SPACE
Can signs of life be detected from Saturn’s frigid moon?
Enceladus’ ice plumes may hold the building blocks of life
Peer-Reviewed PublicationIMAGE:
THIS ARTISTIC RENDERING SHOWS ICE PLUMES BEING EJECTED FROM ENCELADUS AT SPEEDS OF UP TO 800 MILES/HOUR.
view moreCREDIT: NASA
As astrophysics technology and research continue to advance, one question persists: is there life elsewhere in the universe? The Milky Way galaxy alone has hundreds of billions of celestial bodies, but scientists often look for three crucial elements in their ongoing search: water, energy and organic material. Evidence indicates that Saturn’s icy moon Enceladus is an ‘ocean world’ that contains all three, making it a prime target in the search for life.
During its 20-year mission, NASA’s Cassini spacecraft discovered that ice plumes spew from Enceladus’ surface at approximately 800 miles per hour (400 m/s). These plumes provide an excellent opportunity to collect samples and study the composition of Enceladus’ oceans and potential habitability. However, until now it was not known if the speed of the plumes would fragment any organic compounds contained within the ice grains, thus degrading the samples.
Now researchers from the University of California San Diego have shown unambiguous laboratory evidence that amino acids transported in these ice plumes can survive impact speeds of up to 4.2 km/s, supporting their detection during sampling by spacecraft. Their findings appear in The Proceedings of the National Academy of Sciences (PNAS).
Beginning in 2012, UC San Diego Distinguished Professor of Chemistry and Biochemistry Robert Continetti and his co-workers custom-built a unique aerosol impact spectrometer, designed to study collision dynamics of single aerosols and particles at high velocities. Although not built specifically to study ice grain impacts, it turned out to be exactly the right machine to do so.
“This apparatus is the only one of its kind in the world that can select single particles and accelerate or decelerate them to chosen final velocities,” stated Continetti. “From several micron diameters down to hundreds of nanometers, in a variety of materials, we’re able to examine particle behavior, such as how they scatter or how their structures change upon impact.”
In 2024 NASA will launch the Europa Clipper, which will travel to Jupiter. Europa, one of Jupiter’s largest moons, is another ocean world, and has a similar icy composition to Enceladus. There is hope that the Clipper or any future probes to Saturn will be able to identify a specific series of molecules in the ice grains that could point to whether life exists in the subsurface oceans of these moons, but the molecules need to survive their speedy ejection from the moon and collection by the probe.
Although there has been research into the structure of certain molecules in ice particles, Continetti’s team is the first to measure what happens when a single ice grain impacts a surface.
To run the experiment, ice grains were created using electrospray ionization, where water is pushed through a needle held at a high voltage, inducing a charge that breaks the water into increasingly smaller droplets. The droplets were then injected into a vacuum where they freeze. The team measured their mass and charge, then used image charge detectors to observe the grains as they flew through the spectrometer. A key element to the experiment was installing a microchannel plate ion detector to accurately time the moment of impact down to the nanosecond.
The results showed that amino acids — often called the building blocks of life — can be detected with limited fragmentation up to impact velocities of 4.2 km/s.
“To get an idea of what kind of life may be possible in the solar system, you want to know there hasn’t been a lot of molecular fragmentation in the sampled ice grains, so you can get that fingerprint of whatever it is that makes it a self-contained life form,” said Continetti. “Our work shows that this is possible with the ice plumes of Enceladus.”
Continetti’s research also raises interesting questions for chemistry itself, including how salt affects the detectability of certain amino acids. It is believed that Enceladus contains vast salty oceans — more than is present on Earth. Because salt changes the properties of water as a solvent as well as the solubility of different molecules, this could mean that some molecules cluster on the surface of the ice grains, making them more likely to be detected.
“The implications this has for detecting life elsewhere in the solar system without missions to the surface of these ocean-world moons is very exciting, but our work goes beyond biosignatures in ice grains,” stated Continetti. “It has implications for fundamental chemistry as well. We are excited by the prospect of following in the footsteps of Harold Urey and Stanley Miller, founding faculty at UC San Diego in looking at the formation of the building blocks of life from chemical reactions activated by ice grain impact.”
This work was supported by the Air Force Office of Science Research (MURI-22, grant FA9550-22-0199) and the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (grant 80NM0018D0004).
JOURNAL
Proceedings of the National Academy of Sciences
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Cells
ARTICLE TITLE
Detection of intact amino acids with a hypervelocity ice grain impact mass spectrometer
ARTICLE PUBLICATION DATE
4-Dec-2023
Dark galactic region nicknamed "The Brick" explained with Webb telescope findings
UF astronomer Adam Ginsburg harnesses the James Webb Space Telescope to explore a galactic enigma
In a recent study led by University of Florida astronomer Adam Ginsburg, groundbreaking findings shed light on a mysterious dark region at the center of the Milky Way. The turbulent gas cloud, playfully nicknamed “The Brick” due to its opacity, has sparked lively debates within the scientific community for years.
To decipher its secrets, Ginsburg and his research team, including UF graduate students Desmond Jeff, Savannah Gramze, and Alyssa Bulatek, turned to the James Webb Space Telescope (JWST). The implications of their observations, published in The Astrophysical Journal, are monumental. The findings not only unearth a paradox within the center of our galaxy but indicate a critical need to re-evaluate established theories regarding star formation.
The Brick has been one of the most intriguing and highly studied regions of our galaxies, thanks to its unexpectedly low star formation rate. It has challenged scientists’ expectations for decades: as a cloud full of dense gas, it should be ripe for the birth of new stars. However, it demonstrates an unexpectedly low star formation rate.
Using the JWST’s advanced infrared capabilities, the team of researchers peered into the Brick, discovering a substantial presence of frozen carbon monoxide (CO) there. It harbors a significantly larger amount of CO ice than previously anticipated, carrying profound implications for our understanding of star formation processes.
No one knew how much ice there was in the Galactic Center, according to Ginsburg. “Our observations compellingly demonstrate that ice is very prevalent there, to the point that every observation in the future must take it into account,” he said.
Stars typically emerge when gases are cool, and the significant presence of CO ice should suggest a thriving area for star formation in the Brick. Yet, despite this wealth of CO, Ginsburg and the research team found that the structure defies expectations. The gas inside the Brick is warmer than comparable clouds.
These observations challenge our understanding of CO abundance in the center of our galaxy and the critical gas-to-dust ratio there. According to the findings, both measures appear to be lower than previously thought.
“With JWST, we're opening new paths to measure molecules in the solid phase (ice), while previously we were limited to looking at gas,” said Ginsburg. “This new view gives us a more complete look at where molecules exist and how they are transported. “
Traditionally, the observation of CO has been limited to emission from gas. To unveil the distribution of CO ice within this vast cloud, the researchers required intense backlighting from stars and hot gas. Their findings move beyond the limitations of previous measurements, which were confined to around a hundred stars. The new results encompass over ten thousand stars, providing valuable insights into the nature of interstellar ice.
Since the molecules present in our Solar System today were, at some point, likely ice on small dust grains that combined to form planets and comets, the discovery also marks a leap forward toward understanding the origins of the molecules that shape our cosmic surroundings.
These are just the team’s initial findings from a small fraction of their JWST observations of the Brick. Looking ahead, Ginsburg sets his sights on a more extensive survey of celestial ices.
“We don't know, for example, the relative amounts of CO, water, CO2, and complex molecules,” said Ginsburg. “With spectroscopy, we can measure those and get some sense of how chemistry progresses over time in these clouds.”
With the advent of the JWST and its advanced filters, Ginsburg and his colleagues are presented with their most promising opportunity yet to expand our cosmic exploration.
In a recent study led by University of Florida astronomer Adam Ginsburg, groundbreaking findings shed light on a mysterious dark region at the center of the Milky Way. The turbulent gas cloud, playfully nicknamed “The Brick” due to its opacity, has sparked lively debates within the scientific community for years.
To decipher its secrets, Ginsburg and his research team, including UF graduate students Desmond Jeff, Savannah Gramze, and Alyssa Bulatek, turned to the James Webb Space Telescope (JWST). The implications of their observations, published in The Astrophysical Journal, are monumental. The findings not only unearth a paradox within the center of our galaxy but indicate a critical need to re-evaluate established theories regarding star formation.
The Brick has been one of the most intriguing and highly studied regions of our galaxies, thanks to its unexpectedly low star formation rate. It has challenged scientists’ expectations for decades: as a cloud full of dense gas, it should be ripe for the birth of new stars. However, it demonstrates an unexpectedly low star formation rate.
Using the JWST’s advanced infrared capabilities, the team of researchers peered into the Brick, discovering a substantial presence of frozen carbon monoxide (CO) there. It harbors a significantly larger amount of CO ice than previously anticipated, carrying profound implications for our understanding of star formation processes.
No one knew how much ice there was in the Galactic Center, according to Ginsburg. “Our observations compellingly demonstrate that ice is very prevalent there, to the point that every observation in the future must take it into account,” he said.
Stars typically emerge when gases are cool, and the significant presence of CO ice should suggest a thriving area for star formation in the Brick. Yet, despite this wealth of CO, Ginsburg and the research team found that the structure defies expectations. The gas inside the Brick is warmer than comparable clouds.
These observations challenge our understanding of CO abundance in the center of our galaxy and the critical gas-to-dust ratio there. According to the findings, both measures appear to be lower than previously thought.
“With JWST, we're opening new paths to measure molecules in the solid phase (ice), while previously we were limited to looking at gas,” said Ginsburg. “This new view gives us a more complete look at where molecules exist and how they are transported. “
Traditionally, the observation of CO has been limited to emission from gas. To unveil the distribution of CO ice within this vast cloud, the researchers required intense backlighting from stars and hot gas. Their findings move beyond the limitations of previous measurements, which were confined to around a hundred stars. The new results encompass over ten thousand stars, providing valuable insights into the nature of interstellar ice.
Since the molecules present in our Solar System today were, at some point, likely ice on small dust grains that combined to form planets and comets, the discovery also marks a leap forward toward understanding the origins of the molecules that shape our cosmic surroundings.
These are just the team’s initial findings from a small fraction of their JWST observations of the Brick. Looking ahead, Ginsburg sets his sights on a more extensive survey of celestial ices.
“We don't know, for example, the relative amounts of CO, water, CO2, and complex molecules,” said Ginsburg. “With spectroscopy, we can measure those and get some sense of how chemistry progresses over time in these clouds.”
With the advent of the JWST and its advanced filters, Ginsburg and his colleagues are presented with their most promising opportunity yet to expand our cosmic exploration.
JOURNAL
The Astrophysical Journal
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
CO absorption in the Galactic Center cloud G0.253+0.015
ARTICLE PUBLICATION DATE
4-Dec-2023
Astronomers determine the age of three mysterious baby stars at the heart of the Milky Way
Through analysis of high-resolution data from a ten-metre telescope in Hawaii, researchers at Lund University in Sweden have succeeded in generating new knowledge about three stars at the very heart of the Milky Way. The stars proved to be unusually young with a puzzling chemical composition that surprised the researchers.
The study, which has been published in The Astrophysical Journal Letters, examined a group of stars located in the nuclear star cluster that makes up the heart of the galaxy. It concerns three stars that are difficult to study because they are extremely far away from our solar system, and hidden behind enormous clouds of dust and gas that block out light. The fact that the area is also full of stars makes it very complicated to discern individual stars.
In a previous study, the researchers put forward a hypothesis that these specific stars in the middle of the Milky Way could be unusually young.
“We can now confirm this. In our study we have been able to date three of these stars as relatively young, at least as far as astronomers are concerned, with ages of 100 million to about 1 billion years. This can be compared with the sun, which is 4.6 billion years old,” says Rebecca Forsberg, researcher in astronomy at Lund University.
The nuclear star cluster has mainly been seen, quite rightly, as a very ancient part of the galaxy. But the researchers’ new discovery of such young stars indicates that there is also active star formation going on in this ancient component of the Milky Way. However, dating stars 25,000 light years from Earth is not something that can be done in a hurry.
The researchers used high-resolution data from the Keck II telescope in Hawaii, one of the world’s largest telescopes with a mirror ten metres in diameter. For further verification, they then measured how much of the heavy element, iron, the stars contained. The element is important for tracing the galaxy’s development, as the theories the astronomers have about how stars are formed and galaxies develop indicate that young stars have more of the heavy elements, as heavy elements are formed to an increasing extent over time in the universe.
To determine the level of iron, the astronomers observed the stars’ spectra in infrared light which, compared with optical light, are parts of the light spectrum that can more easily shine through the densely dust-laden parts of the Milky Way. It was shown that the iron levels varied considerably, which surprised the researchers.
“The very wide spread of iron levels could indicate that the innermost parts of the galaxy are incredibly inhomogeneous, i.e. unmixed. This is something we had not expected and not only says something about how the centre of the galaxy appears, but also how the early universe may have looked,” says Brian Thorsbro, researcher in astronomy at Lund University.
The study sheds significant light on our understanding of the early universe and the functioning of the very centre of the Milky Way. The results may also be of benefit to inspire continued and future explorations of the heart of the galaxy, as well as the further development of models and simulations of the formation of galaxies and stars.
“Personally, I think it is very exciting that we can now study the very centre of our galaxy with such a high level of detail. These types of measurements have been standard for observations of the galactic disc where we are located, but have beenunreachable goal for more faraway and exotic parts of the galaxy. We can learn a lot about how our home galaxy was formed and developed from such studies,” concludes Rebecca Forsberg.
In addition to Lund University, the following organisations and higher education institutions participated in the study: Observatoire de la Côte d'Azur, the University of Tokyo, Observatoire de Paris, the University of California Los Angeles, and Miyagi University of Education.
JOURNAL
The Astrophysical Journal Letters
ARTICLE TITLE
A Wide Metallicity Range for Gyr-old Stars in the Nuclear Star Cluster
10 billion year, 50,000 light-year journey to black hole
IMAGE:
THE CENTRAL REGION OF THE MILKY WAY GALAXY AS CAPTURED BY THE SUBARU TELESCOPE. THE IMAGE SHOWS MANY STARS IN A FIELD OF VIEW ABOUT 0.4 LIGHT-YEARS ACROSS. THE STAR S0-6 (BLUE CIRCLE), THE SUBJECT OF THIS STUDY, IS LOCATED ABOUT 0.04 LIGHT-YEARS FROM THE SUPERMASSIVE BLACK HOLE SAGITTARIUS A* (SGR A*, GREEN CIRCLE).
view moreCREDIT: MIYAGI UNIVERSITY OF EDUCATION/NAOJ
A star near the supermassive black hole at the center of the Milky Way Galaxy originated outside of the Galaxy according to a new study. This is the first time a star of extragalactic origin has been found in the vicinity of the super massive black hole.
Many stars are observed near the supermassive black hole known as Sagittarius A* at the center of our Galaxy. But the black hole’s intense gravity makes the surrounding environment too harsh for stars to form near the black hole. All the observed stars must have formed somewhere else and migrated towards the black hole. This raises the question, where did the stars form.
Research by an international team led by Shogo Nishiyama at Miyagi University of Education indicates the some of the stars may have come from farther away than previously thought, from completely outside of the Milky Way. The team used the Subaru Telescope over the course of eight years to observe the star S0-6 located only 0.04 light-years away from Sagittarius A*. They determined that S0-6 is about 10 billion years old and has a chemical composition similar to stars found in small galaxies outside the Milky Way, such as the Small Magellanic Cloud and the Sagittarius dwarf galaxy.
The most likely theory to explain the composition of S0-6 is that it was born in a now extinct small galaxy orbiting the Milky Way that was absorbed. This is the first observational evidence suggesting that some of the stars in the vicinity of Sagittaius A* formed outside of the Galaxy. Over its 10 billion year life, S0-6 must have travelled more than 50,000 light-years from outside of the Milky Way to reach the vicinity of Sagittarius A*. Almost certainly S0-6 traveled much more than 50,000 light-years, slowly spiraling down to the center rather than making a straight shot.
There are still many questions according to Nishiyama, “Did S0-6 really originate outside the Milky Way galaxy? Does it have any companions, or did it travel alone? With further investigation, we hope to unravel the mysteries of stars near the supermassive black hole.”
JOURNAL
Proceedings of the Japan Academy Series B
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Origin of an Orbiting Star around the Galactic Supermassive Black Hole
ARTICLE PUBLICATION DATE
1-Dec-2023
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