A team of researchers from UCLA has published a new study that presents new evidence that suggests Earth is not unique. UCLA professor Edward Young says that the team has raised the probability that many rocky planets are like Earth. The team was led by a UCLA graduate student of geochemistry and astrochemistry called Alexandra Doyle.
Doyle developed a new method of analyzing the detail in the geochemistry of planets outside our solar system. She did this by analyzing the elements in rocks from asteroids or rocky planet fragments that orbited six white dwarf stars. White dwarfs are dense, burned-out remains of normal stars.
The stars have stong gravitational pull that causes heavy elements like carbon, oxygen, and nitrogen to sink rapidly into their interiors where the heavy elements can’t be detected by telescopes. The closest white dwarf in the study was 200 light-years from Earth with the furthest 665 light-years away.
Most of the data in the study was gathered by the W.M. Keck Observatory in Hawaii. Doyle said that observing a white dwarf is like doing an “autopsy” on the contents it has gobbled up. Doyle says that as she looked at a white dwarf, she would expect to see hydrogen and helium. In the data, she saw other materials like silicon, magnesium, carbon, and oxygen. She says that material accreted onto the white dwarf by bodies that were orbiting them.
She says that rocks from Earth, Mars, and elsewhere in the solar system are similar in chemical composition and have a high level of oxidized iron. Doyle says that the team is finding that rocks are rocks everywhere with very similar geophysics and geochemistry. The study shows that the oxidation of rocks is true around other stars, and that bodes well for looking for Earth-like planets in the universe.
“All the chemistry that happens on the surface of the Earth can ultimately be traced back to the oxidation state of the planet,” Young said. “The fact that we have oceans and all the ingredients necessary for life can be traced back to the planet being oxidized as it is. The rocks control the chemistry.”