Illustration of a carbon-rich planet with diamond and silica as the two main minerals. Water can turn a carbide planet into a diamond-rich planet. Inside, the main minerals are diamond and silica (a layer with crystals in the illustration). The core (dark blue) may be an alloy of iron and carbon. Credit: Shim / Arizona State University / Vecteezy
Like tasks like NASA‘s Hubble Space Telescope, he-goatKepler has continued to provide insights into the properties of exoplanets (planets around other stars), and scientists are increasingly able to synthesize what these planets look like, what their components are, and whether they could be habitable or even inhabited.
In a new study published recently in The Journal of Planetary Sciences, And a team of researchers from Arizona State University and University of Chicago They determined that some carbon-rich exoplanets, under the right conditions, could be made of diamond and silica.
“These exoplanets are unlike anything in our solar system,” said lead author Harrison Allen-Sutter of the School of Earth and Space Exploration at Arizona State University.
The unchanged carbon planet (left) is transforming from a mantle dominated by silicon carbide to a mantle dominated by silica and diamond (right). The reaction also produces methane and hydrogen. Credit: Harrison / Arizona State University
Exoplanet diamond formation
When stars and planets form, they do so from the same gas cloud, so their mass formations are similar. A star with a low carbon to oxygen ratio would have planets like Earth, consisting of silicates and oxides with a very small diamond content (ground diamond content is around 0.001%).
But exoplanets around stars with a higher carbon to oxygen ratio than our Sun are likely to be rich in carbon. Allen-Sutter and co-authors Emily Jarhart, Kurt Leninweber, and Dan Shim of Arizona State University, together with Vitaly Brakapinka and Iran Greenberg of the University of Chicago, hypothesized that these carbon-rich exoplanets could turn into diamonds and silicates, if water (which is abundant in the universe) , Resulting in a formula rich in diamonds.
In a diamond anvil cell, two gem-quality single crystal diamonds are formed into an anvil (flat top pictured) and then face each other. Samples are loaded between the anvils (flat surfaces), and then the sample is compressed between the anvils. Credit: Chim / Arizona State University
Diamond anvil and x-rays
To test this hypothesis, the research team needed to simulate the interior of the carbide exoplanets using high heat and high pressure. To do this, they used high-pressure diamond anvil cells in Shim’s Lab for Earth and Planetary Materials.
First, they immersed silicon carbide in water and pressed the sample between the diamonds to an extremely high pressure. Then, to monitor the reaction between silicon carbide and water, they performed laser heating at Argonne National Laboratory in Illinois, and took X-ray measurements while laser heating the sample at high pressures.
They also expected, as temperature and pressure increased, silicon carbide would react with water and turn into diamond and silica.
The cylindrical shaped objects in this photo are diamond anvil cells. Diamond anvil cells are attached to copper holders and then inserted into the X-ray path / laser beam path. The image shows diamond anvil cells and spikes prior to alignment of the X-ray / laser experiments. Credit: Chim / Arizona State University
Housing and housing
So far, we haven’t found life on other planets, but the search is continuing. Planetary scientists and astrobiologists use sophisticated tools in space and on Earth to find planets with the right characteristics and the right location around their stars where life could exist.
For the carbon-rich planets that are the focus of this study, they likely don’t have the properties necessary for life.
While the Earth is geologically active (an indicator of habitability), the results of this study show that carbon-rich planets are very difficult to be geologically active and this lack of geological activity may make atmospheric formation uninhabitable. Atmosphere is essential to life because it provides us with air to breathe, protection from the harsh environment of space and even pressure to allow liquid water.
“Habitability regardless of habitability,” said Allen Sutter, “is one more step in helping us understand and characterize our increased and improved observations of exoplanets.” “The more we learn, the more we can interpret new data from upcoming future tasks such as James Webb Space Telescope And the Romanian Nancy Grace Space Telescope to understand worlds outside our solar system. “
The reference: “Carbide oxidation of the inner parts of the exoplanets” by H. Allen-Sutter, E. Garhart, and K. Leninweber and F. Pracabenka, E. Greenberg and S.-H. Shem, 26 August 2020, The Journal of Planetary Sciences.
DOI: 10.3847 / PSJ / abaa3e
