Caltech Astronomer Finds Planets in Unusually Intimate Dance around Dying Star

PASADENA, Calif.—Hundreds of extrasolar planets have been found over the past decade and a half, most of them solitary worlds orbiting their parent star in seeming isolation. With further observation, however, one in three of these systems have been found to have two or more planets. Planets, it appears, come in bunches. Most of these systems contain planets that orbit too far from one another to feel each other's gravity. In just a handful of cases, planets have been found near enough to one another to interact gravitationally.

Now, however, John A. Johnson, an assistant professor of astronomy at the California Institute of Technology (Caltech), and his colleagues have found two systems with pairs of gas giant planets locked in an orbital embrace.

In one system—a planetary pair orbiting the massive, dying star HD 200964, located roughly 223 light-years from Earth-the intimate dance is closer and tighter than any previously seen. "This new planet pair came in an unexpected package," says Johnson.

Adds Eric Ford of the University of Florida in Gainsville, "A planetary system with such closely spaced giant planets would be destroyed quickly if the planets weren't doing such a well synchronized dance. This makes it a real puzzle how the planets could have found their rhythm."

A paper by Johnson, Ford, and their collaborators describing the planets and their intriguing orbital dynamics has been accepted for publication in the Astronomical Journal (see http://arxiv.org/abs/1007.4552 for a preprint).

All of the four newly discovered exoplanets are gas giants more massive than Jupiter, and like most exoplanets were discovered by measuring the wobble, or Doppler shift, in the light emitted by their parent stars as the planets orbit around them. Surprisingly, however, the members of each pair are located remarkably close to one another.

For example, the distance between the planets orbiting HD 200964 occasionally is just .35 astronomical units (AU)—roughly 33 million miles—comparable to the distance between Earth and Mars. The planets orbiting the second star, 24 Sextanis (located 244 light-years from Earth) are .75 AU, or about 70 million miles. By comparison, Jupiter and Saturn are never less than 330 million miles apart.

Because of their large masses and close proximity, the exoplanet pairs exert a large gravitational force on each other. The gravitational tug between HD 200964's two planets, for example, is 3,000,000 times greater than the gravitational force between Earth and Mars, 700 times larger than that between the Earth and the moon, and 4 times larger than the pull of our sun on the Earth.

Unlike the gas giants in our own solar system, the new planets are located comparatively close to their stars. The planets orbiting 24 Sextanis have orbital periods of 455 days (1.25 years) and 910 days (2.5 years), and the companions to HD 200964 periods of 630 days (1.75 years) and 830 days (2.3 years). Jupiter, by contrast, takes just under 12 Earth years to make one pass around the sun.

Planets often move around after they form, in a process known as migration. Migration is thought to be commonplace—it even occurred to some extent within our own solar system—but it isn't orderly. Planets located farther out in the protoplanetary disk can migrate faster than those closer in, "so planets will cross paths and jostle each other around," Johnson says. "The only way they can 'get along' and become stable is if they enter an orbital resonance."

When planets are locked in an orbital resonance, their orbital periods are related by the ratio of two small integers. In a 2:1 resonance, for example, an outer planet will orbit its parent star once for every two orbits of the inner planet; in a 3:2 resonance, the outer planet will orbit two times for every three passes by the inner planet, and so forth. Such resonances are created by the gravitational influence of planets on one another.

"There are many locations in a protoplanetary disk where planets can form," says Johnson. "It's very unlikely, however, that two planets would just happen to form at locations where they have periods in one of these ratios."

A 2:1 resonance—which is the case for the planets orbiting 24 Sextanis—is the most stable and the most common pattern. "Planets tend to get stuck in the 2:1. It's like a really big pothole," Johnson says. "But if a planet is moving very fast"—racing in from the outer part of the protoplanetary disk, where it formed, toward its parent star—"it can pass over a 2:1. As it moves in closer, the next step is a 5:3, then a 3:2, and then a 4:3."

Johnson and his colleagues have found that the pair of planets orbiting HD 200964 is locked in just such a 4:3 resonance. "The closest analogy in our solar system is Titan and Hyperion, two moons of Saturn which also follow orbits synchronized in a 4:3 pattern," says Ford. "But the planets orbiting HD 200964 interact much more strongly, since each is around 20,000 times more massive than Titan and Hyperion combined."

"This is the tightest system that's ever been discovered," Johnson adds, "and we're at a loss to explain why this happened. This is the latest in a long line of strange discoveries about extrasolar planets, and it shows that exoplanets continuously have this ability to surprise us. Each time we think we can explain them, something else comes along."

Johnson and his colleagues found the two systems using data from the Keck Subgiants Planet Survey—a search for planets around stars from 40 to 100 percent larger than our own sun. Subgiants represent a class of stars that have evolved off the "main sequence," and have run out of hydrogen for nuclear fusion, causing their core to collapse and their outer envelope to swell. Subgiants eventually become red giants—voluminous stars with big, puffy atmospheres that pulsate, making it difficult to detect the subtle spectral shifts caused by orbiting planets.

"Subgiants are rotating very slowly and they're cool," unlike rapidly rotating, hot main sequence stars, "but they haven't expanded enough to be too fluffy and too jittery," Johnson says. "They're 'Goldilocks' stars: not too fast, not too hot, not too fluffy, not too jittery"—and, therefore, ideal for planet hunting.

"Right now, we're monitoring 450 of these massive stars, and we are finding swarms of planets," he says. "Around these stars, we are seeing three to four times more planets out to a distance of about 3 AU—the distance of our asteroid belt—than we see around main sequence stars. Stellar mass has a huge influence on frequency of planet occurrence, because the amount of raw material available to build planets scales with the mass of the star."

Eventually, perhaps 10 or 100 million years from now, subgiant stars like HD 200964 and 24 Sextanis will become red giants. They will throw off their outer atmospheres, swelling to the point where they could engulf the inner planet of their dancing pair, and will throw off mass, changing the gravitational dynamics of their whole system. "The planets will then move out, and their orbits will become unstable," Johnson says. "Most likely one of the planets will get flung out of the system completely"-and the dance will end.

The paper, "A Pair of Interacting Exoplanet Pairs Around the Subgiants 24 Sextanis and HD 200964," was coauthored by Matthew Payne and Eric B. Ford of the University of Florida; Andrew W. Howard and Geoffrey W. Marcy of the University of California, Berkeley; Kelsey Clubb of San Francisco State University; Brendan P. Bowler of the University of Hawai'i at Manoa,; Gregory W. Henry of Tennessee State University; Debra A. Fischer, John Brewer, and Christian Schwab of Yale University; Sabine Reffert of ZAH-Landessternwarte; and Thomas Lowe of the UCO/Lick Observatory.

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Kathy Svitil
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Astronomers Discover an Unusual Cosmic Lens

PASADENA, Calif.—Astronomers at the California Institute of Technology (Caltech) and Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have discovered the first known case of a distant galaxy being magnified by a quasar acting as a gravitational lens. The discovery, based in part on observations done at the W. M. Keck Observatory on Hawaii's Mauna Kea, is being published July 16 in the journal Astronomy & Astrophysics.

Quasars, which are extraordinary luminous objects in the distant universe, are thought to be powered by supermassive black holes in the cores of galaxies. A single quasar could be a thousand times brighter than an entire galaxy of a hundred billion stars, which makes studies of their host galaxies exceedingly difficult. The significance of the discovery, the researchers say, is that it provides a novel way to understand these host galaxies.

"It is a bit like staring into bright car headlights and trying to discern the color of their rims," says Frédéric Courbin of EPFL, the lead author on the paper. Using gravitational lensing, he says, "we now can measure the masses of these quasar host galaxies and overcome this difficulty."

According to Einstein's general theory of relativity, if a large mass (such as a big galaxy or a cluster of galaxies) is placed along the line of sight to a distant galaxy, the part of the light that comes from the galaxy will split. Because of this, an observer on Earth will see two or more close images of the now-magnified background galaxy.

The first such gravitational lens was discovered in 1979, and produced an image of a distant quasar that was magnified and split by a foreground galaxy. Hundreds of cases of gravitationally lensed quasars are now known. But, until the current work, the reverse process—a background galaxy being lensed by the massive host galaxy of a foreground quasar—had never been detected.

Using gravitational lensing to measure the masses of distant galaxies independent of their brightness was suggested in 1936 by Caltech astrophysicist Fritz Zwicky, and the technique has been used effectively for this purpose in recent years. Until now, it had never been applied to measure the masses of quasar hosts themselves.

To find the cosmic lens, the astronomers searched a large database of quasar spectra obtained by the Sloan Digital Sky Survey (SDSS) to select candidates for "reverse" quasar-galaxy gravitational lensing. Follow-up observations of the best candidate—quasar SDSS J0013+1523, located about 1.6 billion light years away—using the W. M. Keck Observatory's 10-meter telescope, confirmed that the quasar was indeed magnifying a distant galaxy, located about 7.5 billion light years away.

"We were delighted to see that this idea actually works," says Georges Meylan, a professor of physics and leader of the EPFL team. "This discovery demonstrates the continued utility of gravitational lensing as an astrophysical tool."

"Quasars are valuable probes of galaxy formation and evolution," says Professor of Astronomy S. George Djorgovski, leader of the Caltech team. Furthermore, he adds, "discoveries of more such systems will help us understand better the relationship between quasars and the galaxies which contain them, and their coevolution."

Other coauthors of the Astronomy & Astrophysics paper, entitled "First case of strong gravitational lensing by a QSO: SDSS J0013+1523 at z = 0.120," are Malte Tewes and François Rerat of EPFL, Ashish Mahabal of Caltech, and Dominique Sluse of the Astronomical Research Institute in Heidelberg, Germany. The work done at Caltech was supported by the National Science Foundation and the Ajax Foundation.

Images are available at http://www.astro.caltech.edu/~george/qsolens/.

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Kathy Svitil
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A Mine for Dark Matter

For two weeks in mid-December 2009, the physics world was abuzz with speculation. The Cryogenic Dark Matter Search (CDMS), which had just finished analyzing its final data set, was rumored to have struck gold—they'd actually detected dark matter, the unknown stuff that makes up nearly a quarter of the universe. The rumors had spread through the blogosphere and into the mainstream media.

In the 1930's, Caltech's Fritz Zwicky first proposed the existence of dark matter to account for mass that appeared to be missing in the Coma galaxy cluster. Although astronomers now have lots of evidence to convince themselves dark matter is out there, no one knows for sure what it's made of. The best guess, however, is the hypothetical weakly interacting massive particle, or WIMP. If WIMPs are all around us, they'd be zooming about at hundreds of kilometers per second. But because they hardly interact with regular matter, you can't see or feel them. There could be billions of them streaming through your body right now. Once in a while, though, a WIMP could crash into an atomic nucleus like a cue ball hitting an eight ball, and that's the idea behind most dark-matter searches, including CDMS.

The CDMS detector consists of 30 hockey-puck-sized crystals of germanium waiting for a WIMP to come along. To block cosmic rays that might confuse the signal, CDMS sits about 230 stories deep in the Soudan Underground Laboratory, a research facility run by the University of Minnesota in the bowels of an old iron mine nestled among the lakes and forests at the northeast tip of Minnesota. The CDMS team numbers nearly 80 people from 16 institutions around the world, including Caltech.

Each CDMS detector is a 230-gram germanium crystal. Six detectors are stacked to form one of the five towers that make up the whole apparatus.
Credit: CDMS Collaboration

Although CDMS is far from alone in trying to detect WIMPs, it's been the standard bearer for the past few years. No experiment has yet detected anything, but each silent result narrows down what WIMPs might look like—any theory that predicts something the experiments don't see has to be refined or ruled out. CDMS has provided the tightest constraints yet, and these latest results, taken over a period of more than a year, have doubled the collaboration's data. If physicists are close to finding WIMP collisions, then CDMS will be the first experiment to do so—which explains why people became so anxious upon hearing the rumors. The hype underscores just how momentous a dark-matter discovery would be. "It's a really exciting topic," says Sunil Golwala, associate professor of physics and a member of the CDMS team. His two graduate students, Zeeshan Ahmed (MS '08) and David Moore, did a lot of the number crunching for the new data. "Suppose you have conclusive evidence that you just discovered the dark matter in the universe," Golwala says. "I mean, that's just amazing."

WIMP fever was running high on December 17, when physicists packed into auditoriums in California and Illinois to hear what, if anything, CDMS had discovered. The Economist had written on that day, "If the rumors are true, a solution to one of the great problems of physics may now be within reach." JoAnne Hewett, a particle physicist at the Stanford Linear Accelerator Center, even liveblogged the event on Cosmic Variance, a popular physics blog. "The excitement in the air is palpable," she wrote. "Not much work is being done—everyone is pretty much talking in the hallways, trying to pass the time until 2:00."

Finally, the results were announced—two events had been found! But before booking flights to Stockholm, the team calculated that there was a 23 percent chance these signals were caused by background—likely collisions with electrons, instead of nuclei, that had snuck past their set of criteria for a true WIMP detection. As Golwala points out, "No one claims discovery with that high of a chance." The team couldn't say they had discovered dark matter, but they couldn't rule it out, either.

So CDMS hasn't revolutionized our understanding of the universe—yet. As for all the hype? "In a couple of months, no one will remember this," Golwala says. Still, their results—published in the March 26 issue of Science—are noteworthy, placing the most stringent constraints yet on what WIMPs could be. "It's an exciting time in the bigger sense, because we've been producing results from this experiment for about five years," he says. "We've been the premier experiment in this field." These data sets are marking the end of the current chapter in dark-matter searches. But new experiments are already under way, and in the next couple of years, a half-dozen more projects will begin—and they'll be many times more sensitive than CDMS. Says postdoc and CDMS team member Jeff Filippini, "It's very possible that in the next five years we might be talking about WIMP astronomy, rather than just trying to detect something."

Read the full story at E&S online.

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Marcus Woo
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Astronomical Society of the Pacific Honors Caltech Achievements

A constellation of Caltechers has been honored this week by the Astronomical Society of the Pacific, the world's largest general astronomy society. The ASP announced eight 2010 awards for "excellence in astronomy research and education," four of them recognizing people and programs affiliated with the Caltech community.

The honorees are Gerry Neugebauer, Caltech's Millikan Professor of Physics, Emeritus; Robert Quimby, a postdoctoral scholar in astronomy at Caltech; Alex Filippenko, the Goldman Distinguished Professor in the Physical Sciences at UC Berkeley and a Caltech alumnus; and the Spitzer Space Telescope team, based on the Caltech campus and at Pasadena's Jet Propulsion Laboratory. One of NASA's four "Great Observatories," the telescope is operated by Caltech and JPL on behalf of NASA.

The awards will be presented at the ASP awards banquet on August 3 in Boulder, Colorado, as part of the society's annual meeting.

Neugebauer, who joined the Institute faculty shortly after earning his Caltech PhD in 1960, is the recipient of the ASP's Catherine Wolfe Bruce Gold Medal for lifetime achievement in astronomy. The Caltech scientist is widely recognized as one of the pioneers in the field of infrared astronomy, working with colleagues to make the first infrared map of the galactic center, the first infrared survey of the sky, and leading the science team of the Infrared Astronomical Satellite (IRAS), the first space-based telescope to survey the cosmos at infrared wavelengths.  

Quimby, who came to Caltech after earning his PhD at the University of Texas, was honored with the Robert J. Trumpler Award for his outstanding recent PhD thesis, which "led to improved understanding of the detonation process" in certain types of supernovae.He was also cited for his discovery of the "first 'pair instability supernova'—a phenomenon now thought to occur in very massive stars like those that formed at the end of the cosmological 'dark ages,' when the universe's first stars and galaxies condensed out of matter.

Filippenko, who received his PhD from Caltech in 1984, was presented with the Richard H. Emmons Award for excellence in the teaching of college-level introductory astronomy for non-science majors. Internationally known for his research on supernovas, gamma-ray bursts, black holes, quasars, and dark energy, Filippenko has received Berkeley's "best professor" award six times in his career, as well as numerous other national teaching honors, and has produced four astronomy video courses and coauthored an award-winning textbook.

The Spitzer Space Telescope Team received the Maria and Eric Muhlmann Award, which recognizes "recent significant observational results made possible by innovative advances in astronomical instrumentation and techniques." Launched in 2003 as a successor to IRAS, the telescope is carrying out the most detailed and comprehensive survey ever made of the infrared sky.

The team was cited for innovative engineering approaches, including "the extensive use of radiative cooling that extended the cryogenic lifetime of the telescope from the planned nominal mission of two and half years to nearly six before the liquid helium coolant was exhausted."

A newly expanded image of the Helix nebula lends a festive touch to the fourth anniversary of the launch of NASA's Spitzer Space Telescope.
Credit: NASA/JPL-Caltech/ J. Hora (Harvard-Smithsonian CfA)

These technologies kept the telescope cooled to very low temperatures and shielded it from the heat of the sun and other extraneous infrared sources, including Earth and the telescope itself.  

In May 2009, the telescope's liquid coolant ran dry. Spitzer is now in the "warm"phase of its mission, continuing to return scientific data on two infrared channels that are able to operate without coolant.

Established in 1889, the Astronomical Society of the Pacific aims to increase the understanding and appreciation of astronomy by engaging scientists, educators, enthusiasts, and the public to advance science and science literacy through mission-based astronomy and space-science education and public outreach activities. Today, its membership comprises professional and amateur astronomers and educators from more than 70 countries. 

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Heidi Aspaturian
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Caltech Receives More than $33 Million from American Recovery and Reinvestment Act

Neuroeconomics and the fundamentals of jet noise just some of the many projects supported

PASADENA, Calif.-Research in genomic sciences, astronomy, seismology, and neuroeconomics are some of the many projects being funded at the California Institute of Technology (Caltech) by the American Recovery and Reinvestment Act (ARRA).

As part of the federal government program of stimulating the economy, ARRA is providing approximately $21 billion for research and development. The goal is for the funding to lead to new scientific discoveries and to support jobs.

ARRA provides the funds to federal research agencies such as the National Institutes of Health, the National Science Foundation, and the Department of Energy, which then support proposals submitted by universities and other research institutions from across the country.

Caltech has received 82 awards to date, totaling more than $33 million. Spending from the grants began in the spring of 2009 and thus far has led to the support of 93 jobs at the Institute.

"This funding will help lead to substantive and important work here at Caltech," says Caltech president Jean-Lou Chameau. "We're grateful to have this opportunity to advance research designed to benefit the entire country."

For biologist Paul Sternberg, the Thomas Hunt Morgan Professor of Biology at Caltech and a Howard Hughes Medical Institute investigator, the ARRA funds mean an opportunity to improve upon WormBase, an ongoing multi-institutional effort to make genetic information on the experimental animal C. elegans freely available to the world.

"All biological and biomedical researchers rely on publicly available databases of genetic information," says Sternberg. "But it has been expensive and difficult to extract information from scientific research articles. We have developed some tools to make it less expensive and less tedious to get the job done, for WormBase and many other groups."

Sternberg's ARRA funds-$989,492-will go towards developing a more efficient approach to extracting key facts from published biological-science papers.

Among the other diverse Caltech projects receiving ARRA funds are:

  • a catalog of jellyfish DNA;
  • improving the speed of data collection at Caltech's Center of Excellence in Genomic Science;
  • studies into the fundamentals of particle physics;
  • the California High School Cosmic Ray Observatory (CHICOS) program, which provides high school students access to cosmic ray research;
  • the search for new astronomical objects such as flare stars and gamma-ray bursts, and the means to make those discoveries accessible to the public; and
  • a $1 million upgrade of the Southern California Seismic Network.

Caltech Professor of Mechanical Engineering Tim Colonius received ARRA funds for research into better understanding how noise is created by turbulence in the exhaust of turbofan aircraft engines and what might be done to mitigate it. Jet noise is an environmental problem subject to increasingly severe regulation throughout the world.

"To meet the ambitious noise-reduction goals under discussion, a greatly enhanced understanding of the basic physics is needed," says Colonius. "Very large-scale computer simulations and follow-up analyses will bring us much closer to the goal of discovering the subtle physical mechanisms responsible for the radiation of jet noise and allow us to develop methods for suppressing it."

Colonius received $987,032 in ARRA funds from the National Science Foundation.

Colin Camerer, the Robert Kirby Professor of Behavioral Economics, received his ARRA funds to explore the application of neurotechnologies to solving real-life economic problems.

"Our project, with my Caltech colleague Antonio Rangel, will explore the psychological and neural correlates of value and decision-making and their use in improving the efficiency of social allocations," says Camerer.

Camerer and his colleagues previously found that they could use information obtained through functional magnetic resonance imaging measurements to develop solutions to economic challenges.

Rangel, an associate professor of economics, has a second ARRA-funded project to analyze the neuroeconomics of self-control in dieting populations.

"Funding of this nature is critical to much of the work we do here at Caltech," adds Chameau. "And with ARRA support, dramatic discoveries may be just around the corner."

For a complete list of ARRA projects, visit: http://www.recovery.gov

# # #

About Caltech:

Caltech is recognized for its highly select student body of 900 undergraduates and 1,200 graduate students, and for its outstanding faculty. Since 1923, Caltech faculty and alumni have garnered 32 Nobel Prizes and five Crafoord Prizes.

In addition to its prestigious on-campus research programs, Caltech operates the Jet Propulsion Laboratory (JPL), the W. M. Keck Observatory in Mauna Kea, the Palomar Observatory, and the Laser Interferometer Gravitational-Wave Observatory (LIGO). Caltech is a private university in Pasadena, California. For more information, visit http://www.caltech.edu.

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Jon Weiner
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Caltech Physicist Named National Security Science and Engineering Faculty Fellow

PASADENA, Calif.-The Department of Defense (DoD) has named H. Jeff Kimble, William L. Valentine Professor and professor of physics at the California Institute of Technology (Caltech), one of 11 university faculty scientists and engineers in its 2010 class of National Security Science and Engineering Faculty Fellows (NSSEFF).

Up to $4.2 million of direct research support will be given to each NSSEFF fellow for up to five years to conduct unclassified research on topics of interest to the DoD. The grants are intended to engage the next generation of outstanding scientists and engineers in exploring the most challenging technical issues facing the DoD.

"These distinguished researchers have a demonstrated record of success in fields of strategic importance to the DoD. Their NSSEFF work will not only contribute to preparing the DoD and the nation for an uncertain future, but will also develop the necessary high quality science, technology, engineering, and mathematics talent that will be essential to the department's continued success," says the DoD's Zachary J. Lemnios, director of Defense Research and Engineering.

The fellows conduct basic research in core science and engineering disciplines that are expected to underpin future DoD technology development. Kimble's research proposal will be carried out by graduate students and postdoctoral associates in his Quantum Optics Group at Caltech. The research will build on the foundation of an existing advanced laboratory infrastructure for the manipulation of single atoms and photons.

"The receipt of the NSSEFF award is wonderful news for my research group," says Kimble. "In a time of increasingly proscriptive funding of basic research, this grant will enable exciting new opportunities for achieving strong interactions between single atoms, photons, and phonons."

Kimble's research program will attempt to harness strong interactions between light and matter to implement complex quantum networks and thereby to investigate qualitatively new phenomena in quantum information science.

More than 800 nomination letters from academic institutions led to the selection of the 21 NSSEFF semifinalists and the final 11 fellows.

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Jon Weiner
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Caltech Mourns the Passing of Andrew Lange

Dr. Andrew Lange, the Marvin L. Goldberger Professor of Physics at Caltech, passed away Friday, January 22, 2010.

Lange had been at Caltech since 1993. He graduated from Princeton University with his BA in 1980 and received his PhD from UC Berkeley in 1987. He first came to the Institute as a visiting associate in 1993-94, was appointed a full professor in 1994, and was named the Goldberger Professor in 2001. In 2006 he was named a senior research scientist at the Jet Propulsion Laboratory and in 2008 was appointed chair of the Division of Physics, Mathematics and Astronomy. He had recently resigned from his chairmanship of the division.

The principal focus of Lange's research was the Cosmic Microwave Background (CMB)-a gas of thermal radiation left over from the Big Bang-that filled the entire universe. He developed a new generation of radio-frequency detectors and led a string of experiments that employed this novel technology to study the CMB. He is perhaps best known for co-leading the BOOMERanG experiment, the first experiment to image the CMB with sufficiently high fidelity and angular resolution to determine that the spatial geometry of the universe is flat. The data further allowed precise measurement of the age of the universe and the abundance of the dark matter known to hold galaxies together. The data also supported previous measurements that suggested that the cosmological expansion is actually accelerating, implying either a violation of Einstein's general relativity or that the Universe is filled with "dark energy," some exotic new negative-pressure fluid. BOOMERanG also confirmed the predictions of inflation, an ambitious theory that aims to explain the very earliest fraction of a nanosecond after the Big Bang.

Lange's subsequent work has improved upon these measurements and aimed also to detect the primordial gas of gravitational waves predicted by inflation through their effect on the CMB polarization. Lange was also one of the leaders of the recently launched Planck satellite, a collaboration between US and European scientists that aims to image the CMB with unprecedented precision.

Lange was a member of the American Academy of Arts and Sciences, the National Academy of Sciences, and the American Physical Society. Lange and Dr. Saul Perlmutter (from the Lawrence Berkeley National Laboratory) were jointly named the 2003 California Scientist of the Year for their seminal contributions to cosmology. Lange shared the 2006 Balzan Prize for Observational Astronomy and Astrophysics with Paolo de Bernardis (of the University of Rome), his BOOMERanG coleader. The two shared the 2009 Dan David Prize with Paul Richards, a coleader of the parallel MAXIMA experiment.

Counseling services are available 24 hours a day to Caltech students at the Counseling Center. Other members of the campus community may visit the Counseling Center website or call the Staff and Faculty Consultation Center at (626) 395-8360.

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Jon Weiner
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Caltech Astronomer Spots Second Smallest Exoplanet

Discovery highlights new potential for eventually finding Earth-mass planets

PASADENA, Calif.-Astronomers from the California Institute of Technology (Caltech) and other institutions, using the highly sensitive 10-meter Keck I telescope atop Hawaii's Mauna Kea, have detected an extrasolar planet with a mass just four times that of Earth. The planet, which orbits its parent star HD156668 about once every four days, is the second-smallest world among the more than 400 exoplanets (planets located outside our solar system) that have been found to date. It is located approximately 80 light-years from Earth in the direction of the constellation Hercules.

The find, made possible through NASA's Eta-Earth Survey for Low-Mass Planets was announced last week at the 215th American Astronomical Society meeting held January 4-7, 2010, in Washington, D.C.

Dubbed HD 156668b, the planet-a so-called "super Earth" that would glow with blast-furnace-like temperatures-offers a tantalizing hint of discoveries yet to come. Astronomers hope those discoveries will include Earth-size planets located in the "habitable zone," the area roughly the distance from the earth to the sun, and thus potentially favorable to life.

HD 156668b was discovered with the radial velocity or wobble method, which relies on Keck's High Resolution Echelle Spectrometer (HIRES) to spread light collected from the telescope into its component wavelengths or colors, producing a spectrum. As the planet orbits the star, it causes the star to move back and forth along our line of sight, which causes the starlight to become redder and then bluer in a periodic fashion.

The color shifts give astronomers the mass of the planet and the characteristics of its orbit, such as how much time it takes to orbit the star. The majority of the exoplanets discovered have been found in this way.

The discovery of low-mass planets like HD 156668b has become possible due to the development of techniques to watch stars wobble with increasing clarity, and of software that can pluck the signals of increasingly smaller planets from amid the 'noise' made by their pulsating, wobbling parent stars.

"If the stars themselves have imperfections and are unstable, their wobbling would cause jumps in velocity that could mimic or hide the existence of a planet," says John A. Johnson, assistant professor of astronomy at Caltech and codiscoverer of the new planet along with Andrew Howard and Geoff Marcy of the University of California at Berkeley, Debra Fischer of Yale University, Jason Wright of Penn State University, and the members of the California Planet Survey collaboration.

"We have been doing simulations to understand the astrophysics of these imperfections, and how to distinguish them from the signals from a planet," says Johnson. "We hope to use these simulations to design even better observing strategies and data-analysis techniques."

The discovery of a planet that is comparable in size to Earth and found within the habitable zone, however, "will require a great deal of work," he says. "If we could build the best possible radial-velocity instrument tomorrow, we might have answers in three years, and a solid census of Earthlike planets within a decade. We'll need gigantic leaps in sensitivity to get there, and we're hot on the trail."

Johnson is also currently building a new camera for the 60-inch telescope at Caltech's Palomar Observatory. The camera will allow astronomers to search for the passages-or transits-of low-mass planets like HD156668 across the faces of their stars.

"If we catch the planet in transit, we can measure the planet's radius and density, and therefore address the question of whether the planet has a composition more like Earth, with a solid surface and thin atmosphere, or is a miniature version of Neptune, with a heavy gaseous atmosphere," he says.

The Keck I telescope is part of the Keck Observatory, a joint effort of Caltech and the University of California.

For more information about extrasolar planet discoveries, visit http://exoplanets.org.

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Kathy Svitil
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Caltech Physicists Propose Quantum Entanglement for Motion of Microscopic Objects

PASADENA, Calif.—Researchers at the California Institute of Technology (Caltech) have proposed a new paradigm that should allow scientists to observe quantum behavior in small mechanical systems. 

Their ideas, described in the early online issue of the Proceedings of the National Academy of Sciences, offer a new means of addressing one of the most fascinating issues in quantum mechanics: the nature of quantum superposition and entanglement in progressively larger and more complex systems. 

A quantum superposition is a state in which a particle, such as a photon or atom, exists simultaneously in two locations. Entanglement, which Albert Einstein called "spooky action at a distance," allows particles to share information even if they are physically separated.

A key challenge in observing quantum behavior in a small mechanical system is suppressing interactions between the system and its noisy environment—i.e., the surrounding material supporting the system or any other external contact. The random thermal vibrations of the system's surroundings, for example, can be transferred to the mechanical object and destroy its fragile quantum properties. To address this issue, a number of groups worldwide have begun to use cryogenic setups in which the immediate environment is cooled down to a very low temperature to reduce the magnitude of these random vibrations.

The Caltech team suggests a fundamentally different approach: using the forces imparted by intense beams of light to "levitate" the entire mechanical object, thereby freeing it from external contact and material supports. This approach, the researchers show, can dramatically reduce environmental noise, to the point where diverse manifestations of quantum behavior should be observable even when the environment is at room temperature. 

Among the scientists involved in the work are Darrick Chang, a postdoctoral scholar at Caltech's Institute for Quantum Information; Oskar Painter, associate professor of applied physics; and H. Jeff Kimble, Caltech's William L. Valentine Professor and professor of physics.

The idea of using optical forces to trap or levitate small particles is actually well established. It was pioneered by Arthur Ashkin of Bell Laboratories in the 1970s and 1980s, and has since formed the basis for scientific advances such as the development of "optical tweezers"—which are frequently used to control the motion of small biological objects—and the use of lasers to cool atoms and trap them in space. These techniques provide an extremely versatile toolbox for manipulating atoms, and have been employed to demonstrate a variety of quantum phenomena at the atomic level. 

In the new work, Chang and his colleagues demonstrate theoretically that similar success can be achieved when an individual atom is replaced by a much more massive—but still nanoscale—mechanical system. A related scheme has been presented simultaneously by a group at the Max Planck Institute of Quantum Optics in Garching, Germany [http://arxiv.org/abs/0909.1469]. 

The system proposed by the Caltech team consists of a small sphere made out of a highly transparent material such as fused silica. When the sphere comes into contact with a laser beam, optical forces naturally push the sphere toward the point where the intensity of light is greatest, trapping the sphere at that point. The sphere typically spans about 100 nm in diameter, or roughly a thousandth the width of a human hair.  Because of its small size, the sphere's remaining interactions with the environment—any that don't involve direct contact with another material, because the sphere is levitating—are sufficiently weak that quantum behavior should easily emerge.

For such behavior to appear, however, the sphere must also be placed inside an optical cavity, which is formed by two mirrors located on either side of the trapped sphere. The light that bounces back and forth between the mirrors both senses the motion of the sphere and is used to manipulate that motion at a quantum-mechanical level.

The researchers describe how this interaction can be used to remove energy from, or cool, the mechanical motion until it reaches its quantum ground state—the lowest energy allowable by quantum mechanics. A fundamental limit to this process is set by the relative strengths of the optical cooling and the rate at which the environment tends to heat (return energy to) the motion, bringing it back to the ambient temperature. 

In principle, the motion of the well-isolated sphere can be cooled starting from room temperature down to a final temperature that is ten million times lower; in that super-cooled state, the center of mass of the sphere moves by only the minimum possible amount set by intrinsic quantum fluctuations. 

The researchers also propose a scheme to observe a feature known as entanglement, which lies at the heart of quantum mechanics. Two remotely located systems that are quantum entangled share correlations between them that are stronger than classically allowed. In certain circumstances, entanglement can be a very valuable resource; it forms the basis for proposals to realize improved metrology and more powerful (quantum) computers.

The proposed scheme consists of sending a pair of initially entangled beams of light —the production of which was first accomplished by Kimble's group at Caltech in 1992—into two separate cavities, each containing a levitated sphere. Through a process known as quantum-state transfer, all of the properties of the light—in particular, the entanglement and its associated correlations—can be mapped onto the motion of the two spheres. 

While the sizes of these nanomechanical objects are still very far from those we associate with everyday experience, the Caltech researchers believe that their proposal presents an exciting opportunity to realize and control quantum phenomena at unprecedented scales—in this case, for objects containing approximately 10 million atoms.

Other researchers involved in this work include graduate student Dalziel Wilson and postdoctoral scholars Cindy Regal and Scott Papp at Caltech; Jun Ye, a fellow at JILA, a joint institute of the University of Colorado at Boulder and the National Institute of Standards and Technology; and Peter Zoller, a professor at the University of Innsbruck. The work was initiated while Ye and Zoller were visiting as Gordon and Betty Moore Distinguished Scholars at Caltech.

The work in the PNAS paper, "Cavity optomechanics using an optically levitated nanosphere," was supported by the Gordon and Betty Moore Foundation, the National Science Foundation, the Army Research Office, Northrop Grumman Space Technology, the Austrian Science Fund, and European Union Projects.

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High Energy Physicists Set New Record for Network Data Transfer

Caltech-led high-energy physicists show how long range networks can be used to support leading edge science

PASADENA, Calif. - Building on eight years of record-breaking developments, and on the restart of the Large Hadron Collider (LHC), an international team of high-energy physicists, computer scientists, and network engineers led by the California Institute of Technology (Caltech) joined forces to capture the Bandwidth Challenge award for massive data transfers during the SuperComputing 2009 (SC09) conference held in Portland, Oregon.

Caltech's partners in the project include scientists from Michigan (UM), Fermilab, Brookhaven National Laboratory, CERN, San Diego (UCSD), Florida (UF and FIU), Brazil (Rio de Janeiro State University, UERJ, and the São Paulo State University, UNESP), Korea (Kyungpook National University, KISTI), Estonia (NICPB) and Pakistan (NUST).

Caltech's exhibit at SC09 by the High Energy Physics (HEP) group and the Center for Advanced Computing Research (CACR) demonstrated applications for globally distributed data analysis for the LHC at CERN. It also demonstrated Caltech's worldwide collaboration system, EVO (Enabling Virtual Organizations; http://evo.caltech.edu), developed with UPJS in Slovakia; its global-network and grid monitoring system MonALISA (http://monalisa.caltech.edu); and its Fast Data Transfer application (http://monalisa.caltech.edu/FDT), developed in collaboration with the Politechnica University (Bucharest). The CACR team also showed near-real-time simulations of earthquakes in the Southern California region, experiences in time-domain astronomy with Google Sky, and recent results in multiphysics multiscale modeling.
 
The focus of the exhibit was the HEP team's record-breaking demonstration of storage-to-storage data transfer over wide area networks from two racks of servers and a network switch-router on the exhibit floor. The high-energy physics team's demonstration, "Moving Towards Terabit/Sec Transfers of Scientific Datasets: The LHC Challenge," achieved a bidirectional peak throughput of 119 gigabits per second (Gbps) and a data flow of more than 110 Gbps that could be sustained indefinitely among clusters of servers on the show floor and at Caltech, Michigan, San Diego, Florida, Fermilab, Brookhaven, CERN, Brazil, Korea, and Estonia.
 
Following the Bandwidth Challenge, the team continued its tests and established a world-record data transfer between the Northern and Southern hemispheres, sustaining 8.26 Gbps in each direction on a 10 Gbps link connecting São Paulo and Miami.

By setting new records for sustained data transfer among storage systems over continental and transoceanic distances using simulated LHC datasets, the HEP team demonstrated its readiness to enter a new era in the use of state-of-the-art cyber infrastructure to enable physics discoveries at the high energy frontier, while demonstrating some of the groundbreaking tools and systems they have developed to enable a global collaboration of thousands of scientists located at 350 universities and laboratories in more than 100 countries to make the next round of physics discoveries.
  
"By sharing our methods and tools with scientists in many fields, we hope that the research community will be well-positioned to further enable their discoveries, taking full advantage of current networks, as well as next-generation networks with much greater capacity as soon as they become available," says Harvey Newman, Caltech professor of physics, head of the HEP team, colead of the U.S. LHCNet, and chair of the U.S. LHC Users Organization. "In particular, we hope that these developments will afford physicists and young students throughout the world the opportunity to participate directly in the LHC program, and potentially to make important discoveries."

The record-setting demonstrations were made possible through the use of fifteen 10 Gbps links to the SC09 booth provided by SCinet, together with National Lambda Rail (11 links including six dedicated links to Caltech) and CENIC, Internet2 (two links), ESnet, and Cisco. The Caltech HEP team used its dark-fiber connection to Los Angeles provided by Level3 and a pair of DWDM optical multiplexers provided by Ciena Corporation to light the fiber with a series of 10G wavelengths to and from the Caltech campus in Pasadena. Ciena also supported a portion of the Caltech traffic with a single serial 100G wavelength running into the SC09 conference from the Portland Level3 PoP, operating alongside other links into SC09 from Portland. Onward connections to the partner sites included links via Esnet and Internet2 to UCSD; FLR to University of Florida as well as FIU and Brazil; MiLR to Michigan; Starlight and USLHCNet to CERN; AMPATH, together with RNP and ANSP, to Brazil via Southern Light; GLORIAD and KREONet to Korea; and Internet2 and GEANT3 to Estonia.
 
The network equipment at the Caltech booth was a single heavily populated Nexus 7000 series switch-router provided by Cisco and a large number of 10 gigabit Ethernet server-interface cards provided by Myricom. The server equipment on the show floor included five widely available Supermicro 32 core servers using Xeon quad core processors with 12 Seagate SATA disks each, and 18 Sun Fire X4540 servers, each with 12 cores and 48 disks provided by Sun Microsystems.

One of the features of next-generation networks supporting the largest science programs-notably the LHC experiments-is the use of dynamic circuits with bandwidth guarantees crossing multiple network domains. The Caltech team at SC09 used Internet2's recently announced ION service-developed together with ESnet, GEANT and in collaboration with US LHCNet-to create a dynamic circuit between Portland and CERN as part of the bandwidth-challenge demonstrations.

One of the key elements in this demonstration was Fast Data Transfer (FDT), an open-source Java application developed by Caltech in close collaboration with Politechnica University in Bucharest.  FDT runs on all major platforms and uses the NIO libraries to achieve stable disk reads and writes coordinated with smooth data flow using TCP across long-range networks. The FDT application streams a large set of files across an open TCP socket, so that a large data set composed of thousands of files-as is typical in high-energy physics applications-can be sent or received at full speed, without the network transfer restarting between files. FDT can work on its own, or together with Caltech's MonALISA system, to dynamically monitor the capability of the storage systems as well as the network path in real time, and send data out to the network at a moderated rate that achieves smooth data flow across long-range networks. 


Since it was first deployed at SC06, FDT has been shown to reach sustained throughputs among storage systems at 100 percent of network capacity where needed in production use, including among systems on different continents. FDT also achieved a smooth bidirectional throughput of 191 Gbps (199.90 Gbps peak) using an optical system carrying an OTU-4 wavelength over 80 km provided by CIENA last year at SC08.

Another new aspect of the HEP demonstration was large-scale data transfers among multiple file systems widely used in production by the LHC community, with several hundred terabytes per site. This included two recently installed instances of the open-source file system Hadoop, where in excess of 9.9 Gbps was read from Caltech on one 10 Gbps link, and up to 14 Gbps was read on shared ESnet and NLR links, a level just compatible with the production traffic on the same links. The high throughput was achieved through the use of a new FDT/Hadoop adaptor-layer written by NUST in collaboration with Caltech.

The SC09 demonstration also achieved its goal of clearing the way to Terabit/sec (Tbps) data transfers. The 4-way Supermicro servers at the Caltech booth-each with four 10GE Myricom interfaces-provided 8.3Gbps of stable throughput each, reading or writing on 12 disks, using FDT. A system capable of one Tbps to or from storage could therefore be built today in just six racks at relatively low cost, while also providing 3840 processing cores and 3 Petabytes of disk space, which is comparable to the larger LHC centers in terms of computing and storage capacity.

An important ongoing theme of SC09-including at the Caltech booth, where the EVOGreen initiative (www.evogreen.org) was highlighted-was the reduction of carbon footprint through the use of energy-efficient information technologies. A particular focus is the use of systems with a high ratio of computing and I/O performance to energy consumption. In the coming year, in preparation for SC10 in New Orleans, the HEP team will be looking into the design and construction of compact systems with lower power and cost that are capable of delivering data at several hundred Gbps, aiming to reach 1 Tbps by 2011 when multiple 100 Gbps links into SC11 may be available.   

The two largest physics collaborations at the LHC-CMS and ATLAS, each encompassing more than 2,000 physicists, engineers, and technologists from 180 universities and laboratories-are about to embark on a new round of exploration at the frontier of high energies. When the LHC experiments begin to take collision data in a new energy range over the next few months, new ground will be broken in our understanding of the nature of matter and space-time, and in the search for new particles. In order to fully exploit the potential for scientific discoveries during the next year, more than 100 petabytes (1017 bytes) of data will be processed, distributed, and analyzed using a global grid of 300 computing and storage facilities located at laboratories and universities around the world, rising to the exabyte range (1018 bytes) during the following years.

The key to discovery is the analysis phase, where individual physicists and small groups located at sites around the world repeatedly access, and sometimes extract and transport, multi-terabyte data sets on demand from petabyte data stores in order to optimally select the rare "signals" of new physics from the potentially overwhelming "backgrounds" from already-understood particle interactions. The HEP team hopes that the demonstrations at SC09 will pave the way toward more effective distribution and use for discoveries of the masses of LHC data.

The demonstration and the developments leading up to the SC09 Bandwidth Challenge were made possible through the support of the partner network organizations mentioned, the National Science Foundation (NSF), the U.S. Department of Energy (DOE) Office of Science, and the funding agencies of the HEP team's international partners, as well as the U.S. LHC Research Program funded jointly by DOE and NSF.

Further information about the demonstration may be found at http://supercomputing.caltech.edu

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