The crystalline material changes color when absorbing or releasing oxygen. Crystals are black when they are saturated with oxygen and pink when the oxygen has been released again. (Image from sdu.dk)
Danish scientists have invented a revolutionary crystalline material that can absorb and store oxygen in high concentrations. A bucket of such material can suck the oxygen out of a room, which could potentially wave goodbye to heavy oxygen masks.
Imagine if you could get rid of the bulky scuba tank while taking a dive. Now, imagine practically any task to which the storage and timely release of oxygen is absolutely essential. And you have the new crystal developed at the University of Southern Denmark, with help from the University of Sydney, Australia.
A few microscopic grains are enough for one gulp of air, but a bucketful - or 10 liters - can completely suck the oxygen out of a room.
"In the lab, we saw how this material took up oxygen from the air around us,” Professor Christine McKenzie, who led the study, said.
When different things are exposed to oxygen, they react differently – from wine to food to living organisms, varying factors (pressure, temperature etc.) and time of exposure can fundamentally alter things. However, what you get with the new discovery is a way of controlling oxygen by not reacting with it.
This was ascertained by using x-ray diffraction, showing the material’s atomic behavior when it was full of oxygen, then when it was depleted of it.
"An important aspect of this new material is that it does not react irreversibly with oxygen - even though it absorbs oxygen in a so-called selective chemisorptive process. The material is both a sensor, and a container for oxygen - we can use it to bind, store and transport oxygen – like a solid artificial hemoglobin," McKenzie says.
"It is also interesting that the material can absorb and release oxygen many times without losing the ability. It is like dipping a sponge in water, squeezing the water out of it and repeating the process over and over again," she continues.
Image from sdu.dk
To release the stored oxygen, all that is needed is to heat up the material, or pressure it. And those are just the known, natural ways. McKenzie and the team are now looking further than that.
“We are now wondering if light can also be used as a trigger for the material to release oxygen – this has prospects in the growing field of artificial photosynthesis," she says.
What may be surprising to some is how natural the process of storing the oxygen really is. The key component in the new material is the metal cobalt. It possesses a natural quality for absorption and “gives the new material precisely the molecular structure that enables it to absorb oxygen from its surroundings.”
There was also the question of time and speed: different conditions can affect this differently, and so can different versions of the material. This is crucial for the types of applications where controlled release is necessary – like in a gas mask or diving gear. Layering and arranging the material correctly will prevent its ability to just suck up the stuff from the surrounding air or water.
"When the material is saturated with oxygen, it can be compared to an oxygen tank containing pure oxygen under pressure - the difference is that this material can hold three times as much oxygen," McKenzie went on.
This could be valuable for lung patients who today must carry heavy oxygen tanks with them. But also divers may one day be able to leave the oxygen tanks at home and instead get oxygen from this material as it “filters” oxygen from its surroundings.
On April 23, NASA's Swift satellite detected the strongest, hottest, and longest-lasting sequence of stellar flares ever seen from a nearby red dwarf star. The initial blast from this record-setting series of explosions was as much as 10,000 times more powerful than the largest solar flare ever recorded.
"We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks," said Stephen Drake, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who gave a presentation on the "superflare" at the August meeting of the American Astronomical Society’s High Energy Astrophysics Division. "This was a very complex event."
At its peak, the flare reached temperatures of 360 million degrees Fahrenheit (200 million Celsius), more than 12 times hotter than the center of the sun.
In April 2014, NASA's Swift mission detected a massive superflare from a red dwarf star in the binary system DG CVn, located about 60 light-years away. Astronomers Rachel Osten of the Space Telescope Science Institute and Stephen Drake of NASA Goddard discuss this remarkable event.
The "superflare" came from one of the stars in a close binary system known as DG Canum Venaticorum, or DG CVn for short, located about 60 light-years away. Both stars are dim red dwarfs with masses and sizes about one-third of our sun's. They orbit each other at about three times Earth's average distance from the sun, which is too close for Swift to determine which star erupted.
"This system is poorly studied because it wasn't on our watch list of stars capable of producing large flares," said Rachel Osten, an astronomer at the Space Telescope Science Institute in Baltimore and a deputy project scientist for NASA's James Webb Space Telescope, now under construction. "We had no idea DG CVn had this in it."
Most of the stars lying within about 100 light-years of the solar system are, like the sun, middle-aged. But a thousand or so young red dwarfs born elsewhere drift through this region, and these stars give astronomers their best opportunity for detailed study of the high-energy activity that typically accompanies stellar youth. Astronomers estimate DG CVn was born about 30 million years ago, which makes it less than 0.7 percent the age of the solar system.
Stars erupt with flares for the same reason the sun does. Around active regions of the star's atmosphere, magnetic fields become twisted and distorted. Much like winding up a rubber band, these allow the fields to accumulate energy. Eventually a process called magnetic reconnection destabilizes the fields, resulting in the explosive release of the stored energy we see as a flare. The outburst emits radiation across the electromagnetic spectrum, from radio waves to visible, ultraviolet and X-ray light.
At 5:07 p.m. EDT on April 23, the rising tide of X-rays from DG CVn's superflare triggered Swift's Burst Alert Telescope (BAT). Within several seconds of detecting a strong burst of radiation, the BAT calculates an initial position, decides whether the activity merits investigation by other instruments and, if so, sends the position to the spacecraft. In this case, Swift turned to observe the source in greater detail, and, at the same time, notified astronomers around the globe that a powerful outburst was in progress.
"For about three minutes after the BAT trigger, the superflare's X-ray brightness was greater than the combined luminosity of both stars at all wavelengths under normal conditions," noted Goddard's Adam Kowalski, who is leading a detailed study on the event. "Flares this large from red dwarfs are exceedingly rare."
The star's brightness in visible and ultraviolet light, measured both by ground-based observatories and Swift's Optical/Ultraviolet Telescope, rose by 10 and 100 times, respectively. The initial flare's X-ray output, as measured by Swift's X-Ray Telescope, puts even the most intense solar activity recorded to shame.
DG CVn, a binary consisting of two red dwarf stars shown here in an artist's rendering, unleashed a series of powerful flares seen by NASA's Swift. At its peak, the initial flare was brighter in X-rays than the combined light from both stars at all wavelengths under typical conditions.
NASA's Goddard Space Flight Center/S. Wiessinger
The largest solar explosions are classified as extraordinary, or X class, solar flares based on their X-ray emission. "The biggest flare we've ever seen from the sun occurred in November 2003 and is rated as X 45," explained Drake. "The flare on DG CVn, if viewed from a planet the same distance as Earth is from the sun, would have been roughly 10,000 times greater than this, with a rating of about X 100,000."
But it wasn't over yet. Three hours after the initial outburst, with X-rays on the downswing, the system exploded with another flare nearly as intense as the first. These first two explosions may be an example of "sympathetic" flaring often seen on the sun, where an outburst in one active region triggers a blast in another.
Over the next 11 days, Swift detected a series of successively weaker blasts. Osten compares the dwindling series of flares to the cascade of aftershocks following a major earthquake. All told, the star took a total of 20 days to settle back to its normal level of X-ray emission.
How can a star just a third the size of the sun produce such a giant eruption? The key factor is its rapid spin, a crucial ingredient for amplifying magnetic fields. The flaring star in DG CVn rotates in under a day, about 30 or more times faster than our sun. The sun also rotated much faster in its youth and may well have produced superflares of its own, but, fortunately for us, it no longer appears capable of doing so.
Astronomers are now analyzing data from the DG CVn flares to better understand the event in particular and young stars in general. They suspect the system likely unleashes numerous smaller but more frequent flares and plan to keep tabs on its future eruptions with the help of NASA's Swift.