Giant Magnetic Loop Sweeps Through Space Between Stellar Pair.

Artist's conception of Algol star system with radio image superimposed on grid. (Credit: Peterson et al., NRAO/AUI/NSF)

Source: ScienceDaily

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ScienceDaily (Jan. 14, 2010) — Astronomers have found a giant magnetic loop stretched outward from one of the stars making up the famous double-star system Algol. The scientists used an international collection of radio telescopes to discover the feature, which may help explain details of previous observations of the stellar system.

"This is the first time we've seen a feature like this in the magnetic field of any star other than the Sun," said William Peterson, of the University of Iowa.
The pair, 93 light-years from Earth, includes a star about 3 times more massive than the Sun and a less-massive companion, orbiting it at a distance of 5.8 million miles, only about six percent of the distance between Earth and the Sun. The newly-discovered magnetic loop emerges from the poles of the less-massive star and stretches outward in the direction of the primary star. As the secondary star orbits its companion, one side -- the side with the magnetic loop -- constantly faces the more-massive star, just as the same side of our Moon always faces the Earth.
The scientists detected the magnetic loop by making extremely detailed images of the system using an intercontinental set of radio telescopes, including the National Science Foundation's Very Long Baseline Array, Very Large Array, and Robert C. Byrd Green Bank Telescope, along with the Effelsberg radio telescope in Germany. These radio telescopes were used as a single observing system that offered both great detail, or resolving power, and high sensitivity to detect very faint radio waves. When working together, these telescopes are known as the High Sensitivity Array.
Algol, in the constellation Perseus, is visible to the naked eye and well-known to amateur astronomers. As seen from Earth, the two stars regularly pass in front of each other, causing a notable change in brightness. The pair completes a cycle of such eclipses in less than three days, making it a popular object for amateur observers. The variability in brightness was discovered by an Italian astronomer in 1667, and the eclipsing-binary explanation was confirmed in 1889.
The newly-discovered magnetic loop helps explain phenomena seen in earlier observations of the Algol system at X-ray and radio wavelengths, the scientists said. In addition, they now believe there may be similar magnetic features in other double-star systems.
Peterson worked with Robert Mutel, also of the University of Iowa, Manuel Gudel of the Swiss Federal Institute of Technology, and Miller Goss of the National Radio Astronomy Observatory. The scientists reported their findings in the 14 January edition of the scientific journal Nature.

Story Source:
Adapted from materials provided by National Radio Astronomy Observatory.

How Galaxies Form: New Research Resolves Conflict in Theory.

These images depict various stages of galaxy formation under the cold dark matter theory using new computer simulations that account for the effects of supernova explosions. (Credit: Katy Brooks)

Source: ScienceDaily

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ScienceDaily (Jan. 14, 2010) — For more than two decades, the cold dark matter theory has been used by cosmologists to explain how the smooth universe born in the big bang more than 13 billion years ago evolved into the filamentary, galaxy-rich cosmic web that we see today.

There's been just one problem: the theory suggested most galaxies should have far more stars and dark matter at their cores than they actually do. The problem is most pronounced for dwarf galaxies, the most common galaxies in our own celestial neighborhood. Each contains less than 1 percent of the stars found in large galaxies such as the Milky Way.
Now an international research team, led by a University of Washington astronomer, reports Jan. 14 in Nature that it resolved the problem using millions of hours on supercomputers to run simulations of galaxy formation (1 million hours is more than 100 years). The simulations produced dwarf galaxies very much like those observed today by satellites and large telescopes around the world.
"Most previous work included only a simple description of how and where stars formed within galaxies, or neglected star formation altogether," said Fabio Governato, a UW research associate professor of astronomy and lead author of the Nature paper.
"Instead we performed new computer simulations, run over several national supercomputing facilities, and included a better description of where and how star formation happens in galaxies."
The simulations showed that as the most massive new stars exploded as supernovas, the blasts generated enormous winds that swept huge amounts of gas away from the center of what would become dwarf galaxies, preventing millions of new stars from forming.
With so much mass suddenly removed from the center of the galaxy, the pull of gravity on the dark matter there is diminished and the dark matter drifts away, Governato said. It is similar to what would happen if our sun suddenly disappeared and the loss of its gravitational pull allowed the Earth to drift off into space.
The cosmic explosions proved to be the missing piece of the puzzle, and adding them to the simulations generated formation of galaxies with substantially lower densities at their cores, closely matching the observed properties of dwarf galaxies.
"The cold dark matter theory works amazingly well at telling where, when and how many galaxies should form," Governato said. "What we did was find a better description of processes that we know happen in the real universe, resulting in more accurate simulations."
The theory of cold dark matter, first advanced in the mid 1980s, holds that the vast majority of the matter in the universe -- as much as 75 percent -- is made up of "dark" material that does not interact with electrons and protons and so cannot be observed from electromagnetic radiation. The term "cold" means that immediately following the big bang these dark matter particles have speeds far lower than the speed of light.
In the cold dark matter theory, smaller structures form first, then they merge with each other to form more massive halos, and finally galaxies form within the halos.
Coauthors of the Nature paper are Chris Brook of the Jeremiah Horrocks Institute in the United Kingdom; Lucio Mayer of the Institut für Astronomie and the Institute for Theoretical Physics in Switzerland; Alyson Brooks of the California Institute of Technology; George Rhee of the University of Nevada; James Wadsley and Gregory Stinson of McMaster University in Canada; Patrik Jonsson and Piero Madau of the University of California, Santa Cruz; Beth Willman of Haverford College in Pennsylvania and Thomas R. Quinn of the UW.
The research was funded by NASA and the National Science Foundation, and was conducted using facilities of NASA's Advanced Supercomputing Division, the University of Washington Computing Center, the Arctic Region Supercomputing Center in Alaska and the TeraGrid supercomputer coordinated through the Grid Infrastructure Group at the University of Chicago.

Story Source:
Adapted from materials provided by University of Washington.

Astronomers Capture First Direct Spectrum of an Exoplanet.

By studying a triple planetary system that resembles a scaled-up version of our own Sun’s family of planets, astronomers have been able to obtain the first direct spectrum of a planet around a star, thus bringing new insights into its formation and composition. The spectrum is that of a giant exoplanet, orbiting around the bright and very young star HR 8799, about 130 light-years away. This montage shows the image and the spectrum of the star and the planet as seen with the NACO adaptive optics instrument on ESO’s Very Large Telescope. (Credit: ESO/M. Janson)

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Source:

ScienceDaily

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ScienceDaily (Jan. 13, 2010) — By studying a triple planetary system that resembles a scaled-up version of our own Sun's family of planets, astronomers have been able to obtain the first direct spectrum -- the "chemical fingerprint" [1] -- of a planet orbiting a distant star [2], thus bringing new insights into the planet's formation and composition. The result represents a milestone in the search for life elsewhere in the Universe.

"The spectrum of a planet is like a fingerprint. It provides key information about the chemical elements in the planet's atmosphere," says Markus Janson, lead author of a paper reporting the new findings. "With this information, we can better understand how the planet formed and, in the future, we might even be able to find tell-tale signs of the presence of life."
The researchers obtained the spectrum of a giant exoplanet that orbits the bright, very young star HR 8799. The system is at about 130 light-years from Earth. The star has 1.5 times the mass of the Sun, and hosts a planetary system that resembles a scaled-up model of our own Solar System. Three giant companion planets were detected in 2008 by another team of researchers, with masses between 7 and 10 times that of Jupiter. They are between 20 and 70 times as far from their host star as the Earth is from the Sun; the system also features two belts of smaller objects, similar to our Solar System's asteroid and Kuiper belts.
"Our target was the middle planet of the three, which is roughly ten times more massive than Jupiter and has a temperature of about 800 degrees Celsius," says team member Carolina Bergfors. "After more than five hours of exposure time, we were able to tease out the planet's spectrum from the host star's much brighter light."
This is the first time the spectrum of an exoplanet orbiting a normal, almost Sun-like star has been obtained directly. Previously, the only spectra to be obtained required a space telescope to watch an exoplanet pass directly behind its host star in an "exoplanetary eclipse," and then the spectrum could be extracted by comparing the light of the star before and after. However, this method can only be applied if the orientation of the exoplanet's orbit is exactly right, which is true for only a small fraction of all exoplanetary systems. The present spectrum, on the other hand, was obtained from the ground, using ESO's Very Large Telescope (VLT), in direct observations that do not depend on the orbit's orientation.
As the host star is several thousand times brighter than the planet, this is a remarkable achievement. "It's like trying to see what a candle is made of, by observing it from a distance of two kilometres when it's next to a blindingly bright 300 Watt lamp," says Janson.
The discovery was made possible by the infrared instrument NACO, mounted on the VLT, and relied heavily on the extraordinary capabilities of the instrument's adaptive optics system [3]. Even more precise images and spectra of giant exoplanets are expected both from the next generation instrument SPHERE, to be installed on the VLT in 2011, and from the European Extremely Large Telescope.
The newly collected data show that the atmosphere enclosing the planet is still poorly understood. "The features observed in the spectrum are not compatible with current theoretical models," explains co-author Wolfgang Brandner. "We need to take into account a more detailed description of the atmospheric dust clouds, or accept that the atmosphere has a different chemical composition from that previously assumed."
The astronomers hope to soon get their hands on the fingerprints of the other two giant planets so they can compare, for the first time, the spectra of three planets belonging to the same system. "This will surely shed new light on the processes that lead to the formation of planetary systems like our own," concludes Janson.

Notes:
[1] As every rainbow demonstrates, white light can be split up into different colours. Astronomers artificially split up the light they receive from distant objects into its different colours (or "wavelengths"). However, where we distinguish five or six rainbow colours, astronomers map hundreds of finely nuanced colours, producing a spectrum -- a record of the different amounts of light the object emits in each narrow colour band. The details of the spectrum -- more light emitted at some colours, less light at others -- provide tell-tale signs about the chemical composition of the matter producing the light. This makes spectroscopy, the recording of spectra, an important investigative tool in astronomy.
[2] In 2004, astronomers used NACO on the VLT to obtain an image and a spectrum of a 5 Jupiter mass object around a brown dwarf -- a "failed star." It is however thought that the pair probably formed together, like a petite stellar binary, instead of the companion forming in the disc around the brown dwarf, like a star-planet system.
[3] Telescopes on the ground suffer from a blurring effect introduced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way that delights poets but frustrates astronomers, since it smears out the fine details of the images. However, with adaptive optics techniques, this major drawback can be overcome so that the telescope produces images that are as sharp as theoretically possible, i.e. approaching conditions in space. Adaptive optics systems work by means of a computer-controlled deformable mirror that counteracts the image distortion introduced by atmospheric turbulence. It is based on real-time optical corrections computed at very high speed (several hundreds of times each second) from image data obtained by a wavefront sensor (a special camera) that monitors light from a reference star.

More information:
This research was presented in a paper in press as a Letter to the Astrophysical Journal ("Spatially resolved spectroscopy of the exoplanet HR 8799 c," by M. Janson et al.).
The team is composed of M. Janson (University of Toronto, Canada), C. Bergfors, M. Goto, W. Brandner (Max-Planck-Institute for Astronomy, Heidelberg, Germany) and D. Lafrenière (University of Montreal, Canada). Preparatory data were taken with the IRCS instrument at the Subaru telescope.

Story Source:
Adapted from materials provided by ESO.
Journal Reference:
1. M. Janson et al. Spatially resolved spectroscopy of the exoplanet HR 8799 c. Astrophysical Journal, 2010 (in press).

Across the Multiverse: Physicist Considers the Big Picture.

Source: ScienceDaily

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ScienceDaily (Jan. 13, 2010) — Is there anybody out there? In Alejandro Jenkins' case, the question refers not to whether life exists elsewhere in the universe, but whether it exists in other universes outside of our own.

While that might be a mind-blowing concept for the layperson to ponder, it's all in a day's work for Jenkins, a postdoctoral associate in theoretical high-energy physics at The Florida State University. In fact, his deep thoughts on the hypothetical "multiverse" -- think of it as a mega-universe full of numerous smaller universes, including our own -- are now receiving worldwide attention, thanks to a cover article he co-wrote for the January 2010 issue of Scientific American magazine.
In "Looking for Life in the Multiverse," Jenkins and co-writer Gilad Perez, a theorist at the Weizmann Institute of Science in Israel, discuss a provocative hypothesis known as the anthropic principle, which states that the existence of intelligent life (capable of studying physical processes) imposes constraints on the possible form of the laws of physics.
"Our lives here on Earth -- in fact, everything we see and know about the universe around us -- depend on a precise set of conditions that makes us possible," Jenkins said. "For example, if the fundamental forces that shape matter in our universe were altered even slightly, it's conceivable that atoms never would have formed, or that the element carbon, which is considered a basic building block of life as we know it, wouldn't exist. So how is it that such a perfect balance exists? Some would attribute it to God, but of course, that is outside the realm of physics."
The theory of "cosmic inflation," which was developed in the 1980s in order to solve certain puzzles about the structure of our universe, predicts that ours is just one of countless universes to emerge from the same primordial vacuum. We have no way of seeing those other universes, although many of the other predictions of cosmic inflation have recently been corroborated by astrophysical measurements.
Given some of science's current ideas about high-energy physics, it is plausible that those other universes might each have different physical interactions. So perhaps it's no mystery that we would happen to occupy the rare universe in which conditions are just right to make life possible. This is analogous to how, out of the many planets in our universe, we occupy the rare one where conditions are right for organic evolution.
"What theorists like Dr. Perez and I do is tweak the calculations of the fundamental forces in order to predict the resulting effects on possible, alternative universes," Jenkins said. "Some of these results are easy to predict; for example, if there was no electromagnetic force, there would be no atoms and no chemical bonds. And without gravity, matter wouldn't coalesce into planets, stars and galaxies.
"What is surprising about our results is that we found conditions that, while very different from those of our own universe, nevertheless might allow -- again, at least hypothetically -- for the existence of life. (What that life would look like is another story entirely.) This actually brings into question the usefulness of the anthropic principle when applied to particle physics, and might force us to think more carefully about what the multiverse would actually contain."
"Looking for Life in the Multiverse" can be purchased, or accessed by Scientific American subscribers, at the magazine's Web site. The January issue of the magazine is also on sale now throughout the United States.
"Having an article in Scientific American is a magnificent accomplishment, but being selected for the cover story is special indeed," said Mark Riley, chairman of the Department of Physics at Florida State. "My congratulations to Dr. Jenkins and our High Energy Physics Group."
Jenkins has degrees from Harvard University and the California Institute of Technology, and he previously conducted postgraduate research on the topic of alternative universes while at the Massachusetts Institute of Technology. Despite all of his training, however, the Scientific American article was unexpected.
"I am very proud of our research, but to be honest, I think that this had something to do with the fact that people are naturally intrigued by speculative ideas about cosmology and the 'big picture.'
"The idea of parallel universes, in particular, is one that many people find exciting," Jenkins said. "The current season of (the Fox-TV comedy) 'Family Guy' recently premiered with an episode called 'Road to the Multiverse,' which was premised on the idea that one can visit other universes -- although that seems impossible given what we know about physics. Nevertheless, whether other universes actually exist is a question that has consequences for our understanding of physics in this world. I think our research raises important questions in that regard."

Story Source:
Adapted from materials provided by Florida State University.

Journal Reference:
1.Alejandro Jenkins and Gilad Perez. Looking for Life in the Multiverse. Scientific American, 2010; 302 (1): 42 DOI: 10.1038/scientificamerican0110-42

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How Earth Survived Its Birth: New Simulation Reveals Planet Migration Prevents Plunge Into Sun.

Source: ScienceDaily

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ScienceDaily (Jan. 8, 2010) — For the last 20 years, the best models of planet formation -- or how planets grow from dust in a gas disk -- have contradicted the very existence of Earth. These models assumed locally constant temperatures within a disk, and the planets plunge into the Sun. Now, new simulations from researchers at the American Museum of Natural History and the University of Cambridge show that variations in temperature can lead to regions of outward and inward migration that safely trap planets on orbits.

When the protoplanetary disk begins to dissipate, planets are left behind, safe from impact with their parent star.
The results of this research are being presented at the 2010 meeting of the American Astronomical Society in Washington, D.C.
"We are trying to understand how planets interact with the gas disks from which they form as the disk evolves over its lifetime," says Mordecai-Mark Mac Low, Curator of Astrophysics and Division Chair of Physical Sciences at the Museum. "We show that the planetoids from which the Earth formed can survive their immersion in the gas disk without falling into the Sun."
During the birth of a star, a disk of gas and dust forms. The midplane of this dusty disk is opaque and cannot quickly cool by radiating heat to outer space. Until recently, no one has included temperature variation in models of planet formation.
Co-author Sijme-Jan Paardekooper of the University of Cambridge ran groundbreaking new simulations like that most recently published online (http://arxiv.org/abs/0909.4552). His work shows that the direction of migration of low-mass planets in disks depends on the detailed temperature structure of the disk. This key insight lays the groundwork for the current work.
The American Astronomical Society presentation incorporates the results of Paardekooper's local models into the long-term evolution of the temperature and density structure of a protoplanetary disk. The result of the simulation is that, over the lifetime of a disk, planets get trapped in orbits between regions of inward and outward migration. The orbits slowly move inward as the disk dissipates. Once the gas densities drop low enough for the planets to no longer be influenced by disk, the planets are dropped into an orbit similar to the orbits of planets around the Sun. The radius of the orbit at which a planet is released depends on its mass.
"We used a one-dimensional model for this project," says co-author Wladimir Lyra, a postdoctoral researcher in the Department of Astrophysics at the Museum. "Three dimensional models are so computationally expensive that we could only follow the evolution of disks for about 100 orbits -- about 1,000 years. We want to see what happens over the entire multimillion year lifetime of a disk."
Mac Low is presenting this research at the upcoming American Astronomical Society meetings in Washington, D.C. on January 6 with a press conference on the following day (January 7 at 10:30 am: "Spicing up the solar system.") A research paper is currently submitted to The Astrophysical Journal, authored by Lyra, Paardekooper, and Mac Low. This research was funded by the American Museum of Natural History, the National Science Foundation, and NASA.

Story Source:
Adapted from materials provided by American Museum of Natural History, via EurekAlert!, a service of AAAS.

World's Most Sensitive Astronomical Camera Developed.

SOURCE

ScienceDaily (Sep. 30, 2009) — A team of Université de Montréal researchers, led by physics PhD student Olivier Daigle, has developed the world's most sensitive astronomical camera. Marketed by Photon etc., a young Quebec firm, the camera will be used by the Mont-Mégantic Observatory and NASA, which purchased the first unit.

The camera is made up of a CCD controller for counting photons; a digital imagery device that amplifies photons observed by astronomical cameras or by other instruments used in situations of very low luminosity. The controller produces 25 gigabytes of data per second.
Electric signals used to pilot the imagery chip are 500 times more precise than those of a conventional controller. This increased precision helps reduce noise that interferes with the weak signals coming from astronomical objects in the night sky. The controller allows to substantially increase the sensitivity of detectors, which can be compared to the mirror of the Mont-Mégantic telescope doubling its diameter.
"The first astronomical results are astounding and highlight the increased sensitivity acquired by the new controller," says Daigle. "The clarity of the images brings us so much closer to the stars that we are attempting to understand."
A thriving Quebec company Photon etc. developed a commercial version of the controller devised by Daigle and his team and integrated it in complete cameras. NASA was first to place an order for one of these cameras and was soon followed by a research group from the University of Sao Paulo, and by a European-Canadian consortium equipping a telescope in Chili. In addition, researchers in nuclear medicine, bioluminescence, Raman imaging and other fields requiring rapid imagery have expressed interest in purchasing the cameras.
Photon etc. is a Quebec research and development company that specializes in the manufacting of photonic measurement and analysis instruments. The company is growing rapidly after spending four years in the Université de Montréal and its affiliated École Polytechnique IT business incubator.
"The sensitivity of the cameras developed by the Centre de recherche en astrophysique du Québec (CRAQ) and Photon etc. will not only help us better understand the depths of the universe but also better perceive weak optical signals coming from the human body. These signals can reveal the early signs of several diseases such as macular degeneration and certain types of cancer. An early diagnostic leads to early intervention, hopefully before the disease becomes more serious thus saving lives and important costs," says Sébastien Blais-Ouellette, president of Photon etc.
Scientific results for the camera were recently featured in the Publications of the Astronomical Society of the Pacific, a prestigious instrumentation journal.
This research was made possible thanks to the financial support of the Natural Sciences And Engineering Research Council of Canada, Photon etc., the Canada Foundation for Innovation, the Fonds québécois de la recherche sur la nature et les technologies.
Adapted from materials provided by University of Montreal.