colbert, Spitzer Science
Center, first author of the study.
That's where Spitzer comes in. Spitzer can sense the infrared glow from the
dusty galaxies inside the blobs. When Colbert and colleagues used Spitzer to
look at four well-known blobs located in a galactic filament 11 billion
light-years away, they discovered that one of them appears to be made up of
three galaxies falling into each other -- an unusual cosmic event. The finding
is intriguing because previous observations from NASA's Hubble Space Telescope
found that another one of the four blobs surrounds a merger between two
galaxies. The astronomers speculate that all blobs might share this trait;
however, more evidence is needed to close the case.
One clue that the scientists might be on the right track has to do with the
infrared brightness of the blob galaxies. To visible-light telescopes, these
galaxies appear unremarkable. Spitzer measurements revealed that all four of the
galaxies studied are among the brightest in the universe, giving off the
equivalent light of trillions of Suns. Such luminous galaxies are often
triggered when smaller, gas-rich ones crash together, supporting the notion that
galactic mergers might make up the cores of blobs.
Even if galactic mergers are fingered as the culprit, the mystery of the giant
galactic blobs will persist. Astronomers will have to figure out why mergers are
producing such tremendous clouds of material.
"Far from solving the mystery of the blobs, these observations only deepen
it. Not only are the gas clouds bizarre, we now know that they contain some of
the brightest and most violent galaxies in the universe," said Teplitz.
[Other authors of this work include Dr. Paul Francis, The Australian National
University Canberra, Australia; Dr. Povilas Palunas, University of Texas at
Austin; Dr. Gerard Williger, Johns Hopkins University, Baltimore, Md.; and Dr.
Bruce E. Woodgate, NASA's Goddard Space Flight Center, Greenbelt, Md.]
Images and additional information about the Spitzer Space Telescope are
available at http://www.spitzer.caltech.edu/Media.
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, Calif.
Source: http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-011105.html
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