Galaxies come in all shapes and sizes. We have wonderful, well-structured spirals. Between them are fuzzy elliptical galaxies and lenticular patches. Among all these variations there are galaxies that are a little weird, with some quirks that give them something special. And one of these unusual galaxies is the subject of a new galaxy portrait taken by the James Webb Space Telescope.

It’s called NGC 3256, and it may look like a fairly standard spiral galaxy. But NGC 3256 bears evidence of a violent past: a collision and merger between two galaxies that led to an ongoing burst of star formation that destroyed their interstellar dust and clouds.

Although there is quite a bit of empty space, the galaxies are slowly pulled by the invisible threads of the cosmic web, where they collide and merge to form larger galaxies. This is a fairly routine part of galactic evolution, and NGC 3256, a Milky Way-sized galaxy about 120 million light-years away, illustrates its effects nicely.

One such effect is long tails of matter emanating from the galaxy and spiraling out towards each other during the gravitational dance.

Another effect is the rate of star formation.

Stars are born in huge, dense clouds of dust and gas. When the mass of this material becomes dense enough, it collapses under the influence of gravity to form a star seed, which then grows and becomes stronger, feeding the cloud that surrounds it. During a galactic merger, the molecular clouds in the two galaxies collide and merge, compressing the gas to form clumps much larger than normal.

These clouds turn into star formation like fireworks, but there is a problem. The clouds around them are very thick and opaque, which means we cannot see them at shorter wavelengths.

But the JWST is an infrared instrument, meaning it can detect light at longer wavelengths that can pass through dust clouds without scattering as visible light does. That way, it can see signs of star formation that devices like Hubble can’t.

The 2018 Hubble image of NGC 3256 shows dark dust lanes. (NASA/ESA)
In the new JWST image, these markings appear red and orange as the dust absorbs infrared starlight. As you can see, there’s quite a bit of it, and it neatly overlaps with the dark dust lanes visible in Hubble’s field of view.

This makes NGC 3256 what we classify as a starburst galaxy. Scientists estimate that about 49 new solar-mass stars form each year, compared to eight or fewer in the Milky Way.

NGC 3256 is still in the process of merging. It has two galactic centers, each with its own supermassive black hole, separated by about 2,770 light-years. Eventually, they will merge to form an even larger supermassive black hole, but probably a few million years from now. While we wait for that day, NGC 3256’s nature makes it an excellent laboratory for studying the evolution of these massive mergers. Source