Tycho's supernova, a large stellar explosion that was observed in 1572, left an expanding cloud of debris which is the remnants of the explosion. This article describes a study that observes the cloud from Tycho's supernova that is expanding into interstellar space. These researchers found that the material ejected from Tycho's supernova is colliding with surrounding material, which consists of molecular clouds. This study gives astronomers better insight into the long-term behavior of supernova remnants and their surrounding interstellar medium.

http://www.raa-journal.org/raa/index.php/raa/article/view/614