Latest and clearer measurements of celestial bodies within the Large Magellanic cloud, which is a satellite of our Milky Way, has strengthened the diversity within two methods of calculating expansion rate of universe. In past five years two groups have been at odds over acceptance of Hubble Constant as a rate to calculate rate of expansion of the universe. While one group relies on cosmic microwave background the other one uses a combination of local measurements that are part of cosmic distance ladder. Its first rung is made up of astronomical measurements comprising of pulsating starts which are called Cepheids.
These stars act as candles to gauge distance between galaxies through their periodic pulsations and luminosity. These and other stars make up the cosmic distance ladder and some minor errors can lead to distortion of measurements. Grzegorz Pietrzyski from Nicolaus Copernicus Astronomical Center and his colleagues have now managed to make the most accurate estimate of distance between earth and Large Magellanic Cloud (LMC) till date. In their calculation they used a unique 20 star system named as detached eclipsing binaries to measure this distance and say that LMC is around 162,000 light years away from earth.
Adam Reiss, Noble laureate from John Hopkins University who is also the leader of Supernovae HO of Equation of Date of Dark Energy (SHOES) project used these calculations to fine-tune their calibration of luminosity relation of Cepheids. This is the first time that Hubble telescope has been used for study of both Cepheid variables within LMC and also Cepheids within host galaxies of the supernovae. Earlier multiple telescopes had been used for study of Cepheids within LMC and supernovae hosts but the systemic difference between these telescopes led to variations and uncertainties in the estimation of distances. Reiss says that with this measurement the uncertainty about Hubble constant has gone down to 1.9 %.