Interstellar comet 3I/ATLAS and strange water

 Strange water never seen before was observed at Interstellar comet 3I/ATLAS

A mysterious comet from beyond our solar system is giving astronomers a rare glimpse into alien worlds, and it may have formed in a place far colder and stranger than anything around our Sun. The interstellar visitor, called 3I/ATLAS, contains an astonishingly high amount of “heavy water,” far exceeding anything seen in our own solar system. A new study of the interstellar comet 3I/ATLAS led by the University of Michigan shows that its water has a remarkably high content of deuterium. This form of hydrogen is comparatively less abundant in our solar system, enabling researchers to glean new insights about other planetary processes at work in our galaxy. This comet from beyond our solar system is giving astronomers a rare look at how alien planetary systems may form under conditions very different from those that shaped our own cosmic neighborhood. The object, called 3I/ATLAS, was discovered less than a year ago as it traveled through our solar system. Although scientists still do not know exactly where it originated, research suggests the comet formed in an extremely cold region of space. 

The study, published in Nature Astronomy, found that 3I/ATLAS contains unusually high levels of deuterium-rich water, often called “heavy water.” The project received support in part from NASA, the US National Science Foundation, and Chile’s National Research and Development Agency. Additional support for the research came from the Michigan Society of Fellows and the Heising-Simons Foundation. ALMA is operated through a partnership involving the European Southern Observatory, the NSF and Japan's National Institutes of Nature Sciences in cooperation with the Republic of Chile. “Our new observations show that the conditions that led to the formation of our solar system are much different from how planetary systems evolved in different parts of our galaxy,” said Luis Salazar Manzano, lead author of the study at the U-M Department of Astronomy. Study led by researchers at the University of Michigan suggests the comet was born in conditions far colder than those that shaped our own solar system. The findings come from an analysis of the comet's unusual water composition, which revealed extraordinarily high levels of deuterium, a heavier form of hydrogen.

Less than a year ago, astronomers spotted a comet passing through our solar system that originated far beyond it. The object, known as 3I/ATLAS, is only the third confirmed interstellar visitor ever detected, and scientists are now uncovering clues about the alien environment where it formed. Water molecules are made up of two hydrogen atoms and one oxygen atom, giving water its familiar H2O formula. In ordinary water, hydrogen atoms contain only a proton. But some forms of water contain deuterium, an isotope of hydrogen that includes both a proton and a neutron. Researchers discovered that a surprisingly large portion of the comet’s water contains deuterium. Heavy water can also be found on Earth and in comets from our solar system, but the amount detected in 3I/ATLAS was far greater. "The amount of deuterium with respect to ordinary hydrogen in water is higher than anything we've seen before in other planetary systems and planetary comets," Salazar Manzano said. According to the researchers, the deuterium ratio in the comet was about 30 times higher than what has been measured in comets from our solar system and roughly 40 times higher than the ratio found in Earth's oceans.

The researchers said the study was only possible because astronomers detected 3I/ATLAS early enough for detailed follow-up observations. Following the discovery, Salazar Manzano and collaborators secured observing time at the MDM Observatory in Arizona, where they detected some of the earliest signs of gas being released from the comet (MDM stands for Michigan, Dartmouth, and the Massachusetts Institute of Technology, the observatory’s original partners). Salazar Manzano then teamed up with Paneque-Carreño, who brought expertise using the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile. ALMA's instruments are sensitive enough to distinguish deuterated water from ordinary water, allowing the team to precisely measure the ratio between the two. The researchers say this marks the first time scientists have successfully performed this type of water analysis on an interstellar object. "Being at the University of Michigan and having access to these facilities was the key to making this work possible," Salazar Manzano said. "We were part of a team that was very talented and very experienced in multiple areas, all of us complemented each other and that's what allowed us to analyze and interpret these data sets."

Scientists can use these chemical ratios to understand the conditions present when comets and planets formed. By comparing the chemistry of 3I/ATLAS with objects in our solar system, researchers concluded the comet likely formed in a colder environment with lower radiation levels. The researchers explained that carrying out such a detailed study required several fortunate circumstances, beginning with the comet being discovered early enough for additional observations. The team concluded that 3I/ATLAS likely formed in a much colder region with lower radiation levels than the environment that created the planets and comets in our solar system. "This is proof that whatever the conditions were that led to the creation of our solar system are not ubiquitous throughout space," said Teresa Paneque-Carreño, co-leader of the study and assistant professor of astronomy at U-M. "That may sound obvious, but it's one of those things that you need to prove." So far, astronomers have detected only three known interstellar objects passing through our solar system, including 3I/ATLAS. However, Paneque-Carreño said discoveries like these could become much more common as new observatories begin scanning the skies. She also emphasized the importance of protecting dark night skies so astronomers can continue detecting faint objects from deep space. “We need to be taking care of our night skies and keeping them clear and dark so we can detect these tiny and faint objects,” she said. The study also demonstrates that astronomers may soon be able to chemically analyze additional interstellar objects to better understand how planetary systems form across the galaxy.