Double Rainbow

Photonic Image

Here is an image of a spectacular double rainbow seen recently over my home in Sussex, England. I just grabbed the camera! It goes to show you don't need to be in space or have sophisticated equipment to capture arial phenomena (though of course it may help!): Steve

another image of the rainbow is here

Photonic Image

Spiral Galaxy M109

new NASA image

Beautiful barred spiral galaxy M109, 109th entry in Charles Messier's famous catalog of bright Nebulae and Star Clusters, is found just below the Big Dipper's bowl in the northern constellation Ursa Major. In telescopic views, its striking central bar gives the galaxy the appearance of the Greek letter "theta", θ, a common mathematical symbol representing an angle. Of course M109 spans a very small angle in planet Earth's sky, about 7 arcminutes or 0.12 degrees. But that small angle corresponds to an enormous 120,000 light-year diameter at the galaxy's estimated 60 million light-year distance. The brightest member of the now recognized Ursa Major galaxy cluster, M109 (aka NGC 3992) is joined by three spiky foreground stars strung out across this frame. The three small, fuzzy bluish galaxies also on the scene, identified left to right as UGC 6969, UGC 6940 and UGC 6923, are possibly satellite galaxies of the larger M109.

Photonic Space

Scientists confirm that the Justinianic Plague was caused by the bacterium Yersinia pestis

DNA evidence from Johannes Gutenberg University, Mainz shed light on a plague that ravaged Europe in the 6th to 8th centuries AD and confirm it was caused by the same bacterium as the Black Death of the middle ages. here is their report. This settles a debate whether the various plagues had the same causative agent, that has raged for many years.

From the several pandemics generally called 'pestilences' three are historically recognized as due to plague, but only for the third pandemic of the 19th-21st centuries AD there were microbiological evidences that the causing agent was the bacterium Yersinia pestis. "For a long time scholars from different disciplines have intensively discussed about the actual etiological agents of the past pandemics. Only ancient DNA analyses carried out on skeletal remains of plague victims could finally conclude the debate", said Dr. Barbara Bramanti of the Palaeogenetics Group at the Institute of Anthropology at Johannes Gutenberg University Mainz (JGU). About two years ago, she headed the international team which demonstrated beyond any doubt that Y. pestis also caused the second pandemic of the 14th-17th centuries including the Black Death, the infamous epidemic that ravaged Europe from 1346-1351. Bramanti and her Mainz colleague Stephanie Hänsch now cooperated with the University of Munich, the German Bundeswehr, and international scholars to solve the debate as to whether Y. pestis caused the so-called Justinianic Plague of the 6th-8th centuries AD. The results of ancient DNA analyses carried out on the early medieval cemetery of Aschheim in Bavaria were published last week in PloS Pathogens. They confirmed unambiguously that Y. pestis was indeed the causing agent of the first pandemic, in contrast to what has been postulated by other scientists recently. This revolutionary result is supported by the analysis of the genotype of the ancient strain which provide information about the phylogeny and the place of origin of this plague. As for the second and third pandemic, the original sources of the plague bacillus were in Asia.

"It remains questionable whether at the time of the Byzantine Emperor Justinian only one strain or more were disseminated in Europe, as it was at the time of the Black Death," suggested Bramanti and Hänsch. To further investigate this and other open questions about the modalities and route of transmission of the medieval plagues, Bramanti has recently obtained an ERC Advanced Grant for the project "The medieval plagues: ecology, transmission modalities and routes of the infection" (MedPlag) and will move to the Center for Ecological and Evolutionary Synthesis (CEES) at the University of Oslo in Norway. The CEES, chaired by Nils Chr. Stenseth, has an outstanding and rewarded record of excellence in the research on infectious diseases and in particular on Y. pestis.

Photonic Progress

Secret Streets of Britain’s Atlantis are Revealed

A University of Southampton professor has carried out the most detailed analysis ever of the archaeological remains of the lost medieval town of Dunwich, dubbed ‘Britain’s Atlantis’.

Funded and supported by English Heritage, and using advanced underwater imaging techniques, the project led by Professor David Sear of Geography and Environment has produced the most accurate map to date of the town’s streets, boundaries and major buildings, and revealed new ruins on the seabed. Professor Sear worked with a team from the University’s GeoData Institute; the National Oceanography Centre, Southampton; Wessex Archaeology; and local divers from North Sea Recovery and Learn Scuba.

He comments, “Visibility under the water at Dunwich is very poor due to the muddy water. This has limited the exploration of the site.

“We have now dived on the site using high resolution DIDSON ™ acoustic imaging to examine the ruins on the seabed – a first use of this technology for non-wreck marine archaeology.

“DIDSON technology is rather like shining a torch onto the seabed, only using sound instead of light. The data produced helps us to not only see the ruins, but also understand more about how they interact with the tidal currents and sea bed.”

Peter Murphy, English Heritage’s coastal survey expert who is currently completing a national assessment of coastal heritage assets in England, says: “The loss of most of the medieval town of Dunwich over the last few hundred years – one of the most important English ports in the Middle Ages – is part of a long process that is likely to result in more losses in the future. Everyone was surprised, though, by how much of the eroded town still survives under the sea and is identifiable.

“Whilst we cannot stop the forces of nature, we can ensure what is significant is recorded and our knowledge and memory of a place doesn’t get lost forever. Professor Sear and his team have developed techniques that will be valuable to understanding submerged and eroded terrestrial sites elsewhere.”

Present day Dunwich is a village 14 miles south of Lowestoft in Suffolk, but it was once a thriving port – similar in size to 14th Century London. Extreme storms forced coastal erosion and flooding that have almost completely wiped out this once prosperous town over the past seven centuries. This process began in 1286 when a huge storm swept much of the settlement into the sea and silted up the Dunwich River. This storm was followed by a succession of others that silted up the harbour and squeezed the economic life out of the town, leading to its eventual demise as a major international port in the 15th Century. It now lies collapsed and in ruins in a watery grave, three to 10 metres below the surface of the sea, just off the present coastline.

The project to survey the underwater ruins of Dunwich, the world’s largest medieval underwater town site, began in 2008. Six additional ruins on the seabed and 74 potential archaeological sites on the seafloor have since been found. Combining all known archaeological data from the site, together with old charts and navigation guides to the coast, it has also led to the production of the most accurate and detailed map of the street layout and position of buildings, including the town’s eight churches. Findings highlights are:

* Identification of the limits of the town, which reveal it was a substantial urban centre occupying approximately 1.8 km2 – almost as large as the City of London
* Confirmation the town had a central area enclosed by a defensive, possibly Saxon earthwork, about 1km2
* The documentation of ten buildings of medieval Dunwich, within this enclosed area, including the location and probable ruins of Blackfriars Friary, St Peter’s, All Saint’s and St Nicholas Churches, and the Chapel of St Katherine
* Additional ruins which initial interpretation suggests are part of a large house, possibly the town hall
* Further evidence that suggests the northern area of the town was largely commercial, with wooden structures associated with the port
* The use of shoreline change analysis to predict where the coastline was located at the height of the town’s prosperity

Visualisation of St Katherine

University of Southampton

Commenting on the significance of Dunwich, Professor Sear says: “It is a sobering example of the relentless force of nature on our island coastline. It starkly demonstrates how rapidly the coast can change, even when protected by its inhabitants.
“Global climate change has made coastal erosion a topical issue in the 21st Century, but Dunwich demonstrates that it has happened before. The severe storms of the 13th and 14th Centuries coincided with a period of climate change, turning the warmer medieval climatic optimum into what we call the Little Ice Age.
“Our coastlines have always been changing, and communities have struggled to live with this change. Dunwich reminds us that it is not only the big storms and their frequency – coming one after another, that drives erosion and flooding, but also the social and economic decisions communities make at the coast. In the end, with the harbour silting up, the town partly destroyed, and falling market incomes, many people simply gave up on Dunwich.”

Professor Sear’s full report can be found at: http://www.dunwich.org.uk/                  link to article

Photonic Progress

Visions of Exoplanets: NASA report

In a new JPL report, Whitney Clavin gives an update on the imaging of exoplanets: impossible magic, or so we would have thought a generation ago. 

This image shows the HR 8799 planets with starlight optically suppressed and data processing conducted to remove residual starlight. The star is at the center of the blackened circle in the image. The four spots indicated with the letters b through e are the planets. This is a composite image using 30 wavelengths of light and was obtained over a period of 1.25 hours on June 14 and 15, 2012. Image courtesy of Project 1640 (NASA)

Gone are the days of being able to count the number of known planets on your fingers. Today, there are more than 800 confirmed exoplanets -- planets that orbit stars beyond our sun -- and more than 2,700 other candidates. What are these exotic planets made of? Unfortunately, you cannot stack them in a jar like marbles and take a closer look. Instead, researchers are coming up with advanced techniques for probing the planets' makeup. 

One breakthrough to come in recent years is direct imaging of exoplanets. Ground-based telescopes have begun taking infrared pictures of the planets posing near their stars in family portraits. But to astronomers, a picture is worth even more than a thousand words if its light can be broken apart into a rainbow of different wavelengths.

Those wishes are coming true as researchers are beginning to install infrared cameras on ground-based telescopes equipped with spectrographs. Spectrographs are instruments that spread an object's light apart, revealing signatures of molecules. Project 1640, partly funded by NASA's Jet Propulsion Laboratory, Pasadena, Calif., recently accomplished this goal using the Palomar Observatory near San Diego.

"In just one hour, we were able to get precise composition information about four planets around one overwhelmingly bright star," said Gautam Vasisht of JPL, co-author of the new study appearing in the Astrophysical Journal. "The star is a hundred thousand times as bright as the planets, so we've developed ways to remove that starlight and isolate the extremely faint light of the planets."

Along with ground-based infrared imaging, other strategies for combing through the atmospheres of giant planets are being actively pursued as well. For example, NASA's Spitzer and Hubble space telescopes monitor planets as they cross in front of their stars, and then disappear behind. NASA's upcoming James Webb Space Telescope will use a comparable strategy to study the atmospheres of planets only slightly larger than Earth.

In the new study, the researchers examined HR 8799, a large star orbited by at least four known giant, red planets. Three of the planets were among the first ever directly imaged around a star, thanks to observations from the Gemini and Keck telescopes on Mauna Kea, Hawaii, in 2008. The fourth planet, the closest to the star and the hardest to see, was revealed in images taken by the Keck telescope in 2010.

That alone was a tremendous feat considering that all planet discoveries up until then had been made through indirect means, for example by looking for the wobble of a star induced by the tug of planets.

Those images weren't enough, however, to reveal any information about the planets' chemical composition. That's where spectrographs are needed -- to expose the "fingerprints" of molecules in a planet's atmosphere. Capturing a distant world's spectrum requires gathering even more planet light, and that means further blocking the glare of the star.

Project 1640 accomplished this with a collection of instruments, which the team installs on the ground-based telescopes each time they go on "observing runs." The instrument suite includes a coronagraph to mask out the starlight; an advanced adaptive optics system, which removes the blur of our moving atmosphere by making millions of tiny adjustments to two deformable telescope mirrors; an imaging spectrograph that records 30 images in a rainbow of infrared colors simultaneously; and a state-of-the-art wave front sensor that further adjusts the mirrors to compensate for scattered starlight.

"It's like taking a single picture of the Empire State Building from an airplane that reveals a bump on the sidewalk next to it that is as high as an ant," said Ben R. Oppenheimer, lead author of the new study and associate curator and chair of the Astrophysics Department at the American Museum of Natural History, N.Y., N.Y.

Their results revealed that all four planets, though nearly the same in temperature, have different compositions. Some, unexpectedly, do not have methane in them, and there may be hints of ammonia or other compounds that would also be surprising. Further theoretical modeling will help to understand the chemistry of these planets.

Meanwhile, the quest to obtain more and better spectra of exoplanets continues. Other researchers have used the Keck telescope and the Large Binocular Telescope near Tucson, Ariz., to study the emission of individual planets in the HR8799 system. In addition to the HR 8799 system, only two others have yielded images of exoplanets. The next step is to find more planets ripe for giving up their chemical secrets. Several ground-based telescopes are being prepared for the hunt, including Keck, Gemini, Palomar and Japan's Subaru Telescope on Mauna Kea, Hawaii.

Ideally, the researchers want to find young planets that still have enough heat left over from their formation, and thus more infrared light for the spectrographs to see. They also want to find planets located far from their stars, and out of the blinding starlight. NASA's infrared Spitzer and Wide-field Infrared Survey Explorer (WISE) missions, and its ultraviolet Galaxy Evolution Explorer, now led by the California Institute of Technology, Pasadena, have helped identify candidate young stars that may host planets meeting these criteria.

"We're looking for super-Jupiter planets located faraway from their star," said Vasisht. "As our technique develops, we hope to be able to acquire molecular compositions of smaller, and slightly older, gas planets."

Still lower-mass planets, down to the size of Saturn, will be targets for imaging studies by the James Webb Space Telescope.

"Rocky Earth-like planets are too small and close to their stars for the current technology, or even for James Webb to detect. The feat of cracking the chemical compositions of true Earth analogs will come from a future space mission such as the proposed Terrestrial Planet Finder," said Charles Beichman, a co-author of the P1640 result and executive director of NASA's Exoplanet Science Institute at Caltech.

Though the larger, gas planets are not hospitable to life, the current studies are teaching astronomers how the smaller, rocky ones form.

"The outer giant planets dictate the fate of rocky ones like Earth. Giant planets can migrate in toward a star, and in the process, tug the smaller, rocky planets around or even kick them out of the system. We're looking at hot Jupiters before they migrate in, and hope to understand more about how and when they might influence the destiny of the rocky, inner planets," said Vasisht.

NASA's Exoplanet Science Institute manages time allocation on the Keck telescope for NASA. JPL manages NASA's Exoplanet Exploration program office. Caltech manages JPL for NASA. 
A visualization from the American Museum of Natural History showing where the HR 8799 system is in relation to our solar system is online at http://www.youtube.com/watch?v=yDNAk0bwLrU . 

More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov .

Photonic Space

King Richard III team now digs up 1700 year old Roman cemetery

jet ring just after it had been uncovered

The University of Leicester, England, archaeological unit that discovered English King Richard III buried in a car park (as described in our February blog) has spearheaded another dig and discovered a 1,700-old- Roman cemetery – under another car park in Leicester.

The latest dig follows the historic discovery of King Richard III by colleagues from the same unit. 

The find has revealed remains thought to date back to 300AD – and includes personal items such as hairpins, rings, belt buckles and remains of shoes.

In addition, the team has found a jet ring with a curious symbol etched onto it, apparently showing the letters IX overlain.  Opinion as to its meaning is divided; it may just be an attractive design but it is also reminiscent of an early Christian symbol known as an IX (Iota-Chi) monogram taken from the initials of Jesus Christ in Greek.

The University of Leicester archaeologists have also identified the unusual practice of Christian burials alongside pagan burials.

In total, archaeologists have identified 13 sets of remains at the car park in Oxford Street in Leicester’s historic city centre.

Archaeological Project Officer John Thomas said: “We have discovered new evidence about a known cemetery that existed outside the walled town of Roman Leicester during the 3rd-4th Centuries AD. 

“The excavation, at the junction of Oxford Street and Newarke Street, lay approximately 130m outside the south gate of Roman Leicester, adjacent to one of the main routes into the town from the south (Oxford Street).  Roman law forbade burial within the town limits so cemeteries developed outside the walls, close to well-used roads.

“Previous excavations on Newarke Street had discovered numerous burials to the immediate east and north of the present site, all of which appeared to have been buried according to Christian traditions - buried in a supine position, facing east with little or no grave goods.

“Unusually the 13 burials found during the recent excavations, of mixed age and sex, displayed a variety of burial traditions including east to west & north  to south oriented graves, many with personal items such as finger rings, hairpins, buckles and hob-nailed shoes. 

“One in particular appears to have been buried in a Christian tradition, facing east and wearing a polished jet finger ring on their left hand which has a possible early Christian Iota - Chi monogram etched onto it, taking the initial letters from the Greek for Jesus Christ.  If so this would represent rare evidence for a personal statement of belief from this period. 

“In contrast a nearby and probably near contemporary grave appeared to indicate very different beliefs.  This grave had a north-south orientation, with the body laid on its side in a semi-foetal position, with the head removed and placed near the feet alongside two complete pottery jars that would have held offerings for the journey to the afterlife.  This would seem to be a very pagan burial, so it is possible from the variety of burials found that the cemetery catered for a range of beliefs that would have been important to people living in Leicester at this time.”

The excavations also add information to the increasingly well documented medieval southern suburb of the town, revealing remains of 12th-13th century quarries, cess-pits and rubbish pits that would have been dug in the backyards of properties fronting onto Oxford Street.

Mr Thomas added: “All of these pits contained a wealth of information from pottery, bone and environmental remains to help build a picture of medieval life in this part of the town.  A large 17th century defensive ditch running alongside Newarke Street was also discovered which was part of the town’s defences during the English Civil War.”

The site is currently earmarked for development.

The Search for Richard III was led by the University of Leicester, working with Leicester City Council, and in association with the Richard III Society.

via AlphaGalileo

link: University of Leicester 

Photonic Progress

NASA's Spitzer Telescope and the Hot Jupiter Class of Exoplanets

Space Infrared Telescope Facility

The Spitzer Space Telescope is the fourth and final element in the National Aeronautics and Space Administration's family of orbiting "Great Observatories," which includes the Hubble Space Telescope, the Compton Gamma-Ray Observatory and the Chandra X-Ray Observatory. This new infrared observatory is also an important scientific and technical bridge to NASA's Origins Program - an attempt to address such fundamental questions as "Where did we come from? Are we alone?"

Our galaxy is teeming with a wild variety of planets. In addition to our solar system's eight near-and-dear planets, there are more than 800 so-called exoplanets known to circle stars beyond our sun. One of the first "species" of exoplanets to be discovered is the hot Jupiters, also known as roasters. These are gas giants like Jupiters, but they orbit closely to their stars, blistering under the heat. 

Thanks to NASA's Spitzer Space Telescope, researchers are beginning to dissect this exotic class of planets, revealing raging winds and other aspects of their turbulent nature. A twist to come out of the recent research is the planets' wide range of climates. Some are covered with a haze, while others are clear. Their temperature profiles, chemistries and densities differ as well.

"The hot Jupiters are beasts to handle. They are not fitting neatly into our models and are more diverse than we thought," said Nikole Lewis of the Massachusetts Institute of Technology, Cambridge, lead author of a new Spitzer paper in the Astrophysical Journal examining one such hot Jupiter called HAT-P-2b. "We are just starting to put together the puzzle pieces of what's happening with these planets, and we still don't know what the final picture will be."

The very first exoplanet discovered around a sun-like star was, in fact, a hot Jupiter, called 51 Pegasi b. It was detected in 1995 by Swiss astronomers using the radial velocity technique, which measures the wobble of a star caused by the tug of a planet. Because hot Jupiters are heavy and whip around their stars quickly, they are the easiest to find using this strategy. Dozens of hot Jupiter discoveries soon followed. At first, researchers thought they might represent a more common configuration for other planetary systems in our galaxy beyond our own solar system. But new research, including that from NASA's Kepler space telescope, has shown that they are relatively rare.

In 2005, scientists were thrilled when Spitzer became the first telescope to detect light emitted by an exoplanet. Spitzer monitored the infrared light coming from a star and its planet -- a hot Jupiter -- as the planet disappeared behind the star in an event known as a secondary eclipse. Once again, this technique works best for hot Jupiters, because they are the biggest and hottest planets.

In addition to watching hot Jupiters slip behind their stars, researchers also use Spitzer to monitor the planets as they orbit all the way around a star. This allows them to create global climate maps, revealing how the planets' atmospheres vary from their hot, sun-facing sides to their cooler, night sides, due in part to fierce winds. (Hot Jupiters are frequently tidally locked, with one side always facing the star, just as our moon is locked to Earth.)

Since that first observation, Spitzer has probed the atmospheres of dozens of hot Jupiters, and some even smaller planets, uncovering clues about their composition and climate.

"When Spitzer launched in 2003, we had no idea it would prove to be a giant in the field of exoplanet science," said Michael Werner, the Spitzer project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Now, we're moving farther into the field of comparative planetary science, where we can look at these objects as a class, and not just as individuals."

In the new study, Lewis and colleagues made the longest Spitzer observation yet of a hot Jupiter. The infrared telescope stared at the HAT-P-2 system continuously for six days, watching it cross in front of its star, slip behind, and then reappear on the other side, making a full orbit. What makes the observation even more exciting to scientists is that the planet has a comet-like eccentric orbit, carrying it as close as 2.8 million miles (4.5 million kilometers) to the star and out to as far as 9.3 million miles (15 million kilometers). For reference, Mercury is about 28.5 million miles from our sun.

"It's as if nature has given us a perfect lab experiment with this system," said Heather Knutson, a co-author of the new paper at the California Institute of Technology, Pasadena, Calif. "Because the planet's distance to the sun changes, we can watch how fast it takes to heat up and cool down. It's as though we're turning the heat knob up on our planet and watching what happens." Knutson led the first team to create a global "weather" map of a hot Jupiter, called HD 189733 b, in 2007.

The new HAT-P-2b study is also one of the first to use multiple wavelengths of infrared light, instead of just one, while watching a full orbit of a hot Jupiter. This enables the scientists to peer down into different layers of the planet.

The results reveal that HAT-P-2b takes about a day to heat up as it approaches the hottest part of its orbit, and four to five days to cool down as it swings away. It also exhibits a temperature inversion -- a hotter, upper layer of gas -- when it is closest to its star. What's more, the carbon chemistry of the planet seems to be behaving in unexpected ways, which the astronomers are still trying to understand.

"These planets are much hotter and more dynamic than our own Jupiter, which is sluggish by comparison. Strong winds are churning material up from below, and the chemistry is always changing," said Lewis.

Another challenge in understanding hot Jupiters lies in parsing through the data. Lewis said her team's six-day Spitzer observation left them with 2 million data points to map out while carefully removing instrument noise.

"Theories are being shot down right and left," said Nick Cowan of Northwestern University, Evanston, Ill., a co-author of the HAT-P-2b study. "Right now, it's like the wild, wild west."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu and http://www.nasa.gov/spitzer .

NASA

Photonic Space

Deep Space: a great interactive web site from Olaf Frohn

I want to mention if you haven't seen it that Olaf Frohn has made a series of interactive charts detailing just about everything about earth's efforts in space exploration so far. This is an impressive collection well worth sharing or book-marking as a reference. Click here to enter the site. The chart below is a copy of one example from the site, but you need to visit to see the amount of detail.  In particular I like the exploration history chart. Great work!

Photonic Space