“The R-Process Alliance aims to answer the big, unanswered questions related to decoding the mysteries of the oldest stars in the Milky Way–by bringing together an interdisciplinary group of observers, theorists, and experimentalists,” University of Michigan astronomer Ian Roederer wrote in an email to The Daily Galaxy, about the discovery of a relatively bright star HD 222925. The ancient object is a rare, ninth-magnitude star located toward the southern constellation Tucana, where astronomers have been able to identify the widest range of elements in its photosphere, more than in any star beyond our solar system.
An exciting new era in astronomy began billions of years ago with a collision between two black holes that sent gravitational waves rippling through the universe. In 2019, signals from these waves were detected at the gravitational wave observatory LIGO and the detector Virgo. Fast forward to 2022, Princeton researchers announced the discovery of 10 new black hole mergers hiding in the data from LIGO and Virgo gravitational wave detectors.
Astronomers have known since the 1990s that planets exist around pulsars. It’s a reasonable hypothesis that planets might also exist around black holes, which have a weaker impact on their local environment than rotating neutron stars. In 2019, Harvard astrophysicist Avi Loeb and NASA’s Jeremy Schnittman proposed that inhabited planets might exist around the black holes harbored at the center of most galaxies. Such planets are similar to the fictional water-world planet Miller, the closest planet in the star system orbiting the supermassive black hole, Gargantua, in the movie Interstellar.
“Neutron star mergers are extremely rare,” explained Columbia University astrophysicist Brian Metzger in an email to The Daily Galaxy about the exotic phenomenon known as a kilonova, “occurring only once every 10 or 100 thousand years in galaxies like our own. There certainly were many kilonovae in the distant past in the Milky Way that may have appeared similar to bright novae on the night sky to our ancestors, but likely none since the advent of modern astronomy.”
The heaviest natural elements on the periodic table such as gold, platinum, and uranium were forged during the mergers of binary neutron stars. Astronomers have previously estimated that tens of thousands of such binary neutron star mergers must have occurred throughout our Milky Way Galaxy during the past 10 billion years, sprinkling neutron-rich elements throughout the gas that eventually formed the next generation of stars and planets. By studying the composition of meteorites, astronomers now conclude that a single collision of neutron stars occurred shortly before and near to the formation of our solar system, producing a measurable fraction of the heavy elements here on Earth.