NASAのインスタグラム(nasagoddard) - 3月2日 02時07分

NASA Study Hints at Possible Change in Water ‘Fingerprint’ of Comet

A trip past the sun may have selectively altered the production of one form of water in a comet – an effect not seen by astronomers before, a new NASA study suggests.

Astronomers from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, observed the Oort cloud comet C/2014 Q2, also called Lovejoy, when it passed near Earth in early 2015. Through NASA’s partnership in the W. M. Keck Observatory on Mauna Kea, Hawaii, the team observed the comet at infrared wavelengths a few days after Lovejoy passed its perihelion – or closest point to the sun.

The team focused on Lovejoy’s water, simultaneously measuring the release of H2O along with production of a heavier form of water, HDO. Water molecules consist of two hydrogen atoms and one oxygen atom. A hydrogen atom has one proton, but when it also includes a neutron, that heavier hydrogen isotope is called deuterium, or the “D” in HDO. From these measurements, the researchers calculated the D-to-H ratio – a chemical fingerprint that provides clues about exactly where comets (or asteroids) formed within the cloud of material that surrounded the young sun in the early days of the solar system. Researchers also use the D-to-H value to try to understand how much of Earth’s water may have come from comets versus asteroids.
Credit: NASA #nasagoddard #science #space #comet

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