Space technologies available for astronomers have become increasingly sophisticated and advanced and these have undeniably contributed to mankind's growing knowledge of the vast universe. These new technologies also help correct earlier notions about astronomical objects and their behaviors that turned out to be wrong and this appears to be in the case of dwarf galaxies.
The so-called dwarf galaxies only have up to several billion stars, which is small when compared to the Milky Way, that galaxy that contains our Solar System, which is estimated to be made up of 200 to 400 billion stars and while some galaxies are immense, most of the billions of galaxies that make up the universe are dwarf galaxies.
For many years, astronomers attempted to predict how these small galaxies should orbit bigger galaxies and most arrived at the conclusion that these dwarfs orbit somewhat randomly. New findings by a team of astronomers from France and Australia which were published in the journal Nature on July 20, however, suggest otherwise. They found that many of these smaller galaxies do not actually swarm like bees around giant galaxies but rather dance in systematic disc-shaped orbits.
To learn more about how galaxies orbit, Geraint Lewis, from the School of Physics at The University of Sydney in New South Wales, Australia, and colleagues examined thousands of galaxies using the Sloan Digital Sky Survey, which provides detailed 3D maps of the universe. They found that many of the satellite galaxy pairs have velocities that are oppositely directed if they are positioned on opposite sides of their bigger galaxy host.
"Here we report measurements of the velocities of pairs of diametrically opposed satellite galaxies," the researchers wrote. "In the local Universe (redshift z < 0.05), we find that satellite pairs out to a distance of 150 kiloparsecs from the galactic centre are preferentially anti-correlated in their velocities (99.994 per cent confidence level)."
Lewis said that they observed what appears to be a choreographed motion of dwarf galaxies everywhere and based on this infer that the behavior is universal, a concept that challenges current notions on how the universe evolved and works.
"Everywhere we looked we saw this strangely coherent coordinated motion of dwarf galaxies," Lewis said. "From this we can extrapolate that these circular planes of dancing dwarfs are universal, seen in about 50 percent of galaxies."
Lewis and colleagues believe that the answer to this mystery lies in what still remains an unknown physical process that governs that flow of gas in the universe.
