Comet 46P / Wirtanen released unusually high amounts of alcohol during its passage through Earth 2.5 years ago.
Scientists have discovered extremely high amounts of alcohol in comet 46P / Wirtanen as well as a mysterious heat source heating this comet through observations with the W. M. Keck Observatory in Maunakea, Hawai’i. “46P / Wirtanen has the highest alcohol-to-aldehyde ratio ever measured of any comet,” said Neil Dello Russon, comet scientist at the Johns Hopkins University Applied Physics Laboratory, co-author of the study. “This gives us information about how the molecules of carbon, oxygen and hydrogen were distributed at the start of the solar system, when Wirtanen formed.”
Data from the Keck Observatory also revealed a strange feature. Normally, as comets get closer to the Sun, the frozen particles in their nucleus heat up and then sublimate, passing directly from hard ice to gas, bypassing the liquefaction phase. This process, called gassing, is the production of the comet’s head (coma), the giant glowing gas and dust surrounding the comet’s nucleus.
As the comet approaches the Sun, solar radiation moves part of the comet’s head away, forming a trailing tail. However, with 46P / Wirtanen, the team found that in addition to radiation, another mysterious process is also causing comets to warm. They found that the temperature measured with the water-filled gas at the comet’s tip did not drop significantly compared to the distance from the nucleus, suggesting a heating mechanism, said Professor Erika Gibb, head of the department. of Physics and Astronomy from the University of Missouri – St. Louis, co-author of the study.
Gibb said there were two possibilities. One is a chemical reaction in which sunlight can ionize certain atoms or molecules at the tip of a comet near the nucleus, releasing electrons at high speed. When electrons collide with other molecules, they can transfer some of their momentum and heat the water-filled gas at the tip of the comet.
Another possibility is that there is a block of hard ice that gushes out from 46P / Wirtanen. Researchers have seen it in several comets visited by spacecraft, such as Hartley 2 during NASA’s EPOXI mission. These pieces of ice flew from the core and sublimated, releasing energy.
This hypothesis is very consistent with observations of very active comets such as 46P / Wirtanen, whose class of comets release more water than expected if they eject all the gas directly from the frozen nucleus as they approach the Sun. Water spurts out as a gas but can later condense into liquid form if it comes into contact with the planet’s surface. This is why scientists suspect that comets as well as asteroids can bring water to Earth.
Data from the Keck Observatory shows that Comet Wirtanen releases relatively more water molecules from its head after sublimation than other molecules such as ethane, hydrogen cyanide, and acetylene. This shows that the water came from ice particles deep inside the comet’s head. The results of the study were published in detail in the journal Planetary Science.
