As the saying goes, we are made of stardust, and two studies including the University of Michigan have found that this may be more real than we previously thought.
The research led by UM researcher Jackie (Jackie) was published in Scientific progress, Found that most of the carbon on the earth is likely to be released from the interstellar medium, which is the material that exists in the space between the stars of the Milky Way. This is likely to happen after the protoplanetary disk, when a cloud of dust and gas surrounds our young sun and contains the planet̵
Carbon may also be sequestered as a solid within one million years after the birth of the sun, which means that carbon is the backbone of life on earth and survives interstellar travel.
Previously, researchers believed that the carbon in the Earth came from molecules that originally existed in the gas of the nebula, and then when the gas was cooled enough to precipitate the molecules, the carbon would be absorbed into the rocky planets. Li and her research team pointed out that this study indicated that gas molecules carrying carbon would not be able to build the earth because once the carbon evaporates, it will not condense back into a solid.
“The condensation model has been widely used for decades. It assumes that during the formation of the sun, all the elements of the planet are evaporated. As the disk cools, some of the gas condenses and provides the chemical composition to the solid. But it does not apply. Yu carbon.” said Li, a professor in the Department of Earth and Environmental Sciences at the University of California.
A lot of carbon is transferred to the disk in the form of organic molecules. However, when carbon evaporates, more volatile substances are produced, requiring very low temperatures to form a solid. More importantly, the carbon will not condense into organic form again. Therefore, Li and her team inferred that most of the carbon on the planet is likely to be directly inherited from the interstellar medium, thus completely avoiding evaporation.
In order to better understand how the earth obtains carbon, Mr. Li estimated the maximum amount of carbon the earth may contain. To this end, she compared the speed of seismic waves through the core with the known speed of sound in the core. This tells researchers that carbon may only account for less than half of the earth’s mass. Knowing the upper limit of how much carbon the earth may contain can tell researchers about when carbon may be transported here.
Bergin, professor and chair of the Department of Astronomy at UM University, said: “We asked a different question: We asked how much carbon you can fill in the core of the earth and still be consistent with all constraints.” “There is uncertainty here. Let us Embrace the uncertainty and ask what is the true upper limit of how much carbon there is in the depths of the earth. This will tell us the true landscape we are in.”
We know that planetary carbon must exist in an appropriate proportion to sustain life. With too much carbon, the earth’s atmosphere is like Venus, capturing heat from the sun and maintaining a temperature of about 880 degrees Fahrenheit. With too little carbon, the earth will resemble Mars: this is a desolate place, unable to sustain aquatic life, and the temperature is about minus 60.
In a second study by the same group of authors, led by Hirschmann of the University of Minnesota, the researchers studied how the planet’s small precursors (called asteroids) retain carbon during their early formation. Deal with carbon. By examining the metal nuclei of these objects that are now preserved as iron meteorites, they found that in this critical step of planetary origin, as planetary asteroids melt, form nuclei and lose gas, a lot of carbon must be lost. Hirschman said this subverted previous ideas.
Hirschmann, professor of earth and environmental sciences, said: “Most models have carbon and other life-essential materials from nebulae to primitive rock bodies, such as water and nitrogen, and then transfer these materials to growing planets such as Earth or Mars.” . “But this skips a critical step. In this critical step, planets and asteroids lose a lot of carbon before they accumulate on planets.”
Hirschmann’s research was recently published in Proceedings of the National Academy of Sciences.
Belkin said: “The earth needs carbon to regulate the climate and allow life to exist, but this is a very delicate thing.” “You don’t want to have too much, but you don’t want to have too much.”
Belkin said that both studies describe two different aspects of carbon loss and show that carbon loss appears to be an important aspect of making the earth a habitable planet.
Ciesla, a professor of geophysical sciences at American University, said: “Only when astronomy and geochemistry intersect, can the question of whether there are earth-like planets elsewhere can be solved.” “Although the research methods and the specific questions that researchers have to answer are in Each field is different, but to build a coherent story, you need to identify topics of common interest and find ways to bridge the intellectual gap between them. Although this is challenging, the effort is both encouraging and inspiring. People uplifting. Helpful.”
Blake is a co-author of this research and a professor of cosmology and planetary science and chemistry at the California Institute of Technology. He said this kind of interdisciplinary research is essential.
He said: “In the history of the Milky Way alone, rocky planets like the Earth or larger have gathered hundreds of millions of times around stars such as the Sun.” “We can extend this work to study carbon in planetary systems more widely. Loss? This kind of research will attract all kinds of scholars.”
Comet Katarina suggests that comets send carbon to rocky planets
“Earth carbon deficit due to early losses caused by irreversible sublimation” Scientific progress (2021). advances.sciencemag.org/lookup….1126 / sciadv.abd3632
Provided by the University of Michigan
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