NASA WISE reveals the Milky Way's ancient brown dwarf population

A brown dwarf from the thick-disk or halo is shown. 

Although astronomers observe these objects as they pass near to the solar system, they spend much of their time away from the busiest part of the Galaxy, and the Milky Way's disk can be seen in the background. 

Credit: John Pinfield

A team of astronomers led by Dr David Pinfield at the University of Hertfordshire have discovered two of the oldest brown dwarfs in the Galaxy.

These ancient objects are moving at speeds of 100-200 kilometres per second, much faster than normal stars and other brown dwarfs and are thought to have formed when the Galaxy was very young, more than 10 billion years ago.

Intriguingly the scientists believe they could be part of a vast and previously unseen population of objects. The researchers publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

Brown dwarfs are star-like objects but are much less massive (with less than 7% of the Sun's mass), and do not generate internal heat through nuclear fusion like stars.

Because of this brown dwarfs simply cool and fade with time and very old brown dwarfs become very cool indeed - the new discoveries have temperatures of 250-600 degrees Celsius, much cooler than stars (in comparison the Sun has a surface temperature of 5600 degrees Celsius).

Pinfield's team identified the new objects in the survey made by the Wide-field Infrared Survey Explorer (WISE), a NASA observatory that scanned the mid-infrared sky from orbit in 2010 and 2011.

The object names are WISE 0013+0634 and WISE 0833+0052, and they lie in the Pisces and Hydra constellations respectively.

Additional measurements confirming the nature of the objects came from large ground-based telescopes (Magellan, Gemini, VISTA and UKIRT).

The infrared sky is full of faint red sources, including reddened stars, faint background galaxies (large distances from our own Milky Way) and nebulous gas and dust.

Identifying cool brown dwarfs in amongst this messy mixture is akin to finding needles in a haystack. But Pinfield's team developed a new method that takes advantage of the way in which WISE scans the sky multiple times.

This allowed them to identify cool brown dwarfs that were fainter than other searches had revealed.

The team of scientists then studied the infrared light emitted from these objects, which are unusual compared to typical slower moving brown dwarfs.

The spectral signatures of their light reflects their ancient atmospheres, which are almost entirely made up of hydrogen rather than having the more abundant heavier elements seen in younger stars.

Pinfield comments on their venerable ages and high speeds, "Unlike in other walks of life, the Galaxy's oldest members move much faster than its younger population".

More information: "A deep WISE search for very late type objects and the discovery of two halo/thick-disk T dwarfs: WISE 0013+0634 and WISE 0833+0052", D. J. Pinfield et al, Monthly Notices of the Royal Astronomical Society, in press. A pre-publication version of the paper is available on arXiv: arxiv.org/abs/1308.0495

NASA LandSat: Catastrophic growth of China’s megacities and Pollution levels

In 1973, NASA and United States Geological Survey’s Landsat 3 satellite took the image above of quiet, rural land (plant-covered land is red) along China’s Pearl River Delta. 

Six years later, in 1979, the region began to grow as China set up two economic zones north of Hong Kong. 

Then, 30 years later, in 2003, Landsat 7 satellite took this dramatic shot:

Images: NASA/USGS

It’s a catastrophic urban shift, happening all over China, with an unsupportable increase in demand for natural resources and the associated suchoking rge in pollution levels.

You can see the booming urban areas in gray, a major contrast to the mostly red image from 1973.

In the image you can see part of Guangzhou, the most populous urban area in the region today with 12,700,000 people; Dongguan, an urban area with more than 8 million people; and Foshan with more than 7 million. As of 2010, the Pearl District Economic Zone had a population of 36 million.

You can see more before and after images from 10 other cities across the globe. Or, at The Atlantic Cities, check out Nate Berg’s slightly jarring animated GIF rendition of the urban shift.

Spy Satellite Images expose 8,000 years of civilization

Hidden in the landscape of the fertile crescent of the Middle East, scientists say, lurk overlooked networks of small settlements that hold vital clues to ancient civilizations.

Beyond the impressive mounds of earth, known as 'tells' in Arabic, that mark lost cities, researchers have found a way to give archaeologists a broader perspective of the ancient landscape.

By combining spy-satellite photos obtained in the 1960s with modern multi-spectral images and digital maps of Earth's surface, the researchers have created a new method for mapping large-scale patterns of human settlement.

The approach, used to map some 14,000 settlement sites spanning eight millennia in 23,000 square kilometres of northeastern Syria, is published today in the Proceedings of the National Academy of Sciences.

“Traditional archaeology goes straight to the biggest features, the palaces or cities, but we tend to ignore the settlements at the other end of the social spectrum,” says Jason Ur, an archaeologist at Harvard University in Cambridge, Massachusetts, who is co-author of the study.

“The people who migrated to cities came from somewhere; we have to put these people back on the map.”

Such comprehensive maps promise to uncover long-term trends in urban activity. “This kind of innovative large-scale application is what remote sensing has been promising archaeology for some years now; it will certainly help us to focus our attention on the big picture,” says Graham Philip, an archaeologist at Durham University, UK.

Soil signatures
The satellite-based method relies on the fact that human activity leaves a distinctive signature on the soil, called anthrosols.

Formed from organic waste and decayed mud-brick architecture, anthrosols are imbued with higher levels of organic matter and have a finer texture and lighter appearance than undisturbed soil, resulting in reflective properties that can be seen by satellites.

To sift through satellite images for those signatures, co-author Bjoern Menze, a research affiliate in computer science at the Massachusetts Institute of Technology in Cambridge, built on his skills from his day job identifying tumours in clinical images.

Menze trained software to detect the characteristic wavelengths of known anthrosols in images spanning 50 years of seasonal differences.

This automation was key. “You could do this with the naked eye using Google Earth to look for sites, but this method takes the subjectivity out of it by defining spectral characteristics that bounce off of archaeological sites,” says Ur.

Menze and Ur also used digital elevation data collected in 2000 by the space shuttle as part of NASA's Shuttle Radar Topography Mission (SRTM).

This information enabled the authors to estimate the volume of the larger sites for the first time — and to use this volume as a proxy for a site’s longevity. The bigger the mound, the longer the settlement survived.

Tony Wilkinson, an archaeologist at Durham University and Ur’s former mentor, says that being able to measure the volume of many sites over large areas remotely is a breakthrough.

However, Philip cautions that the resolution of the SRTM data may be too coarse to provide an accurate measurement for the volume of the smaller settlements. Nonetheless, he expects that the method will spark new archaeological insights for several different regions.

Read more at Nature 

• Jason Ur
• Bjoern Menze
• Graham Philip

Giant Red Crabs invade the Antartic Abyss

Huge crabs more than a metre across have invaded the Antarctic abyss, wiped out the local wildlife and now threaten to ruin ecosystems that have evolved over 14 million years.

Three years ago, researchers predicted that as the deep waters of the Southern Ocean warmed, king crabs would invade Antarctica within 100 years.

But video taken by a remotely operated submersible shows that more than a million Neolithodes yaldwyni have already colonised Palmer Deep, a basin that forms a hollow in the Antarctic Peninsula continental shelf.

They are laying waste to the landscape. Video footage taken by the submersible shows how the crabs prod, probe, gash and puncture delicate sediments with the tips of their long legs.

"This is likely to alter sediment processes, such as the rate at which organic matter is buried, which will affect the diversity of animal communities living in the sediments," says Craig Smith of the University of Hawaii at Manoa, whose team discovered the scarlet invaders.

Hungry invaders

The crabs also appear to have a voracious appetite. Echinoderms – sea urchins, sea lilies, sea cucumbers, starfish and brittle stars – have vanished from occupied areas, and the number of species in colonised areas is just a quarter of that in areas that have escaped the invasion.

"[Echinoderms] constitute a significant proportion of the large animals on the seafloor in many Antarctic shelf habitats," says Smith.

The crabs come from further north and moved in as Antarctic waters have warmed, probably swept into Palmer Deep as larvae in warm ocean currents. 

They now occupy the deepest regions of Palmer Deep, between 1400 and 950 metres. In 1982, the minimum temperature there was 1.2 °C – too cold for king crabs – but by last year it had risen to a balmier 1.47 °C.

Melting ice sheets tend to make shallower waters in Antarctica cooler than deeper ones. There were no king crabs at depths of 850 metres or less, suggesting that these waters are still too cold for them. But with waters warming so rapidly, they could spread to regions as shallow as 400 metres within as little as 20 years, says Smith.

More than 12 pct of China's population over 60: state media

More than 12 pct of China's population over 60: state media

More than 12 out of every 100 people in China are now over the age of 60, putting increasing pressure on the care system for the elderly, which is already not satisfying demand, state media reported.

The number of people above 60 reached 160 million at the end of last year, the Xinhua news agency said late Wednesday, citing Wang Suying, a senior official at the civil affairs ministry.

That is 12.3 percent of the country's total population of 1.3 billion.

Wang said China was facing a "grave trend" of an ageing population while the nation's care services for the elderly were "severely insufficient" and "far from meeting demand", according to Xinhua.

The country currently has only 2.5 million beds in rest homes, while an estimated eight million elderly were seeking accommodation in such facilities, the report said.

About 10 million nurses and specialists are needed to look after those who cannot take care of themselves, while care facilities for the aged had only 220,000 employees, 90 percent of whom were under-qualified, it said.

Ageing is a long-term trend affecting more and more of the world but China faces the unusual situation of growing old before it grows rich, officials have said.

The problem has become even more complicated as better nutrition and improved health care have helped people live longer lives, while birth control and changing cultural norms result in fewer young people.

Japanese election, blogs and Twitter silenced

The day the blogging stopped. As campaigning begins in the On Tuesday, 1,370 Japanese stopped blogging and Twittering.

There's perhaps nothing unusual about that; after all, hundreds give up social media efforts every day but for these people the halt to their online activities has been brought on by the law.

No, they haven't done anything wrong. But they are candidates in Japan's upcoming national election, and with the official 12-day campaigning window now underway, online communication is off-limits.

It's the result of a 59-year-old election law that has failed to keep up with the times. In an era when politicians are turning to the Internet to interact with potential voters and mobilize a support base -- something demonstrated so vividly by U.S. President Obama in his election campaign -- Japanese politicians are restricted to stump speeches, leaflets and posters, and even those are regulated too.

"Today is the beginning of campaigning. I must end Twitter today, I feel it's unreasonable," wrote Seiji Ohsaka, a lawmaker from the northern island of Hokkaido, to his 6,361 followers on Twitter.

The Public Offices Election Law doesn't specifically ban use of the Internet, but it does place restrictions on the use of literature and images in campaigning, and that has been interpreted by all to include the Internet.

The result is that during election campaigns in Japan, the airwaves are not filled with political commercials and streets are not covered in posters. Election billboards, with a space allotted to each candidate for an 83cm-by-58cm poster, are erected throughout cities, and candidates are allowed to distribute only a limited number of posters. Leaflets must be counted and numbered.

Candidates get a brief slot on public television, usually in the early or late-night hours when few are watching, to make their pitch. The rest of the time it's down to campaigning in neighborhoods, walking through the streets and making speeches outside railway stations.

It's all designed, the law's defenders say, to stop the candidate with the deepest pockets from dominating the race.

Unfortunately, this law has an increasing number of critics, and not just Twittering politicians. Voter turnout among the young is poor and some believe it's because the old-fashioned way of campaigning has failed to energize a population that is surrounded by digital media from the day they are born.

"The Internet must be made available for election campaigns as soon as possible," the Asahi Shimbun, Japan's second-largest newspaper, wrote in a recent editorial but the Aug. 30 election could be the law's last stand.

If you believe the opinion polls, the ruling Liberal Democratic Party is on the verge of a historic defeat. After more than 50 years of rule, broken only once for a few months, Japanese voters look set to reject the party and hand control of the powerful lower house to the opposition

Democratic Party of Japan. The DPJ already controls the upper house and plans some swift changes should it win at the polls. Hopefully, among those is likely to be the election law.