Taking help from Twitter, two astronomers have uncovered the strongest evidence yet that an enormous X-shaped structure made of stars lies within the central bulge of the Milky Way galaxy.
Previous computer models and observations of our own galaxy have suggested that the X-shaped structure existed.
But no one had observed it directly. Some astronomers argued that previous research that pointed indirectly to the existence of the X could be explained in other ways.
“There was controversy about whether the X-shaped structure existed. But our paper gives a good view of the core of our own galaxy. I think it has provided pretty good evidence for the existence of the X-shaped structure,” said Dustin Lang, Research Associate at the Dunlap Institute for Astronomy & Astrophysics, University of Toronto.
The Milky Way Galaxy is a barred spiral galaxy – a disk-shaped collection of dust, gas and billions of stars, 100,000 light-years in diameter.
The central bulge, like other barred galaxy’s bulges, resembles a rectangular box or peanut when viewed – as we view it – from within the plane of the galaxy.
The X-shaped structure is an integral component of the bulge.
Lang’s analysis was originally intended to aid in his research in mapping the web of galaxies beyond the Milky Way galaxy.
To help explore the maps he had developed from Nasa’s Wide-field Infrared Survey Explorer (WISE) telescope data, he created an interactive map-browsing website and tweeted an image of the entire sky.
“Melissa Ness, post-doctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, saw the tweet and immediately recognised the importance of the X-shaped structure,” Lang noted.
“The bulge is a key signature of formation of the Milky Way galaxy. If we understand the bulge we will understand the key processes that have formed and shaped our galaxy,” Ness added in a paper appeared The results appear in the Astronomical Journal.
It is also evidence that our galaxy did not experience major merging events since the bulge formed. If it had, interactions with other galaxies would have disrupted its shape.