Twin Galaxies Set For Collision Form Stunning Butterfly-Shaped Nebula

The giant gas cloud hides a dark secret: it stops new stars from emerging in the evolving galaxy.

Composite of Hubble data depicting the butterfly-shaped nebula of galaxy NGC 6240.
NASA

The giant gas cloud hides a dark secret: it stops new stars from emerging in the evolving galaxy.

In 2015, NASA released a smashing Hubble image of the majestic NGC 6240 galaxy, which is, more accurately put, a galaxy waiting to happen. NGC 6240 actually describes two twin galaxies on the verge of colliding that will eventually give way to a single large galaxy.

These twin galaxies, found in the final stages before their imminent merger, are “talking” to each other in a violent interaction of gas and dust clouds. The result: a beautiful giant cloud in the shape of a butterfly’s wings.

Although magnificent and luminous in appearance, this butterfly-shaped gas cloud has a dark side to it, reveals a new study published on April 18 in the journal Nature.

The research, conducted by scientists from the University of Colorado Boulder, examined the giant nebula and found that it has a deep effect of newly emerging stars within the NGC 6240 galaxy, ScienceDaily reports.

“We dissected the butterfly,” said study leader Francisco Muller-Sanchez of the university’s department of Astrophysical and Planetary Sciences (APS).

It seems the butterfly-shaped gas cloud thwarts the production of new stars inside the forming galaxy, or at least it considerably slows it down, CU Boulder Today explains in a news release.

Here’s how it all happens.

Each of the twin galaxies hides a supermassive black hole in its core. Since they are headed for collision, these too will ultimately blend into a single, even larger black hole.

However, since this has yet to happen, NGC 6240 — located just 400 million light-years away in the constellation Ophiuchus — is currently one of the few galaxies with two supermassive black holes at their centers.

The twin black holes are whirling around each other, spewing “distorted tidal tails of stars, gas, and dust,” shows NASA, painting a tragic picture of their impending collision.

As the two dying galaxies are gradually molded into something new, their furious interaction shoots off “bubbles and jets of gas” from galaxy NGC 6240, which reach out more than 30,000 light years into space, details CU Boulder Today.

When observed from a distance, all of this raging turmoil of death and new birth creates a staggering visual effect that resembles the wings of a butterfly in flight.

“Galaxies with a single supermassive black hole never show such a phenomenal structure,” indicates Muller-Sanchez.

His study unveiled that the butterfly-shaped nebula was created under the action of two different forces: stellar winds produced by stars within NGC 6240 and a cone of gas and galactic dust expelled from the merging black holes.

According to Muller-Sanchez, this phenomenon is unique to galaxy NGC 6240 and has never been documented before.

“This is the first galaxy in which we can see both the wind from the two supermassive black holes and the outflow of low ionization gas from star formation at the same time,” he said.

The downside is that these two winds push out a staggering amount of gas, thereby depriving the galaxy of the materials it needs to create new stars.

Each year, the confrontation of the two winds that go rampant inside the butterfly nebula kicks out gases amounting to about 100 times the mass of our sun, note the researchers.

But maybe it’s not all bad, says study co-author Julie Comerford, APS assistant professor.

“NGC 6240 is in a unique phase of its evolution,” Comerford points out.

Just like any new forming galaxy, it is undergoing “fast and furious bursts of star formation,” NASA explains.

In order to let this frenzy subside, NGC 6240 “needs the extra strong kick of two winds to slow down that star formation and evolve into a less active galaxy,” Comerford believes.