An international team of scientists has found radioactive iron-60 in sediment and crust samples taken from the Pacific, Atlantic and Indian Oceans. They report that a series of massive supernova explosions occurring between 3.2 and 1.7 million years ago from stars less than 300 light-years away showered the Earth with radioactive debris.
Stars are born inside a rotating cloud of interstellar gas and dust. Before finding itself on the star, however, most of the cloud lands onto a circumstellar disc forming around the star. The manner in which the material is transported through the disc onto the star, causing the star to grow in mass, has recently become a major research topic in astrophysics.
An international team of researchers have found a new way to measure the pull of gravity at the surface of a star. The new method allows scientists to measure surface gravity with an accuracy of about four percent, for stars too distant and too faint to apply current techniques. For remote stars with planets orbiting them, this information is key in determining whether any of those planets can harbour life.
Astronomers have used modern techniques to create a 3-D visualisation of all of the O- and B-type stars within 500 parsecs (1,630 light-years) of the Sun using data from ESA’s Hipparcos satellite. This new visualisation uncovers evidence for new structures in the distribution of these nearby hot stars, and new and surprising theories of how those stars formed.