How Twitter led the way to finding the Milky Way's giant “X”
Prompted by a series of tweets, a pairof astronomers have used data from NASA's Wide-field Infrared SurveyExplorer (WISE) orbital telescope to identify an image of a massive"X"-shaped star formation located in our galaxy's central bulge.The feature had been picked up in previous studies that observed thegalactic center, but this is the first ever instance of an actualimage of the unexplained phenomenon.
Our Milky Way is what is known as aspiral galaxy, and planet Earth is located in the OrionSpur of the Perseus spiral arm. While we know in general terms wherewe are, and what form our galaxy takes, we are constantly discoveringclues that point to the evolutionary path taken by the Milky Way.Occasionally, we uncover a new large scale structural feature of ourgalaxy, which reveals itself as our methods of observing the heavensmature.
The latest large scale discoveryregarding the structure of the Milky Way has its routes in anunlikely source ... a series of tweets. It all began in May 2015 when Dustin Lang, an astronomer from the University of Toronto, shared a series of images created from infrared data captured by theWISE telescope.
The infrared capabilities of WISE hasallowed astronomers to peer through the interstellar clouds of dustand gas that characterise visible light images of our Milky Way, andobserve bounty of cosmic objects that lurk behind the veil. Lang hadposted the images to his Twitter feed following the culmination of aprevious study he had undertaken attempting to map the disposition ofnearby galaxies.
It didn't take long for astronomers tocomb through the tweets and further infrared data from WISE that wasmade available via an interactive website, and to begin commenting on an apparent "X" shaped formation ofstars in the central bulge.
Acentral bulge is a feature shared by many spiral galaxies, whichoccurs when the central bar of a spinning galaxy buckles due to instabilities that creep in overtime. This partial deformation leads to stars traversing an orbitthat lays perpendicular to the disk of the galaxy. The Milky Way'scentral bulge appears somewhat like an American football when viewedfrom Earth, and it is within this feature that the "X" shapedstar formation was discovered.
Postdoctoralresearcher Melissa Ness, of the Max Planck Institute for Astronomy,Heidelberg, Germany, was among the astronomers who took note of theoddity. Ness contacted Lang, and soon after the two embarked on acollaboration aimed at analyzing the unusual "X"-like feature.Their work has effectively confirmed the presence of the "X"structure in the central bulge.
"To me, this study is an exampleof the interesting, serendipitous science that can come from largedata sets that are publicly available," comments Lang. "I'mvery pleased to see my WISE sky maps being used to answer questionsthat I didn't even know existed."
The discovery provides evidence for theargument that the Milky Way has experienced no large scale galacticmergers in the past 9 billion years, as any collision during thistime frame would have significantly disturbed the "X" formation.
In more general terms, discoveries of features such as this allowastronomers to hone our understanding of the formation of our galaxy,and others like it, by developing new theories, or adapting existingones to account for a new element, and discarding those that donot.
Astronomers are now engaged in furtherresearch aimed at discerning the composition of the many stars thatmake up the "X" feature.