News Section | Astronomy and Space
NASA’s Hubble reveals galaxies recycle fuels to build generations of stars
Astronomers have discovered that galaxies continuously recycle immense volumes of hydrogen gas and heavy elements, thanks to new observations by NASA’s Hubble Space Telescope.
This process allows galaxies to build successive generations of stars stretching over billions of years.
This ongoing recycling keeps some galaxies from emptying their “fuel tanks” and stretches their star-forming epoch to over 10 billion years.
The astronomers’ conclusion is based on a series of Hubble Space Telescope observations that flexed the special capabilities of its Cosmic Origins Spectrograph (COS) to detect gas in the halo of our Milky Way and more than 40 other galaxies.
Data from large ground-based telescopes in Hawaii, Arizona and Chile also contributed to the studies by measuring the properties of the galaxies.
The three studies investigated different aspects of the gas-recycling phenomenon.
The COS observations of distant stars demonstrate that a large mass of clouds is falling through the giant halo of our Milky Way, fuelling its ongoing star formation.
These clouds of hot hydrogen reside within 20,000 light-years of the Milky Way disk and contain enough material to make 100 million suns.
Some of this gas is recycled material that is continually being replenished by star formation and the explosive energy of novae and supernovae, which kicks chemically enriched gas back into the halo.
Researchers also found that this gas is nearly absent from galaxies that have stopped forming stars. In these galaxies, the “recycling” process ignites a rapid firestorm of star birth, which can blow away the remaining fuel, essentially turning off further star-birth activity.
The results are published in the November 18 issue of Science magazine.
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