Smallest Galaxies Solve a Big Problem

PASADENA, Calif.--An unusual population of the darkest, most lightweight galaxies known has shed new light on a cosmic conundrum. Astronomers used the W. M. Keck Observatory in Hawaii to show that the recently uncovered dwarf galaxies each contain 99 percent of a mysterious type of matter known as dark matter. Dark matter has gravitational effects on ordinary atoms but does not produce any light. It accounts for the majority of the mass in the universe.

New observations of eight of these galaxies now suggest that the "Missing Dwarf Galaxy" problem--a discrepancy between the number of extremely small, faint galaxies that cosmological theories predict should exist near the Milky Way, and the number that have actually been observed--is not as severe as previously thought, and may have been solved completely.

"These new dwarf galaxies are fascinating systems, not only because of their major contribution to the Missing Dwarf problem, but also as individual galaxies," says Josh Simon, a Millikan Postdoctoral Scholar at the California Institute of Technology and the lead author of the study. "We had no idea that such small galaxies could even exist until these objects were discovered last year."

The Missing Dwarf Galaxy puzzle comes from a prediction of the "Cold Dark Matter" model, which explains the growth and evolution of the universe. The theory predicts that large galaxies like the Milky Way should be surrounded by a swarm of up to several hundred smaller galaxies, known as "dwarf galaxies" because of their diminutive size. But until recently, only 11 such companions were known to be orbiting the Milky Way. To explain why the missing dwarfs were not seen, theorists suggested that although hundreds of the galaxies indeed may exist near the Milky Way, most have few, if any, stars. If so, they would be comprised almost entirely of dark matter.

In the past two years, researchers struggling to prove the existence of nearly invisible galaxies were aided by images from the Sloan Digital Sky Survey that revealed as many as 12 additional very faint dwarf galaxies near the Milky Way. The new systems are unusually small, even compared to other dwarf galaxies; the least massive among them contain only 1 percent as many stars as the most minuscule galaxies previously known.

"When they were discovered, we didn't know if all of these ultrafaint objects were actually galaxies," says Marla Geha, a Plaskett Research Fellow at the National Research Council Canada's Herzberg Institute of Astrophysics. "We thought some of them might simply be globular star clusters, or that they could be the shredded remnants of ancient galaxies torn apart by the Milky Way long ago. To test these possibilities, we needed to measure their masses."

Simon and Geha used the DEIMOS spectrograph on the 10-meter Keck II telescope at the W. M. Keck Observatory in Hawaii to conduct follow-up studies of eight of the new galaxies. The duo used the Doppler effect--a shift in the wavelength of the light coming from the galaxies caused by their motion with respect to the earth--to determine the speeds of stars within the dwarf galaxies. "Because stars in galaxies move only under the influence of gravity, their speeds are determined by the total mass of the galaxy," says Simon. To the researchers' surprise, each system was among the smallest ever measured, more than 10,000 times less massive than the Milky Way.

"It seems that very small, ultrafaint galaxies are far more plentiful than we thought. I'm astonished that so many tiny, dark matter-dominated galaxies have now been discovered," says Geha.

"The formation of such small galaxies is not very well understood from a theoretical perspective," adds Simon. "Explaining how stars form inside these remarkably tiny galaxies is difficult, and so it is hard to predict exactly how many star-containing dwarfs we should find near the Milky Way. Our work narrows the gap between the Cold Dark Matter theory and observations by significantly increasing the number of Milky Way dwarf galaxies and telling us more about the properties of these galaxies."

Numerous, repeated measurements of 814 stars in the eight dwarf galaxies were obtained at W. M. Keck Observatory. The speeds of the stars, ranging from about 4 to 7 km/s, were much slower than the stellar velocities in any other known galaxy. For comparison, the sun orbits the center of the Milky Way at about 220 km/s. The astronomers measured precise speeds for 18 to 214 stars in each galaxy, three times more stars per galaxy than any previous study.

"This is a significant paper," says Taft Armandroff, director of the W. M. Keck Observatory, whose research includes the study of dwarf galaxies. "It is a compelling example of how large, ground-based telescopes can precisely measure the orbits of distant stars on the sky to just a few kilometers per second. I expect DEIMOS will soon tell us about the chemical composition of these stars to help us better understand how star formation takes place in such small galaxies."

Some parameters of the Cold Dark Matter theory can now be updated to match observed conditions in the local universe. Based on the masses measured for the new dwarf galaxies, Simon and Geha conclude that the fierce ultraviolet radiation given off by the first stars, born just a few hundred million years after the Big Bang, may have blown away all of the hydrogen gas from dwarf galaxies also forming at that time. The loss of gas prevented the galaxies from creating new stars, leaving them very faint, or, in many cases, completely dark. When this effect is included in theoretical models, the number of expected dwarf galaxies agrees with the number of observed dwarf galaxies.

"One implication of our results is that up to a few hundred completely dark galaxies really should exist in the Milky Way's cosmic neighborhood," says Geha. "If the Cold Dark Matter model is correct they have to be out there, and the next challenge for astronomers will be finding a way to detect their presence."

Although the Sloan Digital Sky Survey was successful in finding a dozen ultrafaint dwarfs, it covered only about 25 percent of the sky. Future surveys that scan the remainder of the sky are expected to discover as many as 50 additional dark matter-dominated dwarf galaxies orbiting the Milky Way. Telescopes for one such effort, the Pan-STARRS project on Maui, are now under construction.

The paper, "Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem," will be published in the November 10 issue of The Astrophysical Journal. Funding for the project was provided by Caltech under the Millikan Fellowship program and by the Herzberg Institute of Astrophysics of the National Research Council Canada, and through a grant from the National Science Foundation (AST 0071048).

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Scientists available for comment:

Joshua D. Simon California Institute of Technology Pasadena, California USA Phone: (626) 395-3693

Marla Geha National Research Council Canada, Hertzberg Institute of Astrophysics Victoria, BC Canada Phone: (250) 363-8103

Taft Armandroff Director W. M. Keck Observatory Phone: (808) 881-3855

Kathy Svitil

Astronomers Find Largest Exoplanet to Date

PASADENA, Calif.—An international team of astronomers has discovered the largest-radius and lowest-density exoplanet of all those whose mass and radius are known. It is a gas-giant planet about twice the size of Jupiter, and is likely to have a curved cometlike tail. It has been named TrES-4, to indicate that it is the fourth planet detected by the Trans-atlantic Exoplanet Survey (TrES) network of telescopes.

TrES-4 is in the constellation Hercules and is the 19th transiting planet discovered so far. It orbits the star catalogued as GSC02620-00648, which is about 440 parsecs (1,435 light-years) away from Earth.

A transiting planet is one that passes directly in front of its host star as seen from Earth. When a transiting planet passes between its star and Earth, the planet blocks some of the light from the star in a manner similar to that caused by the moon's passing between the sun and Earth during a solar eclipse. In the case of TrES-4, this reduces the starlight by one percent, a tiny, yet detectable, effect.

TrES-4 is noteworthy for having a radius 1.67 times that of Jupiter, yet a mass only 0.84 times Jupiter's, resulting in an extremely low density of 0.222 g cm-3. In comparison, Jupiter has a density of 1.3 g cm-3. The density of TrES-4 is so low that the planet would float on water.

The transiting planet also causes the star to undergo a small orbital motion, but measuring this effect (from which we can tell the mass of the planet) requires much larger telescopes, such as the Keck 10-meter telescope in Hawaii, as was used in the case of TrES-4. Measuring the mass of the planet is a vital step in confirming that the transiting object is indeed a planet and not a star.

"We continue to be surprised by how relatively large these giant planets can be", says Francis O'Donovan, a graduate student in astronomy at the California Institute of Technology who operates one of the TrES telescopes. "But if we can explain the sizes of these bloated planets in their harsh environments, it may help us better understand our own solar system's planets and their formation."

The study's lead author, Georgi Mandushev of Lowell Observatory in Arizona, noted the challenges such big planets present for theories of planet formation and evolution: "This find presents a new puzzle for astronomers who model the structure and atmospheres of giant planets. It highlights the diversity of physical properties among giant planets around other stars and indicates that we can expect more discoveries of unusual and enigmatic exoplanets in the near future."

TrES is a global network of three small telescopes utilizing mostly amateur-astronomy components and off-the-shelf four-inch camera lenses: Sleuth telescope at Caltech's Palomar Observatory in San Diego County; the Planet Search Survey Telescope (PSST) at Lowell Observatory; and the STellar Astrophysics and Research on Exoplanets (STARE) telescope in the Canary Islands.

Planet TrES-4 makes a complete revolution around its parent star every 3.55 days, so a year on this planet is shorter than a week on Earth. The planet is about seven million kilometers away from its star—over ten times closer than Mercury is to the Sun—and so it is heated by the intense starlight to about 1600 degrees Kelvin (about 2300 degrees Fahrenheit).

In terms of mass and distance to its sun, TrES-4 is similar to HD209458b, and like that planet, it may have an extended outer atmosphere. Astronomers hypothesize that the outer atmospheric layers may be able to escape the planet's gravity and form a curved cometlike tail.

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 approximately 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 the 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 accurately measure the size and other properties of TrES-4, astronomers used the 0.8-meters telescope at Lowell Observatory, the 1.2-meter telescope at the Whipple Observatory (both in Arizona) and the 10-meter Keck Telescope in Hawaii.

Observations were carried out from September 2006 to April 2007.

The paper about the discovery of this extrasolar planet, "TrES-4: A Transiting Hot Jupiter of Very Low Density," has been accepted for publication by the Astrophysical Journal.

The paper's authors are Georgi Mandushev and Edward Dunham of Lowell Observatory; Francis O'Donovan, a graduate student at Caltech; Lynne Hillenbrand, an associate professor of astronomy at Caltech; David Charbonneau (Alfred P. Sloan Research Fellow), Guillermo Torres, David W. Latham, Gáspár Bakos (Hubble Fellow), Alessandro Sozzetti, José Fernández and Guilbert Esquerdo of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; Mark Everett of the Planetary Science Institute in Tucson, Arizona; Timothy Brown of Las Cumbres Observatory Global Telescope Network; and Markus Rabus and Juan A. Belmonte of the Instituto de Astrofísica de Canarias in Tenerife, Spain.

This research is funded by NASA through its Origins program. The paper is available online at

Robert Tindol

International Consortium Is Created to Build World's Largest Submillimeter Telescope

PASADENA, Calif.—Five institutions from North America and Europe have created a consortium to oversee the building of a 25-meter submillimeter telescope on a high elevation in Chile. When completed in 2013, the $100 million instrument will be the premier telescope of its kind in the world.

The project is formally known as the Cornell Caltech Atacama Telescope (CCAT), and has been in the works since a $2 million feasibility/concept design study was begun in 2004 by the California Institute of Technology and Cornell University. Now that the study has been completed, the partners are moving to the next phase of the process.

The consortium members are the California Institute of Technology and its Jet Propulsion Laboratory (JPL), Cornell University, the University of Colorado at Boulder, the University of British Columbia, and the United Kingdom Astronomy Technology Centre, which is part of the Science and Technology Facilities Council.

According to deputy project manager Simon Radford, who is based on the Caltech campus, the telescope will employ recent advances in technology that will provide unprecedented views of astronomical phenomena that cannot be studied at other wavelengths.

Because submillimeter-wavelength astronomy is especially effective for imaging phenomena that do not emit much visible light, the Atacama telescope will allow observations of stars and planets forming from swirling disks of gas and dust, will make measurements to determine the composition of the molecular clouds from which the stars are born, and could even discover large numbers of galaxies undergoing huge bursts of star formation in the very distant universe.

Also, the 25-meter telescope could be used to study the origin of large-scale structure in the universe.

The Atacama telescope will be located at an 18,400-foot altitude atop Cerro Chajnantor in Chile's Atacama Desert. The high altitude and dry conditions are important for submillimeter research, which is hampered by moisture in the air.

Of the projected $100 million cost, $20 million will go to state-of-the-art instrumentation. In particular, large submillimeter cameras will complement the huge size of the dish, which, at 25 meters, will have more than twice the area of the largest submillimeter telescope currently in existence.

The new cameras are made possible by recent developments in sensitive superconducting detectors, an area in which Caltech physics professor Jonas Zmuidzinas and his colleagues have been making important contributions. The new wide-field cameras will produce very sensitive panoramic images of the submillimeter sky.

Scientists from Caltech and JPL who will be involved in the project include Andrew Blain, Geoff Blake, Paul Goldsmith, Sunil Golwala, Andrew Lange, Tom Phillips, Anthony Readhead, Anneila Sargent, Eugene Serabyn, Tom Soifer, and Michael Werner, among others. The director of CCAT is Riccardo Giovanelli of Cornell, and the project manager is Thomas Sebring, also based at Cornell.

The 25-meter telescope is a natural progression in Caltech and JPL's long-standing interest in submillimeter and infrared astronomy, which started in the 1960s with the first infrared sky survey, carried out by professors Robert Leighton and Gerry Neugebauer on Mount Wilson.

In 1983, under Neugebauer's leadership, JPL launched the Infrared Astronomical Satellite, or IRAS, which discovered huge numbers of infrared-bright objects. This success paved the way to JPL's current infrared mission, the Spitzer Space Telescope. Meanwhile, Leighton went on to design a 10.4-meter submillimeter telescope, which by 1987 led to the construction and operation of the Caltech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. The CSO is funded by the National Science Foundation, and Tom Phillips, a professor of physics at Caltech, serves as director.

The CSO is fitted with sensitive submillimeter detectors and cameras, making it ideal for seeking out and observing the diffuse gases and their constituent molecules, crucial to understanding star formation. This experience served as the foundation for JPL's participation in the European Space Agency's Herschel Space Observatory.

The advantages of the new telescope, in addition to technological advances in instrumentation and the dry sky of the Atacama region, will also include a larger and more accurate mirror. The 25-meter telescope should provide six to 12 times the light-gathering ability of the CSO, depending on the exact wavelength. Also, the larger diameter and better surface will result in much sharper images of the sky.

The CCAT is designed to emphasize wide-field surveys of the submillimeter sky that will guide follow-up observations with telescope arrays such as the Combined Array for Research in Millimeter-wave Astronomy (CARMA), which Caltech played a leading role in developing, and the international Atacama Large Millimeter Array (ALMA), also located in northern Chile.

"CCAT will be a particularly important complement to ALMA," said Caltech astronomy professor Anneila Sargent, director of CARMA and chair of the interim CCAT board. "CCAT will enable consortium scientists to make optimal use of ALMA's submillimeter capabilities to address fundamental questions about star and galaxy formation."

A great opportunity therefore exists for submillimeter astronomy. In fact, an independent blue-ribbon panel chaired by Robert W. Wilson, 1978 Nobel Laureate who earned his doctorate in physics at Caltech, recently reported that the Atacama project "will revolutionize astronomy in the submillimeter/far infrared band and enable significant progress in unraveling the cosmic origin of stars, planets, and galaxies.

"CCAT is very timely and cannot wait," the panel said.

"It is a very exciting time for submillimeter astronomy," Zmuidzinas said when the 2004 feasibility study began. "We are making rapid progress on all fronts-in detectors, instruments, and new facilities-and this is leading to important scientific discoveries."

For more information, go to

Robert Tindol

Dwarf Star Gulps Giant to Form Supernova

PASADENA, Calif.—A team of European and American astronomers has announced the discovery of the best evidence yet for the nature of the star systems that explode as type Ia supernovae. The team obtained a unique set of observations with the European Southern Observatory's Very Large Telescope and the Keck I 10-meter telescope in Hawaii.

The researchers were able to detect the signature of the material that surrounded the star before it exploded. The evidence strongly supports the scenario in which the explosion occurred in a double-star system where a white dwarf is fed by a red giant.

"The powerful 10 meter Keck Telescope with its recently refurbished high-resolution spectrograph finally gives us the capability to follow these supernovae for months, as we have done here. We are now busy taking advantage of this new window of opportunity," says Avishay Gal-Yam, an astronomer at the California Institute of Technology who led the Caltech research team. "This is really an exciting avenue that Keck opens up to us."

Because type Ia supernovae are extremely luminous and quite similar to one another, these exploding events have been used extensively as cosmological reference beacons to trace the expansion of the universe.

However, despite significant recent progress, the nature of the stars that explode and the physics that governs these powerful explosions have remained poorly understood.

In the most widely accepted models of type Ia supernovae, the pre-explosion white dwarf star interacts with a much larger companion star. Because of the proximity of the two stars and the strong gravitational attraction produced by the very compact white dwarf, the companion star continuously loses mass, "feeding" the white dwarf. When the mass of the white dwarf exceeds a critical value slightly higher than the mass of the sun, it explodes.

"To shed some light on the systems that explode as type Ia supernovae, we decided to search for signatures of the material transferred to the white dwarf in the surrounding material," says Ferdinando Patat, lead author of the paper reporting the results in this week's issue of Science Express, the online version of the research journal Science.

The team of astronomers studied in great detail SN 2006X, a type Ia supernova that exploded 70 million light-years away from us, in the stunning spiral galaxy Messier 100.

The observations were made with the Ultraviolet and Visual Echelle Spectrograph mounted at ESO's 8.2 meter Very Large Telescope on four different occasions, over a time span of four months. A fifth late-time epoch spectrum of SN 2006X was secured with the Keck Telescope. The astronomers also made use of radio data obtained with National Radio Astronomy Observatory's Very Large Array as well as with images extracted from the NASA/European Space Agency Hubble Space Telescope archive.

The most remarkable finding is the clear evolution seen in the absorption profile of the sodium lines over the few months following the explosion. This, the astronomers deduce, is linked to the presence of a number of expanding shells surrounding the system. These shells are left over from the star that was force-feeding the white dwarf until its sudden catastrophic and spectacular death.

"The material we have uncovered probably lies in a series of shells having a radius of the order of 0.05 light-years, or roughly 3,000 times the distance between Earth and the sun," explains Patat. "The material is moving with a velocity of 50 km/s, implying that the material would have been ejected some 50 years before the explosion."

Such a velocity is typical for the winds of red giant stars. The system that exploded was thus most likely composed of a white dwarf that acted as a giant "vacuum cleaner," drawing gas off of its red giant companion. In this case, however, the cannibal act proved mortal for the white dwarf. This is the first time that any clear and direct evidence for material surrounding the exploding star has been found.

"We are still not certain whether SN 2006X is a unique case, or is instead representative of all type Ia supernovae. Additional studies of similar objects will be crucial for determining that-and we are already working on observations of another type Ia supernova," says Caltech astronomer Josh Simon, who is leading a similar study of the recent event SN 2007af using observations collected at Keck and other facilities. "We should know even more within the next year," he concludes.

The team is composed of Patat and Luca Pasquini (ESO), Poonam Chandra and Roger Chevalier (University of Virginia), Stephen Justham, Philipp Podsiadlowski, and Christian Wolf (University of Oxford), Gal-Yam and Simon (Caltech), Ian Crawford (Birkbeck College London), Paolo Mazzali, Wolfgang Hillebrandt, and Nancy Elias-Rosa (Max Planck Institute for Astrophysics), Adi Pauldrach (Ludwig Maximilians University), Kenichi Nomoto (University of Tokyo), Stefano Benetti, Enrico Cappellaro, Alvio Renzini, Franco Sabbadin, and Massimo Turatto (INAF-Astronomical Observatory), Douglas Leonard (San Diego State University), and Andrea Pastorello (Queen's University Belfast).

A high-resolution image of SN 2006X in the spiral galaxy Messier 100 is available at

Robert Tindol

Caltech, JPL, Northrop Grumman to Celebrate 50 Years of Space Exploration

PASADENA, Calif.--Before October 1957, space flight was a thing of fantasy. Today we are experienced space explorers with unlimited voyages to undertake. Where is space flight's next horizon? What constitutes sensible space investment? How did the space pioneers accomplish their goals? These topics will be addressed at "50 Years in Space: An International Aerospace Conference Celebrating 50 Years of Space Technology," which will take place from September 19 to 21 at the California Institute of Technology.

The conference is hosted by Caltech, the Graduate Aeronautical Laboratories at Caltech (GALCIT), Northrop Grumman Corporation, and the Jet Propulsion Laboratory.

NASA Administrator Michael Griffin, astronaut Harrison "Jack" Schmitt, space industry pioneers and experts, and representatives from foreign space programs will speak on the history of space exploration, sensible space investment, and the future of space exploration from the perspectives of the aerospace industry, academia, government, and science. The opening keynote speaker will be the chairman of Northrop Grumman, Ronald Sugar.

"Our speakers represent all the institutions that essentially created and successfully sustained space exploration," said Ares Rosakis, Theodore von Karman Professor of Aeronautics and Mechanical Engineering and GALCIT director, and co-organizer of the conference with Dwight Streit, vice president, foundation technologies in Northrop Grumman's Space Technology sector. "This group crosses international and institutional boundaries. Each of our speakers is a preeminent expert in at least one of the many disciplines required for space travel. Their passion for space science and technology will make this conference the definitive observance worldwide commemorating 50 years in space," Streit noted.

"Many technologies developed as a result of space exploration have become integral terrestrial technologies--and our efforts benefit society in surprising ways that are completely separate from their initial impetus. As we look to the future, we will see how this important aspect of aeronautics continues--especially in the areas of tracking weather changes, global temperatures, and greenhouse gases, as well as the formations of the earth's crust related to seismic activity," Rosakis said.

The launch of Sputnik on October 4, 1957, began the space age. Within weeks, the Ramo-Wooldridge Corporation spun off Space Technology Laboratories (STL), with Simon Ramo as its president. STL and Ramo-Wooldridge became part of TRW Inc. in 1958, and then eventually part of Northrop Grumman in 2002.

In 1958, the JPL-built Explorer 1 put the U.S. in the space race, followed soon thereafter by Pioneer 1, built by TRW and the first spacecraft launched by NASA.

Ramo, the "R" in TRW, earned his PhD at Caltech in 1936. TRW's Space and Electronics Group became the Space Technology sector at Northrop Grumman. The president of the company's Space Technology sector, Alexis Livanos (also a Caltech graduate, having earned his bachelor's, master's, and PhD at Caltech), will give a special tribute to Ramo, 94, at the conference.

Livanos will join JPL director Charles Elachi (who earned his MS and PhD at Caltech), and Caltech president Jean-Lou Chameau as chairs of the conference. Elachi and Chameau will also be speaking.

Caltech alumnus Harrison "Jack" Schmitt, a geologist, one of the last two men to walk on the moon, and a NASA adviser, will be joined by Ed Stone, former director of JPL, and Gentry Lee, chief engineer for the Planetary Flight Systems Directorate at JPL, for a "look back" at the accomplishments of the past 50 years, many of which they bravely spearheaded. JPL, which became part of NASA after its formation in 1958, remains at the center of robotic planetary exploration and Earth-observing science. JPL is managed by Caltech.

Representatives of the top-tier space programs around the globe will also be present, including NASA's Griffin; European Space Agency Director General Jean-Jacques Dordain; President of Centre National d'Études Spatiales Yannick d'Escatha; and Masato Nakamura of the Japanese Institute of Space and Astronautical Science, all of whom will discuss the future of space exploration.

Miles O'Brien, CNN chief technology and environment correspondent, will moderate a panel discussion titled "Space and the Environment: Sensible Space Investment." Participating in the panel, and also presenting a separate talk, is A.P.J. Abdul Kalam, the 11th president of India and a noted scientist and aeronautical engineer.

Other distinguished guests include keynote speaker John C. Mather, James Webb Space Telescope senior project scientist; Elon Musk, SpaceX CEO; Burt Rutan, founder of Scaled Composites; and Hayden Planetarium Director Neil deGrasse Tyson. Mather was awarded the 2006 Nobel Prize in Physics for his work in the areas of black body form, cosmic microwave background radiation, and Big-Bang theory. PayPal creator Musk, whose space-transportation company, SpaceX, has opened up a whole new segment of the aerospace industry, will be speaking on a panel discussing the future of space exploration from an industry perspective. Closing keynote speaker Tyson is the recipient of eight honorary doctorates and was named one of Time magazine's 100 Most Influential People of 2007.

Several speakers will address the aerospace industry's perspective on the future of space flight. These include Musk; David Thompson, chairman and CEO of Orbital Science Corporation; Joanne Maguire, executive vice president, space systems, at Lockheed Martin; and David Whelan, corporate vice president, Boeing.

The perspective from academia will come from, among others, Caltech alumna and president of Purdue University France Córdova and Charles Kennel, the former director of Scripps Institution of Oceanography. Ronald Sega, undersecretary, United States Air Force, and the Defense Department's executive agent for space, will also speak on the future of space exploration.

Participants will be able to view large replicas of spacecrafts, rovers, and satellites. "This is more than a sit-and-listen event," said Rosakis. "It is an interactive learning experience. Guests will meet and exchange ideas with like-minded people and professionals in between formal presentations. The displays and replicas will also add to the guests' visual understanding of space exploration. They will be able to understand what the presence of these structures really feels like."

Full registration is $550. To register, go to Registration is on a first-come, first-served basis, and seating is limited.

Caltech, JPL, Northrop Grumman, California Space Authority employees, Southern California high-school and college students and teachers with ID are welcome to attend the talks free of charge, but they must register via the website. 

Jill Perry

Astronomers Claim to Find the Most Distant Known Galaxies

PASADENA, Calif.- Using natural "gravitational lenses," an international team of astronomers claim to have found the first traces of a population of the most distant galaxies yet seen-the light we see from them today left more than 13 billion years ago, when the universe was just 500 million years old.

Team leader Richard Ellis, the Steele Family Professor of Astronomy at the California Institute of Technology, will present images of these faint and distant objects in his talk on July 11 at the "From IRAS to Herschel and Planck" conference at the Geological Society in London. The meeting is being held to celebrate the 65th birthday of Royal Astronomical Society President Professor Michael Rowan-Robinson.

When light from very distant bodies passes through the gravitational field of much nearer massive objects, it bends in an effect known as "gravitational lensing." In a pioneering technique, the Caltech-led group used massive clusters of galaxies-the best example of natural gravitational lenses-in a series of campaigns to locate progressively more distant systems that would not be detected in normal surveys. The team found the galaxies using the 10-meter Keck II telescope, sited atop Mauna Kea on the Big Island of Hawaii.

Ellis explains, "Gravitational lensing is the magnification of distant sources by foreground structures. By looking through carefully selected clusters, we have located six star-forming galaxies seen at unprecedented distances, corresponding to a time when the universe was only 500 million years old, or less than four percent of its present age."

It is thought that when the universe was 300,000 years old it entered a period when no stars were shining. Cosmologists refer to this phase of cosmic history as the "Dark Ages." Pinpointing the moment of "cosmic dawn" when the first stars and galaxies began to shine and the Dark Ages ended is a major observational quest and provides the motivation for building future powerful telescopes such as the Thirty Meter Telescope, and the space-borne James Webb Telescope.

The new survey is the culmination of three years' painstaking observations which represent the thesis of Caltech graduate student Dan Stark. "Using Keck II, we have detected six faint star-forming galaxies whose signal has been boosted about 20 times by the magnifying effect of a foreground cluster. That we should find so many distant galaxies in our small survey area suggests they are very numerous indeed. We estimate the combined radiation output of this population could be sufficient to break apart (ionize) the hydrogen atoms in space at that time, thereby ending the Dark Ages," said Stark.

Proving definitively that each of the six objects is unambiguously at these enormous distances (and hence being viewed at such early times) is hard, even with the most powerful instruments. "As with all work at the frontiers, skeptics may wish to see further proof that the objects we are detecting with Keck are really so distant," confessed Ellis. However, in addition to numerous checks the team has made (described in their published scientific article) following their initial discovery a year ago, Ellis and Stark point to supporting evidence from galaxies containing old stars that are seen when the universe was just a bit older.

"We can infer the universe had a lot of star formation at these early times from Spitzer Space Telescope measurements of larger galaxies seen when the universe was about 300 to 500 million years older," explains Stark. "These galaxies show the tell-tale sign of old stars (and were described in earlier work by Ellis and Stark with UK scientist Andrew Bunker). To produce these old stars requires significant earlier activity, most likely in the fainter star-forming galaxies we have now seen."

Also associated with the program is Caltech postdoctoral scholar Johan Richard, who is leading a similar, but independent, survey of magnified galaxies detected with the Hubble and Spitzer space telescopes. Although that work is not yet complete, preliminary findings support the conclusions of the Keck II survey. European collaborators include Jean-Paul Kneib of the Laboratory of Astrophysics at Marseilles, and Graham Smith at the University of Birmingham.

FURTHER INFORMATION Details of the conference can be found at:

IMAGES: Images of the new galaxies and a description of the technique used can be seen at:

SCIENTIFIC ARTICLE The refereed scientific article can be found on the Astrophysical Journal website: (Volume 663, pages 10-28, 2007)

CONTACTS: Richard Ellis Astronomy Department California Institute of Technology Pasadena CA 91125 E-mail: Mobile: (626) 676-5530 (UK time zone)

Dan Stark Astronomy Department California Institute of Technology Pasadena CA 91125 E-mail: Mobile: (626) 315-2939 (U.S. West Coast and Hawaii time zones)

Jean-Paul Kneib Laboratoire d'Astrophysique de Marseille Traverse du Siphon - B.P.8 F-13376 Marseille Cedex 12 E-mail: Mobile 011-33 685 988 265 (Central European time zone)

Robert Massey Royal Astronomical Society Tel: 44 (0)20 7734 4582 Mobile: 44 (0)794 124 8035 E-mail:


Jill Perry

Pioneer of 20th-Century Mathematics John Todd Dies

PASADENA, Calif.-John Todd, one of the pioneers of numerical analysis, died Thursday, June 21, at his home in Pasadena, California. He was 96.

Todd's legacy and impact on modern-day mathematics can be seen in his contributions to analysis, linear algebra, and computation. His work was a precursor to and helped shape the foundation for today's computer science field. An emeritus professor at the California Institute of Technology, Todd developed the first undergraduate courses at Caltech in numerical analysis and numerical algebra, which play a key role in scientific computing.

Born in Ireland in 1911, Todd grew up near Belfast. After earning his BSc degree from Queen's University in 1931, he went to St. John's College at Cambridge University for graduate studies under renowned mathematicians J.E. Littlewood and G.H. Hardy.

Subsequently, Todd went to work at King's College in London, where he soon met his intellectual and romantic match, Olga Taussky, a matrix and number theorist. They wed in 1938.

In 1939, when Britain declared war on Germany, Todd found an opening with the British Admiralty, which assigned him to Portsmouth to help develop methods for degaussing-or demagnetizing-ships to keep them from being blown up by enemy torpedoes.

Referred to by some as the "Savior of Oberwolfach," one of Todd's most stellar achievements was his salvation of the Mathematical Research Institute at Oberwolfach in Germany. Near the war's end, Todd and his colleagues went to investigate rumors that mathematicians were being held as prisoners of war in Germany's Black Forest. What they found was the Mathematical Research Institute at Oberwolfach, where the University of Freiburg was protecting the mathematicians. Todd claimed the building for the Admiralty and prevented Moroccan troops from destroying the institute and its work. In his Caltech oral history, Todd recalls the incident as "probably the best thing I ever did for mathematics."

In 1945, with peace restored, Todd returned to teaching at King's, developing a specialty in numerical analysis. In 1947, he and Olga came to the United States to help establish the National Applied Mathematical Laboratories at UCLA, part of the National Bureau of Standards. They later moved to the NBS headquarters in Washington, D.C., where they helped launch the field of high-speed computer programming and analysis and also became U.S. citizens. Todd was chief of the computation laboratory and later headed the numerical analysis section, while Olga served as a consultant.

In 1956, the couple received job offers from Caltech, which was just entering computer science. The following year, they arrived at the Institute, where Todd developed and taught courses in mathematics. As a faculty research associate, Olga Taussky-Todd also broke new ground-she was the first woman to receive a formal Caltech teaching appointment, and, in 1971, a full professorship. She remained active in research until her death in 1995.

Thomas A. Tombrello, chair of the Division of Physics, Mathematics, and Astronomy and William R. Kenan, Jr. Professor of Physics at Caltech says, "Jack and his wife Olga were among the pioneers who made us what we are in teaching and research in mathematics. Our sense of collegiality and common purpose are a tribute to them."

"It was a terrific day for the mathematics department when we succeeded in attracting Jack and Olga to come to Caltech," says Gary Lorden, professor of mathematics.

"Not only did we gain eminent scholars, but wonderful colleagues and teachers. They made a remarkably generous commitment to the future of Caltech and the mathematics department, and their legacy also includes the inspiring stories of their lives and careers-Olga, as one of the very first women to make a mark in 20th-century mathematics, and Jack as a pioneer in numerical analysis and computing.

"These two remarkable people will always be remembered with great affection and regard by mathematicians and the Caltech community."

Deborah Williams-Hedges

Ooguri Appointed Fred Kavli Professor of Theoretical Physics

PASADENA, Calif.—Like many Japanese schoolchildren, Hirosi Ooguri read about the physicist Hideki Yukawa, who became Japan's first Nobel laureate in 1949 for predicting the existence of mesons, elementary particles that hold atomic nuclei together. Ooguri says, "I was very impressed by the power of mathematics in discovering how the universe works."

Today, "Ooguri is one of the leading theoretical physicists in the world," says his fellow string theoretician John Schwarz, the Harold Brown Professor of Theoretical Physics at the California Institute of Technology. The Institute has named Ooguri as its first Fred Kavli Professor of Theoretical Physics, a new professorship endowed by the Kavli Foundation.

String theory shows promise for unifying a theory of gravity with what physicists call the Standard Model, which successfully describes the other three of nature's four known fundamental interactions. Besides string theory, Ooguri has another long-term project: to help build an infrastructure for physicists exploring at the frontiers of high-energy physics. Specifically, he wants to develop the right mathematical language for quantum gauge theory, which describes how elementary particles interact.

Yet he now believes his two projects are converging, allowing physicists to choose suitable models from either string theory or quantum gauge theory. It could take physics half a century to develop these tools. "You need something analogous to the invention of calculus," he says. "My prejudice is that string theory is in the right direction."

Ooguri received his BA in 1984 and his MA in 1986 from Kyoto University. He earned his PhD at the University of Tokyo in 1989. He worked as an associate professor of physics at the University of Chicago from 1989 to 1990, followed by a four-year stint at Kyoto University as an associate professor of mathematical physics.

In 1994, Ooguri returned to the United States as a professor of physics at UC Berkeley. From 1996 to 2000, he was the faculty senior scientist at the Lawrence Berkeley National Laboratory. He arrived at Caltech in 2000 as a professor of theoretical physics.

The Kavli Foundation was established in December 2000 by its founder and benefactor, Fred Kavli, a prominent California business leader and noted philanthropist whose foundation is currently actively involved in establishing major research institutes at leading universities throughout the United States and in Europe and Asia.

John Avery
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Newly Discovered Olympian Galaxy Will Provide Fresh Insights into Galactic Formation

PASADENA, Calif.—A newly discovered dwarf galaxy in our local group has been found to have formed in a region of space far from our own and is falling into our system for the first time in its history.

The dwarf is formally known as Andromeda XII because it is the 12th dwarf galaxy associated with Andromeda, our nearest galactic neighbor. The discoverers have nicknamed it the Olympian Galaxy after the 12 Olympian gods in the Greek pantheon. The discovery was made possible with data obtained at the W. M. Keck Observatory atop Mauna Kea, Hawaii.

According to Andrew Blain, an astronomer at the California Institute of Technology and a member of the discovery team, the Olympian Galaxy marks the best piece of evidence that at least some small galaxies are just now arriving in our local group, which primarily includes the Milky Way, Andromeda, and various dwarf galaxies in the vicinity of both. The finding provides an important test for simulations of galaxy formation.

Dwarf galaxies and streams of stellar material mark the visible remnants of galactic merging events from which large galaxies are made. Cosmology models predict that small galaxies form along a web of filamentary structures in the universe and then gradually fall into dense groups and cluster environments. Small galaxies should still be falling into the local group, yet none have been found--until now.

"Other local group dwarf galaxies are thought to have extreme orbits, including Leo I, Andromeda XIV and Andromeda XI, but the Olympian Galaxy really stands out as a contender for a new entrant into the local group," says the lead author of the study, Scott C. Chapman of the University of Cambridge Institute of Astronomy. "The others have likely already been seriously harassed by Andromeda and the Milky Way."

The Olympian Galaxy was first discovered in October 2006 during a wide-field survey taken with the Canada-France-Hawaii Telescope's MegaCam instrument. It is the faintest dwarf galaxy ever discovered near Andromeda (also known as M31), and may have the lowest mass ever measured. Dwarf galaxies are the smallest stellar systems showing evidence for a substantial amount of dark matter.

Chapman's observations confirmed that the Olympian Galaxy is distinct from all other satellite galaxies in the local group. It is a fast-moving galaxy on a highly eccentric orbit, located at a great distance-about 115 kiloparsecs (375,000 light-years)-from the center of M31. Importantly, the Olympian Galaxy lies significantly behind M31 as viewed from the Milky Way, which indicates that it is almost certainly falling in for the first time. Because the dwarf galaxy has lived its life in a very different environment from that of the local group, it gives astronomers a pristine object for studying star-formation histories, dark-matter distribution, and other parameters that would be influenced by the local-group gravity that has affected other dwarf galaxies.

"The Olympian Galaxy may be the first galaxy of the local group ever observed that has not yet been disrupted by the strong gravity of the local group," says Jorge Penarrubia of the University of Victoria, a coauthor of the study.

The Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS) at Keck II, one of two 10-meter telescopes the W. M. Keck Observatory operates on the summit of Mauna Kea, was key in making the discovery. It was used to observe 49 stars in the region of the Olympian Galaxy, and confirmed that eight were members of the new dwarf galaxy. Follow-up observations were also conducted at the Green Bank Telescope in West Virginia to measure the amount of interstellar gas in the galaxy, and the Subaru telescope in Hawaii helped determine a more precise distance.

"Without the spectra we obtained with DEIMOS, it would have been impossible to make any useful claims about the orbit of the Olympian Galaxy, its evolution, its speed, or its dark-matter content," adds Chapman.

The Olympian Galaxy is falling very quickly through the local group from behind Andromeda, and is the only one of Andromeda's satellites that exceeds the apparent escape velocity for Andromeda. It is possible that the Olympian Galaxy may be just a short-term visitor. It is such a low-mass galaxy that it may not slow down much as it passes through the local group.

"It is a pleasure to see the speed of this new, fascinating member of the local group clocked using Keck II and DEIMOS," adds W. M. Keck Observatory director Taft Armandroff. "The powerful combination of Keck and DEIMOS has added many contributions to our understanding of local-group galaxies."

The age of the universe is not old enough for the Olympian Galaxy to have started in the dense local group and be on its second trip through our system. The dwarf galaxy probably formed in a dense filament structure, toward the general direction of the M81 group. However, the distance to that group is about three times too far for the galaxy to have actually come from there. A likely scenario is that the Olympian Galaxy formed in a filamentary region of space that connects the local group to the M81 group.

"The high speed really surprised me; I wasn't expecting to see any of our newly discovered dwarfs moving so fast. We will likely have to revise our mass estimates of Andromeda upward as a result," adds Rodrigo Ibata, another author of the study.

A paper reporting the discovery, "Strangers in the Night: The Discovery of a Dwarf Spheroidal Galaxy on its First Local Group Infall," will appear in an upcoming issue of the Astrophysical Journal. Funding was provided by a fellowship from the Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada. Additional support was provided by Adrian Jenkins, who made available important computer simulations.

The study was coauthored by Jorge Penarrubia, Alan McConnachie, and Aaron Ludlow of the University of Victoria; Rodrigo Ibata, Observatoire de Strasbourg; Nicolas F. Martin, Max-Planck-Institut für Astronomie; Andrew Blain and Bruno Letarte, California Institute of Technology; Michael Irwin, University of Cambridge Institute of Astronomy; Geraint Lewis, University of Sydney Institute of Astronomy; Fred Lo and Karen O'Neil, NRAO Green Bank Telescope.

The W. M. Keck Observatory is operated by the California Association for Research in Astronomy (CARA), a nonprofit 501 (c) (3) corporation whose governing board includes directors from the California Institute of Technology and the University of California. In addition, the National Aeronautics and Space Administration and the W. M. Keck Foundation each have liaisons to the board. Construction of the twin Keck telescopes and domes was made possible with generous grants totaling more than $140 million from the W. M. Keck Foundation in Los Angeles.


Kathy Svitil

Caltech and Berkeley Astronomers Identify a New Class of Cosmic Explosions

PASADENA, Calif.--Astronomers are announcing today the discovery of a new class of stellar explosions. The finding is based on observations of a flash seen in the Virgo cluster in a galaxy known as Messier 85.

According to Shrinivas R. Kulkarni, the team leader announcing the discovery of M85OT2006-1, the event is thought to have resulted from the merger of two ordinary stars 49 million years ago.

"The discovery of this enigmatic event is merely the proverbial tip of the iceberg for an emerging class of cosmic transients," says Kulkarni, the MacArthur Professor of Astronomy and Planetary Science at the California Institute of Technology. The team, which consists of astronomers from Caltech and the University of California at Berkeley, is announcing its findings in the current issue of the journal Nature.

The puzzling explosion was discovered during the Lick Observatory Supernova Search with the Katzman Automatic Imaging Telescope, carried out by Alex Filippenko and Weidong Li of UC Berkeley. "Though the primary scientific goal of the program is discovering supernovae and it's quite successful at doing that, it is gratifying to find new classes of transient objects such as M85OT2006-1," said Li, who is in charge of the daily operation of the supernova search.

Kulkarni and his Caltech colleagues had been speculating on possible new classes of cosmic explosions. They mounted a major follow-up program with the Palomar 60-inch telescope, the famous Hale 200-inch telescope, and the Keck telescopes atop Mauna Kea, Hawaii. Later, other telescopes in Hawaii and Chile were pressed into service.

The explosion was surprising because it was far too faint for a supernova, in which a star literally explodes, but clearly too bright for a nova or a thermonuclear explosion from the surface of a white dwarf star. Arne Rau, a postdoctoral fellow working with Kulkarni, said, "I was simply floored. In a short time we went from speculation to a real discovery. It was an exciting moment for me."

It took astronomers nearly a century to identify two major classes of cosmic explosions: novae and supernovae. Forty years ago gamma-ray bursts were added to the astronomical lexicon. M85OT2006-1 solidifies and defines a new class of cosmic explosions that the Caltech astronomers have dubbed as Luminous Red Novae. These events have very distinct (red) color and expand quite slowly when compared with novae, supernovae, and gamma-ray bursts.

The galaxy in which M85OT2006-1 exploded is composed mainly of old stars, which also indicates that the event probably arose from a population of stars with masses very similar to that of the sun. More than a decade ago, one other similar but poorly studied event was observed in the Andromeda galaxy.

Kulkarni speculates that the red luminous novae result when two stars merge and undergo what is called "common envelope evolution." Kulkarni added, "The common envelope phase has been inferred on strong theoretical grounds, but is now caught in flagrante delicto."

In a related study, Rau undertook observations of M85OT2006-1 with NASA's Spitzer Space Telescope. The object is detectable in the mid infrared a year after the explosion, long after it became too faint in the visual, even for the Hubble Space Telescope. The Spitzer telescope is particularly well suited for the study of cold matter in space. Rau added, "Spitzer was vital in confirming that this object is a cosmic oddball. It is hard to imagine both a bright explosion which is also so cold."

There is little doubt that the discovery of this new class of cosmic explosions will make astronomers inspect ongoing searches carefully for similar events. Future imaging surveys will likewise be energized by this discovery. Kulkarni added, "It is a nice feeling when you know you have created a new cottage industry in your field."

Besides Kulkarni and Rau, the other authors of the paper are Eran O. Ofek, Stephen B. Cenko, Alicia M. Soderberg, Avishay Gal-Yam, Peter L. Capak, and Dae-Sik Moon, all of Caltech; Derek B. Fox of the Pennsylvania State University; Li and Filippenko of UC Berkeley; Eiichi Egami of the Steward Observatory; and Jeyhan Kartaltepe and David B. Sanders of the University of Hawaii.


Robert Tindol


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