Stephan’s Quintet comprises five galaxies: four physically interacting members (NGC 7317, 7318A, 7318B, and 7319), located about 290 million light‑years away, plus one foreground galaxy (NGC 7320) just ~40 million light‑years distant.
NGC 7320 (upper-left in most images), being much closer, reveals individual resolved stars. Its disk glows with blue and pink star-forming clumps (H II regions) indicating active star birth.
This portrait of Stephan’s Quintet, also known as the Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard the NASA/ESA Hubble Space Telescope. Stephan’s Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy that is about seven times closer to Earth than the rest of the group. (Photo: NASA, ESA and the Hubble SM4 ERO Team)
The four interacting galaxies display:
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Blue star clusters and pink hydrogen emission clouds, marking very young stars (<10 Myr old) in newly triggered starbursts.
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Long tidal tails and distorted spiral arms, populated with numerous star clusters and gas-rich regions, formed by gravitational interactions and collisions.
NGC 7319 (upper-right) is a barred spiral with spiral arms traced by blue dots (star clusters) and red spots near its core—representing clusters of thousands of stars and dust-rich ISM region.
NGC 7318A/B appear as a two-core system where one galaxy (7318B) is colliding through the group, generating shocked gas, young blue clusters, and hydrogen‑rich star‑forming regions in its wake.
NGC 7317 (bottom-left) is an elliptical galaxy with an older stellar population and relatively undisturbed by interactions—fewer active star-forming regions than the others