October 30, 2012
The Fireworks Galaxy, a spiral galaxy in Cepheus and Cygnus
Image Credit & Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona (http://www.caelumobservatory.com/index.html)
Today it’s my birthday, so let’s have a party with fireworks!!
The Fireworks Galaxy (also known as NGC 6946, Arp 29, or Caldwell 12) is an intermediate spiral galaxy of about 20,000 light-years across, located just some 10 million light-years away, on the border between the constellations of Cepheus and Cygnus, and is moving away from us at approximately 45 kilometers per second.
The galaxy is undergoing a tremendous burst of star formation with no obvious cause. In many cases spirals light up when interacting with another galaxy, but this galaxy appears relatively isolated in space. An explanation for the high star formation rate is the recent accretion of many primordial low-mass neutral hydrogen clouds from the surrounding region.
The center of the Fireworks galaxy is home to a nuclear starburst itself, and picturesque dark dust lanes are seen lacing the disk, and it has widespread high-velocity clouds associated with the disk. The colors of the galaxy change from the yellowish light of old stars in the center to young, bright blue star clusters and reddish star-forming regions along its spiral arms. has widespread high-velocity clouds associated with the disc
NGC 6946 is called the “Fireworks Galaxy” because so many supernovae have been spotted there in the last hundred years. Nine supernovae (SN 1917A, SN 1939C, SN 1948B, SN 1968D, SN 1969P, SN 1980K, SN 2002hh, SN 2004et, and SN 2008S) have been observed in the galaxy. With this number of supernovae, NGC 6946 is leading the statistics, just one SN more than follow-up M83, the Southern Pinwheel galaxy.
The Fireworks galaxy is highly obscured by interstellar matter of our own Milky Way galaxy, as it is quite close to the galactic plane.