ESA & NASA's Hubble Confirms That Galaxies Recycle

Distant quasars shine through the gas-rich "fog" of hot plasma encircling galaxies. 

At ultraviolet wavelengths, Hubble's Cosmic Origins Spectrograph (COS) is sensitive to absorption from many ionized heavy elements, such as nitrogen, oxygen, and neon.

COS's high sensitivity allows many galaxies that happen to lie in front of the much more distant quasars. The ionized heavy elements serve as proxies for estimating how much mass is in a galaxy's halo.

(Credit: NASA; ESA; A. Feild, STScI).

New observations by NASA's Hubble Space Telescope are expanding astronomers' understanding of the ways in which galaxies continuously recycle immense volumes of hydrogen gas and heavy elements. 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.

This 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.

Astronomers believe that the color and shape of a galaxy is largely controlled by gas flowing through an extended halo around it. The three studies investigated different aspects of the gas-recycling phenomenon.