| Sep 11, 2017 |
Astronomers spun up by galaxy-shape finding |
| (Nanowerk News) For the first time astronomers have measured how a galaxy's spin affects its shape. |
| It sounds simple, but measuring a galaxy's true 3D shape is a tricky problem that astronomers first tried to solve 90 years ago. |
| "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," said research team leader Dr Caroline Foster of the University of Sydney, who completed this research while working at the Australian Astronomical Observatory. |
| The study is published today in the journal Monthly Notices of the Royal Astronomical Society ("The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies"). |
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| These are galaxies from the SAMI survey, imaged with Japan's Subaru telescope. (Image: D. Taranu (University of Western Australia), C. Foster (University of Sydney), NAOJ (the National Astronomical Observatory of Japan)) (click on image to enlarge) |
| Galaxies can be shaped like a pancake, a sea urchin or a football, or anything in between. |
| Faster-spinning galaxies are flatter than their slower-spinning siblings, the team found. |
| "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. |
| The team made its findings with SAMI (the Sydney-AAO Multi-object Integral field unit), an instrument jointly developed by The University of Sydney and the Australian Astronomical Observatory with funding from CAASTRO, the ARC Centre of Excellence for All-sky Astrophysics. |
| SAMI gives detailed information about the movement of gas and stars inside galaxies. It can examine 13 galaxies at a time and so collect data on huge numbers of them. |
| Dr Foster's team used a sample of 845 galaxies, over three times more than the biggest previous study. This large number was the key to solving the shape problem. |
| Because a galaxy's shape is the result of past events such as merging with other galaxies, knowing its shape also tells us about the galaxy's history. |
| Source: University of Sydney |
