Tag Archives: Hydrocarbons

Saturn’s Moon Titan Could Harbor an Unforeseen Blend of Hydrogen Cyanide and Hydrocarbons

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Titan serves as an intriguing subject for in-depth investigations of organic chemistry under unusual conditions. This Saturnian moon is abundant in nonpolar hydrocarbons like ethane and methane, alongside hydrogen cyanide (HCN), a highly relevant small polar molecule in prebiotic chemistry. Recent studies show that these notably polar compounds can mix at low temperatures, creating structures that challenge traditional chemical theories.

Artistic rendering of Kraken Mare, Titan’s extensive ocean of liquid methane. Image credit: NASA’s John Glenn Research Center.

Hydrogen cyanide is commonly found in the astrochemical landscape and has been detected in numerous celestial bodies, including the interstellar medium, comets, planets, moons, and dwarf planets.

This molecule ranks as the second most prevalent product anticipated from Titan’s atmospheric chemistry.

Dr. Martin Rahm, a researcher from Chalmers University of Technology, stated: “These remarkable discoveries enhance our understanding of something vast—a moon comparable in size to Mercury.”

In laboratory experiments, Rahm and his team combined hydrogen cyanide with methane and ethane at temperatures as low as 90 K (around -180 degrees Celsius).

At this temperature, hydrogen cyanide forms crystals, while methane and ethane exist as liquids.

Using laser spectroscopy to analyze these mixtures at an atomic level, researchers found that while the molecules remained intact, changes were still occurring.

To uncover what was happening, they conducted extensive computer simulations to explore thousands of potential molecular arrangements in the solid phase.

Ultimately, they discovered that the hydrocarbons infiltrated the hydrogen cyanide crystal lattice, leading to the formation of a stable new structure termed a cocrystal.

“The identification of unexpected interactions between these substances may influence our understanding of Titan’s geology and unique features such as lakes, oceans, and sand dunes,” Dr. Rahm explained.

“Moreover, hydrogen cyanide could be crucial in the abiotic synthesis of some life-building blocks, like amino acids for proteins and nucleobases for genetic material.”

“Consequently, our research offers valuable insights into the pre-emergent chemistry of life and the potential for life to evolve in extreme environments.”

of result Published in July 2025. Proceedings of the National Academy of Sciences.

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Fernando Izquierdo Ruiz and others. 2025. Hydrogen cyanide and hydrocarbons mix on Titan. PNAS 122 (30): e2507522122; doi: 10.1073/pnas.2507522122

Source: www.sci.news

Cyanocoronene Discovered: Astronomers Find 7-Ring Polycyclic Aromatic Hydrocarbons in TMC-1

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Polycyclic aromatic hydrocarbons (PAHs) are believed to be the most prevalent class of organic compounds in the universe, yet their lifecycle in interstellar media remains poorly understood. Recently, astronomers using NSF’s Green Bank telescopes identified cyanocoronene (C24H11CN), the largest PAH discovered in space, located within the starless cloud core TMC-1.

Cyanocoronene, composed of seven interconnected benzene rings and cyano groups, is a region known for its abundant chemistry and was discovered in the cold, dark molecular cloud TMC-1, recognized as a new cradle for star formation. Image credits: NSF/AUI/NSF/NRAO/P.VOSTEEN.

Cyanocoronene is a derivative of coronene, often regarded as a prototype compact PAH due to its stability and distinctive structure.

PAHs are thought to play a crucial role in the chemistry that captures a significant portion of the universe’s carbon and contributes to star and planet formation.

Until this discovery, only smaller PAHs had been identified in space, making this finding a significant leap in understanding size limits.

“Each new detection brings us closer to understanding the origins of the complex organic chemistry in the universe, and possibly the building blocks of life,” says Dr. Gabi Wentzel, an astronomer at the Center for Astrophysics at MIT and Harvard & Smithsonian.

Dr. Wentzel and her team first synthesized cyanocoronene in the laboratory and recorded its unique microwave spectrum using advanced spectroscopic methods.

Equipped with this molecular fingerprint, the astronomers searched data from the Green Bank telescope, the primary instrument for the Gotham project (GBT observations of TMC-1: GBT observations of aromatic molecules).

They identified several spectral lines of cyanocoronene, confirming its presence with a statistical significance of 17.3 sigma, a robust detection by astronomical standards.

Cyanocoronene is currently the largest individual PAH molecule found in interstellar space, featuring 24 carbon atoms in its core structure (excluding the cyano group).

The quantity of cyanocoronene detected is comparable to that of smaller PAHs previously identified, challenging the notion that larger molecules are rare in the universe.

This indicates that even more complex aromatic molecules may be prevalent in the cosmos.

“The presence of such a large, stable PAH lends support to the idea that these molecules can serve as significant reservoirs of carbon and potentially facilitate the formation of new planetary systems throughout their lifecycle,” the researchers stated.

“The quantum chemical analysis in this study reveals that the reaction between coronene and CN radicals enables the efficient formation of cyanocoronene in cold space conditions.

“This implies that even prior to star formation, there can be chemical processes that establish complex organic matter.”

“The discovery of cyanocoronene not only adds new chapters to the narrative of astrochemistry but also reinforces the PAH hypothesis. It suggests that these molecules are responsible for the enigmatic infrared emission zones scattered throughout the universe.”

“Additionally, it establishes a direct link between interstellar clouds, meteoroids, and asteroid chemistry, implying that organic molecules present in our solar system might have originated in similar environments long before the Sun was born.”

The scientists presented their Survey results on June 11th at the AAS246, 246th Summer American Astronomical Association.

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Gabi Wenzel & Gotham Collaboration. 2025. Discovery of 7-ring PAH cyanocoronene (C24H11CN) from Gotham observation of TMC-1. AAS246 Summary #75

Source: www.sci.news

Webb uncovers high levels of hydrocarbons in protoplanetary disks surrounding ultra-low-mass stars

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Very low-mass stars orbit rocky exoplanets more frequently than other types of stars. The composition of these planets is poorly understood, but it is thought to be related to the protoplanetary disk in which they form. In the new study, astronomers used the NASA/ESA/CSA James Webb Space Telescope to investigate the chemical composition of the planet-forming disk around ISO-ChaI 147, a red dwarf star just one-tenth the mass of the Sun. They identified emission from 13 carbon-containing molecules, including ethane and benzene.

This is an artist's impression of a young star surrounded by a disk of gas and dust. Image courtesy of NASA/JPL.

ISO-ChaI 147 It is a red dwarf star with a mass 0.11 times that of the Sun, located about 639 light years away in the constellation Chamaeleon.

The star was observed as part of the MIRI Mid-Infrared Disk Survey (MINDS), which aims to bridge the gap between the chemical composition of the disk and the properties of exoplanets.

These observations provide insight into the environments and fundamental elements for the formation of such planets.

Astronomers discovered that the gas in ISO-ChaI 147's planet-forming region is rich in carbon.

This could be due to carbon being removed from the solid material from which rocky planets form, which could explain why Earth is relatively carbon-poor.

“WEBB has greater sensitivity and spectral resolution than conventional infrared space telescopes,” said Dr Aditya Arabavi, an astronomer at the University of Groningen.

“These observations are not possible from Earth because the radiation is blocked by the atmosphere.”

“So far we have only been able to identify acetylene emissions from this object.”

“But Webb's high sensitivity and spectral resolution allowed us to detect faint emissions from fewer molecules.”

“Thanks to Webb, we now know that these hydrocarbon molecules are not only diverse, but abundant as well.”

The spectrum of ISO-ChaI 147 shows the richest hydrocarbon chemical composition ever observed in a protoplanetary disk, consisting of 13 carbon-containing molecules. Image credit: NASA/ESA/CSA/Ralf Crawford, STScI.

The spectrum of ISO-ChaI 147 is Webb's mid-infrared measuring instrument (MIRI) displays the richest hydrocarbon chemical composition ever observed in a protoplanetary disk, consisting of 13 carbon-containing molecules up to benzene.

This includes the first extrasolar detection of ethane, the largest fully saturated hydrocarbon detected outside the solar system.

Fully saturated hydrocarbons are expected to form from more basic molecules, so detecting them here can give researchers clues about their chemical environment.

Astronomers also detected ethylene, propyne, and methyl radicals in a protoplanetary disk for the first time.

“These molecules have already been detected in our solar system, for example in comets such as 67P/Churyumov-Gerasimenko and C/2014 Q2 (Lovejoy),” Dr. Arababi said.

“It's amazing that we can now see these molecules dancing in the cradle of the planet.”

“This is a completely different environment to how we normally think of planet formation.”

The team note that these results have significant implications for the astrochemistry within 0.1 AU and the planets that form there.

“This is very different to the composition found in disks around solar-type stars, where oxygen-containing molecules (such as carbon dioxide and water) dominate,” said Dr Inga Kamp, also from the University of Groningen.

“This object proves that these are unique classes of objects.”

“It's incredible that we can detect and quantify the amount of a molecule that's well known on Earth, such as benzene, in an object more than 600 light years away,” said Dr Agnes Perrin, an astronomer at the French National Center for Scientific Research.

Team result Published in today's journal Science.

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AM Arabavi other2024. Abundant hydrocarbons present in a disk around a very low-mass star. Science 384, 6700: 1086-1090; doi: 10.1126/science.adi8147

Source: www.sci.news

Polycyclic Aromatic Hydrocarbons in Asteroids Found to Predate the Solar System, New Study Shows

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Astronomical observations have shown that polycyclic aromatic hydrocarbons (PAHs) are abundant and widespread in the interstellar medium. A PAH molecule consists of several adjacent aromatic rings terminated with hydrogen. In the new study, scientists conducted laboratory isotope analysis of PAHs in samples of the asteroid Ryugu and meteorite Murchison collected by JAXA’s Hayabusa2 spacecraft. They argue that at least some of the Ryugu PAHs formed in cold interstellar clouds and therefore must be older than our solar system.

This image of asteroid Ryugu was taken on June 26, 2018 by the Telescopic Optical Navigation Camera (ONC-T) aboard JAXA’s Hayabusa 2 spacecraft from a distance of 13.7 miles (22 km).Image provided by: JAXA / University of Tokyo / Kochi University / Rikkyo University / Nagoya University / Chiba Institute of Technology / Meiji University / University of Aizu / AIST

PAHs contain about 20% of the carbon in the interstellar medium.

These can be produced in the circumstellar environment (temperatures above 1000 K), in cold interstellar clouds (temperatures around 10 K), or by the processing of carbon-rich dust particles.

“PAHs are organic compounds composed of carbon and hydrogen that are common on Earth but also occur in celestial bodies such as asteroids and meteorites,” said study co-author and director of the Western Australian Center for Organic Isotope Geochemistry. said researcher Professor Kriti Grice. Curtin University.

“We conducted controlled combustion experiments on plants in Australia and found that PAHs found in debris from the asteroid Ryugu returned to Earth by a Japanese spacecraft in 2020, and comparable to the Murchison meteorite that landed in Australia in 1969. I compared them physically.”

“We analyzed the bonds between light and heavy carbon isotopes in PAHs to reveal the temperatures at which they form.”

“Selected PAHs from Ryugu and Murchison were found to have different characteristics, with smaller ones probably forming in cold outer space and larger ones probably forming in warmer regions such as near stars or inside celestial bodies. It is thought to have been formed in the environment.”

A model of the molecular structure of ribose and an image of the Murchison meteorite. Image credit: Yoshihiro Furukawa.

“Understanding the isotopic composition of PAHs can help elucidate the conditions and environments in which these molecules were formed, providing insight into the history and chemistry of astronomical objects such as asteroids and meteorites,” says the study. said Dr. Alex Holman, co-author and fellow Westerner. Australian Center for Organic and Isotopic Geochemistry at Curtin University.

“This research gives us valuable insight into how organic compounds form extraterrestrially and where in the universe they come from.”

“Through the use of high-tech methods and creative experiments, we show that select PAHs on asteroids can form even in cold space.”

of result Published in this week’s magazine science.

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Sarah S. Zeichner other. 2023. Polycyclic aromatic hydrocarbons in Ryugu samples formed in the interstellar medium. science 382 (6677): 1411-1416; doi: 10.1126/science.adg6304

Source: www.sci.news