Subscribe free to our newsletters via your
. 24/7 Space News .




STELLAR CHEMISTRY
NASA's Spitzer Finds Distant Galaxies Grazed on Gas
by Staff Writers
Pasadena CA (JPL) Jul 01, 2011


This split view shows how a normal spiral galaxy around our local universe (left) might have looked back in the distant universe, when astronomers think galaxies would have been filled with larger populations of hot, bright stars (right). NASA's Spitzer Space Telescope discovered that distant populations of galaxies formed massive, bright stars more commonly than today's "diet-conscious" galaxies. Such early galaxies would have been brighter, bluer and more irregular than spiral galaxies today due to the large proportion of massive stars. The Spitzer observations also demonstrate that these distant galaxies fed off steady streams of gas, rather than bursts of gas stirred up from collisions with other galaxies. This artist's rendering is derived from the Hubble image of NGC 1309. Image credit: NASA/JPL-Caltech/STScI. For a larger version of this image please go here.

Galaxies once thought of as voracious tigers are more like grazing cows, according to a new study using NASA's Spitzer Space Telescope. Astronomers have discovered that galaxies in the distant, early universe continuously ingested their star-making fuel over long periods of time. This goes against previous theories that the galaxies devoured their fuel in quick bursts after run-ins with other galaxies.

"Our study shows the merging of massive galaxies was not the dominant method of galaxy growth in the distant universe," said Ranga-Ram Chary of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena, Calif.

"We're finding this type of galactic cannibalism was rare. Instead, we are seeing evidence for a mechanism of galaxy growth in which a typical galaxy fed itself through a steady stream of gas, making stars at a much faster rate than previously thought."

Chary is the principal investigator of the research, appearing in the Aug. 1 issue of the Astrophysical Journal. According to his findings, these grazing galaxies fed steadily over periods of hundreds of millions of years and created an unusual amount of plump stars, up to 100 times the mass of our sun.

"This is the first time that we have identified galaxies that supersized themselves by grazing," said Hyunjin Shim, also of the Spitzer Science Center and lead author of the paper.

"They have many more massive stars than our Milky Way galaxy."

Galaxies like our Milky Way are giant collections of stars, gas and dust. They grow in size by feeding off gas and converting it to new stars. A long-standing question in astronomy is: Where did distant galaxies that formed billions of years ago acquire this stellar fuel? The most favored theory was that galaxies grew by merging with other galaxies, feeding off gas stirred up in the collisions.

Chary and his team addressed this question by using Spitzer to survey more than 70 remote galaxies that existed 1 to 2 billion years after the Big Bang (our universe is approximately 13.7 billion years old). To their surprise, these galaxies were blazing with what is called H alpha, which is radiation from hydrogen gas that has been hit with ultraviolet light from stars.

High levels of H alpha indicate stars are forming vigorously. Seventy percent of the surveyed galaxies show strong signs of H alpha. By contrast, only 0.1 percent of galaxies in our local universe possess this signature.

Previous studies using ultraviolet-light telescopes found about six times less star formation than Spitzer, which sees infrared light. Scientists think this may be due to large amounts of obscuring dust, through which infrared light can sneak. Spitzer opened a new window onto the galaxies by taking very long-exposure infrared images of a patch of sky called the GOODS fields, for Great Observatories Origins Deep Survey.

Further analyses showed that these galaxies furiously formed stars up to 100 times faster than the current star-formation rate of our Milky Way. What's more, the star formation took place over a long period of time, hundreds of millions of years. This tells astronomers that the galaxies did not grow due to mergers, or collisions, which happen on shorter timescales.

While such smash-ups are common in the universe - for example, our Milky Way will merge with the Andromeda galaxy in about 5 billion years - the new study shows that large mergers were not the main cause of galaxy growth. Instead, the results show that distant, giant galaxies bulked up by feeding off a steady supply of gas that probably streamed in from filaments of dark matter.

Chary said, "If you could visit a planet in one of these galaxies, the sky would be a crazy place, with tons of bright stars, and fairly frequent supernova explosions."

.


Related Links
Spitzer
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








STELLAR CHEMISTRY
Making a Spectacle of Star Formation in Orion
Pasadena CA (JPL) Jul 01, 2011
Looking like a pair of eyeglasses only a rock star would wear, this nebula brings into focus a murky region of star formation. NASA's Spitzer Space Telescope exposes the depths of this dusty nebula with its infrared vision, showing stellar infants that are lost behind dark clouds when viewed in visible light. Best known as Messier 78, the two round greenish nebulae are actually cavities ca ... read more


STELLAR CHEMISTRY
NASA puts space probe into lunar orbit

ARTEMIS Spacecraft Prepare for Lunar Orbit

LRO Showing Us the Moon as Never Before

CMU and Astrobotic Technology Complete Structural Assembly of Lunar Lander

STELLAR CHEMISTRY
New Animation Depicts Next Mars Rover in Action

Islands of Life - Part One

Opportunity Getting Closer to Endeavour Crater

NASA Mars Rover Arrives in Florida After Cross-Country Flight

STELLAR CHEMISTRY
Expert's reentry flap endures hot baptism

Charles Bolden National Press Club Address - July 1

Spend your summer in space...at the Science Museum

Sierra Nevada Space Systems Completes Milestones For Commercial Crew Program

STELLAR CHEMISTRY
China to launch new communication satellite

China's second moon orbiter Chang'e-2 goes to outer space

Building harmonious outer space to achieve inclusive development

China's Fengyun-3B satellite goes into official operation

STELLAR CHEMISTRY
Training for ISS flight operations

Space junk narrowly misses station

Improving Slumber on the Space Station With Sleep-Long

ATV-2: re-entry over the south Pacific

STELLAR CHEMISTRY
Minotaur Rocket Launch from NASA Wallops Re-Scheduled

Parallel Ariane 5 launch campaigns keep up Arianespace's 2011 mission pace

Ariane 5 payload integration underway; First Soyuz launchers arrive

Arianespace to launch Astra 5B satellite

STELLAR CHEMISTRY
Microlensing Finds a Rocky Planet

A golden age of exoplanet discovery

CoRoT's new detections highlight diversity of exoplanets

Rage Against the Dying of the Light

STELLAR CHEMISTRY
Japan's Ricoh to buy Pentax digital camera brand

'Dirty hack' restores Cluster mission from near loss

BAE to support Royal Navy radars

Apple-Microsoft group pays $4.5 bn for Nortel patents




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement