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What Are Astronomers Doing? Week of September 6
Iron in the Wrong Place
The spectrum of an astronomical object such as a star or galaxy is like its fingerprint. Dark lines at specific wavelengths identify specific chemical elements and compounds.
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Finding the chemical composition of stars is an important part of astronomical research. The information provides a clue to how the star formed, and how it will die. Taking that information from many, many stars can even provide clues to the birth and fates of whole galaxies.
Earle Luck, a professor at Case Western Reserve University, is particularly interested in the chemical contents of nearby stars to validate models astronomers have come up with to explain how stars evolve over time.
Earle says observations usually match up with their theory, but not always. “There are a few discrepancies,” he says.
For example, some astronomers recently found stars in an area of the outer part of our Milky Way galaxy whose chemical compositions don’t match up with what theory says they should be.
When massive stars explode as supernovae, they release chemical elements made in their interiors, like iron, in the form of a gas cloud. New stars are then formed in these gas clouds. Finding the chemical composition of these new stars can tell astronomers what elements were in the gas cloud in which they formed.
According to theory, stars in the outer part of our Milky Way galaxy should contain less iron because they weren’t made from a gas cloud that contained a lot of iron. Now some astronomers have found iron-rich stars in this area of the galaxy.
Earle hopes to figure out why this region of the galaxy isn’t following the theory. He will use the 2.1-meter Otto Struve Telescope to find about 750 giant stars and 750 dwarf dwarf stars, and study their chemical compositions. He hopes to learn more which chemical elements were present in the gas cloud in which they formed, and, in turn, the conditions under which the stars formed. He hopes this work will solve the mystery of iron in the wrong place.
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