For a couple of weeks before the holidays I spent some time working with the guys out at Gemini Observatory on the press release that accompanied this great picture of NGC 6946. It was taken using the Gemini North telescope on Mauna Kea, Hawaii on August 12, 2004 and I first saw it sometime last fall when the public information office sent it to me as part of a press package they wanted me to edit. Cool stuff, really! If you look at the image, you can make out dozens and dozens of red splotches of light scattered throughout the spiral arms. These are starbirth regions, and over the next millions of years they’ll be ablaze with the light from hot young stars.
What you don’t see in a single image like this, however, is the incredibly active rate at which massive stars are blowing up as supernovae. In fact, this galaxy has stars that have been, as scientist Jean-Rene Roy says, “exploding like a string of firecrackers!”
That makes sense for a galaxy that is just swarming with star-formation sites. Eventually all those hot, massive young stars evolve into old, massive ones that are the most likely to explode as supernovae. If we had incredibly long lifetimes, like say billions of years long, we could watch NGC 6946 go through wave after wave of star formation, followed by the protracted struggles of star death.
Unfortunately we don’t, but luckily we have telescopes like Gemini to give us snapshots that show us the evidence for stellar evolution on a grand scale in a neighboring galaxy!