Distance to neighbor galaxy measured more accurately
After nearly a decade of careful observations, an international team of astronomers has measured the distance to our neighboring galaxy, the Large Magellanic Cloud, more accurately than ever before. Astronomers Rolf-Peter Kudritzki and Fabio Bresolin, from the University of Hawaiʻi at Mānoa’s Institute for Astronomy, are part of that team. These results appear in the March 7 issue of the journal Nature.
Astronomers ascertain the scale of the universe by first measuring the distances to close-by objects and then using them as standard candles—objects of known brightness—to pin down distances farther and farther out in the universe.
This chain is only as accurate as its weakest link. Up to now, finding an accurate distance to the Large Magellanic Cloud, a satellite galaxy to the Milky Way, has proved elusive. Stars in that galaxy are used to fix the distance scale for more remote galaxies, so it is crucially important.
“For extragalactic astronomers, the distance to the Large Magellanic Cloud represents a fundamental yardstick with which the whole universe can be measured,” said Bresolin. “Obtaining an accurate value for it has been a major challenge for generations of scientists. Our team has overcome the difficulties using an exquisitely accurate method, and is already working to cut the small remaining uncertainty by half in the next few years.“
Careful observations of a rare class of double star have now allowed a team of astronomers to deduce a much more precise value for the Large Magellanic Cloud distance—163,000 light-years.
“This is a true milestone in modern astronomy. Because we know the distance to our nearest neighbor galaxy so precisely, we can now determine the rate at which the Universe is expanding—the Hubble constant—with much better accuracy,” says Kudritzki. “This will allow us to investigate the physical nature of the enigmatic dark energy, the cause of the accelerated expansion of the Universe.”
—Adapted from a UH Mānoa Institute for Astronomy news release