variables are one of the most popular. These have been shown to have a relationship between their absolute luminosity and the period over which their brightness varies. However the variable of metallicity may also need to be taken as a component of this as consensus is this likely affects their period-luminosity relations. Unfortunately, those in the Milky Way typically used to calibrate the relation are more metal-rich than those found in the LMC. Modern 8-meter-class optical telescopes have discovered eclipsing binaries throughout the Local Group. Parameters of these systems can be measured without mass or compositional assumptions. The light echoes of supernova 1987A are also geometric measurements, without any stellar models or assumptions. In 2006, the Cepheid absolute luminosity was re-calibrated using Cepheid variables in the galaxy Messier 106 that cover a range of metallicities. Using this improved calibration, they find an absolute distance modulus of , or . This distance has been confirmed by other authors. By cross-correlating different measurement methods, one can bound the distance; the residual errors are now less than the estimated size parameters of the LMC. The results of a study using late-type eclipsing binaries to determine the distance more accurately was published in the scientific journal Nature in March 2013. A distance of with an accuracy of 2.2% was obtained. Features Like many irregular galaxies, the LMC is rich in gas and dust, and is currently undergoing vigorous star formation activity. It holds the Tarantula Nebula, the most active star-forming region in the Local Group. The LMC has a wide range of galactic objects and phenomena that make it known as an "astronomical treasure-house, a great celestial laboratory for the study of the growth and evolution of the stars", per Robert Burnham Jr. Surveys of the galaxy have found roughly 60 globular clusters, 400 planetary nebulae and 700 open clusters, along with hundreds of thousands of giant and supergiant stars. Supernova 1987A—the nearest supernova in recent years—was in the Large Magellanic Cloud. The Lionel-Murphy SNR (N86) nitrogen-abundant supernova remnant was named by astronomers at the Australian National University's Mount Stromlo Observatory, acknowledging Australian High Court Justice Lionel Murphy's interest in science and its perceived resemblance to his large nose. A bridge of gas connects the Small Magellanic Cloud (SMC) with the LMC, which evinces tidal interaction between the galaxies. The Magellanic Clouds have a common envelope of neutral hydrogen, indicating that they have been