Monday, November 16

Showtime: 7:00 PM

Chautauqua Community House

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New observations with Hubble’s Cosmic Origins Spectrograph, or COS, show that normal spiral galaxies are surrounded by halos of gas that can extend over one million light-years in diameter. The current estimated diameter of the Milky Way, for example, is about 100,000 light-years, with one light-year covering roughly six trillion miles.

John Stocke of the University of Colorado Boulder’s Astrophysical and Planetary Sciences Department will discuss how understanding how the material within these galaxy halos in many ways is the “missing link” in galaxy evolution that we need to understand in detail in order to have a complete picture of this evolutionary process.

The halo material, detected by a CU Boulder team, originally was ejected from galaxies by exploding stars known as supernovae, a product of the star formation process. This gas is stored and recycled through an extended galaxy halo, falling back onto the galaxies to reinvigorate a new generation of star formation.

Building on earlier studies identifying oxygen-rich gas clouds around spiral galaxies by scientists at the Space Telescope Science Institute in Baltimore, the University of Massachusetts, Amherst College and the University of California, Santa Cruz, Stocke and his colleagues determined that such clouds contain almost as much mass as all the stars in their respective galaxies, a finding the team determined to have significant consequences for how spiral galaxies change over time.