“Some rock types might melt at much lower temperatures and produce thicker crust than Earth rocks, and some rock types might be weaker, which might facilitate the development of plate tectonics.”Įarlier studies of polluted white dwarfs had found elements from rocky bodies, including calcium, aluminum, and lithium. “Some of the rock types that we see from the white dwarf data would dissolve more water than rocks on Earth and might impact how oceans are developed,” he explained. Putirka describes what these new rock types might mean for the rocky worlds they belong to. “They have no direct counterparts in the Solar System.” “While some exoplanets that once orbited polluted white dwarfs appear similar to Earth, most have rock types that are exotic to our Solar System,” said Xu.
In fact, some of the compositions are so unusual that Putirka and Xu had to create new names (such as “quartz pyroxenites” and “periclase dunites”) to classify the novel rock types that must have existed on those planets. They found that these white dwarfs have a much wider range of compositions than any of the inner planets in our Solar System, suggesting their planets had a wider variety of rock types. The scientists then used the measured abundances of those elements to reconstruct the minerals and rocks that would form from them. Keck Observatory in Hawai‘i, the Hubble Space Telescope, and other observatories. Putirka and Xu looked at 23 polluted white dwarfs, all within about 650 light-years of the Sun, where calcium, silicon, magnesium, and iron had been measured with precision using the W. Some of the rock compositions are so rare, the scientists had to create new names to classify the types of rocks that once made up these ancient planets. Each white dwarf is “polluted” with material from rocky bodies that originally orbited it but fell into the white dwarf and spread their elements through its atmosphere. By studying the atmospheres of stellar remnants called white dwarfs, the pair has discovered types of rocks not found in our Solar System. By looking for elements that wouldn’t naturally exist in a white dwarf’s atmosphere (anything other than hydrogen and helium), scientists can figure out what the rocky planetary objects that fell into the star were made of.Īccording to new research by a NOIRLab astronomer and a geologist, rocky exoplanets are even stranger than previously thought. These are the dense, collapsed cores of once-normal stars like the Sun that contain foreign material from planets, asteroids, or other rocky bodies that once orbited the star but eventually fell into the white dwarf and “contaminated” its atmosphere. To try to find out, astronomer Siyi Xu of NSF’s NOIRLab partnered with geologist Keith Putirka of California State University, Fresno, to study the atmospheres of what are known as polluted white dwarfs. However, it’s difficult to know what exactly these planets are made of, or whether any resemble Earth. After studying the chemical composition of “polluted” white dwarfs, they have concluded that most rocky planets orbiting nearby stars are more diverse and exotic than previously thought, with types of rocks not found anywhere in our Solar System.Īstronomers have discovered thousands of planets orbiting stars in our galaxy - known as exoplanets. Kosari (NSF’s NOIRLab)Ī new astrogeology study suggests that most nearby rocky exoplanets are quite unlike anything in our Solar System.Īn astronomer from NSF’s NOIRLab has teamed up with a geologist from California State University, Fresno, to make the first estimates of rock types that exist on planets orbiting nearby stars. The results suggest that nearby rocky exoplanets must be even stranger and more diverse than previously thought. Studying the atmospheres of white dwarfs that have been “polluted” by such debris, a NOIRLab astronomer and a geologist have identified exotic rock types that do not exist in our Solar System. Rocky debris, the pieces of a former rocky planet that has broken up, spiral inward toward a white dwarf in this illustration.