Astronomers have studied semi-heavy water in the form of ice in space.

Scientists have detected ice with a high content of semi-heavy water around a young star similar to the Sun. This is the latest discovery announced by the Netherlands Research School of Astronomy (NOVA). Among the authors of the publication on the study is a Polish astronomer.

Heavy water is a type of water in which instead of two ordinary hydrogen atoms in the water molecule, there are two atoms of deuterium, a heavier isotope of hydrogen. Heavy water is known, for example, from its use in nuclear reactors. However, there is also water that is somewhat intermediate between ordinary and heavy. It is called semi-heavy water and in its molecule, one hydrogen atom is normal and the other is deuterium. The chemical formula of semi-heavy water is HDO.

It is precisely this semi-heavy water in the form of ice that astronomers have detected. The object studied is L1527 IRS, which is a protostar 460 light-years away from us and visible in the direction of the constellation Taurus. This protostar is similar to what we think the early stage of the formation of the Sun was.

Scientists have measured levels of deuterium in the water around L1527 IRS. It is similar to some comets, as well as to the protoplanetary disks in more evolved stars. This suggests an ancient, cold chemical origin for the water in these objects.

According to Prof. Ewine van Dishoeck from Leiden University, co-author of the paper, this is additional evidence that most water ice does not change from the earliest to the later stages of star formation.

Measuring the ratio of deuterium water to hydrogen water is one way to track the origin of water. A large amount of semi-heavy water is a sign that it formed in a very cold place, such as the primordial dark clouds of dust, ice, and gas from which stars form.

In the case of Earth and the solar system, in oceans, comets, and icy moons, the level is one molecule of semi-heavy water for several thousand molecules of ordinary water. This is about ten times more than would be expected from the chemical composition of the Sun.

Therefore, hypotheses have been put forward that some of the water in the Solar System comes from ice in dark clouds from hundreds of thousands of years before the birth of the Sun. The results obtained for L1527 IRS are consistent with this hypothesis. A high level of the presence of semi-heavy water ice has been detected in the envelope of this protostar.

The observations were made using the James Webb Space Telescope (JWST). Before the Webb telescope was put into space, accurate measurements of this indicator had only been made for gas. Now they have managed to do it for ice.

The measured level is slightly higher than for some comets in the Solar System and in the oceans on Earth. There could be several reasons, such as differences in the chemical composition of the clouds from which the Sun formed and L1527 IRS is born, or "our" water may have been slightly altered later in the evolution of the planetary system.

Scientists plan to continue observations with the Webb Telescope of 30 more protostars and primordial dark clouds to try to find out what is causing the differences. Observations will also be carried out with the ALMA radio telescope network.

The results of the research were published in "The Astrophysical Journal Letters". The first author of the publication is Katerina Slavicinska, a PhD student at the Leiden Observatory (the Netherlands), and among the authors is Łukasz Tychoniec, a graduate of the Adam Mickiewicz University in Toruń, and currently at the Leiden Observatory. (PAP)

cza/ zan/

The PAP Foundation permits free reprinting of articles from the Nauka w Polsce Service, provided that you inform us by e-mail once a month about the use of the service and provide the source of the article. In portals and internet services, please include the linked address: Source: naukawpolsce.pl, and in journals the annotation: Source: Nauka w Polsce Service - naukawpolsce.pl. The above permission does not apply to: information from the "World" category and any photographs and video materials.