15th April 2015
Search for advanced civilisations beyond Earth finds "nothing obvious" in 100,000 galaxies
A search for possible heat signatures left by advanced extraterrestrial civilisations has found "nothing obvious" in 100,000 galaxies.
After searching 100,000 galaxies for signs of highly advanced extraterrestrial life, a team of scientists using observations from NASA's WISE orbiting observatory has found no evidence of alien civilisations in them. Jason Wright – an assistant professor of astronomy and astrophysics at the Centre for Exoplanets and Habitable Worlds, Penn State University – who conceived of and initiated the research, says: "The idea behind our research is that, if an entire galaxy had been colonised by an advanced spacefaring civilisation, the energy produced by that civilisation's technologies would be detectable in the mid-infrared wavelengths – exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes."
The research team's first paper about its Glimpsing Heat from Alien Technologies Survey (G-HAT) will be published today (15th April 2015) in the Astrophysical Journal Supplement Series.
"Whether an advanced spacefaring civilisation uses the large amounts of energy from its galaxy's stars to power computers, space flight, communication, or something we can't yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in mid-infrared wavelengths," Wright said. "This same basic physics causes your computer to radiate heat while it is turned on."
Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilisations beyond Earth could be detected by the tell-tale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space.
False-colour image of the mid-infrared emission from Andromeda, our nearest galactic neighbour, as seen by Nasa's WISE space telescope. The orange represents emission from the heat of stars forming in the galaxy's spiral arms.
Roger Griffith, lead author of the paper, scoured almost the entire catalogue of the WISE satellite's detections – nearly 100 million entries – for objects consistent with galaxies emitting too much mid-infrared radiation. He then individually examined and categorised 100,000 of the most promising images. Wright reports, "We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilisation."
In any case, Wright said, the team's non-detection of any obvious alien-filled galaxies is an interesting and new scientific result: "Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilisation using most of the starlight in its galaxy for its own purposes. That's interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilisations, if they exist. Either they don't exist, or they don't yet use enough energy for us to recognise them."
"This research is a significant expansion of earlier work in this area," said Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Centre in Pittsburgh and a member of the G-HAT team. "The only previous study of civilisations in other galaxies looked at only 100 or so galaxies, and wasn't looking for the heat they emit. This is new ground."
Matthew Povich, assistant professor of astronomy at Cal Poly Pomona, and a co-investigator on the project, said: "Once we had identified the best candidates for alien-filled galaxies, we had to determine whether they were new discoveries that needed follow-up study, or well-known objects that had a lot of mid-infrared emission for some natural reason." Jessica Maldonado, a Cal Poly Pomona undergraduate, searched the astronomical literature for the best of the objects detected as part of the study to see which were well known and which were new to science. "Ms. Maldonado discovered that about a half dozen of the objects are both unstudied and really interesting looking," Povich said.
"When you're looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it's not what you were looking for," said Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State's Centre for Exoplanets and Habitable Worlds and a co-investigator on the research team. "Sure enough, Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena – but we need to study them more carefully before we can say for sure exactly what's going on."
Nebula surrounding the nearby star 48 Librae. Credit: Roger Griffith (Penn State) / IPAC (NASA/JPL-Caltech)
Among the discoveries within our own Milky Way galaxy are a bright nebula around the nearby star 48 Librae, and a cluster of objects easily detected by WISE in a patch of sky that appears totally black when viewed with telescopes that detect only visible light. "This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study," Povich said.
"As we look more carefully at the light from these galaxies," said Wright, "we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning."
13th April 2015
Complex organic molecules detected in young star system
For the first time, astronomers have detected the presence of complex organic molecules, the building blocks of life, in a protoplanetary disk surrounding a young star. This discovery reaffirms that the conditions that spawned the Earth and Sun are not unique in the Universe.
Credit: B. Saxton (NRAO/AUI/NSF)
For the first time, astronomers have detected the presence of complex organic molecules – the building blocks of life – in a protoplanetary disk surrounding a young star. This discovery, made with the Atacama Large Millimetre/submillimetre Array (ALMA), reaffirms that the conditions that spawned the Earth and Sun are not unique in the Universe. The results are published in the 9th April 2015 issue of the journal Nature.
The new ALMA observations reveal that the protoplanetary disk surrounding the young star MWC 480 contains large amounts of methyl cyanide (CH3CN), a complex carbon-based molecule. There is enough methyl cyanide around MWC 480 to fill all of Earth's oceans.
Both this molecule and its simpler cousin hydrogen cyanide (HCN) were found in the cold outer reaches of the star's newly formed disk, in a region that astronomers believe is analogous to the Kuiper Belt – the realm of icy planetesimals and comets in our own Solar System beyond Neptune.
Comets retain a pristine record of the early chemistry of the Solar System, from the period of planet formation. Comets and asteroids from the outer Solar System are thought to have seeded the young Earth with water and organic molecules, helping set the stage for the development of primordial life.
"Studies of comets and asteroids show that the solar nebula that spawned the Sun and planets was rich in water and complex organic compounds," noted Karin Öberg, astronomer with the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts, USA, and lead author of the paper.
"We now have even better evidence that this same chemistry exists elsewhere in the Universe, in regions that could form solar systems not unlike our own." This is particularly intriguing, Öberg notes, since the molecules found in MWC 480 are also found in similar concentrations in the Solar System's comets.
The star MWC 480 – about twice the mass of our Sun – is located 455 light-years away in the Taurus star-forming region. Its surrounding disk is in the very early stages of development, having recently coalesced out of a cold, dark nebula of dust and gas. Studies with ALMA and other telescopes have yet to detect any obvious signs of planet formation around it – although higher resolution observations may reveal structures similar to HL Tauri, which is of a similar age.
Astronomers have known for some time that cold, dark interstellar clouds are very efficient factories for complex organic molecules – including a group of molecules known as cyanides. These, and most especially methyl cyanide, are important because they contain carbon–nitrogen bonds, which are essential for the formation of amino acids, the foundation of proteins and the building blocks of life.
Until now, it has remained unclear, however, if these same complex organic molecules commonly form and survive in the energetic environment of a newly forming solar system, where shocks and radiation can easily break chemical bonds. By exploiting ALMA's remarkable sensitivity, astronomers can see from the latest observations that these molecules not only survive, but flourish.
Importantly, the molecules ALMA detected are much more abundant than would be found in interstellar clouds. This tells astronomers that protoplanetary disks are very efficient at forming complex organic molecules, and are able to form them on relatively short timescales.
As this system continues to evolve, astronomers speculate that it's likely that the organic molecules safely locked away in comets and other icy bodies will be ferried to environments more nurturing to life.
"From the study of exoplanets, we know the Solar System isn't unique in its number of planets or abundance of water," concludes Öberg. "Now we know we're not unique in organic chemistry. Once more, we have learnt that we're not special. From a life in the Universe point of view, this is great news."
8th April 2015
Western Canadian glaciers will lose 70% of their volume by 2100
Seventy percent of glacier ice in British Columbia and Alberta could disappear by the end of the 21st century, creating major problems for local ecosystems, power supplies, and water quality, according to a new study.
|| Athabasca Glacier and Columbia Ice Fields, Alberta, Canada. The glacier was near this point in the year 2000.
Seventy per cent of glacier ice in British Columbia (B.C.) and Alberta could disappear by the end of the 21st century – creating major problems for local ecosystems, power supplies, and water quality, according to a new study by University of British Columbia researchers.
The study found that while warming temperatures are threatening glaciers in Western Canada, not all glaciers are retreating at the same rate. The Rocky Mountains, in the drier interior, could lose up to 90 per cent of its glaciers. The wetter coastal mountains in northwestern B.C. are only expected to lose about half of their glacier volume.
"Most of our ice holdouts at the end of the century will be in the northwest corner of the province," said Garry Clarke, professor emeritus in the Department of Earth, Ocean and Atmospheric Sciences. "Soon our mountains could look like those in Colorado or California and you don't see much ice in those landscapes."
For the study, researchers used observational data, computer models and climate simulations to forecast the fate of individual glaciers. Under a high emissions scenario (the path we're currently on), many glaciers almost completely disappeared by 2100. However, even under the lowest and most optimistic forecast the ice loss was still significant.
Columbia Icefield, Canadian Rocky Mountains
Low emissions scenario
Columbia Icefield, Canadian Rocky Mountains
High emissions scenario
Frank Mackie region, Coast and St Elias Mountains
Low emissions scenario
Frank Mackie region, Coast and St Elias Mountains
High emissions scenario
There are over 17,000 glaciers in B.C. and Alberta, which play an important role in energy production through hydroelectric power. The glaciers also contribute to the water supply and are essential to mining and agriculture. Clarke says while these issues are a concern, increased precipitation due to climate change could help compensate for glacier loss. The greatest impact, he suspects, will be on freshwater ecosystems. During the late summer, glacier melt provides cool, plentiful water to many of the region's headwaters.
"These glaciers act as a thermostat for freshwater ecosystems," said Clarke. "Once the glaciers are gone, the streams will be a lot warmer and this will hugely change fresh water habitat. We could see some unpleasant surprises in terms of salmon productivity."
Researchers predicted changes in the area and volume of glaciers in western Canada under a range of greenhouse gas emission scenarios used by the Intergovernmental Panel on Climate Change (IPCC) in their most recent assessment of the climate system. An increased level of CO2 in the atmosphere, primarily from fossil fuel combustion, is the main factor that will cause increases in surface air temperatures in the decades ahead.
Researchers say the impact of climate change on glacier health may not be evident at first sight. While the surface area covered by the glacier may not be changing, the glaciers are thinning at a rate of about one metre per year.
"Most glaciers are only 100 to 200 metres thick," said Clarke. "They're losing volume, but this loss we're seeing right now is a bit hidden."
3rd April 2015
Polar bears are unlikely to survive the 21st century
As the Arctic region warms and melts, polar bears forced ashore will be unable to gain sufficient food on land. Two-thirds of polar bears will be lost by 2050 and the species could go extinct by 2100.
A team of scientists led by the U.S. Geological Survey (USGS) has found that polar bears – increasingly forced ashore due to sea ice loss – may be eating terrestrial foods including berries, birds and eggs. However, any nutritional gains are limited to a few individuals and likely cannot compensate for the lost opportunities to consume their traditional, fat-rich prey – ice seals.
“Although some polar bears may eat terrestrial foods, there is no evidence the behaviour is widespread,” said Dr. Karyn Rode, lead author of the study and scientist with the USGS. “In the regions where terrestrial feeding by polar bears has been documented, polar bear body condition and survival rates have declined.”
The study authors have published these latest findings in the peer-reviewed journal Frontiers in Ecology and the Environment. They note that over much of the polar bear’s range, terrestrial habitats are already occupied by grizzly bears. Those grizzly bears occur at low densities and are some of the smallest of their species due to low food quality and availability. Further, they are a potential competitor, as polar bears displaced from their sea ice habitats increasingly use the same land habitats as grizzly bears.
“The smaller size and low population density of grizzly bears in the Arctic provides a clear indication of the nutritional limitations of onshore habitats for supporting large-bodied polar bears in meaningful numbers,” explains Rode. “Grizzly bears and polar bears are likely to increasingly interact and potentially compete for terrestrial resources.”
Last month, the National Snow and Ice Data Centre reported that Arctic sea ice reached its lowest ever extent for the winter, at 1.10 million sq km (425,000 square miles) below the 1981–2010 average of 15.6 million sq km (6 million square miles) and 130,000 sq km (50,200 square miles) below the previous lowest maximum that occurred in 2011. Furthermore, ice thickness during the summer minimum (when the melt season ends in September) plunged by a staggering 85 percent between 1975 and 2012, according to a recent study by the University of Washington. The melting of Arctic sea ice is likely to accelerate as more of the dark water is exposed, absorbing rather than reflecting the Sun's heat. On current trends, the sea is likely to become free of ice during the entire month of September by the 2030s, with up to three months of ice-free conditions by the 2050s.
Here the 2015 maximum is compared to the 1979-2014 average maximum shown in yellow. A distance indicator shows the difference between the two in the Sea of Okhotsk north of Japan.
The study by Rode and her team found that fewer than 30 individual polar bears have been observed consuming bird eggs from any one population, which typically range from 900 to 2,000 individuals. “There has been a fair bit of publicity about polar bears consuming bird eggs,” she said. “However, this behaviour is not yet common – and is unlikely to have population-level impacts on trends in body condition and survival.”
Few foods are as energetically dense as marine prey. Studies suggest that polar bears consume the highest lipid diet of any species, which provides all essential nutrients and is ideal for maximising fat deposition and minimising energetic requirements. Potential foods found in the terrestrial environment are dominated by low-fat animals and vegetation. Polar bears are not physiologically suited to digest plants, and it would be difficult for them to ingest the volumes that would be required to support their large body size.
“The reports of terrestrial feeding by polar bears provide important insights into the ecology of bears on land,” said Rode. “In this paper, we tried to put those observations into a broader context. Focused research will help us determine whether terrestrial foods could contribute to polar bear nutrition despite the physiological and nutritional limitations and the low availability of most terrestrial food resources. However, the evidence thus far suggests that increased consumption of terrestrial foods by polar bears is unlikely to offset declines in body condition and survival resulting from sea ice loss.”
“Why would anyone think this nutritionally poor environment suddenly could support whole populations of the world's largest bears?” says the chief scientist at Polar Bears International, Dr. Steven Amstrup. “There is a big difference between the fact of eating something, and the nutritional value of that eating. While it's tempting to think that polar bears could survive by switching to a terrestrial diet, this paper establishes in no uncertain terms that land-based foods do not offer any hope of polar bear salvation.”
“As the sea ice goes, so goes the polar bear,” he concludes. “We generally expect to lose two-thirds of the world's bears by mid-century, and possibly the rest by the end of the century.”