To reveal the X shape in the Milky Way’s central bulge, researchers took WISE observations and subtracted a model of how stars would be distributed in a symmetrical bulge.

(NASA/JPL-Caltech/D.Lang)

At a Glance

A post to Twitter by one astronomer led to an unlikely collaboration between two astronomers.The collaboration led to strongest evidence yet of a mysterious X-shaped structure formed by stars at the center of the Milky Way.

What began as a map of the galaxy posted to Twitter by an astronomer led to an important discovery.

With that tweet, an unlikely collaboration with a second astronomer was born and the two uncovered the strongest evidence yet of a mysterious X-shaped structure formed by stars at the center of the Milky Way, according to a by the University of Toronto.

Researchers have long suspected that there was an X-shaped structure based on some computer models and observations of other galaxies, as well as of our own, but no one had observed it directly. Other astronomers have argued that "previous research that pointed indirectly to the existence of the X could be explained in other ways," according to the press release.

Tweet Leads to Confirmation

On May 7, 2015, astronomer Austin Lang of the University of Toronto's Dunlap Institute tweeted a photo from his of galaxy maps, compiled from 150-gigapixels-worth of infrared images from NASA's Wide-field Infrared Survey Explorer (WISE) space telescope.

Lang's tweet caught the attention ofMelissa Ness, a postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany, and lead author of the paper published by the two astronomers in the July issue of the , confirming the existence of the stellar X.

“Ness saw the tweet and immediately recognized the importance of the X-shaped structure,” Lang said in the statement. “We arranged to meet at an upcoming conference we were both attending. The paper was born from that meeting. That’s the power of large surveys and open science!”

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In 2010, NASA's Wide-field Infrared Survey Explorer (WISE) mission observed the entire sky twice. Astronomers used these data to point out the X-shaped structure in the bulge of the Milky Way, contained in the small circle at center, as well as the inset image. The circled central portion covers roughly the area of sky that would be blocked by a basketball when held out at arm’s length.

(NASA/JPL-Caltech/D.Lang)

The scientists used original WISE imagery to reveal the actual X shape at the galaxy’s center, according to NASA.

Ness said the central bulge of stars further increases knowledge of the structure and history of our galaxy.

"The bulge is a key signature of formation of the Milky Way," she said."If we understand the bulge, we will understand the key processes that have formed and shaped our galaxy."

The X-Structure Explained

The Milky Way is a type of "disk" galaxy that generally has a “stellar bar" consisting of dense stars moving in a box-shaped orbit around the center.

The astronomers suggest that the stellar X was formed when the bars collapsed at the center of our galaxy after becoming unstable.

NASA says a bulge can also form when galaxies merge, but the Milky Way has not merged with any large galaxy in at least 9 billion years.

"We see the boxy shape and the X within it clearly in the WISE image, which demonstrates that internal formation processes have driven the bulge formation," Ness said. "This also reinforces the idea that our galaxy has led a fairly quiet life, without major merging events since the bulge was formed, as this shape would have been disrupted if we had any major interactions with other galaxies."

Lang said the collaboration enabled him to enter into anew field of research because of the tweets he posted. He generally sticks to researchinglarge-scale astronomical phenomena rather than the dynamics and structure of the Milky Way.

Apparently, Twitter can be far more than just a place to post cute pictures of animals and grumble about the state of the world. It can change the way we see our universe, some would say.