Researchers working on the accurate calculation of the distance of Milky Way to the nearest galaxy, led by Grzegorz Pietrzynski of the Universidad de Concepcion in Chile and Warsaw University Observatory in Poland, found the exact distance to our nearest galaxy. The nearest galaxy to Milky Way is called Large Magellanic Cloud (LMC) and it was found that it lies at a distance of 163000 light years away or exactly 49.97 kiloparsecs.
Large Magellanic Cloud (LMC)
• Large Magellanic Cloud (LMC) is the dwarf galaxy which floats in the space around our galaxy, Milky Way. It floats in a similar trend like that between the Earth and the Moon.
• Large Magellanic Cloud (LMC) encompasses huge clouds of gas in it, which gradually collapse, thereby forming new stars. These new stars are brightened in the colours which are actually visible in the images that are taken by Hubble Space Telescope.
• LMC also includes Tarantula Nebula which is the brightest stellar nursery in the cosmic neighbourhood.
Importance of the findings
The findings about the distance of LMC from Milky Way are crucial because they can help in determining the scale of our universe, which has remained a mystery ever since its inception. These findings could also be used for determining the rate of expansion of the universe. This rate of expansion of the universe is called Hubble Constant, which is named after an astronomer Edwin P Hubble who discovered in 1929 that the Universe was growing continuously.
Determination of the Hubble Constant is highly important for finding out the age as well as size of the universe. Exact distance of Milky Way to LMC has always remained one of the hugest uncertainties which affected the past measurements.
How was the research made?
Lead researcher Grzegorz Pietrzynski declared that they would now work on improving the accuracy of the measurements even more. The calculations of the distance were made by observation of the rare close pairs of stars which are called eclipsing binaries.
Eclipsing binaries are actually bound to each other gravitationally. Once per orbit, the overall brightness from this system of stars drops as one of these stars eclipses its partner. It is possible to find out the hugeness of the stars as well as information of their orbits by tracking changes in the brightness carefully as well as by measuring orbital speeds of stars.
By combining this with the measurement of apparent brightness, it is possible to determine absolutely accurate distances.
In the study, a sample of stars that had extremely long orbital periods was observed for 16 long years. These extremely long orbital periods are absolutely perfect in order to calculate the precise distances. New measurements are useful for decreasing the uncertainty of calculating Hubble Constant to 3 percent while improving it to uncertainty of 2 percent in years to come.