Astronomers can now find out the shape of any galaxy, and these pictures will explain why that's awesome
If you head out into the countryside far from the light pollution generated by the urban sprawl, and look to the skies, you'll be able to see humanity's place in the Milky Way galaxy. While our Solar System lies somewhere in the Orion arm of the galaxy, we are just a mote in its eye. Galaxies come in myriad of shapes and sizes, each containing billions of stars, with superclusters containing hundreds of galaxies.
Now astronomers are looking to find the precise 3-dimensional shape of any galaxy simply by analyzing it. Researchers have been trying to do this for more than 90 years, but a lack of technology, sophisticated telescopes, and computing power, meant they have thus far been unsuccessful.
Also hampering the research has been the continuous movement of the galaxies away from each other as the universe expands. Now, a cohort of researchers from the University of Sydney, with Dr Caroline Foster as lead researcher, has finally found a way to gauge the shape of a galaxy simply by linking it to its rotation and spin speed.
"This is the first time we've been able to reliably measure how a galaxy's shape depends on any of its other properties — in this case, its rotation speed," Dr Caroline stated. The research has been published in the journal Monthly Notices of the Royal Astronomical Society.
"I guess it's the inaccessibility that drew me to this study," Dr Foster told the Sydney Morning Herald.
"It’s possible to see only the alignment of the galaxy depending on the movement it makes along its axis and through space. It’s not possible to see the entire galaxy or even a cross section."
To solve this issue, astronomers examined individual stars present within a galaxy. The data accumulated by the Coonabarabran-based multi-object integral field spectrograph known simply as SAMI was combined with the images of galaxies the astronomers already had. SAMI is used to scale the movement stars make inside a galaxy.
This discovery was made possible because of the spectrograph device used by the researchers. The movements made by the stars within a galaxy were examined over a span of time which aided in finding out the actual structure of the galaxy. The pace at which each galaxy spins was found by comparing the velocities of individual stars and the directions they moved in.
"And among spiral galaxies, which have disks of stars, the faster-spinning ones have more circular disks," said team member Professor Scott Croom of the University of Sydney as quoted by Phys.org.
This research led to the finding that galaxies that didn’t move at all, or moved at a very slow pace, had wider shapes like triaxial ellipsoids and oblate spheroids, which are not usually spotted.