Research Rundown

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Science Journal, Fall 1997 -- Vol 15, No. 1 

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Penn State Students Build New Telescope's
First Scientific Instrument

Two Penn State graduate students built and tested the first scientific instrument for one of the world's largest, most powerful, and most economical optical telescopes, the new Hobby-Eberly Telescope, which is scheduled for its grand-opening ceremony on October 8. Two Penn State undergraduate students built and tested calibration devices for the instrument.

The spectrograph instrument (UFOE), which astronomy graduate students Jason Harlow and David Andersen built in the basement of Penn State's Osmond Laboratory, recently produced the telescope's "first scientifically interesting spectra,"according to their supervisor, Lawrence W. Ramsey, a Penn State professor of astronomy and astrophysics and the telescope's project scientist. Penn State undergraduate students Lester Chou and Eric Mamajek did their work on the instrument's calibration devices in the Department of Astronomy.

The Hobby-Eberly Telescope is uniquely designed for spectroscopy?the collection and analysis of light from astronomical objects such as comets, planets, stars, and galaxies. Spectroscopy provides astronomers with a wealth of information, such as what stars are made of, how far away they are, and how fast they are moving. Astronomers will use the telescope to search for planets in orbit around other stars, learn more about the "dark matter" that surrounds galaxies, and refine theories about how stars and galaxies are born and how they die. "We are going to get exciting new science from this telescope," Ramsey says, "plus it already is giving us a wealth of fantastic training opportunities for the next generation of scientific leaders." In addition to building the UFOE spectrograph, Harlow helped to install it at the telescope site in the Davis Mountains of West Texas at The University of Texas McDonald Observatory at Fort Davis. Another young Penn State scientist, Distinguished Postdoctoral Fellow Christopher Churchill, developed the software that will be used by virtually all scientists who analyze data from the UFOE instrument. Ramsey says the UFOE spectrograph, which was designed specifically for testing and commissioning the telescope, was built for a tiny fraction of the cost of the higher-quality operating instruments currently planned for future installation on the telescope. "On practically a zero budget, the students recycled and upgraded an older instrument that we had built here in the mid 1980s," he says. "It recently has produced test spectra of sufficient quality to serve as a guide for planning the telescope's science program." The Hobby-Eberly Telescope is a joint project of The University of Texas at Austin, The Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

http://www.astro.psu.edu/het/

Barbara K. Kennedy

A team of university scientists using a mini research submarine on a research cruise funded by the National Oceanographic and Atmospheric Administration has discovered, photographed, and collected what appears to be a new species of centipede-like worms living on and within mounds of methane ice on the floor of the Gulf of Mexico, about 150 miles south of New Orleans.

Although scientists had hypothesized that bacteria might colonize methane ice mounds, called gas hydrates, this is the first time animals have been found living in the mounds.

The discovery of dense colonies of these one-to-two-inch-long, flat, pinkish worms burrowing into a mushroom-shaped mound of methane seeping up from the sea floor raises speculation that the worms may be a new species with a pervasive and as yet unknown influence on these energy-rich gas deposits.

The worms were observed using their two rows of oar-like appendages to move about the honeycombed, yellow and white surface of the icy mound. The researchers speculate that the worms may be grazing off chemosynthetic bacteria that grow on the methane or are otherwise living symbiotically with them.

"The old view that the deep sea bottom is a monotonous habitat needs to be discarded. These worms are the major players in a new and unique marine ecosystem," said expedition Chief Scientist Charles Fisher, an associate professor of biology at Penn State, who discovered the methane ice worms in waters 1,800 feet deep in the submersible Johnson Sea Link with sub pilot Phil Santos of the Harbor Branch Oceanographic Institution.

The scientists have also managed to keep a number of the exotic worms alive in shoreside laboratories for further study.

"These are not just another common worm in the mud. We now know that these higher-order organisms can live right on methane hydrates. If these animals turn out to be ubiquitous on shallow seafloor gas deposits, possibly worldwide, they could have a significant impact on how these deposits are formed and dissolve in seawater and on how we go about mining or otherwise harvesting this natural gas as a source of energy," Fisher said.

"It's very cool that while we're busy speculating about life on other planets we continue to discover new forms of life in the most unlikely habitats on Earth," commented Erin McMullin, a Penn State graduate student and a member of the research expedition that discovered the methane-ice worms. Methane ice, a gas hydrate, forms naturally at the high pressure and low temperature of the deep sea, but is usually buried deep in marine sediment. The Gulf of Mexico is one of the few places where hydrate can be found exposed on the ocean bottom. Occasionally this seeping, solid methane bursts through in mounds, often six to eight feet across.

The first leg of the ten-day expedition, which ended July 19, was carried out aboard the Harbor Branch Research Vessel Edwin Link and sponsored by the NOAA National Undersea Research Center at the University of North Carolina at Wilmington and the Minerals Management Service of the U.S. Department of the Interior. In addition to Chief Scientist Charles Fisher, principal investigators included Ian MacDonald of Texas A&M University, Robert Carney of Louisiana State University, Steve Macko of the University of Virginia, and Alissa Arp and David Julian of San Francisco State University.

http://www.bio.psu.edu/faculty/fisher/fhome.htm

Dane Konop, National Oceanographic and Atmospheric Administration

Scientists have discovered how three genes work together to regulate the development of nerve cells?fundamental new knowledge that could boost efforts in other areas, including cancer research.

In a recent issue of the journal Cell, two teams of researchers report that they independently made the same discovery. One team is led by Zhi-Chun Lai, assistant professor of biology, biochemistry, and molecular biology at Penn State, and Richard W. Carthew, assistant professor of biology at the University of Pittsburgh. The leader of the other research team is Gerald M. Rubin, of the University of California at Berkeley. The research is expected to contribute to the understanding of the nervous system and the brain.

To make their discovery, Lai and Carthew's team studied fruit-fly eyes to figure out which genes regulate the development of photoreceptor neurons?cells that convert light signals into chemical signals the brain can understand. The team used both genetic studies and cell-culture studies to complement and confirm their findings. "The fly genes we are studying are amazingly similar to their corresponding human genes and, at the very fundamental cellular level, there is no difference between the human cell and the fly cell," Lai explains. "Plus flies are a very good organism for genetic engineering."

During a fly's development, on about the fourth day of life, certain proto-eye cells receive instructions from the fly's genes to become either light-filtering cone cells or photoreceptor neurons. "That's when we dissect the eyes to look at them under the microscope," Lai says.

External signals tell the developing cells what kind of cell to become by initiating a cascade of internal molecular reactions called the "signal transduction pathway." "Cancer can result if errors occur in the signal-transduction pathway, giving a cell the signal to divide instead of the signal to become a neuron," Carthew explains. "These signal-transduction pathways are indispensible for life because they are critical for neural development, but they also can be a threat to life if a harmful error occurs somewhere along the pathway, resulting in uncontrolled cell division rather than controlled cell differentiation."

Last year Lai discovered an important clue about how a component of the signal-transduction pathway?a special kind of cell-growth regulator known as a neural inhibitor?works genetically. He found that proto-eye cells could become neurons only when the gene for making a protein known as Tramtrack was inactivated.

"Tramtrack is a kind of 'gatekeeper' protein that prevents the cell from differentiating into a neuron," Carthew explains. "When the cell receives a signal to become a neuron the signal-transduction pathway is activated, which induces the production of proteins that somehow get rid of Tramtrack." With that discovery pointing the way, Lai, Carthew, and their research team began a search to discover exactly which proteins were responsible for destroying Tramtrack.

The researchers genetically engineered strains of fruit flies to test a number of genes whose protein products they suspected would be good candidates. "There are two genetic directions you can take," Lai explains. "If you want to show that a gene is important for some function, you take it away and see what happens. Another thing you can do is to cause genes to overproduce their protein product in a cell and see what happens then."

Using this approach, the researchers narrowed down their list of candidate proteins to just two, known as Phyllopod and Sina, and demonstrated that they team up to target the Tramtrack protein for destruction. In the process, they also discovered the first known biochemical function for the Phyllopod and Sina proteins. "Our test-tube experiments demonstrated that Sina and Phyllopod bind to each other to form a partnership and that they also bind to Tramtrack to form a triad," Carthew says.

Using genetically engineered flies with either no Sina or with no Phyllopod proteins, Lai and Carthew discovered that the Tramtrack protein was able to be produced in the photoreceptor precursor cells, which later transform into cone cells. They also found, on the other hand, that overproduction of Phyllopod alone prevented accumulation of the Tramtrack protein as long as the Sina protein also was available in the same cell, which turned cone cells into photoreceptor cells. "We consider that to be a dramatic change," Lai remarks. "It tells us, as do our corresponding studies in cell culture, that together Phyllopod and Sina proteins are essential for targeting the Tramtrack protein for destruction."

"We are pretty confident that together Phyllopod and Sina bind to the gatekeeper protein, Tramtrack, which is the kiss of death that marks it for destruction by the cell's garbage-disposal enzymes," Carthew says. "Once the gatekeeper Tramtrack protein is removed, the cell is free to become a neuron."

"Up until a few years years ago, everyone thought developing cells always received positive signals, but now evidence is building at a rapid rate that the message often carried by the signal-transduction pathway is 'kill the gatekeeper,'" Carthew says.

"Many vertebrate proteins, some known to be involved in cancers, carry a structural feature similar to the Tramtrack protein," Lai says. "We are now searching for other biological systems where genes for Tramtrack-like proteins prevent cell development."

This research was supported in Lai's lab by the National Science Foundation and by a March of Dimes Basil O'Connor Starter Scholar Research Award. This research in Carthew's lab was supported by the National Institutes of Health, the March of Dimes Birth Defects Foundation, and the Pew Foundation.

http://www.bio.psu.edu/faculty/lai/lai.html

Barbara K. Kennedy

X-ray vision beyond Superman's wildest dreams will soon be one step closer to reality with the completion of a powerful X-ray camera for viewing high-energy objects in our galaxy and beyond to the farthest reaches of the universe. "For the first time, we will be able to view the sky in X rays almost as clearly as we can view it from the largest optical telescopes and 10 times better than any X-ray images we have had before," says Gordon Garmire, the Evan Pugh Professor of Astronomy and Astrophysics at Penn State.

Garmire is the principal investigator who conceived and designed the camera, which recently completed its final stage of testing at the Marshall Space Flight Center in Huntsville, Alabama. "It has performed flawlessly, exceeding the most optimistic goals originally set for it in 1989 when NASA accepted the proposal for its flight," Garmire says.

The camera was built under Garmire's direction at the Center for Space Research at the Massachusetts Institute of Technology using sensors built under the direction of George Ricker at MIT's Center for Space Research and large-format detectors known as CCDs developed at MIT Lincoln Laboratory in Lexington, Massachusetts. Its mechanical structure and power-conditioning-and-control unit were built at Lockheed Martin in Denver, Colorado.

The camera, the "AXAF Charge-coupled device Imaging Spectrometer" (ACIS), is one of two cameras slated for installation on the world's most powerful X-ray-astronomy observatory, NASA's Advanced X-ray Astrophysics Facility (AXAF), which is scheduled to be launched into space on the Space Shuttle in late 1998. The ACIS camera is a spectrometer that will record the energy of each X-ray that it detects coming from the high-energy objects as a unique amount of charge, convert the charge into a signal, and then send the spectral signals to scientists on Earth who will use the information to detect the presence of different elements.

AXAF will be the third of NASA's Great Observatories to be launched, following the Hubble Space Telescope, which detects ultraviolet, visible, and infrared rays, and the Compton Gamma-Ray Observatory, which detects gamma rays.

"X rays are the most useful energy band for studying high-energy phenomena associated with the most energetic objects in the universe," says Mark Bautz, a research scientist at MIT's Center for Space Research and a member of the ACIS development team. Scientists expect that the ACIS camera will reveal new information about the cycle of matter that ultimately made life on Earth possible. "We want to understand how stars produced the heavy elements like carbon and calcium, and how they ejected them into the interstellar medium where they eventually formed planets in star systems like our own," Garmire says.

The ACIS camera, when combined with the telescope's X-ray-focusing mirrors, has very high angular resolution, or sharpness of focus, which will allow it to see for the first time individual stars in regions where large numbers of stars are crowded. It also has high spectral resolution, which will give it the ability to determine the energy of individual X rays over a wide range of X-ray energies.

"The ACIS camera is amazingly efficient in the way it responds to X rays," Ricker says. "It records images, photon-by-photon, in 50 X-ray colors simultaneously. In virtually no other part of the electromagnetic spectrum is it possible to do such a thing, and ACIS does so with near perfection."

"The channel of spectral information that we will get from AXAF will be a thousand times higher in energy than the light we can see," Garmire adds. Among the objects the camera is designed to see are massive black holes?100 million to a billion times the mass of the Sun?which are thought to be the power source at the heart of quasars, the most luminous known objects in the universe. The ACIS camera, because it is able to see very-high-energy radiation, may be able to detect the early growth of the seeds of quasars in the early universe. In addition, the ACIS camera will determine the temperature and distribution of hot gas in galaxies and clusters of galaxies?data scientists can use not only to measure their mass but also to estimate the mass of the entire universe.

Because high-energy X rays also can penetrate through dense clouds of dust like those that hide the center of the Milky Way, scientists hope the X-ray camera will be able to see clearly the heart of our own galaxy, which many astronomers suspect harbors a massive black hole.

"We also are interested in the mysterious gamma-ray bursts and their associated X-ray emissions from exploding surfaces of neutron stars, which are almost as massive as black holes, in the flares and coronae of stars that are a thousand times brighter than our Sun, and in other kinds of stars that have very-high-temperature gas around them," Garmire explains. Scientists also plan to study the earliest and latest stages of a star's life, which Garmire says are hard to see in the optical wavelengths, and Sun-like stars that could reveal what our own Sun might eventually do in the later stages of its life.

"The X-ray sky looks totally different from the optical sky, so things will look pretty unusual," Garmire says. For example, around supernovae remnants in our galaxy?stars that exploded several thousand years ago?Garmire expects to see "beautiful expanding hot bubbles of gas that we don't see with optical telescopes because this gas is too hot and tenuous to emit visible light."

The ACIS camera also will be able to see more "colors" with X rays?a much broader range of different wavelengths of energy than the human eye can see. "If we could see in X rays, we would see a more colorful universe with many unnamed colors that you can't imagine," Garmire says.

The camera will next be shipped to Ball Aerospace in Boulder, Colorado, for integration and testing, then to TRW in Redondo Beach, California, where the AXAF observatory is being assembled, integrated, and tested. In the summer of 1998, it is scheduled to be moved to the Kennedy Space Center in Florida, where it will be attached to an inertial upper stage (IUS) manufactured by the Boeing Company of Kent, Washington, and mounted into the Space Shuttle in preparation for its launch.

AXAF is being built for NASA's Marshall Space Flight Center in Huntsville, Alabama, by TRW in Redondo Beach, California. Science data collected by the observatory will be calibrated, processed, and distributed by the AXAF Science Center, which is operated for NASA by the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.

http://www.astro.psu.edu/xray/axaf/

Barbara K. Kennedy

The notion that giant, Jupiter-like bodies may be a common occurrence around stars like the Sun has been bolstered by the discovery of such an object orbiting Rho Coronae Borealis, a star in the constellation Northern Crown. The newly discovered planet offers additional evidence for how such systems form, and bolsters the idea that other worlds like our own may be widespread throughout the galaxy.

The discovery was made by a team of scientists from three institutions?the Smithsonian Institution's Astrophysical Observatory (SAO) in Cambridge, Massachusetts; the National Center for Atmospheric Research (NCAR) in Boulder, Colorado; and Penn State?based on observations made at the Smithsonian's Fred Lawrence Whipple Observatory on Mt. Hopkins, Arizona.

The scientific team includes Sylvain Korzennik, Martin Krockenberger, Peter Nisenson, and Robert Noyes of SAO; Harvard University graduate student Saurabh Jha; Timothy Brown and Edward Kennelly of NCAR; and Scott Horner of Penn State.

Using a special instrument known as the Advanced Fiber Optic Echelle (AFOE) spectrograph located at the 1.5-meter Tillinghast Reflector of the Whipple Observatory, the scientists detected extremely small variations in the recession velocity of Rho Coronae Borealis that are thought to be caused by the presence of an orbiting companion.

With the AFOE capable of measuring velocity variations smaller than 10 meters per second (about 22 miles per hour), the scientists found that the speed of Rho Coronae Borealis varied back and forth by about 67 meters per second, or 150 miles per hour, over a 40-day period. This led the team to conclude that the star has a companion in a 40-day orbit and, from the size of the velocity variation and the mass of the star (almost identical to the Sun), they calculated that the companion must be slightly more massive than the planet Jupiter.

The short orbital period means the planet must lie only about 1/4 of an Astronomical Unit from the star?closer than Mercury orbits the Sun (an AU is the distance of the Earth from the Sun). This also implies its temperature would be about 300 degrees C, or more than 500 degrees F?much too hot for liquid water to exist, and hence not a likely place for life to form.

According to the researchers, the circular nature of the orbit suggests that the planet was formed like the planets in our own solar system, that is, through the slow coalescence of dust and gas from the circularly rotating disk that is thought to surround all newborn stars. A more eccentric, or highly elliptical orbit, could imply that the companion object was a failed star, the unsuccessful second partner in a potential binary star system.

"This discovery helps show that giant planets like Jupiter may be reasonably common around ordinary stars," says Robert Noyes of SAO. "Moreover, they can be found at a variety of distances from their parent stars, ranging from very close in, like the companion to 51 Pegasi, to very far away, like Jupiter relative to the Sun." The planet around Rho Coronae Borealis, like several others, is in between.

"It is exciting to think that there may be many smaller planets much more like the Earth in orbit around these stars, as in our own Solar System," says Noyes. Timothy Brown, of NCAR, who carried out the design and fabrication of the AFOE spectrograph's optics. He added, "All the giant planets found so far orbit Sun-like stars. The star Rho Coronae Borealis is another one of these, but it appears to be about 10 billion years old?twice as old as the Sun."

Scott Horner, of Penn State, designed and built the AFOE's iodine cell (a precise velocity-reference device). "It was the star's similarity to our Sun that led us to target it for study in the first place," he agreed. "Soon after we began to look at it, we thought that its radial velocity was varying. Now, after 11 months of monitoring, we're sure."

As one of the stars forming the "crown" of the constellation, Rho Coronae Borealis is visible from February through September to naked-eye observers in the Northern Hemisphere . It is about 50 light years from Earth.

A scientific paper describing the discovery has been accepted for publication in the Astrophysical Journal Letters. A pre-publication version of the paper is available, along with other details about the AFOE program, on the World-Wide Web at http://cfa-www.harvard.edu/afoe.

http://www.astro.psu.edu/users/horner/planet.html

James Cornell (Harvard Smithsonian Astrophysical Observatory),

Anatta (National Center for Atmospheric Research), and

Barbara K. Kennedy (Penn State)

Poised to run a complex computer model one September day in 1991, Penn State astronomer Alexander Wolszczan had no notion it would make him the first to discover planets outside of our solar system. Two months before, British scientist Andrew G. Lyne announced his team had found a Uranus-sized object orbiting pulsar PSR1829-10. That claim came in the midst of Wolszczan's painstaking work to confirm that millisecond pulsar PSR1257+12 had planets. For all appearances, Wolszczan's achievement would be personal, not historical. "I remember sitting in front of this computer and knew if it didn't work, I would be back to square one," recalled the distinguished professor of astronomy and astrophysics. "It was like getting ready for a one hundred-meter dash and you don't know if you are going to win or not." However, circumstance would soon favor the now-acclaimed Polish-born scientist.

Wolszczan, 50, grew up in the port city of Szczecin. His father, Jerzy, had been a fighter with the Polish Resistance in World War II and was a professor of economics in peacetime. His mother was secretary to the local chapter of the Association of Polish Writers. As a boy, Alex Wolszczan was hobbled one summer by a nasty cut, so his father hoisted him on his shoulders for nighttime star walks, kindling an interest the sky. Alex Wolszczan was schooled at Nicolaus Copernicus University, named for the famed Polish astronomer. Interested in journalism, Wolszczan had a run-in with the authorities over a radio commentary, making him realize honest news was impossible in Iron Curtain Poland, so he turned his full attention to astronomy.

After earning his doctorate in 1975, he became a faculty member at the university and was active in the Solidarity Movement. The government later cracked down on dissent, but fortunately Wolszczan was permitted to leave his homeland with his wife and daughter for the Max Planck Institute in Bonn, Germany. In 1983, he joined the Cornell University staff at Arecibo, Puerto Rico, home of the famed radiotelescope.

In January 1990, the giant dish underwent repairs and the usual long line of astronomers waiting for observation time disappeared. Arecibo could still be used, however, and Wolszczan got permission to explore for millisecond pulsars, a longtime interest. He soon discovered that the signal pattern of PSR1257+12 was oddly irregular. Could it be perturbed by another object? Delving more deeply, he called on Dale A. Frail, stationed at the National Radio Astronomy Observatory's Very Large Array in New Mexico, to pinpoint the pulsar in the sky and eliminate a key source of data error.

In July 1991, Andrew Lyne made his sensational announcement and that news was very much on Frail's mind as he faxed final results to Wolszczan with the note "Don't find any planets." Said Frail recently, "My recollection was getting an e-mail back immediately saying 'two planets'and giving their masses."

Wolszczan and he had found evidence that PSR1257+12 was orbited by two planets?the masses of 3.4 Earths and 2.8 Earths, respectively. (Two other planets were found subsequently.) Confirmation came that September day in 1991 when Wolszczan ran the computer model in his office at Ithaca, New York.

The two published their results in the January 9, 1992 edition of Nature, then went to the American Astronomical Society meeting in Atlanta, Georgia, to formally present their findings. Preceding Wolszczan to the podium was Andrew Lyne, expected by the waiting crowd of journalists and astronomer to triumphantly discuss his "first."

But Lyne stunned his audience by retracting his discovery. He and his team had neglected to take Earth's motion into account, yielding a false positive. The pressure was now on Wolszczan. However, he gave meticulous proofs that day and later, after joining the Penn State faculty, he subsequently published verification in the March 1, 1994 issue of Science.

Since then, there have been a flood of other planetary discoveries, NASA is funding further research, and a half-dozen other teams are in the hunt. Wolszczan is scanning other millisecond pulsars for signs like those of PSR1257+12 and is looking for objects around older white dwarf stars. His work involves two new fast-sampling spectrometers, one installed at Arecibo, the other at Nicolaus Copernicus University.

As important as the substance of Wolszczan's discovery was, it did more than merely catalog the first planets outside this solar system. Like Copernicus, he broke through the human-centered mindset with which astronomers were searching the universe. The hunt for planets now goes beyond parameters of the Earthlike.

"We are now at the beginning of a totally different period," commented Wolszczan. "People have just realized that we just have to keep our eyes wide open."

http://www.astro.psu.edu/users/alex/

Charles C. DuBois

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