NGC 5195, The Dot Under the Question Mark

“Dwarf galaxy NGC 5195 is best known as the smaller companion of spiral M51, the Whirlpool galaxy. Seen together they seem to trace the curve and dot of a cosmic question mark, recorded in Lord Rosse’s 19th century drawings as one of the original spiral nebulae. Dwarfed by enormous M51 (aka NGC 5194), NGC 5195 spans about 20,000 light-years. A close encounter with M51 has likely triggered star formation and enhanced that galaxy’s prominent spiral arms. Processed from image data available in the Hubble Legacy Archive, this majestic close-up of NGC 5195 makes it clear that the dwarf galaxy now lies behind M51. A tidal bridge of dark dust clouds and young blue star clusters stretches from the outskirts of M51 on the right, appearing in silhouette against the dwarf galaxy’s yellowish glow. The famous pair of interacting galaxies lie some 30 million light-years away, toward the handle of the Big Dipper, and the constellation of the Hunting Dogs”


NGC 5195

NGC 5195 is a dwarf galaxy located about 30 million light years away towards the constellation Canes Venatici, the Hunting Dogs. It is the companion to the Whirlpool Galaxy, M51, a much larger spiral galaxy. NGC 5195 only spans 20,000 light years.

NGC 5195 is passing behind the Whirlpool galaxy. As it glides by, its gravity pulls at the larger galaxy, generating waves that compress gas in the spiral arms. This triggers star formation in the galaxy. Some of the gas and stars from the Whirlpool galaxy stretch out in a tidal tail towards NGC 5195, visible in this image.

Image from NASA, information from ESA.

Galactic Tides - The Whirlpool Galaxy And Its Companion 

Astrophysicists were able to determine that the Whirlpool Galaxy (M51) and its small companion galaxy (NGC 5195) are tidally entwined by analyzing the light emitted from Supernova within M51. These Supernova have provided important clues about the structure and composition of these galaxies.

Credit: Cornell Astrophysics/NASA Hubble/IPAC