26/06/2023
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An international team of scientists has used data collected by the NASA/ESA/CSA James Webb Space Telescope to identify the molecule. [1] known as methyl cation (CH3 +) for the first time, which is in the protoplanetary disc around a young star. They did this with the analysis of various experts, including the main points from laboratory spectroscopists.
This simple molecule has a special property: it reacts weakly with the most abundant element in our Universe (hydrogen) but it reacts easily with other molecules and thus causes the growth of more complex carbon molecules. Carbon dioxide is of particular interest to astronomers because all known living organisms contain carbon. The important role of CH3+ in interstellar carbon chemistry was predicted in the 1970s, but Webb’s unique capabilities have made it possible – in the region where habitable planets can form.
Carbon compounds [2] forming the basis of all known life, and therefore of great interest to scientists who work to understand how life began on Earth, and how it can develop elsewhere in our Universe. Thus, interstellar organic chemistry [3] it is a very interesting place for astronomers who study the places where new stars and planets are formed. Molecular ions [4] carbon-containing molecules are very important, because they combine with other small molecules to form very complex substances even at interstellar temperatures. [5].
The methyl cation (CH3 +) is an ion derived from carbon. CH3+ has been established by scientists as important since the 1970s and 1980s. This is due to the attractive effect of CH3 +, which is affected by many other molecules. This tiny structure is so important that it is thought to be the cornerstone of interstellar organic chemistry, yet it has so far remained elusive. The special features of the James Webb Space Telescope made it the ideal instrument to explore this important place – and already, a team of scientists from around the world had seen it with Webb for the first time. Marie-Aline Martin of the University of Paris-Saclay, France, who is a member of the scientific team, explains: “The detection of CH3+ not only confirms the interest of James Webb but also confirms the central importance of CH3+ in stellar chemistry.”
Region of the Orion Bar (enhanced MIRI image)
A signal of CH3+ was found in the star-protoplanetary disc [6] The system known as d203-506, which is about 1350 light years away, in the Orion Nebula. Although the star in d203-506 is a small red star, with a mass of about one-tenth that of the Sun, the system is affected by strong ultraviolet light from nearby hotter, younger, larger stars. Scientists believe that most of the planets that form in these planets go through periods of such intense ultraviolet radiation, since stars tend to form in clusters that often contain large, ultraviolet-forming stars. Interestingly, evidence from meteorites shows that the protoplanetary disk that formed our Sun also contained a lot of ultraviolet light – emitted by a companion star to our Sun that has already died (massive stars burn more and die faster than smaller stars). The conundrum in all this is that ultraviolet radiation has long been seen as too destructive for the creation of complex molecules – yet there is clear evidence that the only life-supporting world we know was born from the disc that existed. more exposed to it.
The research team may have found a solution to this problem. Their work predicts that the presence of CH3+ is linked to ultraviolet light, which provides the energy needed for CH3+ to form. Also, the duration of ultraviolet radiation that the disks are exposed to appears to have a significant effect on their composition. For example, Webb’s observations of protoplanetary disks that do not receive strong ultraviolet radiation from a nearby source show abundant water — unlike d203-506, where the team could detect no water at all. The lead author, Olivier Berné from the University of Toulouse, France, explains clearly, “This clearly shows that ultraviolet light can significantly change the chemistry of the proto-planetary disc. It may have played a very important role in the natural origin of life by helping to create CH3+ – a substance that maybe it wasn’t the least.”
Orion Bar Section (Slider)
Although research published in the early 1970s predicted the importance of CH3+, it was previously impossible to detect. Many molecules in protoplanetary discs are observed using radio telescopes. However, for this to happen the molecules in question must have what is known as a ‘permanent dipole moment’, meaning that the geometry of the molecule is such that its electric potential is unstable, making the molecule both positive and negative ‘END’. CH3+ is homogeneous, so its charge is constant, and it does not have the constant moment required for observations with radio telescopes. We can see the visible lines emitted by CH3+ in the infrared, but Earth’s atmosphere makes this impossible to see from Earth. Therefore, it was necessary to use a telescope that could see signals in the infrared. The NIRSpec equipment, which Europe contributed to Webb’s, and MIRI, half of which was contributed by Europe, were good for the job. In fact, detection of CH3+ was already so difficult that when the team saw the signal in their data, they didn’t know how to detect it. Remarkably, the team was able to interpret the results in less than four weeks, drawing on the expertise of an international team with diverse expertise.
The discovery of CH3+ was only possible thanks to a collaboration between astronomers, astrophysicists, astrophysicists, astrophysicists, and experimental spectroscopists, who combined JWST’s unique skills in space and Earth-based laboratories to better investigate and interpret the state of our universe. and evolution. Marie-Aline Martin added: “What we found was possible because astronomers, modelers, and laboratory observers worked together to understand the unique observations of James Webb.”
The results of the PDRs4ALL ERS panel were published today in the Nature.
Notes
[1] Molecules are small particles made up of two or more atoms that are chemically bonded together.
[2] A compound is a molecule that consists of several elements. Therefore, all molecules are molecules but not all molecules are made. For example, a hydrogen molecule (H2) is a molecule but not a compound, while a water molecule (H2O) is a group.
[3] Organic chemistry refers to the chemistry of carbon-based molecules and compounds. It can also be called carbon chemistry.
[4] An ion is an atom or molecule that has an overall electrical potential, due to the excess or deficiency of negative electrons compared to the number of positive protons in the ion. A cation is an ion with a positive charge (so less electrons).
[5] A more complex molecule is a molecule with more than one carbon atom.
[6] A protoplanetary disk is a circular disk of gas and dust that forms around young stars, and is how planets can form.
More information
Webb is the largest, most powerful telescope ever launched into space. Under the international agreement, ESA provided the mission to launch the telescope, using the Ariane 5 launch vehicle. Working with its partners, ESA was responsible for the design and qualification of the Ariane 5 modification of the Webb mission and the procurement of the launch mission by Arianespace . ESA also presented the workhorse spectrograph NIRSpec and 50% of the middle infrared instrument MIRI, which was designed and built by the European Institutes (The MIRI European Consortium) which receives funding worldwide in collaboration with JPL and the University of Arizona.
Webb is an international collaboration between NASA, ESA and the Canadian Space Agency (CSA).
Contact:
ESA Media Relations
media@esa.int
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