Markarian 209, pictured here, might more closely resemble a nebula or a cluster than a galaxy, but indeed it is a small, compact dwarf galaxy astronomers use to ascertain how galaxies evolved in the early universe.
Markarian 209 is highly effective in this task, since it’s gas rich and lacking in elements heavier than hydrogen and helium. Specifically, it contains vast reservoirs of diffuse gas, with numerous patches of newly-formed stars forging toward its core. These patches are realized in this new image of the galaxy, which shows that Markarian 209 is currently undergoing a starburst phase (seen predominantly in the cloudy blue region in the upper-right).
However, unlike most other Markarian galaxies, which are usually young and bright at ultraviolet wavelengths, Markarian 209 is quite old, yet it shows no signs of slowing down. In fact, researchers believe the galaxy has almost continuously churned out large amounts of new stars over the course of its existence. It shows no evidence of a dormant period lasting longer than 100 million years.
Most of the stars in the galaxy are just 3 million years old (meaning, they are virtual newborns, cosmologically speaking). For the sake of comparison, our sun is well over 4 billion years old, about halfway through its lifespan. It will progress into a red giant in another four billion years, and it will end its life as a white, and then a black, dwarf.
According to the ESA, “The observations used to make this image were taken using Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys, and span the ultraviolet, visible, and infrared parts of the spectrum. A scattering of other bright galaxies can be seen across the frame, including the bright golden oval that could, due to a trick of perspective, be mistaken as part of Markarian 209 but is in fact a background galaxy.”
See a larger image here.