The most detailed three-dimensional map yet of the Milky Way has been revealed, showing that our galaxy is not a flat disc but has a “warped” shape like a fascinator hat or a vinyl record that has been left in the sun.
“The stars 60,000 light years away from the Milky Way’s centre are as far as 4,500 [light years] above or below the galactic plane – this is a big percentage,” said Dr Dorota Skowron of the University of Warsaw, first author of the latest research.
Both the new study and an earlier one published in February, which found a similar shape, are based on the distribution across the galaxy of stars known as Cepheids – bodies whose brightness varies in a regular cycle over time. This phenomenon of dimming and brightening is the key to creating the maps.
While a star might be fainter because it is further away, it could also be because it is less luminous. For Cepheids, the maximum brightness of the star is related to the length of time the cycle of brightening and dimming takes, with brighter Cepheids having longer cycles. By comparing this intrinsic brightness with how bright the star appears to be, researchers can work out how far away a Cepheid is. [Continue reading…]