Since the 1700’s, astronomers have believed that more than half of the stars in the Milky Way Galaxy were binary (two stars in orbit of each other) or multiple star systems (more than two stars in orbit of each other). Now astronomers believe that most stars in our galaxy tend to be alone or single star systems.

The new theory is based on studies done by Charles Lada from the Harvard-Smithsonian Center for Astrophysics, who used surveys from group studies from the University of California at Berkley, the Space Telescope Science Institute, and the Astrophysical Laboratory of Grenoble, France. Lada’s theory is based on the high population of red dwarf stars in our galaxy. Red dwarf stars make up about 70% of all the stars in the Milky Way, so they are the most common type of star. They are low in mass and low in brightness. Most red dwarfs are single stars. That means about two-thirds of the stars in the Milky Way Galaxy are single star systems.

Other studies have indicated that planets probably form easier around single stars. A low-mass planet was discovered orbiting a solitary red dwarf star. Planets also can form around binary star systems. Astronomers believe that half of all wide-orbiting binary systems have planets. The wide orbits would permit planets to form and become stable in their orbit. Either the two stars have to be in close orbit so the planet can orbit both stars, or the stars have to be in wide orbits with the planets can be in close orbits around only one of the stars. There are probably tens of billions of sun-like stars in our galaxy that can have planets in orbit around them.