A Blue Dwarf

No, not a Smurf, a galaxy, ESO 338-4. It’s a blue dwarf galaxy about 100 million light-years away in the constellation Corona Australis. Blue compact dwarf galaxies have intensely blue star-forming regions twithin their cores. The young, blue stars in the cloud of dust and gas ate the center of this image were formed as a result of a merger between a wandering galaxy and ESO 388-4. That interaction disrupted the clouds of gas and dust surrounding ESO 338-4 which caused the rapid formation of a new population of stars.

Image Credit: ESA / NASA

A Blue Compact Dwarf

True blueThis about a kind of galaxy, not a smurf. The blue cluster of stars in this Hubble Space Telescope picture is a galaxy known as UGC 11411. It’s a kind of galaxy known as an irregular blue compact dwarf (BCD) galaxy. BCD galaxies are about a tenth of the size of a typical spiral galaxy such as the Milky Way. They’re made up of large clusters of hot, massive stars that ionize the surrounding gas with their intense radiation. Because these stars are so hot they glow brightly blue hue. The stars in UGC 11411 are very young by stellar standards, only around 10 million years or so. They were created during a starburst, a galaxy-wide episode of furious star formation. UGC 11411 has an extremely high star formation rate, even for a BCD galaxy.

Because BCDs don’t contain either a lot of dust or the heavy elements that are typically found as trace elements in recently formed stars, their composition is very similar to that of the material from which the first stars formed in the early universe. This makes BCD galaxies to be good objects to study to improve our understanding of the primordial star-forming processes in the early history of the Universe.

The bright stars in the image are in our own Milky Way galaxy.

Image Credit: ESA / NASA