Water as a metal

Peer-Reviewed Publication

HELMHOLTZ-ZENTRUM BERLIN FÜR MATERIALIEN UND ENERGIE

 

IMAGE: IN THE SAMPLE CHAMBER, THE NAK ALLOY DRIPS FROM A NOZZLE. AS THE DROPLET GROWS, WATER VAPOUR FLOWS INTO THE SAMPLE CHAMBER AND FORMS A THIN SKIN ON THE DROP'S SURFACE. view more 

CREDIT: HZB

Every child knows that water conducts electricity - but this refers to "normal" everyday water that contains salts. Pure, distilled water, on the other hand, is an almost perfect insulator. It consists of H2O molecules that are loosely linked to one another via hydrogen bonds. The valence electrons remain bound and are not mobile. To create a conduction band with freely moving electrons, water would have to be pressurised to such an extent that the orbitals of the outer electrons overlap. However, a calculation shows that this pressure is only present in the core of large planets such as Jupiter.

Providing electrons

An international collaboration of 15 scientists from eleven research institutions has now used a completely different approach to produce a aqueous solution with metallic properties for the first time and documented this phase transition at BESSY II. To do this, they experimented with alkali metals, which release their outer electron very easily.

Avoiding explosion

However, the chemistry between alkali metals and water is known to be explosive. Sodium or other alkali metals immediately start to burn in water. But the team found a way to keep this violent chemistry in check: They did not throw a piece of alkali metal into water, but they did it the other way round: they put a tiny bit of water on a drop of alkali metal, a sodium-potassium (Na-K) alloy, which is liquid at room temperature.

Experiment at BESSY II

At BESSY II, they set up the experiment in the SOL³PES high vacuum sample chamber at the U49/2 beamline. The sample chamber contains a fine nozzle from which the liquid Na-K alloy drips. The silver droplet grows for about 10 seconds until it detaches from the nozzle. As the droplet grows, some water vapour flows into the sample chamber and forms an extremely thin skin on the surface of the droplet, only a few layers of water molecules. This almost immediately causes the electrons as well as the metal cations to dissolve from the alkali alloy into the water. The released electrons in the water behave like free electrons in a conduction band.

Golden water skin

"You can see the phase transition to metallic water with the naked eye! The silvery sodium-potassium droplet covers itself with a golden glow, which is very impressive," reports Dr. Robert Seidel, who supervised the experiments at BESSY II. The thin layer of gold-coloured metallic water remains visible for a few seconds. This enabled the team led by Prof. Pavel Jungwirth, Czech Academy of Sciences, Prague, to prove with spectroscopic analyses at BESSY II and at the IOCB in Prague that it is indeed water in a metallic state.

Fingerprints of the metallic phase

The two decisive fingerprints of a metallic phase are the plasmon frequency and the conduction band. The groups were able to determine these two quantities using optical reflection spectroscopy and synchrotron X-ray photoelectron spectroscopy: While the plasmon frequency of the gold-coloured, metallic "water skin" is about 2.7 eV (i.e. in the blue range of visible light), the conduction band has a width of about 1.1 eV with a sharp Fermi edge. "Our study not only shows that metallic water can indeed be produced on Earth, but also characterises the spectroscopic properties associated with its beautiful golden metallic luster," says Seidel.

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JOURNAL

Nature

DOI

10.1038/s41586-021-03646-5

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Spectroscopic Evidence for a Gold-Coloured Metallic Water Solution

ARTICLE PUBLICATION DATE

27-Jul-2021

COI STATEMENT

none

Metallic water prepared for first time under terrestrial conditions

Peer-Reviewed Publication

INSTITUTE OF ORGANIC CHEMISTRY AND BIOCHEMISTRY OF THE CZECH ACADEMY OF SCIENCES (IOCB PRAGUE)

 

IMAGE: THE FIRST IMAGE SHOWS A PURE DROP OF SODIUM-POTASSIUM ALLOY; IN THE NEXT IMAGES, WE SEE THE DROP EXPOSED TO THE ACTION OF THE WATER VAPOR AT 10-4 MBAR. A LAYER OF WATER FORMS ON THE DROP, IN WHICH ELECTRONS LIBERATED FROM THE METAL DISSOLVE, GIVING IT A GOLDEN METALLIC SHEEN. view more 

CREDIT: PHOTO: PHIL MASON / IOCB PRAGUE

Pure water is not a good conductor of electricity. It is, in fact, an electrical insulator. In order to conduct electricity, water must contain dissolved salts, for example, yet the conductivity of such an electrolyte is relatively low, several orders lower than that of metals. Is it possible to produce water that is as conductive as, say, copper wire? Scientists have hypothesized that this may take place in the cores of large planets, where high pressure compresses water molecules to the point that their electron shells begin to overlap. At present, generating that kind of pressure on Earth exceeds human capabilities, and it was therefore assumed that preparing metallic water under terrestrial conditions would remain an elusive goal for the foreseeable future. However, an international team of researchers headed by Pavel Jungwirth of IOCB Prague has developed a new method with which they succeeded in making metallic water under terrestrial conditions that lasted for several seconds. Their paper was recently published in Nature.

The idea of using immense pressure to make metal out of water is nothing new. In principle, it should be possible to compress water molecules to the point that their electron shells begin to overlap and form a so-called conduction band similar to the one in metallic materials. The required pressure of 50 Mbar (i.e. approximately 50 million times greater than on the surface of Earth) can be found in the cores of large planets, but we are not yet able to achieve it under terrestrial conditions.

In collaboration with researchers from the University of Southern California, the Fritz Haber Institute, and other institutes, Jungwirth’s team recently developed a method that has allowed them to prepare metallic water while completely sidestepping the need for high pressure. The method builds on earlier research of the Pavel Jungwirth Group focusing on the behavior of alkali metals in water and liquid ammonia. Inspired by work with alkali metal-liquid ammonia solutions, which at high concentrations behave like a metal, the researchers decided to attempt creation of a conduction band not by compressing water molecules but rather by way of massive dissolution of the electrons released from the alkali metal. In doing so, however, they had to overcome a fundamental obstacle: on introduction to water, alkali metals immediately explode.

“Throwing sodium into water is one of the most popular school experiments and the subject of many a YouTube video. As is well known, when you throw a chunk of sodium in water, you don’t get metallic water but an immediate and substantial explosion that takes out your apparatus,” says Jungwirth, who heads a group at IOCB Prague specializing in molecular modeling. “In order to contain this intense and, for laboratory purposes, rather counterproductive chemistry, we approached it the other way around; instead of adding the alkali metal to the water, we added the water to the metal.”

Inside a vacuum chamber, the researchers exposed a drop of sodium-potassium alloy to a small amount of water vapor, which began to condense on its surface. The electrons liberated from the alkali metal dissolved in the layer of water on the surface faster than the chemical reaction that results in the explosion. There were a sufficient number of them to overcome the critical limit for the formation of a conduction band and thus give rise to a metallic water solution, which in addition to the electrons also contained dissolved alkali cations and chemically formed hydroxide and hydrogen.

“Thanks to this, we were able to create a thin layer of gold-colored metallic water solution that lasted for several seconds, and that was enough for us to not only see it with our own eyes but also measure it with spectrometers,” says Jungwirth, adding: “We more or less jury-rigged the necessary apparatus in a small lab at our institute in Prague, which is also where the fist experiments took place. We then obtained the key evidence for the presence of metallic water using X-ray photoelectron spectroscopy on the synchrotron in Berlin.”

Artistic rendering of a pure sodium-potassium alloy drop and a drop with a layer of water, in which electrons liberated from the metal dissolved (IMAGE)

INSTITUTE OF ORGANIC CHEMISTRY AND BIOCHEMISTRY OF THE CZECH ACADEMY OF SCIENCES (IOCB PRAGUE)

CAPTION

On the left is a pure drop of sodium-potassium alloy, on the right is the drop with a layer of water, in which electrons liberated from the metal dissolved, giving it a golden metallic sheen.

CREDIT

Artistic rendering: Tomáš Belloň / IOCB Prague

The study of the researchers at IOCB Prague and their colleagues, now published in Nature, not only shows that metallic water can be prepared under terrestrial conditions, but it also provides a detailed characterization of the spectroscopic properties connected to its beautiful golden metallic sheen.

The original article:

Philip E. Mason, H. Christian Schewe, Tillmann Buttersack, Vojtech Kostal, Marco Vitek, Ryan S. McMullen, Hebatallah Ali, Florian Trinter, Chin Lee, Daniel M. Neumark, Stephan Thürmer, Robert Seidel, Bernd Winter, Stephen E. Bradforth, and Pavel Jungwirth. Spectroscopic evidence for a gold-coloured metallic water solution. Nature 2021. DOI: 10.1038/s41586-021-03646-5

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JOURNAL

Nature

DOI

10.1038/s41586-021-03646-5

METHOD OF RESEARCH

Experimental study

ARTICLE TITLE

Spectroscopic evidence for a gold-coloured metallic water solution

ARTICLE PUBLICATION DATE

27-Jul-2021

Disclaimer: AAAS and Eu

 

More WHITE American parents of teens are purchasing firearms during the pandemic, study finds

One in seven of the households that purchased a gun also had a teen with depression.

Peer-Reviewed Publication

MICHIGAN MEDICINE - UNIVERSITY OF MICHIGAN

Since the start of the COVID-19 pandemic, more parents of teenagers in the United States started buying firearms, according to a recent study.

In a national survey of primary caretakers of teenagers conducted by the Firearm Safety Among Children and Teens, or FACTS, Consortium, 10% of all households with high school-age teens reported buying a firearm in the early months of the pandemic between March and July of 2020, and 3% of U.S. households with teens became first-time gun owners. 

While firearm manufacturing and sales have grown steadily since the 1990s, researchers estimate that in the first few months of the coronavirus pandemic 2.1 million additional firearm purchases were made nationwide – a 64.3% increase over expected volume.

For households that already owned a firearm, these new firearms were more likely to be acquired by those who already reported storing at least one gun unlocked and loaded, noted the study, published in the Journal of Behavioral Medicine.

“This finding is concerning because we know that the single biggest risk factor for adolescent firearm injuries is access to an unsecured firearm,” said Patrick Carter, M.D., a co-author of the paper and co-director of the new Institute for Firearm Injury Prevention at the University of Michigan. “This study demonstrates that we have more work to do to help families that already have firearms, or may purchase new firearms, to reduce the potential risks to their children by promoting safer storage practices that help to reduce the risk of teen firearm injury and death.”

Each year, nearly 50 out of every 100,000 high school-age teens are injured by firearms and 10 out of every 100,000 are killed. As a result, teens in that age group are more likely to die from a firearm injury than any other leading cause of death.

While the mental health statuses of parents and teens weren’t associated with the likelihood of purchasing a firearm, researchers found that one in seven households, 14%, that purchased a gun during the beginning of the COVID pandemic also had a teen who was experiencing depression symptoms.

These findings, taken together, have significant implications for public health practitioners faced with both the COVID-19 pandemic and the firearm injury epidemic, said Marc Zimmerman, Ph.D., a co-author on the publication and co-director of the new U-M Firearm Injury Prevention Institute alongside Carter.

“If we know that families are storing firearms unsafely and that a certain amount of them have teens who are experiencing depression, that can inform how we would tailor messaging around safe storage to families at increased risk,” Zimmerman said.

The Institute for Firearm Injury Prevention The Institute for Firearm Injury Prevention launched in June crises of firearm injury, from which 100 people die each day in the United States. The institute is supported by a $10 million university commitment, with U-M researchers already having secured more federal funding to study the issue than any other academic institute in the nation.

In this study, the research team concluded that strategies geared towards safe storage for parents, as well as stronger child access prevention policy initiatives, could reduce the risk of firearm injury among teens.

“It’s unclear exactly what specific circumstances precipitated this change in firearm purchasing, but we know that future research needs to focus on ways to increase safe storage practices among families with teens,” Zimmerman said. “The implications of this line of research may extend beyond the current COVID-19 pandemic and could help us move forward our goal of reducing and preventing future firearm injuries.”

Paper cited: “Firearm purchasing during the beginning of the COVID-19 pandemic in households with teens: a national study,” Journal of Behavioral Medicine. DOI: 10.1007/s10865-021-00242-w

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JOURNAL

Journal of Behavioral Medicine

DOI

10.1007/s10865-021-00242-w

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Firearm purchasing during the beginning of the COVID-19 pandemic in households with teens: a national study

ARTICLE PUBLICATION DATE

9-Jul-2021

COI STATEMENT

The authors have no conflicts of interest to disclose.

 

Scientists synthesize a material which can completely replace natural gypsum in the construction industry

Peer-Reviewed Publication

NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY MISIS

 

IMAGE: NATURAL GYPSUM STONE view more 

CREDIT: AUTHOR: MAKSIM SAFANIUK

An international team of scientists has proposed a method of production of high-quality gypsum binders based on synthetic calcium sulfate dihydrate produced from industrial waste. Tests of the obtained material have shown that it not only meets all the requirements for materials of this class, but also surpasses binders based on natural gypsum in several parameters. The work has been published in the Journal of Industrial and Engineering Chemistry. 
Gypsum binders are widely used in construction. They have valuable properties such as low weight, low heat and sound conductivity, fire resistance, and they are easy to shape. In addition, gypsum-based binders are hypoallergenic and do not cause silicosis, an occupational disease for builders and repairmen caused by inhalation of dust containing free silicon dioxide. At the same time, the cost of gypsum materials is low, as are the costs of heat energy for their production.
A group of scientists from NUST MISIS, Belarusian State Technological University, University of Limerick and the Institute of General and Inorganic Chemistry of the National Academy of Sciences of Belarus has proposed an innovative method of producing high-strength binders based on synthetic gypsum obtained from industrial waste by neutralizing spent sulfuric acid and carbonate components. Researchers mixed sulfuric acid from waste heat-resistant fibers with water and limestone. The content of calcium sulfate dihydrate in the obtained synthetic gypsum was at least 95% of the mass of the final product.
In the course of the study, scientists obtained three types of synthetic gypsum samples: building gypsum, high-strength gypsum and anhydrite. The building gypsum was made using traditional technology in a gypsum boiler. Anhydrite was also produced according to the traditional technology for this type of gypsum material by firing followed by cooling. An autoclave was used to synthesize high-strength gypsum.
The researchers point out that one of the advantages of producing building gypsum materials from synthetic calcium sulfate dihydrate is that the synthetic gypsum is obtained immediately in the form of a powder product. In the traditional production of gypsum powder, gypsum has to be crushed to the desired state, which requires a significant amount of electricity. Thus, the method proposed by scientists for the production of binders based on synthetic gypsum will significantly reduce production costs by simplifying the production technology. At the same time, the building gypsum obtained in the course of the study fully meets the requirements for gypsum binders of the G5 - G7 grades, for high-strength gypsum - the requirements for gypsum grades G10 - G22.
Synthetic gypsum, obtained from waste sulfuric acid and limestone waste, can completely replace natural gypsum for the production of gypsum binders in countries that do not have gypsum stone deposits.
 

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JOURNAL

Journal of Industrial and Engineering Chemistry

DOI

https://doi.org/10.1016/j.jiec.2021.05.006

ARTICLE TITLE

High-quality gypsum binders based on synthetic calcium sulfate dihydrate produced from industrial waste

 

Bugs find bats to bite thanks to bacteria

Blood-sucking flies may be following chemicals produced by skin bacteria to locate bats to feed on

Peer-Reviewed Publication

FIELD MUSEUM

 

IMAGE: A NATAL LONG-FINGERED BAT (MINIOPTERUS NATALENSIS) PARASITIZED BY A MALE BAT FLY (PENICILLIDIA FULVIDA) ON THE WALL OF A DIATOMITE MINE IN NAKURU, KENYA. view more 

CREDIT: COURTESY OF HOLLY LUTZ

We humans aren’t the only animals that have to worry about bug bites. There are thousands of insect species that have evolved to specialize in feeding on different mammals and birds, but scientists are still learning how these bugs differentiate between species to track down their preferred prey. It turns out, the attraction might not even be skin-deep: a new study in Molecular Ecology found evidence that blood-sucking flies that specialize on bats may be locating their preferred hosts by following the scent of chemicals produced by bacteria on the bats’ skin.

Holly Lutz, the paper’s lead author, got the idea for the project from previous research showing that mosquitoes seem to prefer some people over others. “You know when you go to a barbeque and your friend is getting bombarded by mosquitos, but you’re fine? There is some research to support the idea that the difference in mosquito attraction is linked to your skin microbiome - the unique community of bacteria living on your skin,” says Lutz, a research associate at Chicago’s Field Museum and a project scientist with the labs of Jack Gilbert (who co-authored this study) and Rob Knight at the University of California, San Diego. “Keeping in mind that some people are more attractive to mosquitoes than others, I wondered what makes insects attracted to some bats but not others.”

Lutz encountered plenty of bats during her PhD work and postdoctoral residency at the Field Museum, on fieldwork trips to bat caves in Kenya and Uganda studying malaria. “In these caves, I’d see all these different bat species or even taxonomic families roosting side by side. Some of them were loaded with bat flies, while others had none or only a few. And these flies are typically very specific to different kinds of bats-- you won’t find a fly that normally feeds on horseshoe bats crawling around on a fruit bat.” says Lutz. “I started wondering why the flies are so particular-- clearly, they can crawl over from one kind of bat to another, but they don’t really seem to be doing that.”

The flies in question are cousins of mosquitoes, and while they’re technically flies, most can’t actually fly. “They have incredibly reduced wings in many cases and can’t actually fly,” says Lutz. “And they have reduced eyesight, so they probably aren’t really operating by vision. So some other sensory mechanisms must be at play, maybe a sense of smell or an ability to detect chemical cues.”

​​”How the flies actually locate and find their bats has previously been something of a mystery,” says Carl Dick, a research associate at the Field Museum, professor of biology at Western Kentucky University, and one of the study’s co-authors. “But because most bat flies live and feed on only one bat species, it is clear that they somehow find the right host.”

Furthermore, bat flies transmit malaria between bats, and the malaria parasites are host-specific as well. It’s an intricate, complex system with important parallels to other vector-borne pathways for disease transmission, such as malarial and viral transmission among humans by anopheline mosquitoes. Previous research has shown that different bacterial species associated with skin or even the disease status of individual humans can influence feeding preferences of blood-seeking mosquitoes.

Lutz suspected that, similarly to what’s been observed in humans, the bats’ skin microbiomes may be playing a role in attracting the flies seeking them out. Skin-- whether it belongs to a human or a bat-- is covered with tiny microorganisms that help protect the body from invading pathogens, bolster the immune system, and break down natural products like sweat. Host species evolve alongside their skin microbiomes, leading to different species being home to different sets of bacteria.

All these different kinds of bacteria produce a unique bouquet of airborne chemicals as they metabolize nutrients. And, according to Lutz’s hypothesis, different kinds of insects are attracted to different chemical signals, which could help explain why some bats are more attractive to blood-sucking flies than others-- just like your friend at the barbeque.

To test this hypothesis, Lutz examined dozens of bats from a variety of species. “We went into a ton of different caves where they roost and used long bat nets, which are basically like super sturdy butterfly nets, to catch them,” says Lutz. She and her colleagues took skin and fur samples from the bats’ bodies and wings in order to examine both the bats’ DNA and the microbes living on their skin. The researchers also examined the bats for flies. “You brush the bats’ fur with your forceps, and it’s like you’re chasing the fastest little spider,” says Lutz. “The flies can disappear in a split second. They are fascinatingly creepy.”

“The flies are exquisitely evolved to stay on their bat,” says Dick. “They have special combs, spines, and claws that hold them in place in the fur, and they can run quickly in any direction to evade the biting and scratching of the bats, or the efforts by researchers to capture them.”

The researchers then analyzed the specimens back at the Field Museum’s Pritzker DNA Laboratory. “Once we were back at the lab, we extracted all the DNA from the bacteria and sequenced it. We basically created libraries of all the bacteria associated with each individual skin sample. Then we used bioinformatics methods to characterize the bacteria there and identify which ones are present across different bat groups, comparing bats that were parasitized by flies to those that were not,” says Lutz.

The team found that the different bat families had their own unique combinations of skin bacteria, even when the bats were collected from different locations. “The goal of this study was to ask, ‘Are there differences in the skin microbiome of these different bats, and are there bacteria that are common among bats that have parasites versus those that don’t?’” says Lutz. “Getting these results was really exciting-- this paper is the culmination of years of thinking and wondering and sampling.”

There are still some big questions to answer, however. “We weren’t able to collect the actual chemicals producing cue- - secondary metabolites or volatile organic compounds-- during this initial work. Without that information, we can’t definitively say that the bacteria are leading the flies to their hosts. So, next steps will be to sample bats in a way that we can actually tie these compounds to the bacteria” says Lutz, “In science, there is always a next step.”

In addition to explaining how blind, flightless flies are able to be so picky with which bats they feed on, the study gets at bigger-picture questions of how different organisms coexist. “We live in these complex communities where different types of life are always bumping into each other and interacting and sometimes depending on each other or eating each other,” says Lutz. “In a healthy natural state, these organisms partition themselves so they can coexist. But as habitats are destroyed, organisms are forced to share resources or start utilizing new ones.” Animals that used to be able to give each other a wide berth might no longer be able to, and that can lead to new diseases spreading from one organism to another.

“Humans are affecting these ecosystems, and these ecosystems can in turn affect us,” says Lutz. “That’s why it’s important to study them.”

CAPTION

One of the bat species studied in this project, Hipposideros caffer.

CREDIT

Courtesy of Holly Lutz

  

CAPTION

Eye-shine reflects from thousands of Egyptian fruit bats (Rousettus aegyptiacus) sampled by Lutz and her team at Kitum Cave in Mount Elgon National Park, Uganda.

CREDIT

Courtesy of Holly Lutz

CAPTION

Closeup of a bat fly (Penicillidia fulvida)

CREDIT

Courtesy of Holly Lutz

CAPTION

Natal and African long-fingered bats (Miniopterus natalensis, M. africanus), Mauritian tomb bats (Taphozous mauritianus), and Noack's roundleaf bats (Hipposideros ruber) roosting together in a fossilized coral cave in Arabuko Sokoke Forest, Kenya.

CREDIT

Courtesy of Holly Lutz

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JOURNAL

Molecular Ecology

DOI

10.1111/mec.16044

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE PUBLICATION DATE

2-Aug-2021

Disclaimer: AAAS and Eu

 

Astronomers probe layer-cake structure of brown dwarf’s atmosphere

Peer-Reviewed Publication

W. M. KECK OBSERVATORY

 

IMAGE: ARTIST’S CONCEPT OF 2MASS J22081363+2921215, A NEARBY BROWN DWARF. THOUGH ONLY ROUGHLY 115 LIGHT-YEARS AWAY, THE BROWN DWARF IS TOO DISTANT FOR ANY ATMOSPHERIC FEATURES TO BE PHOTOGRAPHED. INSTEAD, RESEARCHERS USED W. M. KECK OBSERVATORY’S MOSFIRE INSTRUMENT TO STUDY THE COLORS AND BRIGHTNESS VARIATIONS OF THE BROWN DWARF’S LAYER-CAKE CLOUD STRUCTURE, AS SEEN IN NEAR-INFRARED LIGHT. MOSFIRE ALSO COLLECTED THE SPECTRAL FINGERPRINTS OF VARIOUS CHEMICAL ELEMENTS CONTAINED IN THE CLOUDS AND HOW THEY CHANGE OVER TIME. view more 

CREDIT: NASA, ESA, STSCI, LEAH HUSTAK (STSCI), GREG T. BACON (STSCI)

Maunakea, Hawaiʻi – Jupiter may be the bully planet of our solar system because it’s the most massive planet, but it’s actually a runt compared to many of the giant planets found around other stars.

These alien worlds, called super-Jupiters, weigh up to 13 times Jupiter’s mass. Astronomers have analyzed the composition of some of these monsters, but it has been difficult to study their atmospheres in detail because these gas giants get lost in the glare of their parent stars.

Researchers, however, have a substitute: the atmospheres of brown dwarfs, so-called failed stars that are up to 80 times Jupiter’s mass. These hefty objects form out of a collapsing cloud of gas, as stars do, but lack the mass to become hot enough to sustain nuclear fusion in their cores, which powers stars.

Instead, brown dwarfs share a kinship with super-Jupiters. Both types of objects have similar temperatures and are extremely massive. They also have complex, varied atmospheres. The only difference, astronomers think, is their pedigree. Super-Jupiters form around stars; brown dwarfs often form in isolation.

A team of astronomers, led by Elena Manjavacas of the Space Telescope Science Institute in Baltimore, Maryland, has tested a new way to peer through the cloud layers of these nomadic objects. The researchers used an instrument at W. M. Keck Observatory on Maunakea in Hawaiʻi to study in near-infrared light the colors and brightness variations of the layer-cake cloud structure in the nearby, free-floating brown dwarf known as 2MASS J22081363+2921215.

The Keck Observatory instrument, called the Multi-Object Spectrograph for Infrared Exploration (MOSFIRE), also analyzed the spectral fingerprints of various chemical elements contained in the clouds and how they change with time. This is the first time astronomers have used MOSFIRE in this type of study.

These measurements offered Manjavacas a holistic view of the brown dwarf’s atmospheric clouds, providing more detail than previous observations of this object. Pioneered by Hubble observations, this technique is difficult for ground-based telescopes to do because of contamination from Earth’s atmosphere, which absorbs certain infrared wavelengths. This absorption rate changes due to the weather.

"The only way to do this from the ground is by using Keck’s high-resolution MOSFIRE instrument because it allows us to observe multiple stars simultaneously with our brown dwarf,” said Manjavacas, a former staff astronomer at Keck Observatory and the lead author of the study. “This allows us to correct for the contamination introduced by the Earth’s atmosphere and measure the true signal from the brown dwarf with good precision. So, these observations are a proof-of-concept that MOSFIRE can do these types of studies of brown dwarf atmospheres.”

She decided to study this particular brown dwarf because it is very young and therefore extremely bright. It has not cooled off yet. Its mass and temperature are similar to those of the nearby giant exoplanet Beta Pictoris b, discovered in 2008 near-infrared images taken by the European Southern Observatory’s Very Large Telescope in northern Chile.

“We don’t have the ability yet with current technology to analyze in detail the atmosphere of Beta Pictoris b,” Manjavacas said. “So, we’re using our study of this brown dwarf’s atmosphere as a proxy to get an idea of what the exoplanet’s clouds might look like at different heights of its atmosphere.”

Both the brown dwarf and Beta Pictoris b are young, so they radiate heat strongly in the near-infrared. They are both members of a flock of stars and sub-stellar objects called the Beta Pictoris moving group, which shares the same origin and a common motion through space. The group, which is about 33 million years old, is the closest grouping of young stars to Earth. It is located roughly 115 light-years away.

While they're cooler than bona fide stars, brown dwarfs are still extremely hot. The brown dwarf in Manjavacas’ study is a sizzling 2,780 degrees Fahrenheit (1,527 degrees Celsius).

The giant object is about 12 times heavier than Jupiter. As a young body, it is spinning incredibly fast, completing a rotation every 3.5 hours, compared to Jupiter’s 10-hour rotation period. So, clouds are whipping around the planet, creating a dynamic, turbulent atmosphere.

Keck Observatory’s MOSFIRE instrument stared at the brown dwarf for 2.5 hours, watching how the light filtering up through the atmosphere from the dwarf’s hot interior brightens and dims over time. Bright spots that appeared on the rotating object indicate regions where researchers can see deeper into the atmosphere, where it is hotter. Infrared wavelengths allow astronomers to peer deeper into the atmosphere. The observations suggest the brown dwarf has a mottled atmosphere with scattered clouds. If viewed close-up, the planet might resemble a carved Halloween pumpkin, with light escaping from the hot interior.

Its spectrum reveals clouds of hot sand grains and other exotic elements. Potassium iodide traces the object’s upper atmosphere, which also includes magnesium silicate clouds. Moving down in the atmosphere is a layer of sodium iodide and magnesium silicate clouds. The final layer consists of aluminum oxide clouds. The atmosphere’s total depth is 446 miles (718 kilometers). The elements detected represent a typical part of the composition of brown dwarf atmospheres, Manjavacas said.

She and her team used computer models of brown dwarf atmospheres to determine the location of the chemical compounds in each cloud layer.

The study will be published in The Astronomical Journal and is available in pre-print format on arXiv.org.

Manjavacas’ plan is to use Keck Observatory’s MOSFIRE to study other atmospheres of brown dwarfs and compare them to those of gas giants. Future telescopes such as NASA’s James Webb Space Telescope, an infrared observatory scheduled to launch later this year, will provide even more information about a brown dwarf’s atmosphere.

“JWST will give us the structure of the entire atmosphere, providing more coverage than any other telescope,” Manjavacas said.

She hopes that MOSFIRE can be used in tandem with JWST to sample a wide range of brown dwarfs and gain a better understanding of brown dwarfs and giant planets.

“Exoplanets are so much more diverse than what we see locally in the solar system,” said Keck Observatory Chief Scientist John O’Meara. “It’s work like this, and future work with Keck and JWST, that will give us a fuller picture of the diversity of planets orbiting other stars.”

CAPTION

AThis graphic shows successive layers of clouds in the atmosphere of a nearby, free-floating brown dwarf. Breaks in the upper cloud layers allowed astronomers to probe deeper into the atmosphere of the brown dwarf called 2MASS J22081363+2921215. Brown dwarfs are more massive than planets but too small to sustain nuclear fusion, which powers stars. This illustration is based on infrared observations of the clouds' colors and brightness variations, as well as the spectral fingerprints of various chemical elements contained in the clouds and atmospheric modeling.

CREDIT

NASA, ESA, STScI, Andi James (STScI)

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ABOUT MOSFIRE

The Multi-Object Spectrograph for Infrared Exploration (MOSFIRE), gathers thousands of spectra from objects spanning a variety of distances, environments and physical conditions. What makes this large, vacuum-cryogenic instrument unique is its ability to select up to 46 individual objects in the field of view and then record the infrared spectrum of all 46 objects simultaneously. When a new field is selected, a robotic mechanism inside the vacuum chamber reconfigures the distribution of tiny slits in the focal plane in under six minutes. Eight years in the making with First Light in 2012, MOSFIRE's early performance results range from the discovery of ultra-cool, nearby substellar mass objects, to the detection of oxygen in young galaxies only two billion years after the Big Bang. MOSFIRE was made possible by funding provided by the National Science Foundation.

ABOUT W. M. KECK OBSERVATORY

The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two 10-meter optical/infrared telescopes atop Maunakea on the Island of Hawaiʻi feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

For more information, visit www.keckobservatory.org

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JOURNAL

The Astronomical Journal