Irregular Galaxy NGC 4449

NGC 4449 is a relatively nearby galaxy located in the constellation Canes Venatici. It is classified as an irregular galaxy, as is the Large Magellanic Cloud, a satellite of the Milky Way. Both have distinctive bar-like shapes in their cores. In this image, hot bluish-white clusters of massive stars are seen scattered throughout the galaxy, interspersed with numerous dustier, reddish regions of current star formation. Massive dark clouds of gas and dust are silhouetted against the starlight. NGC 4449 is experiencing unusually intense star formation. Such "starbursts" usually occur in the central regions of galaxies, but NGC 4449 has more widespread star formation activity, since the youngest stars are observed both in the nucleus and in streams surrounding the galaxy. A "global" starburst like NGC 4449 resembles much older, "primordial" star-forming galaxies, which grew by merging with and accreting smaller stellar systems. It's likely that the current widespread starburst in NGC 4449 was triggered by interaction or merging with a smaller companion.