The shape of our galaxy revealed
Ingenious research finally reveals the true shape of the Milky Way.
The Milky Way is warped and twisted, a collaboration between Australian and Chinese astronomers has established.
The three-dimensional shape of the galaxy in which Earth resides has been a mystery due to the inherent difficulties in trying to ascertain what any object looks like when restricted to making only internal measurements.
Most assumptions have proceeded by means of analogy. The galaxy is spiral so, the logic runs, it’s probably the same shape as other spiral galaxies. The closest of these is Andromeda, which is pretty much a pancake.
However, we now know it isn’t spiral at all, thanks to research led by Richard de Grijs from Macquarie University and Xiaodian Chen from Chinese Academy of Sciences in Beijing.
To accurately measure the shape of the galaxy the researchers plotted the position of 1339 Cepheids – large pulsating stars each about 100,000 times brighter than the sun. Because their brightness varies only very little, the stars functioned as reference points for the gigantic mapping exercise.
By comparing the distances between the Milky Way Cepheids and those found in other galaxies – the shapes of which can be easily confirmed through direct observation – Chen, de Grijs and colleagues discovered that our home system becomes increasingly warped and twisted as distance increases from its centre.
The researchers say their evidence “suggests that the origin of the warp is associated with torques forced by the massive inner disk”.
The research behind this finding was originally published in the journal Nature Astronomy.