An Odd Dwarf : The Sky Rocket Galaxy

Kiso 5639A firestorm of star birth is lighting up one end of the diminutive galaxy Kiso 5639. The dwarf galaxy is shaped like a flattened pancake, but because we see it edge-on, it resembles a skyrocket with a blazing head and a long tail.

Kiso 5639 is rare among nearby galaxies. It’s an example of a sort of elongated galaxies that occur in abundance at larger distances, where we observe the universe during earlier epochs. The bright gas in the galaxy’s head contains fewer heavier elements (referred to as “metals” by astronomers) such as carbon and oxygen than the rest of the galaxy. Stars consist mainly of hydrogen and helium, but cook up other “heavier” elements. When the stars die, they release their heavy elements and enrich the surrounding gas.

The galaxy, located 82 million light-years away, has taken billions of years to develop because it has been drifting through an isolated “desert” in the universe, devoid of much gas. Several dozen clusters of stars have been observed in the galaxy’s star-forming head, which spans 2,700 light-years across. These clusters have an average age of less than a million years. Other star formation is taking place throughout the galaxy but on a much smaller scale. Star clusters in the rest of the galaxy are between several million to a few billion years old. Observations suggest that less than a million years ago, Kiso 5639’s leading edge encountered a filament of gas in intergalactic space. The filament could have lost a large amount of matter the galaxy, stoking the vigorous star birth.

Image Credit: NASA

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