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Mauna Kea scope uncovers clues to prolific star-forming galaxies

By Michael Tsai


A joint effort between the Hawaii-based Keck Observatory and the European Space Agency’s Herschel space observatory is providing an unprecedented glimpse into what had previously been the greatest extragalactic fireworks show never seen.

Through the combined capacities of the two observatories, scientists have been collecting data on hundreds of so-called “starburst” galaxies.

These highly active galaxies give birth to hundreds of solar masses’ worth of stars each year, compared to an average of “only” one new sun per year in the Milky Way.

“Starburst galaxies are the brightest galaxies in the universe and contribute significantly to cosmic star formation, so it’s important to study them in detail and understand their properties,” said Caitlin Casey, a Hubble Fellow at the University of Hawaii’s Institute for Astronomy and lead author of a study that examines the results of the joint project. The study is published in the current edition of the Astrophysical Journal.

While starburst galaxies produce enough light to greatly outshine the Milky Way, massive amounts of dust produced by the star formations absorb much of the visible light.

However, the Herschel observatory’s infrared technology is able to measure the temperature and brightness of these dusty galaxies, allowing scientists to calculate how quickly stars are formed.

Casey’s team used spectrometers on the twin Keck telescopes to obtain “red shifts” of 767 starburst galaxies.

Galaxies speeding away from our own shine with light that shifts toward the red end of the spectrum, much like a train whistle takes a lower tone when the train is moving away.

The red shift also indicates how long light from each galaxy has traveled across the universe, which provides an indication of when the light was emitted.

“The Herschel data tell us how fiercely and prolifically these galaxies are producing stars,” said Seb Oliver, a professor at the University of Sussex and principal investigator for the herMES Key Programme, which collects data from the studies. “Combining this information with the distances provided by the Keck data, we can uncover the contribution of the star-burst galaxies to the total amount of stars produced across the history of the universe.”

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