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Hot (and cold) spots of the cosmos

ESA / NASA / JPL-Caltech

This map illustrates the numerous star-forming clouds, called cold cores, that Planck observed throughout our Milky Way galaxy. Planck, a European Space Agency mission with significant NASA participation, detected around 10,000 of these cores, thousands of which had never been seen before.

It'll be another couple of years before the European Space Agency's Planck probe delivers its baby picture of the universe, but in the meantime, the long-wavelength surveyor has pinpointed thousands of hot spots (and cold spots) worth watching.

The hot spots are huge galaxy clusters — including one cluster that holds the equivalent of a quadrillion stars, making it one of the most massive structures ever seen in the universe. The cold spots are clouds of chilly gas and dust within our own galaxy that are on the verge of forming their first stars.

Identifying these spots isn't the main reason for the billion-dollar Planck mission, which was launched in May 2009 along with the Herschel Space Telescope. Planck's main goal is to chart the cosmic background radiation in unprecedented detail, in wavelengths ranging from the infrared to the radio spectrum. The mission is expected to produce a map of the cosmic "afterglow" from just 380,000 years after the big bang, at a resolution that's three times bettern than the map produced by NASA's Wilkinson Microwave Anisotropy Probe in 2003.


Such maps provide scientists with their best guide to the infant universe's inflationary expansion. But before scientists can chart the cosmic background radiation, they have to retouch Planck's picture to remove all the "foreground" radiation — that is, all the stars, galaxies and pockets of gas and dust that lent their glow to the all-sky survey. These radiation sources are like "bugs on the windshield," Charles Lawrence of NASA's Jet Propulsion Laboratory, the U.S. project scientist for the Planck mission, told journalists today at the American Astronomical Society's winter meeting in Seattle.

In Planck's case, even the bugs are valuable. The cold spots and the hot spots were the headliners for today's release of the mission's first scientific results. "So today, we're all entomologists," Lawrence joked.

An ESA video, prepared in advance of the Herschel-Planck launch, explains what the probes are designed to do.

Planck's data catalog includes about 10,000 so-called "cold cores," thousands of which are newly discovered. The dark, dense, dusty clouds are expected to fall in on themselves due to gravitational forces, and squeeze stars into existence. "These are the equivalent of a mother's womb before anything has happened," George Helou, a member of the Planck team, said at the Seattle briefing.

Temperatures in the cores approach absolute zero — to be precise, between 7 and 17 Kelvin, or as low as minus-447 degrees Fahrenheit. To measure such temperatures, the Planck detectors had to be chilled to 0.1 Kelvin, or a fraction of a degree above absolute zero.

Helou said astronomers will be studying all those cold cores to come up with a model explaining how the frigid wombs give birth to hot, young stars.

On the other side of the spectrum, the Planck team has identified 189 galaxy clusters so far, including 20 that have never been seen before. Those previously undetected clusters are being confirmed by cross-checking X-ray observations from ESA's XMM-Newton orbiting observatory.

ESA

The newly detected galaxy supercluster PLCK G214.6+37.0 was identified in imagery from the Planck probe (left), and its existence was confirmed by checking X-ray imagery from the XMM-Newton observatory (right).

Studying the clusters could yield new insights into the evolution of galaxies, as well as the effects of dark matter and dark energy. The data from Planck confirm the view that galaxies form along a network of dense regions that spread across empty space like the threads of a spider web.

"They sit in the knots of the cosmic web," said Elena Pierpaoli, a Planck team member from the University of Southern California.

Planck's first findings are the focus of a major scientific conference in Paris this week, based on 25 scientific papers that have been submitted to the journal Astronomy & Astrophysics. As impressive as all that sounds, it's just "the tip of the scientific iceberg," David Southworth, ESA's director fo science and robotic exploration, said in a statement released today.

"This catalog contains the raw material for many more discoveries," Southworth said. "Even then, we haven't got to the real treasure yet, the cosmic microwave background itself."

That big reveal is scheduled for the next data release ... in January 2013.


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