Egypt: Sarcophagus Leads to the Tomb of a Previously Unknown Pharaoh, from 3,600 Years Ago

Jan. 16, 2014 — Archaeologists working at the southern Egyptian site of Abydos have discovered the tomb of a previously unknown pharaoh: Woseribre Senebkay -- and the first material proof of a forgotten Abydos Dynasty, ca. 1650-1600 BC. Working in cooperation with Egypt's Supreme Council of Antiquities, a team from the Penn Museum, University of Pennsylvania, discovered king Senebkay's tomb close to a larger royal tomb, recently identified as belonging to a king Sobekhotep (probably Sobekhotep I, ca. 1780 BC) of the 13th Dynasty.

  

The discovery of pharaoh Senebkay's tomb is the culmination of work that began during the summer of 2013 when the Penn Museum team, led by Dr. Josef Wegner, Egyptian Section Associate Curator of the Penn Museum, discovered a huge 60-ton royal sarcophagus chamber at South Abydos. The sarcophagus chamber, of red quartzite quarried and transported to Abydos from Gebel Ahmar (near modern Cairo), could be dated to the late Middle Kingdom, but its owner remained unidentified. Mysteriously, the sarcophagus had been extracted from its original tomb and reused in a later tomb -- but the original royal owner remained unknown when the summer season ended.
In the last few weeks of excavations, fascinating details of a series of kings' tombs and a lost dynasty at Abydos have emerged. Archaeologists now know that the giant quartzite sarcophagus chamber derives from a royal tomb built originally for a pharaoh Sobekhotep -- probably Sobekhotep I, the first king of Egypt's 13th Dynasty. Fragments of that king's funerary stela were found just recently in front of his huge, badly robbed tomb. A group of later pharaohs (reigning about a century and a half later during Egypt's Second Intermediate Period) were reusing elements from Sobekhotep's tomb for building and equipping their own tombs. One of these kings (whose name is still unknown) had extracted and reused the quartzite sarcophagus chamber. Another king's tomb found just last week is that of the previously unknown pharaoh: Woseribre-Senebkay.
A Lost Pharaoh and a Forgotten Dynasty
The newly discovered tomb of pharaoh Senebkay dates to ca. 1650 BC during Egypt's Second Intermediate Period. The identification was made by Dr. Wegner and Kevin Cahail, Ph.D. student, Department of Near Eastern Languages and Civilizations, University of Pennsylvania. The tomb of Senebkay consists of four chambers with a decorated limestone burial chamber. The burial chamber is painted with images of the goddesses Nut, Nephthys, Selket, and Isis flanking the king's canopic shrine. Other texts name the sons of Horus and record the king's titulary and identify him as the "king of Upper and Lower Egypt, Woseribre, the son of Re, Senebkay."
Senebkay's tomb was badly plundered by ancient tomb robbers who had ripped apart the king's mummy as well as stripped the pharaoh's tomb equipment of its gilded surfaces. Nevertheless, the Penn Museum archaeologists recovered the remains of king Senebkay amidst debris of his fragmentary coffin, funerary mask, and canopic chest. Preliminary work on the king's skeleton of Senebkay by Penn graduate students Paul Verhelst and Matthew Olson (of the Department of Near Eastern Languages and Civilizations) indicates he was a man of moderate height, ca. 1.75 m (5'10), and died in his mid to late 40s.
The discovery provides significant new evidence on the political and social history of Egypt's Second Intermediate Period. The existence of an independent "Abydos Dynasty," contemporary with the 15th (Hyksos) and 16th (Theban) Dynasties, was first hypothesized by Egyptologist K. Ryholt in 1997. The discovery of pharaoh Senebkay now proves the existence of this Abydos dynasty and identifies the location of their royal necropolis at South Abydos in an area anciently called Anubis-Mountain. The kings of the Abydos Dynasty placed their burial ground adjacent to the tombs of earlier Middle Kingdom pharaohs including Senwosret III (Dynasty 12, ca. 1880-1840 BC), and Sobekhotep I (ca. 1780 BC). There is evidence for about 16 royal tombs spanning the period ca. 1650-1600 BC. Senebkay appears to be one of the earliest kings of the "Abydos Dynasty." His name may have appeared in a broken section of the famous Turin King List (a papyrus document dating to the reign of Ramses II, ca. 1200 BC) where two kings with the throne name "Woser...re" are recorded at the head of a group of more than a dozen kings, most of whose names are entirely lost.
The tomb of pharaoh Senebkay is modest in scale. An important discovery was the badly decayed remains of Senebkay's canopic chest. This chest was made of cedar wood that had been reused from the nearby tomb of Sobekhotep I and still bore the name of that earlier king, covered over by gilding. Such reuse of objects from the nearby Sobekhotep tomb by Senebkay, like the reused sarcophagus chamber found during the summer, provides evidence that suggests the limited resources and isolated economic situation of the Abydos Kingdom which lay in the southern part of Middle Egypt between the larger kingdoms of Thebes (Dynasties 16-17) and the Hyksos (Dynasty 15) in northern Egypt. Unlike these numbered dynasties, the pharaohs of the Abydos Dynasty were forgotten to history and their royal necropolis unknown until this discovery of Senebkay's tomb.
"It's exciting to find not just the tomb of one previously unknown pharaoh, but the necropolis of an entire forgotten dynasty," noted Dr. Wegner. "Continued work in the royal tombs of the Abydos Dynasty promises to shed new light on the political history and society of an important but poorly understood era of Ancient Egypt."

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Massive Exoplanets May Be More Earth-Like Than Thought: 'Super-Earths' Likely to Have Oceans, Continents

Jan. 8, 2014 — Massive terrestrial planets, called "super-Earths," are known to be common in our galaxy, the Milky Way. Now a Northwestern University astrophysicist and a University of Chicago geophysicist report the odds of these planets having an Earth-like climate are much greater than previously thought.

Nicolas B. Cowan and Dorian Abbot's new model challenges the conventional wisdom which says super-Earths actually would be very unlike Earth -- each would be a waterworld, with its surface completely covered in water. They conclude that most tectonically active super-Earths -- regardless of mass -- store most of their water in the mantle and will have both oceans and exposed continents, enabling a stable climate such as Earth's.

Cowan is a postdoctoral fellow at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), and Abbot is an assistant professor in geophysical sciences at UChicago.

"Are the surfaces of super-Earths totally dry or covered in water?" Cowan said. "We tackled this question by applying known geophysics to astronomy.

"Super-Earths are expected to have deep oceans that will overflow their basins and inundate the entire surface, but we show this logic to be flawed," he said. "Terrestrial planets have significant amounts of water in their interior. Super-Earths are likely to have shallow oceans to go along with their shallow ocean basins."

In their model, Cowan and Abbot treated the intriguing exoplanets like Earth, which has quite a bit of water in its mantle, the rocky part that makes up most of the volume and mass of the planet. The rock of the mantle contains tiny amounts of water, which quickly adds up because the mantle is so large. And a deep water cycle moves water between oceans and the mantle. (An exoplanet, or extrasolar planet, is a planet outside our solar system.)

Cowan presented the findings at a press conference, "Windows on Other Worlds," held Jan. 7 at the 223rd meeting of the American Astronomical Society (AAS) annual meeting in Washington, D.C.

He also will discuss the research at a scientific session to be held from 2 to 3:30 p.m. EST Wednesday, Jan. 8, at the AAS meeting (Potomac Ballroom D, Gaylord National Resort and Convention Center). The study will be published Jan. 20 in theAstrophysical Journal.

Water is constantly traded back and forth between the ocean and the rocky mantle because of plate tectonics, Cowan and Abbot said. The division of water between ocean and mantle is controlled by seafloor pressure, which is proportional to gravity.

Accounting for the effects of seafloor pressure and high gravity are two novel factors in their model. As the size of the super-Earths increase, gravity and seafloor pressure also go up.

"We can put 80 times more water on a super-Earth and still have its surface look like Earth," Cowan said. "These massive planets have enormous seafloor pressure, and this force pushes water into the mantle."

It doesn't take that much water to tip a planet into being a waterworld. "If Earth was 1 percent water by mass, we'd all drown, regardless of the deep water cycle," Cowan said. "The surface would be covered in water. Whether or not you have a deep water cycle really matters for planets that are one one-thousandth or one ten-thousandth water."

The ability of super-Earths to maintain exposed continents is important for planetary climate. On planets with exposed continents, like Earth, the deep carbon cycle is mediated by surface temperatures, which produces a stabilizing feedback (a thermostat on geological timescales).

"Such a feedback probably can't exist in a waterworld, which means they should have a much smaller habitable zone," Abbot said. "By making super-Earths 80 times more likely to have exposed continents, we've dramatically improved their odds of having an Earth-like climate."

Cowan and Abbot accede that there are two major uncertainties in their model: that super-Earths have plate tectonics and the amount of water Earth stores in its mantle.

"These are the two things we would like to know better to improve our model," Cowan said. "Our model is a shot from the hip, but it's an important step in advancing how we think about super-Earths.
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Universe Measured to One-Percent Accuracy: Most Precise Calibration Yet of Cosmic 'Standard Ruler'

Jan. 8, 2014 — Today the Baryon Oscillation Spectroscopic Survey (BOSS) Collaboration announced that BOSS has measured the scale of the universe to an accuracy of one percent. This and future measures at this precision are the key to determining the nature of dark energy.

"One-percent accuracy in the scale of the universe is the most precise such measurement ever made," says BOSS's principal investigator, David Schlegel, a member of the Physics Division of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). "Twenty years ago astronomers were arguing about estimates that differed by up to fifty percent. Five years ago, we'd refined that uncertainty to five percent; a year ago it was two percent. One-percent accuracy will be the standard for a long time to come."

BOSS is the largest program in the third Sloan Digital Sky Survey (SDSS-III). Since 2009, BOSS has used the Sloan Foundation Telescope at the Apache Point Observatory in New Mexico to record high-precision spectra of well over a million galaxies with redshifts from 0.2 to 0.7, looking back over six billion years into the universe's past. Schlegel says, "We believe the BOSS database includes more redshifts of galaxies than collected by all the other telescopes in the world."

BOSS will continue gathering data until June, 2014. However, says Martin White, a member of Berkeley Lab, a professor of physics and astronomy at the University of California at Berkeley, and chair of the BOSS science survey team, "We've done the analysis now because we have 90 percent of BOSS's final data and we're tremendously excited by the results."

Baryon acoustic oscillations (BAO) are the regular clustering of galaxies, whose scale provides a "standard ruler" to measure the evolution of the universe's structure. Accurate measurement dramatically sharpens our knowledge of fundamental cosmological properties, including how dark energy accelerates the expansion of the universe.

Combined with recent measures of the cosmic microwave background radiation (CMB) and supernova measures of accelerating expansion, the BOSS results suggest that dark energy is a cosmological constant whose strength does not vary in space or time. Although unlikely to be a flaw in Einstein's General Theory of Relativity, the authors of the BOSS analysis note that "understanding the physical cause of the accelerated expansion remains one of the most interesting problems in modern physics."

Among other cosmic parameters, says White, the BOSS analysis "also provides one of the best-ever determinations of the curvature of space. The answer is, it's not curved much."

Calling a three-dimensional universe "flat" means its shape is well described by the Euclidean geometry familiar from high school: straight lines are parallel and triangles add up to 180 degrees. Extraordinary flatness means the universe experienced relatively prolonged inflation, up to a decillionth of a second or more, immediately after the big bang.

"One of the reasons we care is that a flat universe has implications for whether the universe is infinite," says Schlegel. "That means -- while we can't say with certainty that it will never come to an end -- it's likely the universe extends forever in space and will go on forever in time. Our results are consistent with an infinite universe."

The BOSS analysis is based on SDSS-III's Data Releases 10 and 11 (DR 10 and DR 11) and has been submitted for publication in the Monthly Notices of the Royal Astronomical Society.

Ripples in a sea of galaxies

The BOSS analysis incorporates spectra of 1,277,503 galaxies and covers 8,509 square degrees of the sky visible from the northern hemisphere. This is the largest sample of the universe ever surveyed at this density. When complete, BOSS will have collected high-quality spectra of 1.3 million galaxies, plus 160,000 quasars and thousands of other astronomical objects, covering 10,000 square degrees.

Periodic ripples of density in visible matter ("baryons," for short) pervade the universe like raindrops on the surface of a pond. Regular galaxy clustering is the direct descendant of pressure waves that moved through the hot plasma of the early universe, which was so hot and dense that particles of light (photons) and particles of matter, including protons and electrons, were tightly coupled together. Invisible dark matter was also part of the mix.

By 380,000 years after the big bang, however, the temperature of the expanding mixture had cooled enough for light to escape, suffusing the newly transparent universe with intense radiation, which in the 13.4 billion years since has continued to cool to today's faint but pervasive cosmic microwave background.

Minute variations in the temperature of the CMB record periodicity in the original density ripples, of which the European Space Agency's Planck satellite has made the most recent and most accurate measures. The same periodicity is preserved in the clustering of the BOSS galaxies, a BAO signal which also mirrors the distribution of underlying dark matter.

Regular clustering at different eras, starting with the CMB, establishes the expansion history of the universe. BOSS collaborator Beth Reid of Berkeley Lab translates the two-dimensional sky coordinates of galaxies, plus their redshifts, into 3-D maps of the density of galaxies in space.

"It's from fluctuations in the density of galaxies in the volume we're looking at that we extract the BAO standard ruler," she says. "To compare different regions of the sky on an equal footing, first we have to undo variations from atmospheric effects or other patterns caused by how we observe the sky with our telescope." The results depend crucially on accurate measures of redshifts, which disclose the galaxies' positions in space and time. But galaxies don't move in lock step.

"When galaxies are close together their mutual gravitational attraction pushes them around and interferes with attempts to measure large-scale structure," Schlegel says. "Their peculiar motion makes it hard to write a formula for overall gravitational growth."

However, says Reid, "We have a very good model for what these distortions look like. The galaxy density field shows you where there are concentrations of matter, and the peculiar velocity field points in the direction of the net effect of all the local over- and under-densities."

"The BOSS data are awe-inspiring," says Martin White, "but many other pieces had to be put into place before we could get what we're after out of the data." Complex computer algorithms were essential for reconciling the inherent uncertainties. "We made thousands of model universes in a computer, and then observed them as BOSS would do and ran our analysis on them to answer the questions of 'What if?'"

By gauging how well their algorithms could analyze these model universes, known as "mocks" and based on catalogues of realistic but artificial galaxies, the experienced BOSS team was able to assess and fine-tune the algorithms when they were applied to the real BOSS data.

The National Energy Research Scientific Computing Center (NERSC), based at Berkeley Lab, was critical to the analysis and the creation of the mocks. Says White, "NERSC set aside resources for us to push analyses through quickly when we were up against deadlines. They provide a virtual meeting place where members of the collaboration from all around the world can come together on a shared platform, with both the data and the computational resources they need to perform their research."

BOSS has now provided the most accurate calibration ever of BAO's standard ruler. The universe's expansion history has been measured with unprecedented accuracy during the very stretch of ancient time, over six billion years in the past, when expansion had stopped slowing and acceleration began. But accurate as they are, the new BOSS results are just the beginning. Greater coverage and better resolution in scale are essential to understanding dark energy itself.

The proposed Dark Energy Spectroscopic Instrument (DESI), based on an international partnership of nearly 50 institutions led by Berkeley Lab, would enable the Mayall Telescope on Kitt Peak in Arizona to map over 20 million galaxies, plus over three million quasars, in 14,000 square degrees of the northern sky. By filling in the missing eons that BOSS can't reach, DESI could sharpen and extend coverage of the expansion history of the universe from the first appearance of the cosmic background radiation to the present day.

In the meantime, BOSS, ahead of schedule for completion in June, 2014, continues to be the premier instrument for mapping the universe
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Organic Mega Flow Battery Promises Breakthrough for Renewable Energy

Jan. 8, 2014 — A team of Harvard scientists and engineers has demonstrated a new type of battery that could fundamentally transform the way electricity is stored on the grid, making power from renewable energy sources such as wind and solar far more economical and reliable.

The novel battery technology is reported in a paper published in Nature on January 9. Under the OPEN 2012 program, the Harvard team received funding from the U.S. Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E) to develop the innovative grid-scale battery and plans to work with ARPA-E to catalyze further technological and market breakthroughs over the next several years.

The paper reports a metal-free flow battery that relies on the electrochemistry of naturally abundant, inexpensive, small organic (carbon-based) molecules called quinones, which are similar to molecules that store energy in plants and animals.

The mismatch between the availability of intermittent wind or sunshine and the variability of demand is the biggest obstacle to getting a large fraction of our electricity from renewable sources. A cost-effective means of storing large amounts of electrical energy could solve this problem.

The battery was designed, built, and tested in the laboratory of Michael J. Aziz, Gene and Tracy Sykes Professor of Materials and Energy Technologies at the Harvard School of Engineering and Applied Sciences (SEAS). Roy G. Gordon, Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science, led the work on the synthesis and chemical screening of molecules. Alán Aspuru-Guzik, Professor of Chemistry and Chemical Biology, used his pioneering high-throughput molecular screening methods to calculate the properties of more than 10,000 quinone molecules in search of the best candidates for the battery.

Flow batteries store energy in chemical fluids contained in external tanks -- as with fuel cells -- instead of within the battery container itself. The two main components -- the electrochemical conversion hardware through which the fluids are flowed (which sets the peak power capacity), and the chemical storage tanks (which set the energy capacity) -- may be independently sized. Thus the amount of energy that can be stored is limited only by the size of the tanks. The design permits larger amounts of energy to be stored at lower cost than with traditional batteries.

By contrast, in solid-electrode batteries, such as those commonly found in cars and mobile devices, the power conversion hardware and energy capacity are packaged together in one unit and cannot be decoupled. Consequently they can maintain peak discharge power for less than an hour before being drained, and are therefore ill suited to store intermittent renewables.

"Our studies indicate that one to two days' worth of storage is required for making solar and wind dispatchable through the electrical grid," said Aziz.

To store 50 hours of energy from a 1-megawatt power capacity wind turbine (50 megawatt-hours), for example, a possible solution would be to buy traditional batteries with 50 megawatt-hours of energy storage, but they'd come with 50 megawatts of power capacity. Paying for 50 megawatts of power capacity when only 1 megawatt is necessary makes little economic sense.

For this reason, a growing number of engineers have focused their attention on flow battery technology. But until now, flow batteries have relied on chemicals that are expensive or difficult to maintain, driving up the energy storage costs.

The active components of electrolytes in most flow batteries have been metals. Vanadium is used in the most commercially advanced flow battery technology now in development, but its cost sets a rather high floor on the cost per kilowatt-hour at any scale. Other flow batteries contain precious metal electrocatalysts such as the platinum used in fuel cells.

The new flow battery developed by the Harvard team already performs as well as vanadium flow batteries, with chemicals that are significantly less expensive, and with no precious metal electrocatalyst.

"The whole world of electricity storage has been using metal ions in various charge states but there is a limited number that you can put into solution and use to store energy, and none of them can economically store massive amounts of renewable energy," Gordon said. "With organic molecules, we introduce a vast new set of possibilities. Some of them will be terrible and some will be really good. With these quinones we have the first ones that look really good."

Aspuru-Guzik noted that the project is very well aligned with the White House Materials Genome Initiative. "This project illustrates what the synergy of high-throughput quantum chemistry and experimental insight can do," he said. "In a very quick time period, our team honed in to the right molecule. Computational screening, together with experimentation, can lead to discovery of new materials in many application domains."

Quinones are abundant in crude oil as well as in green plants. The molecule that the Harvard team used in its first quinone-based flow battery is almost identical to one found in rhubarb. The quinones are dissolved in water, which prevents them from catching fire.

To back up a commercial wind turbine, a large storage tank would be needed, possibly located in a below-grade basement, said co-lead author Michael Marshak, a postdoctoral fellow at SEAS and in the Department of Chemistry and Chemical Biology. Or if you had a whole field of turbines or large solar farm, you could imagine a few very large storage tanks.

The same technology could also have applications at the consumer level, Marshak said. "Imagine a device the size of a home heating oil tank sitting in your basement. It would store a day's worth of sunshine from the solar panels on the roof of your house, potentially providing enough to power your household from late afternoon, through the night, into the next morning, without burning any fossil fuels."

"The Harvard team's results published in Nature demonstrate an early, yet important technical achievement that could be critical in furthering the development of grid-scale batteries," said ARPA-E Program Director John Lemmon. "The project team's result is an excellent example of how a small amount of catalytic funding from ARPA-E can help build the foundation to hopefully turn scientific discoveries into low-cost, early-stage energy technologies."

Team leader Aziz said the next steps in the project will be to further test and optimize the system that has been demonstrated on the bench top and bring it toward a commercial scale. "So far, we've seen no sign of degradation after more than 100 cycles, but commercial applications require thousands of cycles," he said. He also expects to achieve significant improvements in the underlying chemistry of the battery system. "I think the chemistry we have right now might be the best that's out there for stationary storage and quite possibly cheap enough to make it in the marketplace," he said. "But we have ideas that could lead to huge improvements."

By the end of the three-year development period, Connecticut-based Sustainable Innovations, LLC, a collaborator on the project, expects to deploy demonstration versions of the organic flow battery contained in a unit the size of a horse trailer. The portable, scaled-up storage system could be hooked up to solar panels on the roof of a commercial building, and electricity from the solar panels could either directly supply the needs of the building or go into storage and come out of storage when there's a need. Sustainable Innovations anticipates playing a key role in the product's commercialization by leveraging its ultra-low cost electrochemical cell design and system architecture already under development for energy storage applications.

"You could theoretically put this on any node on the grid," Aziz said. "If the market price fluctuates enough, you could put a storage device there and buy electricity to store it when the price is low and then sell it back when the price is high. In addition, you might be able to avoid the permitting and gas supply problems of having to build a gas-fired power plant just to meet the occasional needs of a growing peak demand."

This technology could also provide very useful backup for off-grid rooftop solar panels -- an important advantage considering some 20 percent of the world's population does not have access to a power distribution network.

William Hogan, Raymond Plank Professor of Global Energy Policy at Harvard Kennedy School, and one of the world's foremost experts on electricity markets, is helping the team explore the economic drivers for the technology.

Trent M. Molter, President and CEO of Sustainable Innovations, LLC, provides expertise on implementing the Harvard team's technology into commercial electrochemical systems.

"The intermittent renewables storage problem is the biggest barrier to getting most of our power from the sun and the wind," Aziz said. "A safe and economical flow battery could play a huge role in our transition off fossil fuels to renewable electricity. I'm excited that we have a good shot at it."

In addition to Aziz, Marshak, Aspuru-Guzik, and Gordon, the co-lead author of the Nature paper was Brian Huskinson, a graduate student with Aziz; coauthors included research associate Changwon Suh and postdoctoral researcher Süleyman Er in Aspuru-Guzik's group; Michael Gerhardt, a graduate student with Aziz; Cooper Galvin, a Pomona College undergraduate; and Xudong Chen, a postdoctoral fellow in Gordon's group.

This work was supported in part by the U.S. Department of Energy's Advanced Research Project Agency-Energy (ARPA-E), the Harvard School of Engineering and Applied Sciences, the National Science Foundation (NSF) Extreme Science and Engineering Discovery Environment (OCI-1053575), an NSF Graduate Research Fellowship, and the Fellowships for Young Energy Scientists program of the Foundation for Fundamental Research on Matter, which is part of the Netherlands Organization for Scientific Research (NWO)
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Hubble Reveals Rogue Planetary Orbit for Fomalhaut B

Jan. 8, 2013 — Newly released NASA Hubble Space Telescope images of a vast debris disk encircling the nearby star Fomalhaut and a mysterious planet circling it may provide forensic evidence of a titanic planetary disruption in the system.

Astronomers are surprised to find the debris belt is wider than previously known, spanning a section of space from 14 to nearly 20 billion miles from the star. Even more surprisingly, the latest Hubble images have allowed a team of astronomers to calculate the planet follows an unusual elliptical orbit that carries it on a potentially destructive path through the vast dust ring.

The planet, called Fomalhaut b, swings as close to its star as 4.6 billion miles, and the outermost point of its orbit is 27 billion miles away from the star. The orbit was recalculated from the newest Hubble observation made last year.

"We are shocked. This is not what we expected," said Paul Kalas of the University of California at Berkeley and the SETI Institute in Mountain View, Calif.

The Fomalhaut team led by Kalas considers this circumstantial evidence there may be other planet-like bodies in the system that gravitationally disturbed Fomalhaut b to place it in such a highly eccentric orbit. The team presented its finding Tuesday at the 221st meeting of the American Astronomical Society in Long Beach, Calif.

Among several scenarios to explain Fomalhaut b's 2,000-year-long orbit is the hypothesis that an as yet undiscovered planet gravitationally ejected Fomalhaut b from a position closer to the star, and sent it flying in an orbit that extends beyond the dust belt.

"Hot Jupiters get tossed through scattering events, where one planet goes in and one gets thrown out," said co-investigator Mark Clampin of NASA's Goddard Space Flight Center in Greenbelt, Md. "This could be the planet that gets thrown out."

Hubble also found the dust and ice belt encircling the star Fomalhaut has an apparent gap slicing across the belt. This might have been carved by another undetected planet. Hubble's exquisite view of the dust belt shows irregularities that strongly motivate a search for other planets in the system.

If its orbit lies in the same plane with the dust belt, then Fomalhaut b will intersect the belt around 2032 on the outbound leg of its orbit. During the crossing, icy and rocky debris in the belt could crash into the planet's atmosphere and create the type of cosmic fireworks seen when Comet Shoemaker-Levy 9 crashed into Jupiter. Most of the fireworks from collisions will be seen in infrared light. However, if Fomalhaut b is not co-planar with the belt, the only thing to be seen will be a gradual dimming of Fomalhaut b as it travels farther from the star.

Kalas hypothesized that Fomalhaut b's extreme orbit is a major clue in explaining why the planet is unusually bright in visible light, but very dim in infrared light. It is possible the planet's optical brightness originates from a ring or shroud of dust around the planet, which reflects starlight. The dust would be rapidly produced by satellites orbiting the planet, which would suffer extreme erosion by impacts and gravitational stirring when Fomalhaut b enters into the planetary system after a millennium of deep freeze beyond the main belt. An analogy can be found by looking at Saturn, which has a tenuous, but very large dust ring produced when meteoroids hit the outer moon Phoebe.

The team has also considered a different scenario where a hypothetical second dwarf planet suffered a catastrophic collision with Fomalhaut b. The collision scenario would explain why the star Fomalhaut has a narrow outer belt linked to an extreme planet. But in this case the belt is young, less than 10,000 years old, and it is difficult to produce energetic collisions far from the star in such young systems.

Fomalhaut is a special system because it looks like scientists may have a snapshot of what our solar system was doing 4 billion years ago. The planetary architecture is being redrawn, the comet belts are evolving, and planets may be gaining and losing their moons. Astronomers will continue monitoring Fomalhaut b for decades to come because they may have a chance to observe a planet entering an icy debris belt that is like the Kuiper Belt at the fringe of our own solar system
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Companion's Comets the Key to Curious Exoplanet System?

Dec. 18, 2013 — The nearby star Fomalhaut A hosts the most famous planetary system outside our own Solar System, containing both an exoplanet and a spectacular ring of comets. Today, an international team of astronomers announced a new discovery with the Herschel Space Observatory that has made this system even more intriguing; the least massive star of the three in the Fomalhaut system, Fomalhaut C, has now been found to host its own comet belt. The researchers published their results today in a letter to the journal Monthly Notices of the Royal Astronomical Society.

Fomalhaut A is one of the brightest stars in the sky. Located 25 light years away in the constellation of Piscis Austrinus, it shines with a blue-white colour and is prominent from the southern hemisphere. From northern latitudes it appears low down in the south during autumn evenings. In contrast, Fomalhaut C, also named LP 876-10, is a dim red dwarf star invisible without a telescope, and was only found to be part of the Fomalhaut system in October this year.

Fomalhaut A's prominence made it a key target for the Hubble Space Telescope, which astronomers used to find the ring of comets, hints of and then a direct image of the planet, Fomalhaut b, in 2008 (astronomers use uppercase letters for stars, and lowercase letters are used for planets, so 'Fomalhaut b' is a planet, and 'Fomalhaut B' is the second star in the system).

The new discovery might hold the key to some of the mysteries of the Fomalhaut system. The lead author Grant Kennedy, an astronomer at the Institute of Astronomy at the University of Cambridge, said, "It's very rare to find two comet belts in one system, and with the two stars 2.5 light years apart this is one of the most widely separated star systems we know of. It made us wonder why both Fomalhaut A and C have comet belts, and whether the belts are related in some way." To get a feeling for how far 2.5 light years is, light from the Sun takes only 8 minutes to get to the Earth, and 5.5 hours to get to Pluto, and the nearest star to the Sun, Proxima Centauri, is only 4 light years away.

This discovery may help solve the major mystery in the Fomalhaut system: the orbits of the comet ring and planet around Fomalhaut A are elliptical (which simply means that the orbits aren't circular). The elliptical orbits are thought to be the result of close encounters with something else in the system, perhaps with another as yet undetected planet or perhaps with one of the two other stars, B or C.

The discovery of the comet belt around C is important because such encounters can not only make the comet belts elliptical, they can also make them brighter by causing the comets to collide more often, releasing massive amounts of dust and ice. Stars are rarely seen to have such bright comet belts, so their detection around both A and C suggests that they may have had their brightnesses enhanced by a previous close encounter between the two.

Paul Kalas of the University of California discovered the orbits are elliptical and is involved in the new work. He said, "We thought that the Fomalhaut A system was disturbed by a planet on the inside -- but now it looks like a small star from the outside could also influence the system. A good test of this hypothesis is to measure the red dwarf's exact orbit over the next few years."

The stellar interaction scenario isn't as unusual as it sounds. Comet ISON, which disintegrated following a close encounter with our Sun at the end of November, may have been put on a Sun-grazing orbit by a star that passed near to the Solar System in the past. Similarly, the proposed encounters between the stars in the Fomalhaut system may have sent a few comets onto star-grazing orbits. You might imagine that if there were any habitable planets around Fomalhaut A or C, their inhabitants might be luckier than us and see truly spectacular comet shows in their night sky.

The Herschel Observatory, which observed the Universe in infrared light ran out of helium coolant and stopped observing in April this year. This was seven months before Fomalhaut C was identified as part of the triple star system, but fortunately the telescope had imaged it back in 2011, so the astronomers have plenty of data on it already.

Kennedy has actually known about the comet belt for several years; "Over the last few years we used Herschel to look for comet belts around many stars within a few hundred light years of the Sun. At that stage Fomalhaut C was just called LP 876-10 and we thought it was a lone red dwarf with a comet belt. It was interesting because such discoveries are very rare, but didn't tell us why it was there. After the discovery that this star was part of the Fomalhaut system, the existence of its comet belt made us think harder about connections between the two stars, and it may be that it helps solve the mystery of the elliptical comet belt around Fomalhaut A."

Kennedy and his team are now trying to check the stellar encounter idea with computer simulations and more detailed observations of the Fomalhaut C belt. The apparent absence of a belt around Fomalhaut B remains a mystery. But if the simulations are in line with what the astronomers see, then this would be a 'smoking gun' for a stellar interaction and proof that other stars can affect how planetary systems form and evolve
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Starless Cloud Cores Reveal Why Some Stars Are Bigger Than Others

Dec. 20, 2013 — Massive stars -- those at least 8 times the mass of our Sun -- present an intriguing mystery: how do they grow so large when the vast majority of stars in the Milky Way are considerably smaller?

To find the answer, astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) telescope to survey the cores of some of the darkest, coldest, and densest clouds in our Galaxy to search for the telltale signs of star formation.

These objects, known as Infrared Dark Clouds, were observed approximately 10,000 light-years away in the direction of the constellations of Aquila and Scutum.

Since these cloud cores are so massive and dense, gravity should have already overwhelmed their supporting gas pressure, allowing them to collapse to form new, Sun-mass stars. If a star had not yet begun to shine, that would be a hint that something extra was supporting the cloud.

"A starless core would indicate that some force was balancing out the pull of gravity, regulating star formation, and allowing vast amounts of material to accumulate in a scaled-up version of the way our own Sun formed," remarked Jonathan Tan, an astrophysicist at the University of Florida, Gainesville, and lead author of a paper published today in the Astrophysical Journal."This suggests that massive stars and Sun-like stars follow a universal mechanism for star formation. The only difference is the size of their parent clouds."

Average stars like our Sun begin life as dense, but relatively low-mass concentrations of hydrogen, helium, and other trace elements inside large molecular clouds. After the initial kernel emerges from the surrounding gas, material collapses under gravity into the central region in a relatively ordered fashion via a swirling accretion disk, where eventually planets can form. After enough mass accumulates, nuclear fusion begins at the core and a star is born.

While this model of star formation can account for the vast majority of stars in our Milky Way, something extra is needed to explain the formation of more massive stars. "Some additional force is needed to balance out the normal process of collapse, otherwise our Galaxy would have a fairly uniform stellar population," said Tan. "Alternatively, there has been speculation that two separate models of star formation are needed: one for Sun-like stars and one for these massive stars."

The key to teasing out the answer is to find examples of massive starless cores -- to witness the very beginnings of massive star birth.

The team of astronomers from the United States, the United Kingdom, and Italy used ALMA to look inside these cores for a unique chemical signature involving the isotope deuterium to essentially take the temperatures of these clouds to see if stars had formed. Deuterium is important because it tends to bond with certain molecules in cold conditions. Once stars turn on and heat the surrounding gas, the deuterium is quickly lost and replaced with the more common isotope of hydrogen.

The ALMA observations detected copious amounts of deuterium, suggesting that the cloud is cold and starless. This would indicate that some counter force is forestalling core collapse and buying enough time to form a massive star. The researchers speculate that strong magnetic fields may be propping up the cloud, preventing it from collapsing quickly.

"These new ALMA observations reveal objects that are quite similar to the nurseries of Sun-like stars, but simply scaled-up by tens or a hundred times. This may mean that nature is more important than nurture when it comes to determining a star's size," concludes Tan.

These observations were conducted during ALMA's early science campaign. Future studies with ALMA's full array of 66 antennas will uncover even more details about these star-forming regions.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc
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