Darkest view ever of interstellar ices

An international team including Southwest Research Institute, Leiden University and NASA used observations from the James Webb Space Telescope (JWST) to achieve the darkest ever view of a dense interstellar cloud. These observations have revealed the composition of a virtual treasure chest of ices from the early universe, providing new insights into the chemical processes of one of the coldest, darkest places in the universe as well as the origins of the molecules that make up planetary atmospheres.

"The JWST allowed us to study ices that exist on dust grains within the darkest regions of interstellar molecular clouds," said SwRI Research Scientist Dr. Danna Qasim, co-author of the study published in Nature Astronomy. "The clouds are so dense that these ices have been mostly protected from the harsh radiation of nearby stars, so they are quite pristine. These are the first ices to be formed and also contain biogenic elements, which are important to life."

NASA's JWST has a 6.5-meter-wide mirror providing remarkable spatial resolution and sensitivity, optimized for infrared light. As a result, the telescope has been able to image the densest, darkest clouds in the universe for the first time.

"These observations provide new insights into the chemical processes in one of the coldest, darkest places in the universe to better understand the molecular origins of protoplanetary disks, planetary atmospheres, and other Solar System objects," Qasim said.

Most interstellar ices contain very small amounts of elements like oxygen and sulfur. Qasim and her co-authors seek to understand the lack of sulfur in interstellar ices.

"The ices we observed only contain 1% of the sulfur we're expecting. 99% of that sulfur is locked-up somewhere else, and we need to figure out where in order to understand how sulfur will eventually be incorporated into the planets that may host life," Qasim explained.

In the study, Qasim and colleagues propose that the sulfur may be locked in reactive minerals like iron sulfide, which may react with ices to form the sulfur-bearing ices observed.

"Iron sulfide is a highly reactive mineral that has been detected in the accretion disks of young stars and in samples returned from comets. It's also the most common sulfide mineral in lunar rocks," Qasim said. "If sulfur is locked-up in these minerals, that could explain the low amount of sulfur in interstellar ices, which has implications for where sulfur is stored in our Solar System. For example, the atmosphere of Venus has sulfur-containing molecules, in which the sulfur could have partially come from interstellar-inherited minerals."

From Science Daily

Origins of the building blocks of life

A new study led by Southwest Research Institute Research Scientist Dr. Danna Qasim posits that interstellar cloud conditions may have played a significant role on the presence of key building blocks of life in the solar system.

"Carbonaceous chondrites, some of the oldest objects in the universe, are meteorites that are thought to have contributed to the origins of life. They contain several different molecules and organic substances, including amines and amino acids, which are key building blocks of life that were critical to creating life on Earth. These substances are necessary to create proteins and muscle tissue," Qasim said.

Most meteorites are fragments of asteroids that broke apart long ago in the asteroid belt, located between Mars and Jupiter. Such fragments orbit the Sun -- sometimes for millions of years -- before colliding with Earth.

One of the questions Qasim and others are trying to answer is how amino acids got into the carbonaceous chondrites in the first place. Because most meteorites come from asteroids, scientists have attempted to reproduce amino acids by simulating asteroid conditions in a laboratory setting, a process called "aqueous alteration."

"That method hasn't been 100% successful," Qasim said. "However, the make-up of asteroids originated from the parental interstellar molecular cloud, which was rich in organics. While there's no direct evidence of amino acids in interstellar clouds, there is evidence of amines. The molecular cloud could have provided the amino acids in asteroids, which passed them on to meteorites."

To determine to what extent amino acids formed from asteroid conditions and to what extent they were inherited from the interstellar molecular cloud, Qasim simulated the formation of amines and amino acids as it would occur in the interstellar molecular cloud.

"I created ices that are very common in the cloud and irradiated them to simulate the impact of cosmic rays," explained Qasim, who conducted the experiment while working at NASA's Goddard Space Flight Center in Greenbelt, Maryland, between 2020 and 2022. "This caused the molecules to break up and recombine into larger molecules, which ultimately created an organic residue."

Qasim then processed the residue again by recreating asteroid conditions through aqueous alteration and studied the substance, looking for amines and amino acids.

"No matter what kind of asteroid processing we did, the diversity of amines and amino acids from the interstellar ice experiments remained constant," she said. "That tells us that interstellar cloud conditions are quite resilient to asteroid processing. These conditions could have influenced the distribution of amino acids we find in meteorites."

However, the individual abundances of amino acids doubled, suggesting the asteroid processing influences the amount of amino acids present.

"Essentially we have to consider both the interstellar cloud conditions and processing by the asteroid to best interpret the distribution," she said.

Qasim looks forward to studies of asteroid samples from missions such as OSIRIS-REx, which is currently on its way back to Earth to deliver samples from the asteroid Bennu here in September, and Hayabusa2, which recently returned from the asteroid Ryugu, to better understand the role the interstellar cloud played in distributing the building blocks of life.

Read more at Science Daily

Supermassive blackhole influences star formation

A European team of astronomers led by Professor Kalliopi Dasyra of the National and Kapodistrian University of Athens, Greece, under participation of Dr. Thomas Bisbas, University of Cologne modelled several emission lines in Atacama Large Millimeter Array (ALMA) and Very Large Telescope (VLT) observations to measure the gas pressure in both jet-impacted clouds and ambient clouds. With these unprecedented measurements, published recently in Nature Astronomy, they discovered that the jets significantly change the internal and external pressure of molecular clouds in their path. Depending on which of the two pressures changes the most, both compression of clouds and triggering of star formation and dissipation of clouds and delaying of star formation are possible in the same galaxy. "Our results show that supermassive black holes, even though they are located at the centers of galaxies, could affect star formation in a galaxy-wide manner" said Professor Dasyra, adding that "studying the impact of pressure changes in the stability of clouds was key to the success of this project. Once few stars actually form in a wind, it is usually very hard to detect their signal on top of the signal of all other stars in the galaxy hosting the wind."

It is believed that supermassive black holes lie at the centers of most galaxies in our Universe. When particles that were infalling onto these black holes are trapped by magnetic fields, they can be ejected outwards and travel far inside galaxies in the form of enormous and powerful jets of plasma. These jets are often perpendicular to galactic disks. In IC 5063 however, a galaxy 156 million light years away, the jets are actually propagating within the disk, interacting with cold and dense molecular gas clouds. From this interaction, compression of jet-impacted clouds is theorized to be possible, leading to gravitational instabilities and eventually star formation due to the gas condensation.

For the experiment, the team used the emission of carbon monoxide (CO) and formyl cation (HCO+) provided by ALMA, and the emission of ionized sulfur and ionized nitrogen provided by VLT. They then used advanced and innovative astrochemical algorithms to pinpoint the environmental conditions in the outflow and in the surrounding medium. These environmental conditions contain information about the strength of the far-ultraviolet radiation of stars, the rate at which relativistic charged particles ionize the gas, and the mechanical energy deposited on the gas by the jets. Narrowing down these conditions revealed the densities and gas temperatures descriptive of different parts of this galaxy, which were then used to provide pressures.

"We have performed many thousands of astrochemical simulations to cover a wide range of possibilities that may exist in IC 5063" said co-author Dr. Thomas Bisbas, DFG Fellow of the University of Cologne and former postdoctoral researcher at the National Observatory of Athens. A challenging part of the work was to meticulously identify as many physical constraints as possible to the examined range that each parameter could have. "This way, we could get the optimal combination of physical parameters of clouds at different locations of the galaxy," said co-author Mr. Georgios Filippos Paraschos, Ph.D. student at the Max Planck Institute for Radio Astronomy in Bonn and former Master's student at the National and Kapodistrian University of Athens.

Read more at Science Daily