This is the blue compact dwarf galaxy known as Markarian 209. Because galaxies of this type are rich in gas and poor in heavy elements, astronomers use them to study star formation. Such conditions are believed to be similar to those existing in the early Universe. Markarian 209 has been studied extensively. It is filled with diffuse gas and peppered with star-forming regions towards its core. The lighter blue cloudy region towards the top right of the galaxy is filled with very young and hot newborn stars.
It was initially thought to be a young galaxy undergoing its initial period of star formation. However, research showed that Markarian 209 is actually very old. It is thought to have never had a dormant period with no stars forming that lasted for longer than 100 million years. Most of stars in Markarian 209 are quite young, under 3 million years old. Our Sun is around 4.6 billion years old.
A scattering of other bright galaxies can be seen across the frame of this Hubble image, including the bright golden oval that could be mistaken as part of Markarian 209 but is in fact a background galaxy.
Image Credit: ESA / NASA
Acknowledgement: Nick Rose