ome stars in our galaxy could harbour planets with thick layers of diamond in their mantles. They may sound like prime real estate but new lab experiments suggest that these blingworlds, though carbon-rich, would be cold, devoid of most of the mechanisms that sustain life on Earth.
Our solar system is relatively carbon-poor. Consequently, Earth’s core is made of iron and its mantle of silica-based minerals. Some stars have high carbon-to-oxygen ratios compared with the sun, however, and such stars might host planets with mineral compositions very different from that of Earth.
In 2005, astronomer Marc Kuchner, now at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and colleagues showed that planetary systems with high carbon-to-oxygen ratios would form planets with layers of graphite. High pressure would convert parts of this layer into layers of diamond many kilometres thick.
Now Wendy Panero and Cayman Unterborn of Ohio State University in Columbus have extended the study to better understand both the composition of such planets and their likely geological processes.