The galaxy next door, our Milky Way's neighbor, is closer than we thought.
Called the Large Magellanic Cloud, the nearby dwarf galaxy is located about 163,000 light-years away, according to new measurements. The distance is closer than previously believed and has important implications for studying the distance of space objects. It may also help unlock the mystery of dark energy, the unknown force causing the universe to accelerate in its expansion.
"I am very excited because astronomers have been trying for a hundred years to accurately measure the distance to the Large Magellanic Cloud, and it has proved to be extremely difficult," says Chile's Universidad de Concepciӧn astronomer Wolfgang Gieren. "Now we have solved this problem by demonstrably having a result accurate to two percent."
The discovery was made by scientists at the European Southern Observatory's La Silla Observatory in Chile, along with scientists from other parts of the world. They conducted their study by observing eight pairs of binary stars over a period of eight years. By combining measurements of size and mass with brightness and color, they were able to find the Large Magellanic Cloud's distance from Earth to an accurate degree.
The new method improves significantly on older ones, despite the continued presence of errors.
"Because the LMC is close and contains a significant number of different stellar distance indicators, hundreds of distance measurements using it have been recorded over the years," says study participant Ian Thompson of the Carnegie Institution for Science in Washington, D.C. "Unfortunately, nearly all the determinations have systemic errors, with each method carrying its own uncertainties."
That said, the astronomers are optimistic about the results.
"We are working to improve our method still further and hope to have a one percent [accurate] LMC distance in a very few years from now," says Dariusz Gracyzk, who wrote the paper published in the journal Nature. "This has far-reaching consequences not only for cosmology, but for many fields of astrophysics."