Astronomers have spotted glowing droplets of condensed water in the distant Spiderweb Galaxy but not where they expected to find them. Detections with the Atacama Large Millimeter/submillimeter Array (ALMA) show that the water is located far out in the galaxy and therefore cannot be associated with central, dusty, star-forming regions, as previously thought.

“Observations of light emitted by water and by dust often go hand-in-hand. We usually interpret them as an insight into star-forming regions, with the illumination from young stars warming dust particles and water molecules until they start to glow. Now, thanks to the power of ALMA, we can -- for the first time -- separate out the emissions from the dust and water populations, and pinpoint their exact origins in the galaxy. The results are quite unexpected in that we've found that the water is located nowhere near the dusty stellar nurseries,” explained Bitten Gullberg, of the Centre for Extragalactic Astronomy, Durham University, UK.

The Spiderweb Galaxy above as seen by the Hubble Space Telescope (optical) in red, the Very Large Array (radio) in green and the Atacama Large Millimeter/submillimeter Array (sub-millimetre) in blue. The red colour shows where the stars are located within this system of galaxies. The radio jet is shown in green, and the position of the dust and water are seen in blue. The water is located to the left and right of the central galaxy. The water to the right is at the position where the radio jet bends down wards. The dust is also seen in blue. The dust is located at the central galaxy and in smaller companion galaxies in its surroundings. Credit: NASA/ESA/HST/STScI/NRAO/ESO

The Spiderweb Galaxy is one of the most massive galaxies known. It lies 10 billion light-years away and is made up of dozens of star-forming galaxies in the process of merging together. The ALMA observations show that the light from the dust originates in the Spiderweb Galaxy itself. However, the light from the water is concentrated in two regions far to the east and west of the galaxy core.

Gullberg and her colleagues believe that the explanation lies with powerful jets of radio waves that are ejected from a supermassive black hole at the centre of the Spiderweb Galaxy. The radio jets compress clouds of gas along their path and heat up water molecules contained within the clouds until they emit radiation.

“Our results show how important it is to pinpoint the exact locations and origins for light in galaxies. We may also have new clues to the processes that trigger star formation in interstellar clouds,” said Gullberg. “Stars are born out of cold, dense molecular gas. The regions in the Spiderweb where we've detected water are currently too hot for stars to form. But the interaction with the radio jets changes the composition of the gas clouds. When the molecules have cooled down again, it will be possible for the seeds of new stars to form. These “dew drop” regions could become the next stellar nurseries in this massive, complex galaxy.”

The Daily Galaxy via RAS

In three days, July 4th, the spacecraft Juno will arrive at Jupiter, the culmination of a five-year, billion-dollar journey. It's mission: to peer deep inside the gas giant and unravel its origin and evolution. One of the biggest mysteries surrounding Jupiter is how it generates its powerful magnetic field, the strongest in the solar system.

One theory is that about halfway to Jupiter's core, the pressures and temperatures become so intense that the hydrogen that makes up 90 percent of the planet -- molecular gas on Earth -- looses hold of its electrons and begins behaving like a liquid metal. Oceans of liquid metallic hydrogen surrounding Jupiter's core would explain its powerful magnetic field.

But how and when does this transition from gas to liquid metal occur? How does it behave? Researchers hope that Juno will shed some light on this exotic state of hydrogen -- but one doesn't need to travel all the way to Jupiter to study it.

Four hundred million miles away, in a small, windowless room in the basement of Lyman Laboratory on Oxford Street in Cambridge, Massachusetts, there was, for a fraction of a fraction of a second, a small piece of Jupiter.

Earlier this year, in an experiment about five-feet long, Harvard University researchers say they observed evidence of the abrupt transition of hydrogen from liquid insulator to liquid metal. It is one of the first times such a transition has ever been observed in any experiment.

"This is planetary science on the bench," said Mohamed Zaghoo, the NASA Earth & Space Science Fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). "The question of how hydrogen transitions into a metallic state -- whether that is an abrupt transition or not -- has huge implications for planetary science. How hydrogen transitions inside Jupiter, for example, says a lot about the evolution, the temperature and the structure of these gas giants interiors."

In the experiment, Zaghoo, Ashkan Salamat, and senior author Isaac Silvera, the Thomas D. Cabot Professor of the Natural Sciences, recreated the extreme pressures and temperatures of Jupiter by squeezing a sample of hydrogen between two diamond tips, about 100 microns wide, and firing short bursts of lasers of increasing intensity to raise the temperature.

This experimental setup is significantly smaller and cheaper than other current techniques to generate metallic hydrogen, most of which rely on huge guns or lasers that generate shock waves to heat and pressurize hydrogen.

The transition of the liquid to metallic hydrogen happens too quickly for human eyes to observe and the sample lasts only a fraction of a second before it deteriorates. So, instead of watching the sample itself for evidence of the transition, the team watched lasers pointed at the sample. When the phase transition occurred, the lasers abruptly reflected.

"At some point, the hydrogen abruptly transitioned from an insulating, transparent state, like glass, to a shiny metallic state that reflected light, like copper, gold or any other metal," Zaghoo said. "Because this experiment, unlike shock wave experiments, isn't destructive, we could run the experiment continuously, doing measurements and monitoring for weeks and months to learn about the transition."

"This is the simplest and most fundamental atomic system, yet modern theory has large variances in predictions for the transition pressure," Silvera said. "Our observation serves as a crucial guide to modern theory."

The results represent a culmination of decades of research by the Silvera group. The data collected could begin to answer some of the fundamental questions about the origins of solar systems.

Metallic hydrogen also has important ramifications here on Earth, especially in energy and materials science. "A lot of people are talking about the hydrogen economy because hydrogen is combustibly clean and it's very abundant," said Zaghoo. "If you can compress hydrogen into high density, it has a lot of energy compacted into it."

"As a rocket fuel, metallic hydrogen would revolutionize rocketry as propellant an order of magnitude more powerful than any known chemical," said Silvera. "This could cut down the time it takes to get to Mars from nine months to about two months, transforming prospects of human space endeavors."

Metallic hydrogen could be used to make room temperature or even higher than room temperature super-conductors. The Juno mission goes hand-in-hand with laboratory experiments into metallic hydrogen, Zaghoo said."The measurements of Jupiter's magnetic field that Juno will be collecting is directly related to our data," he said. "We're not in competition with NASA but, in some ways, we got to Jupiter first."

In the Gemini Observatory image at the top of the page, white indicates cloud features at relatively high altitudes; blue indicates lower cloud structures; and red represents still deeper cloud features. The two red spots appear more white than red, because their tops hover high above the surrounding clouds. Also prominent is the polar stratospheric haze, which makes Jupiter bright near the pole. Other tiny white spots are regions of high clouds, like towering thunderheads. In visible light Jupiter looks orangish, but in the near-infrared the blue color is due to strong absorption features. The blue mid-level clouds are also closest to what one would see in a visual light image.

The Daily Galaxy via Harvard University

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"Both the planet we live on and the star we orbit are made up of 'normal' matter," said Tanmay Vachaspati a theoretical physicist at Arizona State University working at the intersections of particle physics, astrophysics, general relativity, and cosmology. "Although it features in many science fiction stories, antimatter seems to be incredibly rare in nature. With this new result, we have one of the first hints that we might be able to solve this mystery."

In 2001 Vachaspati published theoretical models to try to solve this puzzle, which predict that the entire universe is filled with helical (screw-like) magnetic fields. He and his team were inspired to search for evidence of these fields in data from the NASA Fermi Gamma ray Space Telescope (FGST). Vachaspati has written extensively on cosmic strings, magnetic monopoles, black holes, and cosmological magnetic fields, and has authored the monograph "Kinks and Domain Walls: an introduction to classical and quantum solitons". He was a Rosenbaum Fellow at the Isaac Newton Institute in Cambridge, a Member of the Institute for Advanced Study, Princeton, and is a Fellow of the American Physical Society.

In 2015, a group of scientists, led by Vachaspati, with collaborators at the University of Washington and Nagoya University, announce their result in Monthly Notices of the Royal Astronomical Society.

FGST, launched in 2008, observes gamma rays (electromagnetic radiation with a shorter wavelength than X-rays) from very distant sources, such as the supermassive black holes found in many large galaxies. The gamma rays are sensitive to effect of the magnetic field they travel through on their long journey to the Earth. If the field is helical, it will imprint a spiral pattern on the distribution of gamma rays.

Vachaspati and his team see exactly this effect in the FGST data, allowing them to not only detect the magnetic field but also to measure its properties. The data shows not only a helical field, but also that there is an excess of left-handedness - a fundamental discovery that for the first time suggests the precise mechanism that led to the absence of antimatter.

For example, mechanisms that occur nanoseconds after the Big Bang, when the Higgs field gave masses to all known particles, predict left-handed fields, while mechanisms based on interactions that occur even earlier predict right-handed fields.

This discovery has wide ramifications, as a cosmological magnetic field could play an important role in the formation of the first stars and could seed the stronger field seen in galaxies and clusters of galaxies in the present day.

The image at the top of the page shows colliding matter and antimatter. Credit: NASA/CXC/M. Weiss

The Daily Galaxy via RAS

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