In the Middle

The downtown of a major city is bold, bright, busy — and crowded. And the same thing applies to galaxies. The downtown of our home galaxy, for example, is packed with millions of stars. Some of them are among the biggest and brightest in the entire Milky Way. And new stars are entering the picture at an impressive rate.

The center of the Milky Way is in the constellation Sagittarius. It’s in the southeast in early evening, and its stars form the outline of a teapot. The center of the galaxy is in the “steam” of faint stars above the spout of the teapot.

Astronomers aren’t sure just how far away “downtown” really is. Estimates range from about 23,000 to 30,000 light-years. A study last year came up with a bit less than 26,000.

The hub of the galaxy’s heart is a black hole about four million times the mass of the Sun. It’s encircled by a faint disk of hot gas. Many stars orbit the black hole, including some that come especially close; more about that tomorrow.

Several giant star clusters are within a couple of hundred light-years of the black hole. One of them is one of the busiest nurseries in the galaxy, giving birth to many new stars. Another is the densest cluster in the galaxy, with stars packed millions of times more tightly than out here in the suburbs. And yet another contains several stars that are at least a million times brighter than the Sun — brilliant lights for “downtown” Milky Way.
 

Script by Damond Benningfield