Jupiter-Sized Transiting Planet Found by Astronomers Using Novel Telescope Network

PASADENA, Calif.—Our home solar system may be down by a planet with the recent demotion of Pluto, but the number of giant planets discovered in orbit around other stars continues to grow steadily. Now, an international team of astronomers has detected a planet slightly larger than Jupiter that orbits a star 500 light-years from Earth in the constellation Draco.

Unlike the mythological names associated with the solar system's planets, the newly discovered planet is known by "TrES-2" and passes in front of the star "GSC 03549-02811" every two and a half days.

The new planet is especially noteworthy because it was identified by astronomers looking for transiting planets (that is, planets that pass in front of their home star) with a network of small automated telescopes. The humble telescopes used in the discovery consist of mostly amateur-astronomy components and off-the-shelf 4-inch camera lenses. This is the third transiting planet found using telescopes similar to those used by many amateur astronomers.

By definition, a transiting planet passes directly between Earth and the star, causing a slight reduction in the light in a manner similar to that caused by the moon's passing between the sun and Earth during a solar eclipse. According to Francis O'Donovan, an Irish graduate student in astronomy at the California Institute of Technology, "When TrES-2 is in front of the star, it blocks off about one and a half percent of the star's light, an effect we can observe with our TrES telescopes.

"We know of about 200 planets around other stars," says O'Donovan, lead author of the paper announcing the discovery in an upcoming issue of the Astrophysical Journal, "but it is only for the nearby transiting planets that we can precisely measure the size and mass of the planet, and hence study its composition. That makes each new transiting planet an exciting find. And because TrES-2 is the most massive of the nearby transiting planets, it sets a new limit to our understanding of how these gas planets form around stars."

The planet TrES-2 is also noteworthy for being the first transiting planet in an area of the sky known as the "Kepler field," which has been singled out as the targeted field of view for the upcoming NASA Kepler mission. Using a satellite-based telescope, Kepler will stare at this patch of sky for four years, and should discover hundreds of giant planets and Earth-like planets. Finding a planet in the Kepler field with the current method allows astronomers to plan future observations with Kepler that include searching for moons around TrES-2.

And finally, the research team hails the discovery as the second transiting "hot Jupiter" found with the Trans-Atlantic Exoplanet Survey (TrES), an effort involving the "Sleuth" telescope at Caltech's Palomar Observatory in San Diego County, the Planet Search Survey Telescope (PSST) at Lowell Observatory near Flagstaff, Arizona, and the "STellar Astrophysics and Research on Exoplanets (Stare) telescope in the Canary Islands. The name of the planet, TrES-2, is derived from the name of the survey.

To look for transits, the small telescopes are automated to take wide-field timed exposures of the clear skies on as many nights as possible. When an observing run is completed for a particular field-usually over an approximate two-month period-the data are run through software that corrects for various sources of distortion and noise.

The end result is a "light curve" for each of thousands of stars in the field. If the software detects regular variations in the light curve for an individual star, then the astronomers do additional work to see if the source of the variation is indeed a transiting planet. One possible alternative is that the object passing in front of the star is another star, fainter and smaller.

In order to confirm they had found a planet, O'Donovan and his colleagues switched from the 10-centimeter TrES telescopes to one of the 10-meter telescopes at the W. M. Keck Observatory on the summit of Mauna Kea, Hawaii. Using this giant telescope, they confirmed that they had found a new planet. O'Donovan says, "Each of us had spent countless hours working on TrES at that point, and we had suffered many disappointments. All our hard work was made worthwhile when we saw the results from our first night's observations, and realized we had found our second transiting planet."

TrES-2 was first spotted by the Sleuth telescope, which was set up by David Charbonneau, formerly an astronomer at Caltech who is now at the Harvard-Smithsonian Center for Astrophysics and is a coauthor of the paper. The PSST, which is operated by Georgi Mandushev and Edward Dunham (coauthors from Lowell Observatory), also observed transits of TrES-2, confirming the initial detections.

The other authors of the paper are David Latham and Guillermo Torres of Harvard-Smithsonian; Alessandro Sozetti of Harvard-Smithsonian and the INAF-Osservatorio Astronomico di Torino; Timothy Brown of the Las Cumbres Observatory Global Telescope; John Trauger of the Jet Propulsion Laboratory; Markus Rabus, José Almenara, Juan Belmonte, and Hans Deeg of the Instituto de Astrofísica de Canarias; Roi Alonso of the Laboratoire d'Astrophysique de Marseille and the Institute de Astrofísica de Canarias; Gilbert Esquerdo of Harvard-Smithsonian and the Planetary Science Institute in Tucson; Emilio Falco of Harvard-Smithsonian; Lynne Hillenbrand of Caltech; Anna Roussanova of MIT; Robert Stefanik of Harvard-Smithsonian; and Joshua Winn of MIT.

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Meyerowitz and Lange Awarded Balzan Prize

PASADENA, Calif.- California Institute of Technology faculty Andrew Lange and Elliot Meyerowitz have been named Balzan Prizewinners for 2006 by the International Balzan Foundation. Lange, Goldberger Professor of Physics, will share his award for observational astronomy and astrophysics with Paolo de Bernardis of Università di Roma La Sapienza in Italy "...for their contributions to cosmology, in particular the "BOOMERanG" Antarctic balloon experiment."

Lange and Italian team leader de Bernardis led the international team that developed BOOMERanG (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics), a balloon-borne telescope capable of obtaining images of the universe in its embyronic state, long before the first stars formed. The images obtained in 1998, during a 10-day circumnavigation of Antarctica, revealed that the geometry of the universe is flat, and provided compelling evidence that 95 percent of the universe consists of exotic forms of matter and energy that remain largely a mystery.

Meyerowitz, Beadle Professor of Biology and biology division chair, will share his award for plant molecular genetics with Chris R. Somerville of Stanford University "...for their joint efforts in establishing Arabidopsis as a model organism for plant molecular genetics. This has far-reaching implications for plant science, both on a fundamental level and in potential applications."

Meyerowitz's primary research interest is the genes that control the formation of flowers, how altering these genes will affect flower development; and using computational models to study how plants grow. His laboratory has identified mutations that cause petal cells to develop into stamens instead, and another mutation that causes these same embryonic petals to become sepals. They and their collaborators have also produced computer models that faithfully reproduce the cellular behavior of meristems, the growing tips of shoots.

The winners named will be presented with their Balzan (pronounced bal-ZAHN) Prizes personally by the president of the Italian Republic, Giorgio Napolitano, during an award ceremony November 24 at the Accademia Nazionale dei Lincei, in the Palazzo Corsini in Rome. Each prize is worth one million Swiss francs, about $810,000 US. Because both Lange and Meyerowitz share their prizes with one other person, they will each receive half of the total, or about $405,000 US. Half of the prize money is awarded directly to the prizewinners in recognition of their outstanding scholarly work and they are asked to spend the other half on research projects carried out by young scholars or scientists in their respective fields.

The recipients were chosen by the General Prize Committee, a body chaired by Ambassador Sergio Romano and composed of 20 members representing European cultural institutions, from the candidates nominated by universities, academies, and cultural institutions throughout the world.

Unlike other international forms of recognition, the Balzan Prizes are awarded for different subjects each year, which are chosen annually by the Balzan Foundation. Two prizes are awarded in the humanities (literature, the moral sciences, and the arts) and two in the sciences (medicine and the physical, mathematical, and natural sciences). By rotating subjects, it is possible for the foundation to give preference to new or emerging areas of research, and to sustain important fields of study that may have been previously overlooked.

Additional recipients this year are Ludwig Finscher of the University of Heidelberg, Germany, for history of Western music since 1600, and Quentin Skinner of University of Cambridge, UK, for political thought: history and theory.

In 2007, Balzan Prizes will be awarded in European literature (1000-1500), international law since 1945, innate immunity, and nanoscience. The Prize for Humanity, Peace, and Brotherhood among Peoples will also be awarded next year; past winners include Mother Teresa and the International Committee of the Red Cross.

The International Balzan Foundation was founded in 1961 to promote the worthy causes of culture, the sciences and humanities, and peace and brotherhood in the world. The main concern of the foundation is to award the Balzan Prizes, which are given annually to individuals who have earned international distinction in their field, regardless of their nationality, race, or creed. At intervals of not less than three years, the Balzan Foundation also awards the Prize for Humanity, Peace, and Brotherhood among Peoples, which is worth two million Swiss francs. The Balzan Foundation operates on an international level through its two offices, which are legally distinct bodies: its Milan, Italy, headquarters is concerned with awarding the prizes, while the estate of Eugenio Balzan, which funds the Balzan Prizes, is managed from Zurich, Switzerland.

For details, see the Balzan Foundation website: http://www.balzan.it/default_eng.aspx. ### Contact: Jill Perry (626) 395-3226 jperry@caltech.edu Visit the Caltech Media Relations website at http://pr.caltech.edu/media.

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NSF Awards $11.97 Million to Caltech for Distributed Data Analysis of Neutron Scattering

PASADENA, Calif.—The National Science Foundation today awarded $11.97 million to the California Institute of Technology for computer software to analyze neutron-scattering experiments. This work could show how to design new materials for a huge variety of applications in transportation, construction, electronics, and space exploration.

The five-year Distributed Data Analysis for Neutron Scattering Experiments (DANSE) project is led by Brent Fultz, a professor of materials science and applied physics at Caltech, with coprincipal investigators Michael A. G. Aivazis of the Center for Advanced Computing Research at Caltech, and Ian S. Anderson of the Spallation Neutron Source (SNS) in Oak Ridge, Tennessee.

Neutron scattering is a method of analyzing the stability of materials, molecules, and condensed matter at various temperatures and pressures by looking at the positions and motions of the atoms making up the materials. According to Fultz, the research will find the principles of how atoms can be combined to form stable materials and will eventually show how new materials could be optimized for characteristics such as mechanical strength, electrical conductivity, energy storage, and resistance to corrosion.

To date, many neutron-scattering measurements have been impaired by the low intensities of today's neutron sources. This will change in 2008 as the SNS, constructed at a cost of $1.411 billion, begins to operate at high power. The unprecedented quality of data from the SNS will allow a deeper understanding of atom interactions, for example, and will require better methods for interpreting the measurements.

The DANSE project is an opportunity arising from recent developments in computing, materials theory, and the new experimental facilities at the SNS. The project integrates new materials theory with high-performance computing to push the science of the SNS and other neutron facilities to a higher level of sophistication. The project will also extend a capable software framework developed at Caltech to include distributed computing on today's networked computing hardware.

The DANSE project is centered at Caltech where its software technology effort, inelastic neutron-scattering research, and project administration will be conducted. The total grant includes smaller awards to four other universities for subfields of neutron-scattering research-neutron diffraction (Simon Billinge, Michigan State University), engineering diffraction (Erstan Ustundag, Iowa State University), small-angle scattering (Paul Butler, University of Tennessee), and reflectometry (Paul Kienzle, University of Maryland). All these different subfields need advanced scientific computing for comparing experimental data to underlying physical models or simulations, and all will benefit from a shared development effort. DANSE will develop new methods for doing neutron-scattering research in these subfields.

Planning for DANSE began during the Angular-Range Chopper Spectrometer (ARCS) project at Caltech, a five-year, $14.9 million dollar neutron-scattering instrument project initiated in 2001 with support from the U.S. Department of Energy. A detailed plan for DANSE was developed with a $980,000 design award from the NSF to Caltech in 2004. In a series of software releases, the DANSE project will deliver by 2011 a set of capabilities for neutron scattering, tested with actual science.

The NSF funding will also support an outreach effort in teacher education, which is being created by Iowa State University.

The DANSE award is the first construction award made by the Division of Materials Research under the Instrumentation for Materials Research-Mid-Scale Instrumentation Project since its inception in 2004.

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Robert Tindol
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Thirty Meter Telescope (TMT) Passes Conceptual Design Review

PASADENA, Calif.—The detailed design for the Thirty Meter Telescope (TMT) developed by a U.S.-Canadian team is capable of delivering on the full promise of its enormous light-collecting area, according to the findings of an independent panel of experts.

With the TMT, astronomers will be able to analyze the light from the first stars born after the Big Bang, directly observe the formation and evolution of galaxies, see planets around nearby stars, and make observations that test fundamental laws of physics.

"The successful completion of our conceptual design review means that the TMT has a strong science vision, good technical requirements, a thoroughly reviewed design, and a powerful team to carry our work forward," says Project Manager Gary Sanders.

Now in detailed design, the TMT is a concept for the world's largest telescope. It consists of a primary mirror with 738 individual 1.2-meter segments that span 30 meters in total, three times the effective diameter of the current largest telescopes. All of the segments will be under exquisite computer control so that they work together as a single mirror.

The review panel evaluated all aspects of the project, including its optical design, the telescope structure, science instrumentation, site testing, management and cost estimate procedures. The panel was positive on nearly all fronts and praised in particular the adaptive optics technology being planned for the giant telescope.

Adaptive optics will allow the TMT to reach the "diffraction limit," comparable to a telescope's resolution in space. TMT project engineers are integrating this system with the designs for the eight science instruments under detailed study, so the power of the adaptive optics (AO) system should be available at the beginning of the telescope's science operations in 2016, the external panel reported following the May 8-11 conceptual design review.

The baseline adaptive optics system for TMT involves nine laser beams that are launched from a small telescope at the peak of the structure that supports the telescope's secondary mirror. These laser beams reflect off a layer of sodium gas high in Earth's upper atmosphere to provide artificial points of light analogous to distant stars. These point-like laser reflections drift and wobble just like the star light, giving the AO system reference points to use anywhere in the sky as it compensates for distortions of the star light by Earth's ever-changing atmosphere. This technology has been pioneered at the Lick Observatory, the Gemini Observatory 8-meter telescopes and the Keck Observatory 10-meter telescopes.

TMT is also studying the potential for an adaptive secondary mirror for the telescope. This would involve covering the bottom of a flexible glass surface as large as the primary mirror in many current telescopes (a concave hemisphere 3.6 meters in diameter) with hundreds of tiny pistons to push and pull the surface of the mirror in minute increments. A computer controls these movements many times per second, as it works to adjust the mirror so it has the exact opposite shape of the distortions in the incoming star light.

Much of the TMT's scientific work will be done in the infrared, where the diffraction limit is easier to attain, young stars and galaxies are to be found, and the opportunities for new discoveries are abundant.

The eight scientific instruments in detailed design for the TMT are huge in comparison to current-generation astronomical instruments, and equivalently more complex. Each instrument is the size of school bus or larger, and they rest on two platforms on either side of the telescope that are each the size of a basketball court. The biggest technical challenge among the instruments is the Planetary Formation Instrument, which employs "extreme" adaptive optics in an effort to directly image other planets, the board found.

The technical requirements for the telescope, its structure, and its control system are clear and appropriate for this stage of the project, the review board concluded.

"The panel's report is glowing in its praise and confident that TMT is on track," says Richard Ellis, the Steele Family Professor of Astronomy at the California Institute of Technology, one of the partners in the project. "We'll decide in mid-2008 where to build the telescope and then start construction in early 2009."

The TMT is a collaboration between the California Institute of Technology, the University of California, the Association of Universities for Research in Astronomy, Inc. (AURA), and the Association of Canadian Universities for Research in Astronomy (ACURA), with significant work being done by industry and by university teams studying instrument designs.

Canadians welcome the external panel's endorsement of the depth and quality of the TMT design work. "We look forward to supplying the enclosure, telescope structure and adaptive optics system in time for first science," says Ray Carlberg of the University of Toronto, the Canadian project director for ACURA, an association of 24 Canadian universities in partnership with the National Research Council of Canada.

The design and development phase of the TMT project has a budget of $64 million, including $35 million in private sector contributions from the Gordon and Betty Moore Foundation. The conceptual design review board found that the project is estimating the cost of the TMT using up-to-date industry standards. A formal cost review of the project is scheduled for September 2006.

The TMT project is studying five sites in Chile, Hawaii, and Mexico as possible locations for the telescope. The project office is currently based in Pasadena, CA, where the conceptual design review was held.

Edward Stone, chair of the TMT Board of Directors and former director of NASA's Jet Propulsion Laboratory, is available to answer media questions about the conceptual design review and the status of this exciting project.

For more information on the project, see www.tmt.org.

The TMT is designed to meet the scientific goals of the Giant Segmented Mirror Telescope concept, which was the highest-priority ground-based project in the most recent astronomy decadal survey conducted by the National Academy of Sciences, published in 2000.

 

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Palomar Observes Broken Comet

PALOMAR MOUNTAIN, Calif.—Astronomers have recently been enjoying front-row seats to a spectacular cometary show. Comet 73P/Schwassmann-Wachmann 3 is in the act of splitting apart as it passes close to Earth. The breakup is providing a firsthand look at the death of a comet.

Eran Ofek of the California Institute of Technology and Bidushi Bhattacharya of Caltech's Spitzer Science Center have been observing the comet's tragic tale with the Palomar Observatory's 200-inch Hale Telescope. Their view is helping them and other scientists learn the secrets of comets and why they break up.

The comet was discovered by Arnold Schwassmann and Arno Arthur Wachmann 76 years ago and it broke into four fragments just a decade ago. It has since further split into dozens, if not hundreds, of pieces.

"We've learned that Schwassmann-Wachmann 3 presents a very dynamic system, with many smaller fragments than previously thought," says Bhattacharya. In all, 16 new fragments were discovered as a part of the Palomar observations.

A sequence of images showing the piece of the comet known as fragment R has been assembled into a movie. The movie shows the comet in the foreground against distant stars and galaxies, which appear to streak across the images. Because the comet was moving at a different rate across the sky than the stellar background, the telescope was tracking the comet's motion and not that of the stars. Fragment R and many smaller fragments of the comet are visible as nearly stationary objects in the movie.

"Seeing the many fragments was both an amazing and sobering experience," says a sleepy Eran Ofek, who has been working non-stop to produce these images and a movie of the comet's fragments.

The images used to produce the movie were taken over a period of about an hour and a half when the comet was approximately 17 million kilometers (10.6 million miles) from Earth. Astronomically speaking the comet is making a close approach to Earth this month giving astronomers their front-row seat to the comet's break up. Closest approach for any fragment of the comet occurs on May 12, when a fragment will be just 5.5 million miles from Earth. This is more than 20 times the distance to the moon. There is no chance that the comet will hit Earth.

"It is very impressive that a telescope built more than 50 years ago continues to contribute to forefront astrophysics, often working in tandem with the latest space missions and biggest ground-based facilities," remarks Shri Kulkarni, MacArthur Professor of Astronomy and Planetary Science and director of the Caltech Optical Observatories.

The Palomar observations were coordinated with observations acquired through the Spitzer Space Telescope, which imaged the comet's fragments in the infrared. The infrared images, combined with the visible-light images obtained using the Hale Telescope, will give astronomers a more complete understanding of the comet's break up.

Additional support for the observations and data analysis came from Caltech postdoc Arne Rau and grad student Alicia Soderberg.

Images of the comet and a time-lapse movie can be found at:

http://www.astro.caltech.edu/palomar/images/73p/

Contact:

Scott Kardel Palomar Public Affairs Director (760) 742-2111 wsk@astro.caltech.edu

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CARMA Radio Telescope Array in the Inyo Mountains Dedicated May 5

PASADENA, Calif.—The official dedication of the Combined Array for Research in Millimeter-Wave Astronomy (CARMA) facility was held Friday, May 5, at Cedar Flat in the Inyo Mountains near Bishop.

CARMA is a joint venture of the California Institute of Technology, the University of California at Berkeley, the University of Illinois at Urbana-Champaign, and the University of Maryland. The project has involved moving the six existing 10-meter telescopes at Caltech's Owens Valley Radio Observatory (OVRO) millimeter-wave array, along with the nine 6-meter telescopes at the Berkeley-Illinois-Maryland Association (BIMA) array, to the new Cedar Flat location, about 13 miles east of Big Pine by mountain route.

According to Anneila Sargent, CARMA director, the new facility will give radio astronomers an extremely clear view of the universe due to the dry air and 7,300-foot altitude of the Cedar Flat site.

Inovative technology and better atmospheric transmission make CARMA a much more powerful instrument than merely the sum of the previous arrays, said Sargent, who is Rosen Professor of Astronomy at Caltech. The facility will be used to observe molecular gas and dust in planets, star-forming clouds, planet-forming disks around other stars, nearby galaxies, and galaxies so distant that they must have formed soon after the Big Bang.

"These measurements will enable studies that address directly some of the most important questions in astrophysics today," Sargent said. "These include how the modern universe and the first stars and galaxies formed and evolved, how stars and planetary systems like our own are formed, and what the chemistry of the interstellar gas can tell us about the origins of life."

The new array is operated by the CARMA Association, which comprises the four partner universities. The association will coordinate the separate activities of its members through a board of representatives that includes senior administrators from each partner university and the CARMA science steering committee, made up of scientists from Caltech and from BIMA.

As a multi-university facility, CARMA also has a major educational mission. Innovative astronomy and technical development programs will ensure that the next generation of radio astronomers and instrumentalists will receive hands-on training while conducting frontline research. The National Science Foundation has supported both the OVRO and BIMA arrays since their inception, and will continue to support CARMA operations. Construction costs for the new combined array are being divided equally among the NSF, Caltech, and BIMA, and astronomers around the world will have access to the facility.

Sargent says that funding from the Gordon and Betty Moore Foundation and the Norris Foundation have also been crucial. "We're especially grateful for their getting us started."

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Robert Tindol
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Two from Caltech Faculty Elected to the American Academy of Arts and Sciences

PASADENA, Calif.—Two faculty members at the California Institute of Technology are among this year's newly elected fellows of the American Academy of Arts and Sciences. They join 173 other Americans and 20 foreign honorees as the 2006 class of fellows of the prestigious institution that was cofounded in 1780 by John Adams.

This year's new Caltech inductees are Anneila Sargent, the Rosen Professor of Astronomy and director of the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), and Henry Lester, the Bren Professor of Biology. Their election brings the total number of fellows from Caltech to 83.

Sargent and Lester join an illustrious list of fellows, both past and present. Other inductees in the 2006 class include former presidents George H. W. Bush and William Jefferson Clinton; Supreme Court Chief Justice John Roberts; Nobel Prize-winning biochemist and Rockefeller University President Sir Paul Nurse; the chairman and vice chairman of the 9/11 commission, Thomas Kean and Lee Hamilton; actor and director Martin Scorsese; choreographer Meredith Monk; conductor Michael Tilson Thomas; and New York Stock Exchange chairman Marshall Carter. Past fellows have included George Washington, Benjamin Franklin, Ralph Waldo Emerson, Albert Einstein, and Winston Churchill.

Sargent, a native of Scotland, is an authority on star formation. Most recently she has been investigating the way in which stars like the sun are created and evolve to become planetary systems. She uses various radio and submillimeter telescopes to search for and study other potential planetary systems.

Her interests range from the earliest stages of star formation, when dense cores in interstellar clouds collapse to form stars, to the epochs when individual planets may be born. This field has garnered considerable interest within the scientific community, as well as from the news media and the general public, because of the possibility of locating other worlds beyond the solar system.

She is a former president of the American Astronomical Society, incoming chair of the National Research Council's board of physics and astronomy, cochair of the 1996 "Search for Origins" workshop sponsored by the White House Office of Science and Technology Policy, a former chair of NASA's space science advisory committee, and a member of the 2000 National Research Council's survey committee on astronomy and astrophysics.

Her major honors include the 2002 University of Edinburgh Alumnus of the Year award and the 1998 NASA Public Service Medal.

Lester is a New York City native who has been a Caltech faculty member since 1973. His lab is currently involved in several avenues of research, but he is probably best known for his research on the neuroscience of nicotine addiction. A recipient of research funding from the California-based Tobacco-Related Disease Research Program (TRDRP) and the National Institutes of Health, Lester has published numerous papers showing the underlying mechanisms of nicotine addiction.

In 2004, he and collaborators from Caltech and other institutions announced their discovery that activating the receptor known as alpha4 involved in the release of the neurotransmitter dopamine is sufficient for reward behavior, sensitization, and tolerance to repeated doses of nicotine. The discovery was important, experts said, because knowing precisely the cells and cell receptors that are involved could provide useful targets for addiction therapies.

Lester, Caltech chemist Dennis Dougherty, and a group from the University of Cambridge last year announced their success in finding the "switch" part of receptors like those for nicotine and serotonin.

His other current research interests include ion channels, synaptic transmission, light-flash physiology, and signal transduction. Within the past year he has also published papers on the creation of mouse models for epilepsy, tardive dyskinesia, Alzheimer's disease, and Parkinson's disease. The academy is an independent policy research center that focuses on complex and emerging problems such as scientific issues, global security, social policy, the humanities and culture, and education.

The new fellows and foreign honorary members will be formally recognized at the annual induction ceremony on October 7 at the academy's headquarters in Cambridge, Massachusetts.

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Caltech Physicists and International MINOS Team Discover New Details of Why Neutrinos Disappear

PASADENA, Calif.—Physicists from the California Institute of Technology and an international collaboration of scientists at the Department of Energy's Fermi National Accelerator Laboratory have observed the disappearance of muon neutrinos traveling from the lab's site in Illinois to a particle detector in Minnesota. The observation is consistent with an effect known as neutrino oscillation, in which neutrinos change from one kind to another.

The Main Injector Neutrino Oscillation Search (MINOS) experiment at Fermilab's site in Batavia, Illinois, revealed a value of delta m^2 = 0.0031 eV^2, a quantity that plays a crucial role in neutrino oscillations and hence the role of neutrinos in the evolution of the universe.

The MINOS detector concept and design was originated by Caltech physicist Doug Michael. Caltech physicists also built half of the massive set of scintillator planes for the five-kiloton far detector. Michael led the formulation and pushed forward the program to increase the intensity of the proton beams that are the source of the neutrinos used by MINOS, leading to the present results.

"Only a year ago we launched the MINOS experiment," said Fermilab director Pier Oddone. "It is great to see that the experiment is already producing important results, shedding new light on the mysteries of the neutrino."

Nature provides for three types of neutrinos, yet scientists know very little about these "ghost particles," which can traverse the entire Earth without interacting with matter. But the abundance of neutrinos in the universe, produced by stars and nuclear processes, may explain how galaxies formed and why antimatter has disappeared. Ultimately, these elusive particles may explain the origin of the neutrons, protons and electrons that make up all the matter in the world around us.

"Using a man-made beam of neutrinos, MINOS is a great tool to study the properties of neutrinos in a laboratory-controlled environment," said Stanford University professor Stan Wojcicki, spokesperson of the experiment. "Our first result corroborates earlier observations of muon neutrino disappearance, made by the Japanese Super-Kamiokande and K2K experiments. Over the next few years, we will collect about 15 times more data, yielding more results with higher precision, paving the way to better understanding this phenomenon. Our current results already rival the Super-Kamiokande and K2K results in precision."

Neutrinos are hard to detect, and most of the neutrinos traveling the 450 miles from Fermilab to Soudan, Minnesota-straight through the earth, no tunnel needed-leave no signal in the MINOS detector. If neutrinos had no mass, the particles would not change as they traverse the earth and the MINOS detector in Soudan would have recorded 177 +/- 11 muon neutrinos. Instead, the MINOS collaboration found only 92 muon neutrino events-a clear observation of muon neutrino disappearance and hence neutrino mass.

The deficit as a function of energy is consistent with the hypothesis of neutrino oscillations, and yields a value of delta m^2, the square of the mass difference between two different types of neutrinos, equal to 0.0031 eV^2 +/- 0.0006 eV^2 (statistical uncertainty) +/- 0.0001 eV^2 (systematic uncertainty). In this scenario, muon neutrinos can transform into electron neutrinos or tau neutrinos, but alternative models-such as neutrino decay and extra dimensions-are not yet excluded. It will take the recording of much more data by the MINOS collaboration to test more precisely the exact nature of the disappearance process. Details of the current MINOS results were presented by David Petyt of the University of Minnesota at a special seminar at Fermilab on March 30. On Friday, March 31, the MINOS collaboration commemorated Michael, who was the MINOS co-spokesperson, at a memorial service at Fermilab. Michael died on December 25, 2005, at the age of 45 after a yearlong battle with cancer.

The MINOS experiment includes about 150 scientists, engineers, technical specialists, and students from 32 institutions in six countries, including Brazil, France, Greece, Russia, the United Kingdom, and the United States. The institutions include universities as well as national laboratories. The U.S. Department of Energy provides the major share of the funding, with additional funding from the U.S. National Science Foundation and from the United Kingdom's Particle Physics and Astronomy Research Council (PPARC).

"The MINOS experiment is a hugely important step in our quest to understand neutrinos-we have created neutrinos in the controlled environment of an accelerator and watched how they behave over very long distances," said Professor Keith Mason, CEO of PPARC. "This has told us that they are not totally massless as was once thought, and opens the way for a detailed study of their properties. U.K. scientists have taken key roles in developing the experiment and in exploiting the data from it, the results of which will shape the future of this branch of physics." The Fermilab side of the MINOS experiment consists of a beam line in a 4,000-foot-long tunnel pointing from Fermilab to Soudan. The tunnel holds the carbon target and beam focusing elements that generate the neutrinos from protons accelerated by Fermilab's main injector accelerator. A neutrino detector, the MINOS "near detector" located 350 feet below the surface of the Fermilab site, measures the composition and intensity of the neutrino beam as it leaves the lab. The Soudan side of the experiment features a huge 6,000-ton particle detector that measures the properties of the neutrinos after their 450-mile trip to northern Minnesota. The cavern housing the detector is located half a mile underground in a former iron mine.

The MINOS neutrino experiment follows a long tradition of studying neutrino properties originated at Caltech by physics professor (and former LIGO laboratory director) Barry Barish. Earlier measurements by the Monopole Astrophysics and Cosmic Ray Observatory (MACRO) experiment at the Gran Sasso laboratory in Italy, led by Barish, also showed evidence for the oscillation of neutrinos produced by the interactions of cosmic rays in the atmosphere.

The MINOS result also complemets results from the K2K long-baseline neutrino experiment in Japan. In 1999-2001 and 2003-2004, the K2K experiment in Japan sent neutrinos from an accelerator at the KEK laboratory in Tsukuba to a particle detector in Kamioka, a distance of about 150 miles. Compared to K2K, the MINOS experiment uses a three times longer distance, and the intensity and the energy of the MINOS neutrino beam are higher than those of the K2K beam. These advantages have enabled the MINOS experiment to observe in less than one year about three times more neutrinos than the K2K experiment did in about four years.

"It is a great gift for me to hear this news," said Yoji Totsuka, former spokesperson of the Super-Kamiokande experiment and now director general of KEK. "Neutrino oscillation was first established in 1998, with cosmic-ray data taken by Super-Kamiokande. The phenomenon was then corroborated by the K2K experiment with a neutrino beam from KEK. Now MINOS gives firm results in a totally independent experiment. I really congratulate their great effort to obtain the first result in such a short timescale."

According to Harvey Newman, a professor of physics at Caltech who now leads the MINOS group, the campus group has also had a key role in the research and development of the MINOS scintillators and optical fibers.

"Our Caltech group, then led by Michael, also had a key role in the research and development of the scintillators and optical fibers that led to MINOS having enough light to measure the muons that signal neutrino events.

"We are also working on the analysis of electron-neutrino events that could lead to a determination of the subdominant mixing between the first and third neutrino flavors, which is one of the next major steps in understanding the mysterious nature of neutrinos and their flavor-mixings. We are also leading the analysis of antineutrinos in the data, and the prospects for MINOS to determine the mixing of antineutrinos, where comparison of neutrinos and antineutrinos will test one of the most fundamental symmetries of nature (known as CPT).

"We are leading much of the R&D for the next generation, 25-kiloton detector called NOvA. Building on our experience in MINOS, we have designed the basic 50-foot-long liquid scintillator cell which contains a single 0.8 mm optical fiber to collect the light (there will be approximately 600,000 cells). We will measure and optimize the design this year in Lauritsen [a physics building on the Caltech campus], in time for the start of NOvA construction that will be completed by approximately 2010. We've also started prototype work on a future generation of megaton-scale detectors for neutrino and ultrahigh-energy cosmic rays. This has generated a lot of interest among Caltech undergraduates, who are now starting to contribute to these developments in the lab."

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More information on the MINOS experiment: http://www-numi.fnal.gov/>http://www-numi.fnal.gov/

List of institutions collaborating on MINOS: http://www-numi.fnal.gov/collab/institut.html

The members of the Caltech MINOS group: Caius Howcroft, Harvey Newman, Juan "Pedro" Ochoa, Charles Peck, Jason Trevor, and Hai Zheng.

Writer: 
Robert Tindol
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Astronomers Discover a River of Stars Streaming Across the Northern Sky

PASADENA, Calif.—Astronomers have discovered a narrow stream of stars extending at least 45 degrees across the northern sky. The stream is about 76,000 light-years distant from Earth and forms a giant arc over the disk of the Milky Way galaxy.

In the March issue of the Astrophysical Journal Letters, Carl Grillmair, an associate research scientist at the California Institute of Technology's Spitzer Science Center, and Roberta Johnson, a graduate student at California State University Long Beach, report on the discovery.

"We were blown away by just how long this thing is," says Grillmair. "As one end of the stream clears the horizon this evening, the other will already be halfway up the sky."

The stream begins just south of the bowl of the Big Dipper and continues in an almost straight line to a point about 12 degrees east of the bright star Arcturus in the constellation Bootes. The stream emanates from a cluster of about 50,000 stars known as NGC 5466.

The newly discovered stream extends both ahead and behind NGC 5466 in its orbit around the galaxy. This is due to a process called tidal stripping, which results when the force of the Milky Way's gravity is markedly different from one side of the cluster to the other. This tends to stretch the cluster, which is normally almost spherical, along a line pointing towards the galactic center.

At some point, particularly when its orbit takes it close to the galactic center, the cluster can no longer hang onto its most outlying stars, and these stars drift off into orbits of their own. The lost stars that find themselves between the cluster and the galactic center begin to move slowly ahead of the cluster in its orbit, while the stars that drift outwards, away from the galactic center, fall slowly behind.

Ocean tides are caused by exactly the same phenomenon, though in this case it's the difference in the moon's gravity from one side of Earth to the other that stretches the oceans. If the gravity at the surface of Earth were very much weaker, then the oceans would be pulled from the planet, just like the stars in NGC 5466's stream.

Despite its size, the stream has never previously been seen because it is so completely overwhelmed by the vast sea of foreground stars that make up the disk of the Milky Way. Grillmair and Johnson found the stream by examining the colors and brightnesses of more than nine million stars in the Sloan Digital Sky Survey public database.

"It turns out that, because they were all born at the same time and are situated at roughly the same distance, the stars in globular clusters have a fairly unique signature when you look at how their colors and brightnesses are distributed," says Grillmair.

Using a technique called matched filtering, Grillmair and Johnson assigned to each star a probability that it might once have belonged to NGC 5466. By looking at the distribution of these probabilities across the sky, "the stream just sort of reached out and smacked us.

"The new stream may be even longer than we know, as we are limited at the southern end by the extent of the currently available data," he adds. "Larger surveys in the future should be able to extend the known length of the stream substantially, possibly even right around the whole sky."

The stars that make up the stream are much too faint to be seen by the unaided human eye. Owing to the vast distances involved, they are about three million times fainter than even the faintest stars that we can see on a clear night.

Grillmair says that such discoveries are important for our understanding of what makes up the Milky Way galaxy. Like earthbound rivers, such tidal streams can tell us which way is "down," how steep is the slope, and where the mountains and valleys are located.

By measuring the positions and velocities of the stars in these streams, astronomers hope to determine how much "dark matter" the Milky Way contains, and whether the dark matter is distributed smoothly, or in enormous orbiting chunks.

Writer: 
Robert Tindol
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Quasar Study Provides Insights into Composition of the Stars That Ended the "Dark Ages"

WASHINGTON, D.C.-A team of astronomers has uncovered new evidence about the stars whose formation ended the cosmic "Dark Ages" a few hundred million years after the Big Bang.

In a presentation today at the annual winter meeting of the American Astronomical Society (AAS), California Institute of Technology graduate student George Becker is scheduled to discuss his team's investigation of several faraway quasars and the gas between the quasars and Earth. The paper on which his lecture is based will be published in the Astrophysical Journal in March.

One quasar in the study seems to reveal numerous patches of "neutral" gas, made up of atoms where the nucleus and electrons cling together, floating in space when the universe was only about 10 percent of its present age. This gas is thought to have existed in significant quantities only within a certain time-frame in the early universe. Prior to the Dark Ages, all material would have been too hot for atomic nuclei to combine with their electrons; after, the light from newly-formed stars would have reached the atoms and stripped off the electrons.

"There should have been a period when most of the atoms in the universe were neutral," Becker explains. "This would have continued until stars and galaxies began forming."

In other words, the universe went from a very hot, very dense state following the Big Bang where all atomic nuclei and electrons were too energetic to combine, to a less dense and cooler phase-albeit a dark one-where the nuclei and the electrons were cool enough to hold onto each other and form neutral atoms, to today's universe where the great majority of atoms are ionized by energetic particles of light.

Wallace Sargent, who coined the term Dark Ages in 1985 and who is Becker's supervising professor, adds that analyzing the quasars to learn about the early universe is akin to looking at a lighthouse in order to study the air between you and it. During the Dark Ages, neutral atoms filling the universe would have acted like a fog, blocking out the light from distant objects. To end the Dark Ages, enough stars and galaxies needed to form to burn this "cosmic fog" away.

"We may have detected the last wisps of the fog," explains Sargent, who is Bowen Professor of Astronomy at Caltech.

The uniqueness of the new study is the finding that the chemical elements of the cool, un-ionized gas seem to have come from relatively ordinary stars. The researchers think this is so because the elements they detect in the gas- oxygen, carbon, and silicon-are in proportions that suggest the materials came from Type II supernovae.

These particular explosions are caused when massive stars collapse and then rebound to form a gigantic explosion. The stars needed to create these explosions can be more than ten times the mass of the sun, yet they are common over almost the entire history of the universe.

However, astronomers believe that the very first stars in the universe would have been much more massive, up to hundreds of times the mass of the sun, and would have left behind a very different chemical signature.

"If the first stars in the universe were indeed very massive stars," Becker explains, "then their chemical signature was overwhelmed by smaller, more typical stars very soon after."

Becker and his colleagues believe they are seeing material from stars that was blown into space by the supernovae explosions and mixed with the pristine gas produced by the Big Bang. Specifically, they are looking at the spectra of the light from quasars as it is absorbed during its journey through the mixed-up gas.

The quasars in this particular study are from the Sloan Digital Sky Survey, an ongoing mapping project that seeks, in part, to determine the distances of 100,000 quasars. The researchers focused on nine of the most distant quasars known, with redshifts greater than 5, meaning that the light we see from these objects would have been emitted when the universe was at most 1.2 billion years old.

Of the nine, three are far enough away that they may have been at the edge of the dark period. Those three have redshifts greater than 6, meaning that the universe was less than 1 billion years old when they emitted the light we observe. By comparison, the present age of the universe is believed to be about 13.7 billion years.

Becker says that the study in part promises a new tool to investigate the nature of stars in the early universe. "Now that we've seen these systems, it's reasonable to ask if their composition reflects the output of those first very massive stars, or whether the mix of chemicals is what you would expect from more ordinary stars that ended in Type II supernovae.

"It turns out that the latter is the case," Becker says. "The chemical composition appears to be very ordinary."

Thus, the study provides a new window into possible transitions in the early universe, Sargent adds. "The relative abundance of these elements gives us in principle a way of finding out what the first stars were.

"This gives us insight into what kind of stars ended the Dark Ages."

Observations for this study were performed using the 10-meter (400-inch) Keck I Telescope on Mauna Kea, Hawaii. In addition to Becker and Sargent, the other authors are Michael Rauch of the Carnegie Observatories and Robert A. Simcoe of the MIT Center for Space Research.

This work was supported by the National Science Foundation.

Writer: 
Robert Tindol
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