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Tracing The Cosmic Origin Of Complex Organic Molecules With Their Radiofrequency Footprint - Astrobiology News
The origin of life on Earth is a topic that has piqued human curiosity since probably before recorded history began. But how did the organic matter that constitutes lifeforms even arrive at our planet? Though this is still a subject of debate among scholars and practitioners in related fields, one approach to answering this question involves finding and studying complex organic molecules (COMs) in outer space. Many scientists have reported finding all sorts of COMs in molecular clouds--gigantic regions of interstellar space that contain various types of gases. This is generally done using radio telescopes, which measure and record radiofrequency waves to provide a frequency profile of the incoming radiation called spectrum. Molecules in space are usually rotating in various directions, and they emit or absorb radio waves at very specific frequencies when their rotational speed changes. Current physics and chemistry models allow us to approximate the composition of what a radio telescope is pointed at, via analysis of the intensity of the incoming radiation at these frequencies. In a recent study published in Monthly Notices of the Royal Astronomical Society, Dr Mitsunori Araki from Tokyo University of Science, along with other scientists from across Japan, tackled a difficult question in the search for interstellar COMs: how can we assert the presence of COMs in the less dense regions of molecular clouds? Because molecules in space are mostly energized by collisions with hydrogen molecules, COMs in the low-density regions of molecular clouds emit less radio waves, making it difficult for us to detect them. However, Dr Araki and his team took a different approach based on a special organic molecule called acetonitrile (CH3CN). Acetonitrile is an elongated molecule that has two independent ways of rotating: around its long axis, like a spinning top, or as if it were a pencil spinning around your thumb. The latter type of rotation tends to spontaneously slow down due to the emission of radio waves and, in the low-density regions of molecular clouds, it naturally becomes less energetic or "cold." In contrast, the other type of rotation does not emit radiation and therefore remains active without slowing down. This particular behavior of the acetonitrile molecule was the basis on which Dr Araki and his team managed to detect it. He explains: "In low-density regions of molecular clouds, the proportion of acetonitrile molecules rotating like a spinning top should be higher. Thus, it can be inferred that an extreme state in which a lot of them would be rotating in this way should exist. Our research team was, however, the first to predict its existence, select astronomical bodies that could be observed, and actually begin exploration." Instead of going for radio wave emissions, they focused on radio wave absorption. The "cold" state of the low-density region, if populated by acetonitrile molecules, should have a predictable effect on the radiation that originates in celestial bodies like stars and goes through it. In other words, the spectrum of a radiating body that we perceive on Earth as being "behind" a low-density region would be filtered by acetonitrile molecules spinning like a top in a calculable way, before it reaches our telescope on earth. Therefore, Dr Araki and his team had to carefully select radiating bodies that could be used as an appropriate "background light" to see if the shadow of "cold" acetonitrile appeared in the measured spectrum. To this end, they used the 45 m radio telescope of the Nobeyama Radio Observatory, Japan, to explore this effect in a low-density region around the "Sagittarius molecular cloud Sgr B2(M)," one of the largest molecular clouds in the vicinity of the center of our galaxy. After careful analysis of the spectra measured, the scientists concluded that the region analyzed was rich in acetonitrile molecules rotating like a spinning top; the proportion of molecules rotating this way was actually the highest ever recorded. Excited about the results, Dr Araki remarks: "By considering the special behavior of acetonitrile, its amount in the low-density region around Sgr B2(M) can be accurately determined. Because acetonitrile is a representative COM in space, knowing its amount and distribution though space can help us probe further into the overall distribution of organic matter." Ultimately, this study may not only give us some clues about where the molecules that conform us came from, but also serve as data for the time when humans manage to venture outside the solar system. Additional imagery Astrobiology Please follow Astrobiology on Twitter.
Traces Of Ancient Life Tell Story Of Early Marine Ecosystem Diversity - Astrobiology News
If you could dive down to the ocean floor nearly 540 million years ago just past the point where waves begin to break, you would find an explosion of life--scores of worm-like animals and other sea creatures tunneling complex holes and structures in the mud and sand--where before the environment had been mostly barren. Thanks to research published today in Science Advances by a University of Saskatchewan (USask)-led international research team, this rapid increase in biodiversity--one of two such major events across a 100-million-year timespan 560 to 443 million years ago--is part of a clearer picture emerging of Earth's ancient oceans and life in them. "We can see from the trace fossils--tracks, trails, borings, and burrows animals left behind--that this particular environment of the ocean floor, the offshore, served as a 'crucible' for life," said USask paleobiologist Luis Buatois, lead author of the article. "Over the next millions of years, life expanded from this area outwards into deeper waters and inwards into shallower waters." The research is the culmination of over 20 years of work from Buatois and the team which examined hundreds of rock formations in locations across every continent. "Until now, these two events--the Cambrian Explosion and the Great Ordovician Biodiversification Event--have been understood mostly through the study of body fossils--the shells, carapaces and the bones of ancient sea creatures," said Buatois. "Now we can confidently say that these events are also reflected in the trace fossil record which reveals the work of those soft-bodied creatures whose fleshy tissues rot very quickly and so are only very rarely preserved." For the first time, the team has shown evidence of animals actively "engineering" their ecosystem--through the construction of abundant and diverse burrows on the sea floor of the world's oceans in this ancient time. "Never underestimate what animals are capable of doing," said USask paleobiologist Gabriela Mángano, co-author of the paper. "They can modify their physical and chemical environment, excluding other animals or allowing them to flourish by creating new resources. And they were definitely doing all these things in these ancient seas." The trace fossil-producing animals' engineering efforts may have laid the foundation for greater diversity in marine life. The researchers identified a 20-million-year time lag during the Cambrian Explosion (the time when most of the major groups of animals first appear in the fossil record) between diversification in trace fossils and in animal body fossils, suggesting the later animals exploited changes which enabled them to diversify even more. The research also helps resolve a big question from the geochemical record, which indicated much of the ancient ocean was depleted of oxygen and unsuitable for life. Like oceans today, the Cambrian ocean had certain areas that were full of life, while others lacked the necessary conditions to support it. "The fact that trace fossil distribution shows that there were spots where life flourished adjacent to others devoid of animal activity all through the early Cambrian period is a strong argument in favor of the idea that zones with enough oxygen to sustain a diversity of animals co-existed with oxygen-depleted waters in deeper areas," said Mángano. "It's a situation similar to what happens in modern oceans with oxygen minimum zones in the outer part of the continental shelf and the upper part of the continental slope, but oxygenated ones in shallower water." The research could provide new insights from an evolutionary perspective into the importance of extensive rock formations of a similar vintage found in Canada and elsewhere, and help society to prepare for coming challenges. "Understanding changes that took place early in the history of our planet may help us to face present challenges in modern oceans, particularly with respect to oxygen changes," said Buatois. ### Other members of the team are: USask PhD student Kai Zhou, University of Portsmouth researcher Nic Minter, Senckenberg am Meer institute (Hamburg) researcher Max Wisshak, College of Wooster (Ohio) paleontologist Mark Wilson, and statistician Ricardo Olea of the United States Geological Survey. The research was funded by grants from Canada's Natural Sciences and Engineering Research Council awarded to Buatois and Mángano. Astrobiology Please follow Astrobiology on Twitter.