The tadpole galaxy LEDA 36252 is a rarely seen form of galaxy, and astronomers are still questioning the nature of these enigmatic celestial objects. Seen in a new image from the Hubble Space Telescope, this family of stars, also known as KISO 5639, resembles an immature frog swimming through the blackness of space.
Tadpole galaxies derive their name from their bright heads and lengthy tails. Most modern galaxies fall into two categories — spiral, like our own Milky Way, or elliptical. Today, only one in 500 galaxies are classified as tadpoles, but this form was more common in the early universe.
"I think Kiso 5639 is a beautiful, up-close example of what must have been common long ago. The current thinking is that galaxies in the early universe grow from accreting gas from the surrounding neighborhood. It's a stage that galaxies, including our Milky Way, must go through as they are growing up," said Debra Elmegreen of Vassar College, lead researcher on the project that recorded the image.
Astronomers hope that by studying this object, they can learn more about the evolution of galaxies, including how gas gathers together in the systems, the processes which form globular clusters and starbursts — areas rich in rapid star formation.
The Wide Field Planetary Camera aboard the Hubble, fitted with a series of filters, was utilized to capture the new image. These filters allow astronomers to carefully measure the distribution of various gases and other materials throughout the target object. Researchers found the head of the galaxy contained fewer heavier components than the tail.
Dozens of clusters of young stars were found in the head of the galaxy, which stretches 2,700 light-years from one side to the other. The young stars in these areas are three to six times more massive than stellar bodies seen elsewhere in the galaxy.
These stars were formed less than 1 million years ago compared to ages between several million and a few billion years old elsewhere in the galaxy. The star birth was likely formed when the galaxy encountered a filament of gas less than 1 million years ago, driving the starburst.
Massive holes seen in the material between the stars in the head of KISO 5639 were formed from the explosions of supernovae — like fireworks within the massive body.
Oddly, there is one particular object called the Tadpole Galaxy, but it is, in fact, a spiral. This system of stars received its name in honor of its elongated appearance.
Analysis of the new image from Hubble was detailed in The Astrophysical Journal.