Strange Hyperactive Galaxies Spotted by Hubble Telescope

By SPACE.com Staff
Space.com | SPACE.com – 18 hrs ago

Astronomers have discovered a strange population of tiny, distant galaxies forming stars at a surprisingly rapid clip.

The researchers used the Hubble Space Telescope to spot the 69 hyperactive dwarf galaxies, which are about 9 billion light-years away from Earth. They're churning out stars so fast that their stellar population would double in just 10 million years. By contrast, it took the Milky Way 1,000 times longer to double its number of stars, researchers said.

The new results are unexpected, since they're somewhat at odds with other recent studies of ancient dwarf galaxies.

"Those studies suggest that star formation was a relatively slow process, stretching out over billions of years," study co-authorHarry Ferguson, of the Space Telescope Science Institute (STScI), said in a statement. Ferguson is co-leader of the survey that found the dwarf galaxies, which is called the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS).

"The CANDELS finding that there were galaxies of roughly the same size forming stars at very rapid rates at early times is forcing us to re-examine what we thought we knew about dwarf galaxy evolution," Ferguson added. [Hubble photo & video of new dwarf galaxies]

Tiny, active galaxies

The newly discovered dwarf galaxies are about 100 times smaller than the Milky Way, researchers said. Since it took their light 9 billion years to reach Hubble, the instrument is peering back at the early universe.

Star formation rates were higher back then than they are now, but the newfound dwarf galaxies' rates are still extraordinarily high. Hubble spotted the galaxies because radiation from their young, hot stars lit up the gas around them like a fluorescent sign, researchers said.

Dwarf galaxies are the most common type of galaxy in the universe, and astronomers believe this rapid starbirth phase is likely an important step in their evolution. The team hopes to learn more about this evolution with more Hubble data.

"As our observations continue, we should find many more of these young galaxies and gather more details on their star-forming histories," said co-author Anton Koekemoer, also of STScI.

The study will appear in a forthcoming issue of the Astrophysical Journal.

A cosmic mystery

The study suggests that hyperactive dwarf galaxies were quite common 9 billion years ago. But why they were forming stars at such rapid rates back then is still a mystery, researchers said.

Computer simulations suggest that star formation in small galaxies may be episodic, triggered initially by the cooling of gas, which collapses to form stars. Some of these stars eventually die in violent supernova explosions, heating and blowing away surrounding gas. But eventually the gas cools and collapses again, continuing the cycle, researchers said.

But simulations didn't predict such high star-forming activity.

"While these theoretical predictions may provide hints to explain the star formation in these newly discovered galaxies, the observed 'bursts' are much more intense than those reproduced by the simulations," said study lead author Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany.

NASA's $8.8 billion James Webb Space Telescope, an infrared observatory scheduled to be launched in 2018, could help solve the mystery, researchers said.

"With Webb, we’ll probably see even more of these galaxies, perhaps even pristine galaxies that are experiencing their first episode of star formation," Ferguson said. "Being able to probe down to dwarf galaxies in the early universe will help us understand the formation of the first stars and galaxies."

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Russia struggles to save Mars moon probe

By VLADIMIR ISACHENKOV - Associated Press | AP – Thu, Nov 10, 2011

MOSCOW (AP) — As Russia's space agency struggled Thursday to fix a probe bound for a moon of Mars that instead got stuck in Earth's orbit, some experts said the chances of saving the $170 million craft looked slim.

Roscosmos spokesman Alexei Kuznetsov said efforts to communicate with the unmanned Phobos-Grunt (Phobos-Ground) spacecraft hadn't brought any results yet. The probe will come crashing down in a couple of weeks if engineers fail to fix the problem.

The Phobos-Grunt was launched Wednesday and reached preliminary orbit, but its engines never fired to send it off to the Red Planet. Kuznetsov said controllers on Thursday will continue attempts to fix the probe's engines to steer it to its path to one of Mars' two moons, Phobos.

Roscosmos chief Vladimir Popovkin, said the system that keeps the spacecraft pointed in the right direction may have failed. Otherspace experts suggested that the craft's computer failure was a likely cause.

If a software flaw was the problem, scientists can likely fix it by sending new commands. Some experts think, however, that the failure was rooted in hardware and will be extremely difficult, if not impossible, to fix.

"I think we have lost the Phobos-Grunt," Vladimir Uvarov, a former top space expert at the Russian Defense Ministry, said in an interview published Thursday in the government daily Rossiyskaya Gazeta. "It looks like a serious flaw. The past experience shows that efforts to make the engines work will likely fail."

Complicating the recovery efforts, the space agency only has a few hours a day to reach the probe due to Russia's limited earth-to-space communications network. Kuznetsov said new attempts to contact the craft will be made Thursday evening.

The spacecraft is 13.2 metric tons (14.6 tons), and most of that weight, about 11 metric tons (12 tons), is highly toxic fuel.

Most experts believe the fuel will likely stay liquid if the probe comes down and would harmlessly blow up about 50 miles (80 kilometers) above ground, but some fear it may freeze, survive the fiery reentry and spill on impact.

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Hubble Uncovers Tiny Galaxies Bursting with Star Birth in Early Universe

WASHINGTON — Using its near-infrared vision to peer 9 billion years back in time, NASA's Hubble Space Telescope has uncovered an extraordinary population of young dwarf galaxies brimming with star formation. While dwarf galaxies are the most common type of galaxy in the universe, the rapid star-birth observed in these newly found examples may force astronomers to reassess their understanding of the ways in which galaxies form.

The galaxies are a hundred times less massive, on average, than the Milky Way, yet churn out stars at such a furious pace that their stellar content would double in just 10 million years. By comparison, the Milky Way would take a thousand times longer to double its star population.

The universe is estimated to be 13.7 billion years old, and these newly discovered galaxies are extreme even for the young universe — when most galaxies were forming stars at higher rates than they are today. Astronomers using Hubble's instruments could spot the galaxies because the radiation from young, hot stars has caused the oxygen in the gas surrounding them to light up like a bright neon sign.

"The galaxies have been there all along, but up until recently astronomers have been able only to survey tiny patches of sky at the sensitivities necessary to detect them," said Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany, lead author of a paper on the results being published online on Nov. 14 in The Astrophysical Journal. "We weren't looking specifically for these galaxies, but they stood out because of their unusual colors."

The observations were part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), an ambitious three-year study to analyze the most distant galaxies in the universe. CANDELS is the first census of dwarf galaxies at such an early epoch.

"In addition to the images, Hubble has captured spectra that show us the oxygen in a handful of galaxies and confirmed their extreme star-forming nature," said co-author Amber Straughn at NASA's Goddard Space Flight Center in Greenbelt, Md. "Spectra are like fingerprints. They tell us the galaxies' chemical composition."

The resulting observations are somewhat at odds with recent detailed studies of the dwarf galaxies that are orbiting as satellites of the Milky Way.

"Those studies suggest that star formation was a relatively slow process, stretching out over billions of years," explained Harry Ferguson of the Space Telescope Science Institute (STScI) in Baltimore, Md., co-leader of the CANDELS survey. "The CANDELS finding that there were galaxies of roughly the same size forming stars at very rapid rates at early times is forcing us to re-examine what we thought we knew about dwarf galaxy evolution."

The CANDELS team uncovered the 69 young dwarf galaxies in near-infrared images taken with Hubble's Wide Field Camera 3 and Advanced Camera for Surveys.

The observations suggest that the newly discovered galaxies were very common 9 billion years ago. However, it is a mystery why the newly found dwarf galaxies were making batches of stars at such a high rate. Computer simulations show star formation in small galaxies may be episodic. Gas cools and collapses to form stars. The stars then reheat the gas and blow it away, as in supernova explosions. After some time, the gas cools and collapses again, producing a new burst of star formation, continuing the cycle.

"While these theoretical predictions may provide hints to explain the star formation in these newly discovered galaxies, the observed bursts are much more intense than what the simulations can reproduce," van der Wel said.

The James Webb Space Telescope, an infrared observatory scheduled to launch later this decade, will be able to probe these faint galaxies at an even earlier era to see the glow of their stars, reveal their chemical composition, and offer better details on their formation.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. Goddard manages the telescope. STScI conducts Hubble science operations and is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.

For images and more information about Hubble and the CANDELS results, visit:

http://www.nasa.gov/hubble

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