Researchers have now accurately measured the distance to our nearest galaxy and corrected an astronomical calculation that helps astronomers measure distance between far-flung objects in the universe, according to a new study.
The new study provides an alternative to Type Ia supernovae, which is currently the best way to measure the distance of objects in space.
The Universe is constantly expanding. To know how old the universe is or how far objects in space are, it is important to know at what rate the Universe is expanding. Currently, Hubble constant is used to measure the rate of expansion of the Universe. However, earlier researchers weren't able to accurately measure the distance of certain objects in space, like the distance to Large Magellanic Cloud (LMC).
The LMC, according to NASA, is 200,000 light years away from Earth and is a satellite galaxy to our galaxy - the Milky Way.
According to the new study, the LMC must be around 163,000 light years away from Earth. Researchers say that the new value is accurate to 2 percent. The study is published in the journal Nature.
Researchers in the present study fixed the problem of finding the distance between Earth and LMC by first observing a close pair of stars called eclipsing binaries. Researchers then used this distance as a kind of calibration to find out the distance to LMC.
Eclipsing binary stars appear as one point of light source to the observer. But, the brightness varies on spectroscopic observations and this variation shows that there are two starts that are orbiting very close to each other. Astronomers can deduce information about the star system, like size and distance, by observing the changes in the brightness of the stars.
Although in the past many researchers have tried measuring distance to LMC by this system, none worked as desired because they weren't of either the perfect size or didn't have good orbital periods. The new study, conducted by a group of researchers led by Grzegorz Pietrzynski of the Universidad de Concepcion in Chile and Warsaw University Observatory in Poland, based their work on 16 years of observational data. The binary stars that they looked at were close to each other and had long orbital periods.
"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. Unfortunately, nearly all the determinations have systemic errors, with each method carrying its own uncertainties," Ian Thompson, one of the study authors, said in a news release.