The warm Arctic-cold Eurasia (WACE) climate pattern is the main feature of winter temperature in the Northern Hemisphere in the last 20 years. Extreme cold events related to this pattern have occurred frequently in the Northern Hemisphere.

The ability of climate models to simulate WACE directly affects the skill in simulating winter temperature. Past studies have shown that previous generations of climate models were poor at simulating midlatitude atmospheric response to sea ice, making them simulate a weaker-than-observed WACE.

Now, scientists from the Institute of Atmospheric Physics of the Chinese Academy of Sciences, China Meteorological Administration, and Nanjing University of Information Science and Technology have evaluated the ability of CMIP6 models (i.e., models participating in phase 6 of the Coupled Model Intercomparison Project) to simulate WACE and revealed the key factors influencing the differences in simulation capability.

Results showed that the CMIP6 multi-model ensemble mean was better able to simulate WACE, but there were still large gaps among individual models. Models with good ability in simulating climatic states and extremes of Eurasian winter temperatures also showed more skill in simulating WACE.

"The difference in the simulation of extremes was mainly reflected in the ability to simulate the warming anomalies in the Barents Sea-Kara Sea (BKS) region," said ZHAO Liang, co-author of the study.

Further analysis showed that the models' simulations of BKS warming anomalies were related to their reflection of the location and persistence of the Ural blocking (a large-scale anticyclone that occurs in the Ural Mountains region), which transmits heat northwards to the BKS, thereby warming the Arctic, strengthening the downstream westerly trough, and cooling central Eurasia. Therefore, the simulation of the Ural blocking is the key to improving the capability of climate models in simulating WACE.

An international team led by Lancaster University in England has discovered how electrons can slither rapidly to and fro across a quantum surface when driven by external forces. 

The research, published in Physical Review B, has enabled the visualization of the motion of electrons on liquid helium for the first time.

The experiments, carried out in Riken, Japan, by Kostyantyn Nasyedkin (now at Oak Ridge National Laboratory, USA) in the lab of Kimitoshi Kono (now in Taiwan at Yang Ming Chiao Tung University) detected unusual oscillations whose frequencies varied in time. Although it was unclear how the electrons were moving in the darkness and extreme cold at the bottom of the cryostat, it was evident that the time variations were much like those seen in living systems.

Professor Kono said: “At very low temperatures, the surface of liquid helium is an exceptionally slippery place. Interesting things happen there, and it is important because of the potential for quantum computing using electrons on the helium surface.

“Such electrons move very easily because, with a slippery surface below and a vacuum above, there is nothing to slow them down.”

The Riken data were analyzed at Lancaster University using methods developed by Professor Aneta Stefanovska and her group, mainly for biological applications. Lancaster Ph.D. student Hala Siddiq (now at Jazan University, Saudi Arabia) applied these methods. She and her principal supervisor Professor Stefanovska interpreted the results in collaboration with Riken’s team and Lancaster experts in low-temperature physics, Dmitry Zmeev, Yuri Pashkin, and Peter McClintock.

The work has enabled the electrons’ motion to be visualized, showing how they slide around in part-circular and part-radial patterns of motion in the vacuum above the liquid surface. An additional complication revealed by Siddiq’s analysis is that the surface itself is moving gently in an up-and-down vertical motion. Moreover, her results indicate a combination of quantum and classical dynamics.

Professor Stefanovska said: “Appreciation of these features will be important for practical applications across wide areas of physics, life sciences, and even sociology. Namely, they provide a paradigmatic example of the physics of non-isolated systems and the mathematics of non-autonomous systems. Moreover, the experimental model can be used to study properties of living systems, and similar technical or societal systems, in a very controlled way.”

A study led by Anelise Audibert, a researcher at the Instituto de Astrofísica de Canarias (IAC) in the Canary Islands, Spain, reveals a process that explains the peculiar morphology of the central region of the Teacup galaxy, a massive quasar located 1.3 billion light-years away from us. This object is characterized by the presence of expanding gas bubbles produced by winds emanating from its central supermassive black hole. The study confirms that a compact jet, only visible at radio waves, is altering the shape and increasing the temperature of the surrounding gas, blowing bubbles that expand laterally. These findings, based on observations from the ALMA telescope in Chile and hydrodynamical simulations, are published today in the journal Astronomy & Astrophysics Letters.

When matter falls into supermassive black holes in the centers of galaxies, it unleashes enormous amounts of energy and is called active galactic nuclei (or AGN). A fraction of AGN releases part of this energy as jets that are detectable in radio wavelengths that travel at velocities close to light speed. While the jet travels across the galaxy, it collides with the clouds and gas around it and in some cases may push this material away in the form of winds. However, which conditions preferentially trigger these winds to blow out the gas from galaxies is still poorly understood.

The effect of jets impacting the content of the galaxies, like the stars, dust, and gas, plays an important role in how galaxies evolve in the Universe. The most powerful radio jets, hosted in ´radio-loud’ galaxies, are responsible for drastically changing the fate of galaxies because they heat the gas, preventing new star formation and galaxy growth. Supercomputer simulations of relativistic jets piercing into disk galaxies predict that jets alter the shape of the surrounding gas by blowing bubbles as they penetrate further into the galaxy. One of the key elements in the simulations that make the jets efficient in driving winds is the angle between the gaseous disk and the jet’s direction of propagation. Surprisingly, less powerful jets, like the ones in ‘radio-quiet’ galaxies, are able to inflict more damage on the surrounding medium than the very powerful ones.

An international scientific team, led by the IAC researcher Anelise Audibert, discovered an ideal case in which to study the interaction of the radio jet with the cold gas around a massive quasar: the Teacup galaxy. The Teacup is a radio-quiet quasar located 1.3 billion light years from us and its nickname comes from the expanding bubbles seen in the optical and radio images, one of which is shaped like the handle of a teacup. In addition, the central region (around 3300 light-years in size) harbors a compact and young radio jet that has a small inclination relative to the galaxy disk. 

Effects on star formation

Using observations performed in the Chilean desert with the Atacama Large Millimeter/submillimeter Array (ALMA), the team was able to characterize with an unprecedented level of detail the cold, dense gas in the central part of the Teacup. In particular, they detected the emission of carbon monoxide molecules that can only exist under certain conditions of density and temperature. Based on these observations, the team found that the compact jet, despite its low power, is not only clearly disrupting the distribution of the gas and heating it, but also accelerating it in an unusual way. 

The team expected to detect extreme conditions in the impacted regions along the jet, but when they analyzed the observations, they found that the cold gas is more turbulent and warmer in the directions perpendicular to the jet propagation. “This is caused by the shocks induced by the jet-driven bubble, which heats up and blows the gas in its lateral expansion”, explains A. Audibert “Supported by the comparison with computer simulations, we believe that the orientation between the cold gas disk and the jet is a crucial factor in efficiently driving these lateral winds”, she adds.

“It was previously believed that low-power jets had a negligible impact on the galaxy, but works like ours show that, even in the case of radio-quiet galaxies, jets can redistribute and disrupt the surrounding gas, and this will have an impact on the galaxy's ability to form new stars”, says Cristina Ramos Almeida, an IAC researcher, and co-author of the study. 

The next step is to observe a larger sample of radio-quiet quasars with MEGARA, an instrument installed on the Gran Telescopio CANARIAS (GTC or Grantecan). The observations will help us to understand the impact of the jets on the more tenuous and hot gas, and to measure changes in star formation caused by winds. This is one of the goals of the QSOFEED project, developed by an international team led by C. Ramos Almeida at the IAC, whose aim is to discover how winds from supermassive black holes affect the galaxies that host them.

In just a few hours of observations, the space telescope revealed a dynamic atmosphere on a planet 40 light-years from Earth.

Researchers observing NASA’s James Webb Space Telescope have pinpointed silicate cloud features in a distant planet’s atmosphere. The atmosphere is constantly rising, mixing, and moving during its 22-hour day, bringing hotter material up and pushing colder material down. The resulting brightness changes are so dramatic that it is the most variable planetary-mass object known to date. The team, led by Brittany Miles of the University of Arizona, also made extraordinarily clear detections of water, methane, and carbon monoxide with Webb’s data, and found evidence of carbon dioxide. This is the largest number of molecules ever identified all at once on a planet outside our solar system. 

Cataloged as VHS 1256 b, the planet is about 40 light-years away and orbits not one, but two stars over a 10,000-year period. “VHS 1256 b is about four times farther from its stars than Pluto is from our Sun, which makes it a great target for Webb,” Miles said. “That means the planet’s light is not mixed with light from its stars.” Higher up in its atmosphere, where the silicate clouds are churning, temperatures reach a scorching 1,500 degrees Fahrenheit (830 degrees Celsius).

Within those clouds, Webb detected both larger and smaller silicate dust grains, which are shown on a spectrum. “The finer silicate grains in its atmosphere may be more like tiny particles in smoke,” noted co-author Beth Biller of the University of Edinburgh in Scotland. “The larger grains might be like very hot, very small sand particles.”

VHS 1256 b has low gravity compared to more massive brown dwarfs, which means that its silicate clouds can appear and remain higher in its atmosphere where Webb can detect them. Another reason its skies are so turbulent is the planet’s age. In astronomical terms, it’s quite young. Only 150 million years have passed since it formed – and it will continue to change and cool over billions of years.

In many ways, the team considers these findings to be the first “coins” pulled out of a spectrum that researchers view as a treasure chest of data. They’ve only begun identifying its contents. “We’ve identified silicates, but better understanding which grain sizes and shapes match specific types of clouds is going to take a lot of additional work,” Miles said. “This is not the final word on this planet – it is the beginning of a large-scale modeling effort to fit Webb’s complex data.”

Although all of the features the team observed have been spotted on other planets elsewhere in the Milky Way by other telescopes, other research teams typically identified only one at a time. “No other telescope has identified so many features at once for a single target,” said co-author Andrew Skemer of the University of California, Santa Cruz. “We’re seeing a lot of molecules in a single spectrum from Webb that detail the planet’s dynamic cloud and weather systems.”

The team came to these conclusions by analyzing data known as spectra gathered by two instruments aboard Webb, the Near-Infrared Spectrograph (NIRSpec) and the Mid-Infrared Instrument (MIRI). Since the planet orbits at such a great distance from its stars, the researchers were able to observe it directly, rather than using the transit technique or a coronagraph to take this data.

There will be plenty more to learn about VHS 1256 b in the months and years to come as this team – and others – continue to sift through Webb’s high-resolution infrared data. “There’s a huge return on a very modest amount of telescope time,” Biller added. “With only a few hours of observations, we have what feels like the unending potential for additional discoveries.”

What might become of this planet billion of years from now? Since it’s so far from its stars, it will become colder over time, and its skies may transition from cloudy to clear.

The researchers observed VHS 1256 b as part of Webb’s Early Release Science program, which is designed to help transform the astronomical community’s ability to characterize planets and the disks where they form.

The team’s paper, entitled “The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b,” will be published in The Astrophysical Journal Letters on March 22.