Billions and Billions of Baby Stars

When Carl Sagan said there were billions and billions of stars, he wasn’t wrong. But just how many billions, we still don’t know.

Moreover, scientists would like to know how many of each size and type of star there is, and how our sun fits into the larger populations of stars in our galaxy and our universe.

To further that goal, astronomers recently used the CISCO infrared camera on the Subaru telescope in Hawaii to observe a region called W3 Main, a well known baby star factory. The new images revealed the area, located about 6,000 light years away in the constellation Cassiopeia, in unprecedented detail.

Studying star-forming regions is a good strategy for taking a census of stars, since most stars we see in these areas were formed at roughly the same time. When time is taken out of the equation, astronomers can get a better handle on how many stars of each mass range are formed, to discover which sizes are most common.

The new study of W3 Main found that very small stars, called Brown dwarfs, which have less mass than normal stars and don’t shine as brightly, are more common here than they seem to be in other regions of the galaxy. This finding suggests that the relative numbers of brown dwarfs may strongly vary across different areas of the Milky Way.

Most of the stars in W3 Main, however, are massive stars. These giant stars are visible as red lights at the left side of the image above. The bright clouds are made of ionized gas that reflects light from the shining stars nearby.