An international team of researchers have spotted the most fuel-efficient galaxy yet, which converts nearly 100 percent of its hydrogen gas into stars.
The tiny red spot in this image is one of the most efficient star-making galaxies ever observed, converting gas into stars at the maximum possible rate. Visible-light observations from NASA's Hubble Space Telescope (inset) reveal that the starlight in this galaxy is extraordinarily compact, with most of the light emitted by a region just a fraction of the size of the Milky Way galaxy.
NASA/JPL-Caltech/STScI/IRAM
EnlargeSix billion or so light years from here, there's a galaxy that seems to take seriously the old Lakota maxim about using the whole buffalo.
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Except by "use" we mean "form stars out of" and by "buffalo" we mean "interstellar hydrogen gas."?
Hydrogen gas is the fuel that galaxies use to make new stars, and most galaxies are the equivalent of a Hummer with a broken oxygen sensor, four flat tires, and a buffalo carcass strapped to the roof. Most of the gas meant to transport you gets wasted. But a new study has spotted a galaxy that is converting gas into stars at a rate hundreds of times that of our galaxy with almost 100 percent efficiency.
An international team of scientists looked at data from?NASA's Wide-field Infrared Survey Explorer (WISE) and spotted a galaxy that was just blazing with infrared radiation, equivalent, they say, to a trillion suns. Observations from the Hubble telescope confirmed that the galaxy, which is affectionately known as?SDSSJ1506+54, is extremely compact, with most of the infrared light pouring from an area that is a fraction of the size of our own Milky Way.?
The researchers then used data from the IRAM Plateau de Bure interferometer in the French Alps to detect the presence of carbon monoxide, which indicates the presence of hydrogen. By combining the gas measurements with the rate of star formation, the scientists found that the galaxy was forming stars out of the gas at a rate that is close to the theoretical maximum. Their paper, which has been accepted for publication in the Journal of Astrophysical Letters, calls it "star formation at its most extreme."
A NASA press release explains just how this galaxy is achieving such efficiency:
In regions of galaxies where new stars are forming, parts of gas clouds are collapsing due to gravity. When the gas is dense enough to squeeze atoms together and ignite nuclear fusion, a star is born. But this process can be halted by other newborn stars, as their winds and radiation blow the gas outward. The point at which this occurs sets the theoretical maximum for star formation. The galaxy SDSSJ1506+54 was found to be making stars right at this point, just before the gas clouds would otherwise be blown apart.
"We see some gas outflowing from this galaxy at millions of miles per hour, and this gas may have been blown away by the powerful radiation from the newly formed stars," said Ryan Hickox, an astrophysicist at Dartmouth College, Hanover, N.H., and a co-author on the study.
Why is this galaxy so efficient at converting hydrogen into stars while all the others are such slouches? It actually comes down to timing. We just happen to be witnessing the time period, six billion years ago, when this galaxy produces lots of stars. The researchers speculate that this period could have been triggered by the merging of two galaxies into one.?
In any case, it's a bright spot in our sky. As Discovery News's Ian O'Neill points out those living on a planet on the outskirts of this prolific star factory will have a "night" sky that is actually brighter than daylight.
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