Stellar Census

StarDate: March 30, 2009

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Next year is census time in the United States. But astronomers are already conducting a census of their own -- a census of all the stars in our cosmic neighborhood.

Over the last few decades, much of astronomy has focused on objects that are big, bright, and far away -- from exploding stars to superclusters of galaxies. Our own neighborhood, on the other hand, has been a bit neglected.

Yet the neighborhood is important. We can take a more complete census of all types of stars -- including small, faint ones that are hard to see at greater distances. The numbers provide important information about how stars form, and how stars and galaxies evolve.

The leading census effort is called RECONS. It's led by Todd Henry of Georgia State. It's discovered several dozen stars within about 30 light-years of Earth. Two of them are the "dead" stars known as white dwarfs -- corpses of stars that were once like our own Sun.

But most of them are red dwarfs -- stars that are much smaller and cooler than the Sun. They're so faint that not even one is visible to the unaided eye, even though they're some of the closest stars of all.

To date, the total census shows 10 stars that are hotter and more massive than the Sun, and about 60 that are similar to or a little less massive than the Sun. But the bulk of the stars are red dwarfs -- more than 250 of them.

The census isn't finding the objects known as brown dwarfs. More about that tomorrow.

Script by Damond Benningfield, Copyright 2009

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