Water Formation on Habitable Planets

Scientists at the University of Michigan in Ann Arbor, Michigan are exploring the origins of water on habitable planets. According to their research, water vapor forms spontaneously in regions of solar systems capable of supporting life. This water forms a protective layer shielding against stellar radiation that could otherwise destroy organic molecules necessary for life.
 The protoplanetary disk HH-30. (Source: NASA)
The protoplanetary disk HH-30. (Source: NASA)

Associate professor of astronomy Ted Bergin and postdoctoral student Thomas Bethell determined that water vapor forms in this manner at temperatures of 300 degrees Kelvin or higher (approximately 80 degrees Fahrenheit or 27 degrees Celsius). This corresponds to regions of a solar system fairly close to their central star, approximately at the same distance away from their star as the earth is from the sun. In these regions the water vapor forms quickly enough to create a shell similar to the ozone layer both in form and function. Organic molecules necessary for life such as amino acids and sugars are protected within the shell as is the water found within the shell.

Without this protection from the radiation emitted by the nearby star, these molecules would be broken down into their constituent parts well before the formation of planetismals and planets capable of harboring life. While water also breaks down into hydrogen and hydroxide (which further breaks down into hydrogen and oxygen molecules), these molecules reform into water vapor very quickly within the relevant temperature ranges, replenishing the shield quickly and maintaining protection for the interior regions.

Bergin and Bethell modeled several circumstellar disks including DR Tau, AS 205A, and AA Tau to form their hypothesis. Although only a limited sample of data from the Spitzer Space Telescope has been processed at this point, all of the current observations of systems with water vapor are consistent with this shielding model. The scientists hope to process further data collected by Spitzer to learn more about these shields and further verify their results.

TFOT has previously reported on research into planetary evolution including the discovery of a planet forming region around an infant star by the Spitzer Space Telescope, an MIT study showing that young planets stay hot longer than previous expected, models of the Earth’s early interior at the point when magma crystallized into its solid form, and a National Geographic video outlining the origins of water on the earth.

Read more about Dr. Bergen’s research in this University of Michigan press release.