Astronomers have released a beautiful photo taken by the NASA/ESA Hubble Space Telescope of the dwarf irregular galaxy NGC 5238.
This Hubble image shows NGC 5238, a dwarf irregular galaxy located 14.5 million light-years away in the constellation Canes Venatici. The color image is made up of observations from Hubble’s Advanced Camera for Surveys (ACS) in the near-infrared and optical parts of the spectrum. Two filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / F. Annibali.
NGC 5238 resides approximately 14.5 million light-years away from Earth in the constellation of Canes Venatici.
Also known as Mrk 1479 or UGC 8565, the galaxy’s unexciting, blob-like appearance resembles more an oversized star cluster than a galaxy.
“NGC 5238 is theorized to have recently — here meaning no more than a billion years ago — had a close encounter with another galaxy,” the Hubble astronomers said in a statement.
“The evidence for this is the tidal distortions of NGC 5238’s shape, the kind produced by two galaxies pulling on each other as they interact.”
“There’s no nearby galaxy which could have caused this disturbance, so the hypothesis is that the culprit is a smaller satellite galaxy that was devoured by NGC 5238.”
“Traces of the erstwhile galaxy might be found by closely examining the population of stars in NGC 5238, a task for which Hubble is an astronomer’s best tool.”
“Two tell-tale signs would be groups of stars with properties that look out of place compared to most of the galaxy’s other stars, indicating that they were originally formed in a separate galaxy, or stars that look to have all formed abruptly at around the same time, which would occur during a galactic merger.”
“Despite their small size and unremarkable appearance, it’s not unusual for dwarf galaxies like NGC 5238 to drive our understanding of galaxy formation and evolution,” the astronomers said.
“One main theory of galaxy evolution is that galaxies formed ‘bottom-up’ in a hierarchical fashion: star clusters and small galaxies were the first to form out of gas and dark matter, and they gradually were assembled by gravity into galaxy clusters and superclusters, explaining the shape of the very largest structures in the Universe today.”
“A dwarf irregular galaxy like NGC 5238 merging with an even smaller companion is just the type of event that might have begun this process of galaxy assembly in the early Universe.”
“So, it turns out that this tiny galaxy may serve as a test of some of the most fundamental predictions in astrophysics.”
