NGC 4449

As Americans celebrate their Independence Day today, I thought we should look to the heavens to find a celestial celebration.  In the distant galaxy NGC 4449, you can find the colors red, white, and blue ablaze in new star forming regions which resemble fireworks!

NGC 4449 is also known as Caldwell 21.  It is an irregular galaxy in the constellation Canes Venatici and lies about 12 million light years away from Earth.  NGC 4449 has very active star forming regions.  The bluish white areas are clusters of hot, massive stars.  The reddish regions are areas where new stars are forming.

What makes NGC 4449 so unusual is that stellar formation is so intense that it has been classified as experiencing a global starburst event.  A starburst event means that the galaxy is having a higher than expected number of new stars forming.  Usually, starbursts occurr near the center of a galaxy.  NGC 4449 has them spread throughout it’s entire mass.

It is thought that the starburst was triggered by the gravitational interaction with a smaller companion galaxy.  There are several galaxies in the Canes Venatici group and it is highly likely that tidal influences from it’s neighbors sparked the outburst.

PHOTO CREDIT:  Hubble/ESA

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