H-alpha Tail of D100

Long Streamer of Hydrogen Gas Trails Behind Plunging Galaxy

A long streamer of hydrogen gas is being stripped from the spiral galaxy D100 as it plunges toward the center of the giant Coma galaxy cluster. This wide view is a composite of the Hubble Space Telescope's visible-light view of the galaxy combined with a photo of a glowing red streamer of hydrogen gas taken by the Subaru Telescope in Hawaii.

The narrow funnel-shaped feature emanating from the galaxy's center is the red glow of hydrogen gas. This glowing tail extends for nearly 200,000 light-years, but the pencil-like structure is comparatively narrow – only 7,000 light-years wide. The tail's clean edges and smooth structure suggests that magnetic fields play a prominent role in shaping it.

Hubble's sharp vision uncovered the blue, glowing clumps of young stars in the tail. The brightest clump, near the middle of the tail [the blue feature], contains at least 200,000 stars, triggered by the ongoing gas loss from the galaxy.

The gas-loss process occurs when a galaxy, due to the pull of gravity, falls toward the dense center of a massive cluster of thousands of galaxies. During its plunge, the galaxy plows through intergalactic material, like a boat moving through water. This material pushes gas and dust out of the galaxy. Once the galaxy loses all of its gas – its star-making fuel – it can no longer create new stars. The gas-stripping process in D100 began roughly 300 million years ago.

The reddish galaxies in the image contain older stars between the ages of 500 million to 13 billion years old. One of those galaxies is D99, just below and to the left of D100. It was stripped of its gas by the same process as the one that is siphoning gas from D100. The blue galaxies contain a mixture of young and old stars. Some of the stars are less than 500 million years old.

The Coma cluster is located 330 million light-years from Earth.

This image is a blend of several exposures taken in visible light between May 10 and July 10, 2016, and November 2017 to January 2018, by Hubble's Advanced Camera for Surveys. Researchers overlaid an image of the glowing, red, hydrogen tail, taken in visible light between April 28 and May 3, 2006, by the Subaru Telescope's Subaru Prime Focus Camera (Suprime-Cam) in Hawaii.