Scientists at the European Southern Observatory’s (ESO) La Silla Observatory in northern Chile have measured the distance to our neighbouring galaxy, the Large Magellanic Cloud (LMC), more accurately than ever before – to within 2 percent difference when comparing separate measurements taken.
The new measurement is set to improve our understanding of the Hubble Constant – the rate at which the universe expands – and in turn help scientists to unlock the secrets of dark matter.
When taking measurements in the universe, astronomers use a fixed scale of “standard candles” – nearby cosmological objects, whose distances from the Earth are known. These distances, however, exist at varying degrees of accuracy, and such a fine measurement of the LMC has never been done before.
“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,” Wolfgang Gieren, of Chile’s Universidad de Concepción and one of the leaders of the team, said. “Now we have solved this problem by demonstrably having a result accurate to 2 percent.”
The scientists came up with the measurement by observing rare close pairs of stars known as eclipsing binaries. By studying the changes in light as the stars pass in front of one another, scientists are able to measure their size, orbit speed, and brightness, and in turn infer measurements of their distances from earth to great accuracy.
This method has been used before, though astronomers pointed to the power and sensitivity of the tools available to them for this new improved reading.
According to the lead author on the paper Grzegorz Pietrzyński,“ESO provided the perfect suite of telescopes and instruments for the observations needed for this project: HARPS for extremely accurate radial velocities of relatively faint stars, and SOFI for precise measurements of how bright the stars appeared in the infrared.”
Accurately measuring distances in the universe is imperative if scientists are to make sense of the relationship between the expansion of the universe, its mass, and the existence of dark matter.
“We are working to improve our method still further and hope to have a 1% LMC distance in a very few years from now.” Dariusz Graczyk, the paper’s second author, said. “This has far-reaching consequences not only for cosmology, but for many fields of astrophysics.”
These new findings come as President Sebastián Piñera has called in a new age for astronomy and innovation. Due to its almost non-existent humidity and clear skies, the Atacama is the world’s premier location for astronomy. Chile is home to almost half the world’s telescope infrastructure, and this is set to increase to over two thirds in the next decade.