. | . |
Simulating nature's cosmic laboratory, one helium droplet at a time by Staff Writers Heidelberg, Germany (SPX) Mar 26, 2019
Two astronomers from the Max Planck Institute for Astronomy and from the University of Jena have found an elegant new method to measure the energy of simple chemical reactions, under similar conditions as those encountered by atoms and molecules in the early solar system. Their method promises accurate measurements of reaction energies that can be used to understand chemical reactions under space conditions - including those reactions that were responsible of creating organic chemicals as the raw material for the development of life. The results have been published in the journal Nature Astronomy. In order for life to form, nature needed plenty raw materials in the shape of complex organic molecules. Some of those molecules are likely to have formed long before, in space, during the birth of the solar system. Systematic studies of the necessary chemical reactions, which take place on the craggy and convoluted surfaces of dust grains, were and are hampered by a lack of data. Which elementary reactions, involving which individual reactants are possible? What temperature is required for a reaction to take place? Which molecules are produced in those reactions? Now, Thomas Henning, director at the Max Planck Institute for Astronomy (MPIA), and Sergiy Krasnokutskiy of the MPIA's Laboratory Astrophysics Group at the University of Jena have developed an elegant method to study such elementary surface reactions - using minute liquid helium droplets. In the early solar system, long before the formation of Earth, complex chemical reactions took place, creating substantial amounts of organic molecules. The cosmic laboratory for these works of chemical synthesis was provided by grains of dust - clusters of mostly silicates and carbon, covered with a mantle of ice, with complicated and delicate tendrils and ramifications, and on this basis with one crucial property: A comparatively large surface on which chemical reactions could take place. In the millions of years that follows, many of those dust grains would cluster together for form ever larger structures, until finally, solid planets emerged, orbiting the young Sun.
Creating the Raw Ingredients for Life In order to understand the early natural chemical experiments in our universe, we need to know the properties of the various reactions. For instance, do certain reactions need a specific activation energy to happen? What is the eventual product of a given reaction? Those parameters determine which reactions can happen under what conditions in the early solar system, and they are key for any realistic reconstruction of early solar system chemistry.
Scarce Data About Low-Temperature Surface Reactions If this energy is not passed on to the environment, the new molecule will quickly be destroyed. This prevents the formation of many species of in the gas phase. On a surface, or in a medium, where energy can readily be absorbed by the additional matter present, the conditions for certain types of reactions building complex molecules, step by step, are much more favorable. Henning and Krasnokutskiy developed an elegant method for measuring the energetics of such reactions. Their mock-ups of cosmic laboratories are miniature helium droplets, a few nanometers in size, drifting in a high vacuum. The reactants - that is, the atoms or molecules meant to take part in the reaction - are brought into the vacuum chamber as gases, but in such minute amounts that helium droplets are overwhelmingly likely to pick up either a single molecule of each required species or none, but not more. The helium droplets act as a medium that, similar to the surface of a dust grain, can absorb reaction energy, allowing reactions to happen under similar conditions to those in the early solar system. This reproduces a key feature of the relevant surface chemistry (although other properties, such as catalytic properties of a specific dust surface, are not modeled).
Nanodrops as Measuring Devices By calibrating their method using reactions that had been studied in detail beforehand, and whose properties are well-known, the two astronomers were able to increase the method's accuracy considerably. All in all, the new method provides an elegant new way of investigating the formation pathway of complex organic molecules in space. This should enable researchers to be more specific about the raw materials nature had to work with in the run-up of the emergence of life on Earth. But there is more: The first measurements using the new technique confirm a trend that had already been visible in other recent experiments: On surfaces, at low temperatures, carbon atoms are surprisingly reactive. The researchers found a surprisingly high number - almost a dozen - of reactions involving carbon atoms which are barrierless, that is, which do not require extra energy input to proceed, and hence can occur at very low temperatures. Evidently, the condensation of atomic gas at low temperatures is bound to lead to the formation of a large variety of organic molecules. But that large possible variety also means that molecules of each specific species will be very rare. This, in turn, suggests that astronomers might be drastically underestimating the amount of organic molecules in outer space. When it comes to estimating abundances, astronomical observations examine the trace signatures (spectral lines) of each molecular species separately. If there are many different species of organic molecules out there, each separate species can "fly under the radar." Its molecules might be present only in amounts too minute for astronomers to detect, and in addition, even the telltale signatures of the molecules (more generally those of specific functional groups common to different types of molecules) could be slightly altered, making the molecule evade detection. But added up, it is possible that all these separate species of molecule together could make up a substantial amount of matter in outer space - a hidden outer-space world of organic chemistry.
Research Report: "Experimental Characterization of the Energetics of Low-Temperature Surface Reactions," Thomas K. Henning and Serge A. Krasnokutski, 2019 March 25, Nature Astronomy
Witnessing the birth of a massive binary star system Tokyo, Japan (SPX) Mar 19, 2019 Scientists from the RIKEN Cluster for Pioneering Research in Japan, Chalmers University of Technology in Sweden and the University of Virginia in the USA and collaborators have made observations of a molecular cloud that is collapsing to form two massive protostars that will eventually become a binary star system. While it is known that most massive stars possess orbiting stellar companions it has been unclear how this comes about - for example, are the stars born together from a common spiraling ... read more
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |