So, why is the Milky Way a barred spiral?
The scientists, Andrew Benson of the California Institute of Technology (Caltech) and Nick Devereux of Embry-Riddle University in Arizona, tracked the evolution of galaxies over thirteen billion years from the early universe to the present day. Their results appear in the journal Monthly Notices of the Royal Astronomical Society. Galaxies are the collections of stars, planets, gas, and dust that make up most of the visible component of the cosmos. The smallest have a few million and the largest as many as a million million (a trillion) stars. American astronomer Edwin Hubble first developed a taxonomy for galaxies in the 1930s that has since become known as the ‘Hubble Sequence‘. There are three basic shapes: • spiral, where arms of material wind out in a disk from a small central bulge, • barred spirals, where the arms wind out in a disk from a larger bar of material, • elliptical, where the galaxy’s stars are distributed more evenly in a bulge without arms or disk.
