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The tremendous concentration of mass, equivalent to 40 million suns, in the center of the galaxy NGC 4258 in the constellation Canes Venatici, was revealed by the apparent rotation of a surrounding molecular disk. The observations showed that the disk of dense material is orbiting within the galaxy's nucleus at velocities (up to 650 miles per second) that require the gravitational pull of such a massive object. The high angular resolution and sensitivity of the Very Long Baseline Array of the National Radio Astronomy Observatory allowed precise measurements of the differential rotation of the material in the disk, thus providing the most direct and definitive evidence to date for the presence of a supermassive black hole in the center of another galaxy.
Black holes, so dense that nothing--not even light--can escape their gravitational fields, have long been thought to be present in the centers of active galaxies, where they would act as central engines driving a variety of exotic and energetic phenomena that are seen on much larger scales, such as jets and powerful x-ray emission. NGC 4258, a spiral some 90,000 light-years across, is known to have jets of gas that are twisted into the shape of a helix emerging from the nucleus at speeds of 400 miles per second.
Moran, James Herrnstein, and Lincoln Greenhill of CfA; Naomasa Nakai and Makoto Inoue of Japan's Nobeyama Radio Observatory; Philip Diamond of the National Radio Astronomy Observatory in Socorro, New Mexico; and Makoto Miyoshi of Japan's Mizusawa Astrogeodynamics Observatory presented their discovery at the 185th meeting of the AAS. The work was also reported in the January 12 issue of Nature.
"The beautiful definition of the motion in the disk and its structure, and the high density of the central object--at least ten thousand times that of any known star clusters--convinces us that this must be a black hole," says Moran. "The dynamics of the disk are fairly simple, and we suspect it may offer us a laboratory for measuring a host of other fundamental phenomena in astrophysics."
The team of astronomers used the VLBA to study a disk of molecules deep within the nucleus of NGC 4258. The disk, tiny compared to the galaxy, contains heated water molecules that amplify microwave radio emissions in a manner similar to the way in which a laser amplifies light. The disk is oriented fortuitously so that pencil-like beams of microwaves are directed toward the earth.
These powerful naturally occurring microwave amplifiers, called masers, were discovered in the galaxy in 1982. In 1992, Nakai, Inoue, and Miyoshi, using a radio telescope at Nobeyama, Japan, made the surprising discovery that some of the masers had very high velocities with respect to the galaxy. The large apparent velocities they observed could not be accounted for by the galaxy's normal rotation. At that time, the Japanese researchers suggested that the masers might be orbiting a black hole. Research by Greenhill and colleagues, using the technique of Very Long Baseline Interferometry (VLBI), provided preliminary support for this hypothesis. The VLBA, an instrument built specifically for VLBI, now has confirmed the hypothesis and allowed astronomers to paint a surprisingly clear picture of activity in the depths of this galactic nucleus.
The astronomers calculate that the density of the central object is at least 100 million solar masses per cubic light-year. If this mass were in the form of a star cluster, the stars would be separated by average distances only somewhat greater than the diameter of the Solar System. Such a cluster could probably not survive the inevitable collisions between the stars, leading to the conclusion that the central mass is probably a black hole. The mass density estimated to lie in this central region is at least ten times greater than that of any other black-hole candidate. "The properties of this disk provide compelling evidence for the presence of a massive black hole," the astronomers wrote in their paper in Nature.
Independent measurements, made at the Haystack Observatory and at the Max-Planck-Institut fuer Radioastronomie in Germany, of the gravitational acceleration of the masers as they are swept along in the disk also allowed the astronomers to determine the distance to the galaxy with greater precision than had been done before. Previous estimates of the galaxy's distance ranged from about 11 million to nearly 23 million light-years. Incorporating these VLBA observations, the astronomers obtained a distance estimate of 20.8 million light years, plus or minus 4.2 million light-years. This direct geometric distance estimate provides an important reference point in the ongoing work to measure the size and age of the universe.
Fortunately, the explosion of Supernova 1993J in the relatively nearby galaxy M81 provided astronomers with an unusual opportunity to watch the evolution of the remnant and its interaction with surrounding gas and dust in the interstellar medium.
A large international team that included CfA director Irwin Shapiro, CfA scientists Brian Schmidt, Michael Ratner, and Pedro Elosegui, and headed by visiting scientist Jon Marcaide of the University of Valencia, Spain, used the high- resolution capability of Very Long Baseline Interferometry to obtain the closest--and earliest--view of an expanding shell structure. (Supernova 1987A in the Large Magellanic Cloud was closer, but not caught in its development until much later.)
In fact, the studies by Marcaide et al., as reported in the January 5 issue of Nature, showed that the expanding shell of the supernova has nearly perfect circular symmetry, except for a few small regions which shine relatively bright. The 8-month-old radio shell is the youngest ever seen in a supernova.
The Universe seems to be getting younger every day. In fact, according to new measurements made by the Hubble Space Telescope (HST), it seems younger than anyone thought possible.
In announcement last fall that challenged established previous estimates, an international team of astronomers that included CfA's John Huchra, presented the results from the HST suggesting the Universe may be somewhere between 8 and 12 billion years old.
Unfortunately, the new estimate--based on the measurement of the distance to M100, a galaxy located in the Virgo Cluster--conflicts sharply with previous research that dated the oldest stars as 15 to 18 billion years old. Thus, astronomers face the paradox--and problem--of explaining a cosmic whole that is older than some of its parts.
"Not to worry," says CfA's Bob Kirshner. "The Universe may be young, but it's still old enough to vote."
Using a different distance scale derived from measurements of expanding supernovae atmospheres, Kirshner and colleagues, including Brian Schmidt (now at Mt. Stromlo and Siding Spring Observatories), suggest that the Universe may be approximately 14 billion years old, considerably younger than the 20-billion-year age previously cited by many theorists, but ancient enough to have allowed evolution of the oldest observed stars.
Observations of the expanding photospheres of 5 Type II supernovae made at the Cerro Tololo InterAmerican Observatory (CTIO) in Chile, and 13 more from earlier work, Kirshner and other US and Chilean astronomers established a new value for the Hubble Constant, or expansion rate of the universe, at 73 (n6) kilometers per second per megaparsec, a rate that translates into a maximum age of 14 billion years.
Kirshner describes the distance measurements as "completely independent of, but complementary to, other attempts to determine the Hubble Constant, such as using the calibration of Cepheids in nearby galaxies." (The Cepheids are variable stars with a well-defined period-luminosity relationship that allows measurement of their absolute magnitudes to yield accurate distances to nearby galaxies. The HST measurements of M100 actually were of Cepheids in that galaxy.)
The "expanding photosphere method" employed by the US-Chilean group is a direct, one-step process, based on a single and simple geometric measurement of bright objects in galaxies far beyond the local group.
Models of the temperature and density of the atmosphere of an exploding star calculated by Ronald Eastman of the Lawrence Livermore National Laboratory provide observers with the precise dimensions of the emerging blast of light.
Using the color of a supernova and its brightness as measured at Earth, Eastman's models give the angular size of the exploding star. When combined with measurements of the velocity in the expanding gas, the angular size yields a solution for the supernova's distance.
Schmidt, who made several of the observations, notes that the technique works equally well with both nearby and distant supernovae. For example, Supernova 1987A in the Large Magellanic Cloud was one target of this study, but others at distances of more than 500-million light-years were also measured.
"Since supernovae are a million times brighter than Cepheids," Schmidt explains, "we can see them much farther away."
A map of atomic hydrogen pervading the nearby group of galaxies dominated by M81 was compiled by the CfA's Paul Ho and colleagues elsewhere from high-resolution observations made with the Very Large Array (VLA) of the National Radio Astronomy Observatory. It has long been recognized that interactions between galaxies may determine their individual evolution. The distribution of gas out of which stars are born is particularly affected by these interactions; and concentrations of gas near the nucleus of a galaxy may trigger a burst of star formation. Here, the hydrogen surrounding the most prominent galaxies in this group (M81, M82, and NGC3077) shows distinct filamentary structures, suggesting disruption of the system by tidal forces. A color version of this image graced the cover of Nature late last year, the first of two covers devoted to CfA-based research on the international journal in less than a month. (See "Black Hole" above.)
All the supernovae in this survey were Type II, that is, a type with a hydrogen-rich atmosphere, which explodes when the core of a massive star collapses. Such supernovae are thought to form neutron stars and pulsars. However, the size and type of the original progenitor stars are not crucial to this measurement technique, according to Schmidt, since the observed atmospheric temperature, brightness, and velocity provide an accurate size for the expanding shell.
As Kirshner describes it, the expanding photosphere method is not so much a "standard candle" as a "custom yardstick."
Obviously, further refinement of the Universe's age is expected. "At least we know for sure the Universe is older than we are," says Kirshner.
The experiment package was deployed from NASA's Shuttle Discovery (STS-64) on Tuesday, September 13, and spent most of the next 2 days in free flight, orbiting the Earth in a path paralleling that of the Shuttle.
Designed to study the Sun's hot outer atmosphere, or extended corona, the satellite was on its second of four planned, yearly missions aboard the Shuttle.
The Spartan observing program on this flight included polarimetric and spectroscopic observations of the Sun's extended corona with emphasis on coordinated observations with the Ulysses satellite, which detected solar wind from the south polar corona as Spartan observed the source region of that wind. Spartan also observed coronal regions adjacent to the south polar region of the corona and made observations above the north solar pole.
During these observations, the SAO scientific team hoped to measure the temperatures of hydrogen atoms, protons, and electrons found in large structures called coronal holes. Earlier satellite- and ground-based observations discovered ray-like structures called polar plumes, which extend some 2 million miles from the coronal hole (an open magnetic field region) on the Sun's south pole. Coronal holes are thought to be the source of high-speed solar winds--the hot, electrically charged gases that stream from the Sun.
Understanding exactly how and when the Sun creates this wind is the ultimate goal of the experiment, according to principal investigator John Kohl. The findings are of practical as well as scientific interest: The solar wind produces magnetic storms near Earth that can disrupt communication systems and trigger power outages, resulting in losses estimated at $100 million each year worldwide.
The flow properties of the solar wind out to the distance of the Earth have been calculated by Shadia Habbal and Ruth Esser of CfA, with colleagues from NASA/Goddard, using a two-fluid model constrained by data obtained on the first Spartan flight combined with ground-based observations from Mauna Loa.
COMET CRASH: Infrared images of the impact of several fragments of Comet Shoemaker-Levy 9 with Jupiter were obtained July 20 with a special electronic camera known as MIRAC developed in a collaboration between the University of Arizona, CfA, and Naval Research Laboratory. The instrument was attached to a NASA telescope on Mauna Kea, Hawaii.
The project's success was threatened 4 months earlier, when the truck transporting the telescope was rear-ended by another truck traveling at 70 mph. Both vehicles were destroyed in the crash, which occurred as the telescope-toting truck pulled back on the highway after stopping on the shoulder near Little Rock, Arkansas. The telescope was en route to California from Massachusetts, where it was built, assembled, and calibrated at Boston University's Scientific Instrument Facility, under the direction of BU professors Thomas Bania and James Jackson.
According to principal investigator Stark, some critically aligned parts were knocked out of position, and most of the outer skin on the upper part of the telescope had to be replaced.
Nonetheless, he and colleagues were able to remedy the problems, and they spent several weeks debugging the system to perfect the data quality before the winter closing of the South Pole base in mid-February. BU postdoctoral student Richard Chamberlain will remain at the base to winter-over with the telescope.
The dry atmosphere of Antarctica makes it an ideal site for the telescope, since water vapor interferes with submillimeter observations. The scientists plan to study the formation and destruction of molecular clouds in the galactic environment by surveying atomic carbon.
The first successful spectrum came from Sagittarius A, a giant molecular cloud near the galactic center.
Lane is project manager for AST/RO; other collaborating institutions are AT&T Bell Laboratories, University of Colorado, and University of Illinois.
The TSS project is a joint NASA/Italian Space Agency effort managed by the Marshall Space Flight Center. On STS-75, the 5-foot-diameter (1.6-meter), Italian-built satellite is scheduled to be deployed on the end of a 13-mile-long (20-kilometer) conductive tether to study the electrodynamic effects of moving such a tether through the Earth's magnetic field. The experiment also will test techniques for managing the tethered spacecraft at great distances.
The tethered-satellite concept, of course, originated at CfA, the brainchild of Mario Grossi and the late Giuseppe Colombo, whose work is carried on today by the Special Projects group of the Radio and Geoastronomy Division. In fact, two SAO-designed tether systems, both free-flying devices launched by expendable rockets, were successfully flown in the past year.
The more complicated system deployed by astronauts from the Shuttle ran into problems on its first test flight in July 1992 when the tether snagged on the deployment boom and the satellite- on-a-string reeled out only some 300 meters (approximately 900 feet) from the Shuttle bay. Hoffman, who was on that mission and presumably now knows well the quirks of the deployment system, will try again.
Hoffman, 50, will be making his fifth Shuttle flight. His previous space flight experience includes STS 51-D in April 1985, STS-35 in December 1990, STS-46 (the first tether) in 1992, and STS-61 in December 1993. His doctorate in astrophysics was obtained from Harvard University in 1971.
Pending final agreement on terms of SAO's sublease of the site from the University of Hawaii's Institute of Astronomy, ground-breaking ceremonies marking the start of construction for the six-element array and associated control building could be held as early as June.
The new HST results shed light on the properties of these mysterious clouds, the true nature of which remains elusive more than 25 years after their discovery. Understanding this intergalactic material might give important clues to the nature of dark matter and processes occurring in the early universe, including galaxy formation.
The observations were conducted by Foltz, who works at the joint Smithsonian University of Arizona Multiple Mirror Telescope in Arizona, together with other astronomers from U of A, Carnegie Institution, and the Dominion Astronomical Observatory.
The intergalactic gas clouds are so diffuse they cannot be observed directly. The only signatures of their existence are the imprints they leave on the light from more distant background objects. Astronomers have used these signatures to detect the presence of the clouds and to measure some of their physical properties, but have been unable to discover information on cloud sizes and shapes.
"This information is crucial to any attempt to distinguish between the several theoretical explanations for the sites and mechanisms which produce the clouds," says Foltz.
Previous explanations have been that the clouds are the halos of primordial clumps of dark matter, that they are the very outer halos of normal galaxies, or that they are produced by shock waves resulting from explosive galaxy formation.
"These Hubble results do not explain the details of how the clouds are produced, but they directly imply that the clouds are so large that none of the popular scenarios provides an entirely adequate explanation," Foltz says.
The team used Hubble's Faint Object Spectrograph at ultraviolet wavelengths to observe a pair of quasars--extremely luminous and distant objects--separated by an angle on the sky about one- twentieth the diameter of the full Moon. The clouds are detected by the dark absorption lines that they produce in the spectra of the light from the quasars. The quasars act like two flashlights seen from a distance of 5 to 10 billion light-years, shining through an intergalactic "forest" where the "trees" are the clouds.
A problem with such studies in the past has been in finding two quasars that are appropriately paired in the sky, roughly equidistant from the Earth and about equal in brightness. The team used the HST to study a pair of quasars bright at ultraviolet wavelengths but unsuitable for ground-based observations, since ultraviolet observations are impossible to make from Earth.
In the HST observations, several matching absorption lines were seen in the spectra of both quasars, implying that the clouds are at least large enough to cover the lines of sight to both quasars, or at least a million light-years in diameter, roughly 10 times larger than previously thought. (By comparison, the luminous disk of our Milky Way Galaxy is about 100,000 light- years in diameter.) Detailed analysis of the observations allowed the team to estimate that the actual size of the clouds may be as much as twice as large, or 2 million light-years in diameter, and that they may take the form of huge filaments, sheets, or flattened disks of material.
Craig Foltz of the MMTO provided technical assistance and advice, and Carol Heller (December 26) and John McAfee (December 27) were the on-site telescope operators during the experiment. Audio communication between Flagstaff and the MMT was maintained through the use of speaker phones on both ends. "It felt just like being in the MMT control room," reports Wagner.
The computer in Flagstaff was a SparcStation 10 running OpenWindows, which provided remote display of the various observing tasks running in the telescope building, and included control of the detector system and display of spectrograph functions. In the past, these tasks had frequently been done over the Internet from Tucson-based workstations, primarily for daytime testing of the spectrograph or its detector. However, the critical element missing for nighttime Internet-observing had been any method for displaying images from the acquisition camera on the remote observer's screen.
On these nights, the acquisition image of the MMT's field of view was displayed in Flagstaff. Images of the spectrograph slit were "grabbed" by the on-site frame-grabber PC and written in FITS format on the local SparcStation from which they were then available, via standard file transfer programs (ftp), to the remote observer. Typically, an image of the field of view was available in Flagstaff within 25 seconds of the request. Objects as faint as 22nd magnitude could be discerned on the remote image.
In most cases, the operator could position the proper target on the slit simply by comparing the real-time image with finding charts faxed to the mountain at the start of the run. Remote display of the field in Flagstaff allowed the observer to confirm that the correct target was on the spectrograph slit.
Wagner was delighted with the experience. "Some of the bugs were worked out the afternoon of the 26th, but the night was cloudy, so no observing was possible," he reports. "However, the next night was clear, and Flagstaff and Mt. Hopkins were connected for 15 consecutive hours of observing."
"The response of the system was excellent," he notes, "with acquisition of faint targets very easy." "Most important, remote observing saved 12 hours of driving from Flagstaff to the mountain and back again, as well as the travel costs. Even better, the cloudy night on the 26th was spent in a productive manner--working in the office on CCD photometry reductions, proposals, and talking to the occasional colleague who walked by wondering what was going on."
Eric Mandel of the High Energy Astrophysics Division, together with Mark Ackerman, a computer scientist at the University of California/Irvine, have developed new software that creates a single--and simple--Windows-type interface for accessing the multitude of complex programs now existent in astrophysics.
ASSIST is a tool designed to help astrophysicists use, individually and collaboratively, the diverse data-analysis programs that have been developed independently, each with its own special interface and commands.
"Problems usually arise not because the programs are bad, but because current research and data analysis necessitate using more than one type of software," Mandel says.
Astrophysical data gathered from special sources, such as the x-ray satellite ROSAT, are usually multi-dimensional and can only be analyzed by computers. In fact, a researcher often has to use several often incompatible programs: IRAF to extract the data, a Unix shell to format the file, and XSPEC to model the data. Each of these programs has different interfaces, different commands, and help systems. "It gets complicated because there are too many options," Mandel says.
ASSIST organizes the different programs into one user-friendly program in which analysis tasks are organized into graphical "trees." To execute a task, a researcher simply clicks on the appropriate "leaf," and manipulates parameters. The ASSIST activates the proper program; there is no need to know what particular program has been invoked to complete the task.
The software that ASSIST overlays, such as IRAF, also supports multi-wavelength analysis. "Thus, one can use ASSIST to analyze ROSAT, Hubble Space Telescope, or Kitt Peak data," Mandel says. It can also integrate data analysis executed by two separate programs by providing a common interface.
Another problem frequently encountered by researchers using complex software with large data sets is that on-screen information constantly scrolls off as new information is displayed, which makes data analysis difficult if two programs must be viewed at the same time. ASSIST's separate windows allow a researcher to see the menu, help files, and tutorials, as well as the analysis results simultaneously.
About 80 astronomers are currently using ASSIST as an interface for IRAF and other software programs. Further work on ASSIST, which was developed on XII Window systems for Unix-based workstations and some PCs, is being funded at $150,000 a year for the next 3 years. The ASSIST is available via anonymous ftp to sao-ftp.harvard.edu, in the pub/asc directory. For more information, contact Eric Mandel at 495-7135.
But these "students" are not children; they're teachers who have become temporary students in Project ARIES (Astronomy Resources for Intercurricular Elementary Science), a 2-week institute for elementary school teachers conducted by the Science Education Department (SED).
Having completed the second summer of a 3-year pilot program last August, Project ARIES' primary goal is to use children's strong interest in astronomy as a way to introduce more science and math into elementary school classrooms. [SED has applied for additional 3-year funding from the National Science Foundation.]
SED members believe that discovery-based science activities are more effective than most conventional classroom methods in helping students understand difficult concepts. For example, in the module on "Time," students discover that shadows cast by objects in sunlight follow a similar pattern each day. Instead of reading a textbook that explains time's passage, students observe, record, and eventually explain why shadows change with the Sun's positions throughout the day.
Philip Sadler, co-investigator of Project ARIES and head of the SED, says that children in grades 3 to 6 are not developmentally ready to understand standard explanations of physical phenomena. "Kids' brains are different from adults' brains," he says. "They are better able to understand experiences than concepts."
Not only are the activities better for the student; they also help the teacher. "I love it," says 5th grade teacher Gail Tynes of Round Rock, Texas. "The basic thing is the students are not taking in so much, so you can hone in on one topic really well."
Tynes was one of 24 teachers from 16 states selected to participate in ARIES this past August. Teachers are an essential part of the entire project. Because they will be using them, teachers help develop the modules, evaluate them, and create possible classroom uses.
"Personal professional growth in teachers is the key to making things happen in the classroom," says Ward, director of ARIES. "My feeling is that elementary-school teachers have been treated as second-class citizens for too long in the education world--as if they were not capable of learning this stuff."
In fact, Ward says, grade school teachers are very capable, and students who complete science courses taught by ARIES teachers show substantial improvement in understanding basic astronomy concepts, as well as phenomena like shadows and reflections.
"We want children to be excited about science," Ward says. "We take the simplest approach; we're not interested in vocabulary."
"The project takes a close look at the way kids think," agrees Jim McDonald, a participating 5th grade teacher from Concord, California. "After I finish [Project ARIES], I will go away with three really neat modules in areas tough to teach."
Eventually, Ward says, a published version of Project ARIES will be available, and teachers nationwide will be able to use and learn from ARIES via local institutes taught by former ARIES participants.
As part of a major effort to help science and mathematics teachers prepare for the realities of the classroom, the National Science Foundation has awarded a $2 million grant to an educational consortia that includes the Center for Astrophysics, Harvard's Graduate School of Education, MIT, UMass Boston, Wheelock College, and the Boston and Cambridge school systems.
Under NSF's Collaboratives for Excellence in Teacher Preparation (CETP) Program, the universities and local school districts will work together to improve the preparation of future elementary and secondary science and mathematics teachers. The grant supports the first two years of what is intended to be a five-year project.
"Our goal is to prepare future teachers to teach for understanding and to exploit the innate inquisitiveness of students in this process," says Irwin Shapiro, CfA director and principal investigator of the collaborative.
The effort stems from NSF studies that found almost all elementary teachers have responsibilities for science and mathematics instruction, but few have bachelors' degrees in those subjects. The report, "Indicators of Science and Mathematics Education 1992," also found that science teachers feel less qualified overall to teach their subjects than do teachers in other areas.
The collaborative, known as TEAMS-BC (Teacher Education Addressing Mathematics and Science in Boston and Cambridge), will enlist 10 local schools in a program to improve the math and science skills of their teachers.
After the first development year, some 50 specially trained teachers at these schools will act as mentors to 50 more teachers in each of the remaining 4 years of the grant. The project will also support summer institutes, discussion groups, and seminars.
The projects will impact science, mathematics, and education faculty members, in-service teachers, and undergraduates preparing to become teachers. The educational models and instructional materials that are developed will be published so they may be adapted for use elsewhere.
Also, the four participating colleges and universities will develop revised college-level courses for teachers in training. [A possible prototype for such courses has been introduced at the Harvard Extension School. "Science Learning: A Constructivist Approach," team taught by Phil Sadler, Mike Filisky, Chuck Whitney, and Matt Schneps of CfA's SED, draws on the experience of "A Private Universe" to show how learning in science may be blocked by student preconceptions that go unrecognized by teachers.
Nearly 500 people, mainly residents of Arizona's Santa Cruz Valley, attended the official, but decidedly informal, public opening of the newly completed Visitors Center of the Whipple Observatory on Saturday, January 7. An opening reception for staff and volunteers was held the previous Thursday, and a tour for members of the national media attending the AAS was given the following week.
Located in the administrative support facility at the base of Mt. Hopkins, and just within the boundary of the Coronado National Forest, the Visitors Center features displays and exhibits on astronomy and astrophysics, natural science, and cultural history.
Developed in cooperation with the USDA/Forest Service, the 1200-square-foot Visitors Center is intended to provide an introduction to the FLWO for both general public and official users of the mountain-top research facilities and orientation and nature interpretation for recreational users of the forest.
Exhibits include models of the original and soon-to-be converted MMTs, a three-dimensional model of the CfA Redshift Survey results (with the original spectrograph that measured the redshifts), and a touchable topographic map of the Santa Rita Mountains.
Other displays trace the history of optical telescope development from Galileo to the converted MMT, recount the many other Smithsonian research projects in Arizona during the past century, and describe current investigations in gamma-ray astronomy and optical-infrared interferometry. A natural history exhibit examines those animals active in the nighttime, and features a 4-foot-diameter color transparency of the night sky over Southern Arizona. And, in honor of the observatory's founder, one display presents examples from Fred Whipple's personal collection of neckties with astronomical motifs.
All exhibits and public areas are accessible; and major exhibit titles have been translated into Spanish. (A bilingual guide to the exhibits is now in preparation.)
In addition to the interior exhibits, the Visitors Center complex includes an outdoor patio with a petroglyph discovered on site during construction, interpretative signage describing desert flora, and a stunning view of the MMT on the summit of Mt. Hopkins.
A trailhead, rest rooms, and picnic area located just outside the main gate was developed and constructed by the Forest Service and offers benches, grills, and a hardened path that leads to vantage points overlooking Montosa Wash, a deep canyon running parallel to the basecamp site. A kiosk at the trailhead provides information about camping and hiking as well as FLWO public programs.
The Visitors Center exhibitry was conceived and produced by Jim Cornell, with the assistance of Dan Brocious of FLWO and Mary Anna Wheat of the Coronado Forest. The chief designer was William Jacobs of the National Air and Space Museum's Exhibits Department; Jeff Klas and Stan Helin, both of the Forest Service, designed the natural history exhibits and nature trail complex, respectively.
Major support for the fabrication and installation of exhibits came from the Smithsonian Institution's Special Exhibition Fund and the Forest Service. Indeed, the Visitors Center is an unusual example of intra- and interagency cooperation, with scores of people at FLWO, SAO, and NASM, as well as in different offices within SI and the Forest Service, serving as consultants and contributors.
For now, the Visitors Center is open 9 to 5 Monday through Friday, but special Star Parties are held quarterly at the Center on a Saturday, starting in the late afternoon. Reserved-seat bus tours, originating at the Visitors Center, are conducted three times weekly from early spring to late fall. CfA staff and families visiting Arizona can call 602-670-5707 for more information.
PHYSICS LESSON: Whipple Observatory volunteer Jim Trexler, a retired physicist now living in Green Valley, Arizona, described the process of measuring galactic redshifts to some of the several hundred guests who attended the opening of the new Visitors Center.
This year's theme, "Common Questions: Cosmic Connections," will answer some of the queries frequently received by the CfA's Public Affairs Office--but go beyond the simple explanations to describe the more complex processes underlying seemingly simple phenomena.
Topics, and speakers, this year, include: "Why is the day 24 hours and the year 365 days?" by Owen Gingerich, April 5; "Why is the sky blue?" by Sallie Baliunas, April 12; "Why is the sky dark at night?" by Mike Lecar, April 19; and "How did the universe get its lumps?" by Margaret Geller, April 26.
The lectures are given in the museum's Cahners Auditorium starting at 7:30 pm. They are free, but tickets are necessary and can be obtained by calling the Public Affairs Office at ext. 5-7461.
The papers, "Matched Filter Source Detection Applied to the ROSAT PSPC and the Determination of the Number-Flux Relation;" "ROSAT Extended Medium-Deep Sensitivity Survey: Source Counts Down to 1.2 10-15 ergs s-1 cm-2;" and "ROSAT Extended Medium-Deep Sensitivity Survey: Average Source Spectra," were submitted to The Astrophysical Journal.
The Fourth International Conference on Tethers in Space will be held at the Smithsonian Institution in Washington, DC, April 10 14. Sponsored by SAO, NASA, and ASI (the Italian Space Agency), the conference will review the results of various tether missions--SEDS, PMG and TSS-1--and discuss the future deployment of tethers in space.
The successful flight of several tether systems in recent years has demonstrated that such satellites can not only be controlled during deployment and retrieval, but that they also have great potential for a variety of spaceflight operations and science experiments.
Invited and submitted papers will be presented during the first 3 days; workshops on tether dynamics and future flight experiments will follow. Enrico Lorenzini and Mario Cosmo are coordinating contributions from SAO.
Most galaxies fall into two broad groups: egg-shaped ellipticals, or pinwheel-shaped spirals. In 1925, Edwin Hubble created the first system of galaxy classification to distinguish between the wide array of variations within those two groups. Modified forms of his system are still used today; however, the classification process is subjective, and experts don't always agree.
"An objective, automated method for classifying galaxies will help astronomers study the evolution of galaxies, as well as their distribution in the Universe," says study co-author Somak Raychaudhury of the CfA's High Energy Astrophysics Division. A galaxy's shape reveals clues about its formation and stage of evolution.
Led by Ofer Lahav of the University of Cambridge, England, the authors recruited six galaxy-classification experts from the US and Canada, including John Huchra of the CfA's OIR Division. They asked each expert to classify the same 831 galaxy images, selected from Raychaudhury's Equatorial Catalogue of Galaxies, compiled from digital scans of sky photographs using the Cambridge Automated Plate Measuring machine.
Of that total, all six gave the exact same classification to only eight galaxies. However, for 80 percent of the sample, the experts agreed to within two adjacent classes. "These findings suggest that the existing class designations are perhaps too fine," says Raychaudhury.
Not surprisingly, the two astronomers who had been trained by the same senior astronomer tended to agree with their mentor and with one another.
The most significant result, however, was that an artificial neural network--developed by Lahav's graduate student A. Naim--was able to replicate the galaxy classifications to the same degree of agreement as that between any two human experts.
For each of the six individual experts, the ANN was "trained" on three-quarters of the sample galaxies and then, based on an individual expert's recorded response, tested on the remaining quarter of the sample. "Essentially, we're trying to simulate John Huchra's brain," says Raychaudhury, "and those of the other five experts."
The next step was to combine the collective expertise of all six astronomers. Preliminary data from that study will be published soon in the Monthly Notices of the Royal Astronomical Society.
The Science article represents the first systematic comparison based on a uniform sample of galaxy images presented to astronomers representing different styles and traditions of classification.
Artificial neural networks (ANNs) are named for their ability to "learn," or mimic the function of neurons in the human brain. First developed in the 1960s, ANNs are now used for data analysis in a variety of different fields, including space and defense instrumentation, archeology, and economics.
To date, about 20,000 galaxies have been assigned designations by one or more experts. But there are currently millions of galaxy images stored on compact disks, awaiting classification, says Huchra, and millions more will be obtained from extensive, all-sky surveys over the next few years. "Obviously, it will be impossible for humans to classify all those galaxies," he says. "The ANN will not only make it possible to process this vast amount of data, but will also allow for greater sensitivity, since it can detect galaxies up to 100 times fainter than currently classified galaxies," he adds.
Knowing the differences between how spiral and elliptical galaxies are dispersed will lead to a better understanding of the large-scale structure and, ultimately, the formation and origin of the Universe.
Newly discovered comets are now designated by the same system used to denote minor planets, or asteroids. The new naming scheme, adopted by the International Astronomical Union (IAU) last August, reflects an effort to simplify the designations and acknowledges the difficulty that sometimes arises in distinguishing comets from asteroids. The Central Bureau for Astronomical Telegrams (CBAT) of the IAU, headed by Planetary Sciences Associate Director Brian Marsden, is responsible for issuing comet designations.
Starting in January 1995, the nature--or presumed nature--of an objects is indicated by a letter prefix (A for minor planets, C for comets, and P for periodic comets), the year of discovery, an upper-case letter designating the half-month during that year, and a number indicating the order of discovery in that half-month, followed by the name of the discoverer.
The first comet discovered under the new scheme is known as P/1995 A1 (Jedicke), named for Robert Jedicke who found this faint, short-period comet at Kitt Peak on January 8. Though the procedure for actually assigning names to comets is being debated (and now requires vote by an IAU committee of nine), no major changes have yet occurred. Up to three names are still permitted on a single comet, and nondiscoverers may still have their names attached to comets if they were part of the discovery project.
The naming procedures are described in a new 108-page Catalogue of Cometary Orbits (the tenth edition published by CBAT director Brian Marsden in three decades), which also lists comets seen as long ago as 240 B.C. (Halley's comet) and contains orbits, statistics, and designations/names for objects through the end of 1994.
Last fall, more than 3,000 teachers throughout the nation tuned in to the "Private Universe Project" video teleconferences produced by the CfA's Science Media Group. The nine, two-hour programs, designed to address the problem of misconceptions in the classroom, were viewed at 285 sites in the US, as well as sites in Costa Rica, Canada, and England.
Participating teachers called, faxed, or e-mailed their questions, reactions, and ideas about the shows during the broadcasts. Their ideas will be incorporated into the final series of six, half- hour programs, scheduled for completion this summer.
MouseLab, a program developed for the SED scientists to help students understand the physics of motion, received an award from the fifth annual Computers in Physics contest for innovative software in physics education. The award was presented at the January 1995 meeting of the American Association of Physics Teachers in Orlando, Florida.
MouseLab is part of a new generation of computer software that "lets students solve real-world, nontrivial problems in a graphical, user-friendly way," says co-developer Freeman Deutsch. The software was developed for Project InSIGHT (Investigative Stimuli for Intuitive Growth using High Technology), by Deutsch, principal investigator Chuck Whitney, and co-investigator Philip Sadler. Funded by the National Science Foundation, the InSIGHT group explores and creates computer models of physical systems to discover how students perceive simulations and how to use such simulations in conjunction with actual laboratory experiments, according to Whitney. In a 1992 InSIGHT project, the group developed WaveMaker, a program that helps students explore a variety of phenomena associated with waves. WaveMaker, which also won an award for innovative software in physics education from Computers in Physics, will be distributed this summer.
MouseLab targets a different concept in physics education: kinematics. Kinematics, the study of motion, "is one of the most difficult concepts for students to grasp," explains Deutsch. "MouseLab provides them with a tool to explore the relationships between the position, velocity, and acceleration of a moving object." Students can choose among four models: an elevator, race car, rocket, or anvil. Each illustrates a different type of motion. The elevator shows differences in position over time, and the anvil (used as a generic falling body) demonstrates acceleration resulting from gravity. In the program, students can set the object's initial position and velocity, as well as change the settings, using the mouse to click on an object and move it.
Alongside the graphical representations of the objects, the program displays three graphs: displacement vs. time, velocity vs. time, and acceleration vs. time. (Displacement is the difference between the initial position of a body and any later position.) As the student moves the virtual object on the screen, the program calculates and automatically draws in the values on each of the graphs, enabling visualization of the relationship between the motion parameters.
"The program lets them see the solutions right away, which helps reinforce understanding," says Deutsch. "Used in tandem with similar laboratory physics experiments, the program serves as an effective bridge between the real world and the mathematical world," notes Whitney.
LUIS RODRIGUEZ, a frequent visitor to HCO and a long-time collaborator with Jim Moran and other CfA radio astronomers, last year won the prestigious Mexican National Award in the Sciences for his contributions to astrophysics. Also last year, using the Very Large Array, Rodriguez and colleagues discovered the first "superluminal object" detected in our galaxy.
A gaggle of CfAers, with accompanying family members and friends, made considerable "strides against breast cancer" last fall when they walked 5 miles and raised over $2000 for the charity. The striders included, above, front row: Dana Marie Henson, Kathleen Entler, Shadia Habbal, Jessica Piotrowski, Sara Yorke, and Marion Aymie; middle row, Nancy Bills, Lauren Deknis, Erlinda Mullen; and, back row, Tom Mullen, Dave Henson, Linda Rahman, Zie Skobe, Pat McDonough, and Eva Cardarelli.
MARTIN REES, a former Smithsonian Regents Fellow at the CfA, assumed in January the post of Britain's Astronomer Royal, a largely honorary position created in the seventeenth century. Rees is also Royal Society Professor at the Institute of Astronomy in the other Cambridge.
FRED WHIPPLE, former director of SAO, was the guest of honor and keynote speaker at the celebration of the Tucson Amateur Astronomy Association's 40th anniversary last fall. The TAAA provided one of the original Moonwatch teams established by Whipple in 1956-7 for tracking artificial satellites. TAAA members also help run the quarterly star parties at Fred's namesake observatory in Amado.
Two SAO administrative oldtimers, DON HOGAN, head of Support Services at the FLWO, and RALPH DUMAS, property control officer in Cambridge, took advantage of buyouts to retire after a collective 60-some years of service to Smithsonian. And two scientific pioneers, BOB DAVIS and CHUCK WHITNEY, both members of the original and tiny core of professional astronomers on staff when SAO moved to Cambridge at the start of the Space Age, announced their imminent retirements.
Ralph Dumas raises the Smithsonian banner (actually, a bathrobe), one of the many gifts presented him at his retirement bash on January 19.
FLWO utilities specialist DEWAYNE KURTENBACH is serving on the interim town council for the newly incorporated municipality of Sahuarita, Arizona. Kurtenbach already serves on the Sahuarita School District Governing Board and is the president of the Sahuarita Area Council. The town is about 10 miles north of Mt. Hopkins.
Karen Lawley presents Gerry Austin a plaque recognizing his work to establish a radiation safety plan for Porter Exchange.
MARGARET GELLER was one of several local scientific luminaries invited to help celebrate the 1994 Ig Nobel Prizes at MIT October 6. She also presented one of the infamous, 30-second, Heisenberg Lectures.
Last year, in addition to agreeing to continue his tenure as associate director for Optical and Infrared Astronomy and being named director of the FLWO, JOHN HUCHRA was elected a Fellow of the American Association for the Advancement of Science.
Last summer, GERRY AUSTIN, JUDY LEES, and STEVE MURRAY were recognized by the Smithsonian Institution's Safety Program for their contributions to maintaining safe conditions in their respective areas of SAO. Then, at ceremonies in Washington early this year, SAO itself was awarded grand prize for outstanding safety efforts among all Smithsonian bureaus.
MARION AYMIE was cited for "Exemplary Performance" in recognition "for her strong personal commitment and involvement in EEO/Diversity at SAO" at the awards ceremony following an Equal Opportunity Conference sponsored by the Smithsonian's Office of Equal Employment and Minority Affairs, in Washington, last November.
Former Harvard astronomer ROBERT ROSNER, now at the University of Chicago, is the new chair of the CfA Visiting Committee, scheduled to meet here May 4-5. Other members include: Wendy Freedman of the Carnegie Observatories, Miller Goss of NRAO, Richard Larson of Yale, Walter Lewin of MIT, and Judy Pipher of the University of Rochester.
SAO contract specialist and attorney John Harris is one of a select few New Englanders testing prototype electric automobiles in response to a Federal law that will soon mandate the percentage of such vehicles manufactured and sold in the United States. Harris loves his silent-running car, which, until you raise the hood, doesn't look much different than other cars in the Porter Exchange parking lot.
JAMES DAVIS, of the Radio and Geoastronomy Division, was granted an SI Scholarly Studies award for "Estimating Free Core Resonance Parameters Using VLBI-Determined Love Numbers."
LARRY MARSCHALL, a physics professor at Gettysburg College, is visiting the CfA's Science Education Department through August 1995. He is principal investigator of Project CLEA (Contemporary Laboratory Experiences in Astronomy), which has produced a number of computer-based programs to support astronomy instruction in high schools and colleges.
In their quest to probe the origin of matter in the Universe, SAO physicists RON WALSWORTH and EDUARDO OTEIZA have developed a spin-off technology that may greatly enhance a common medical diagnostic test known as magnetic resonance imaging. Their work is described in the current issue (Winter, 1995) of Research Reports.
Noble laureate ROBERT WILSON, formerly of AT&T Bell Laboratories, has joined the CfA's Radio and Geoastronomy Division. Wilson will lend his expertise to the SMA project, as well as consulting on the AST/RO project.
Former Harvard-Smithsonian postdoctoral fellow JANE LUU has returned as an assistant professor of astronomy at Harvard. She is affiliated with the CfA's Solar and Stellar Physics Division. Using the 1.2-meter telescope at Mt. Hopkins, Luu will continue her search for distant, icy bodies encircling the Sun just beyond Neptune's orbit. In 1992, she and colleague Dave Jewitt (U. of Hawaii) discovered the first of these so-called Kuiper belt objects, thought by some to be the source of short-period comets. To date, they and others have found 17 more of these tiny worlds, ranging in size from 100-400 km in diameter.
Following a decade-long stint at the Boston Museum of Science as a senior exhibition planner, ROY GOULD has joined the CfA's Science Education Department. Gould's varied credentials also include a PhD in biophysics from Harvard and working as an associate producer for the acclaimed WGBH science series, NOVA. He did postdoctoral work at Harvard's School of Public Health, working with Lyndon B. Johnson's former science advisor, Don Hornig, on issues in health and environmental policy. At the CfA, Gould will assist various ongoing SED projects, and chart new directions, particularly collaborative programs with science museums.
Shadia Habbal, Solar and Stellar Physics, was appointed the new coordinator of the CfA Women's Program Committee last fall. Elected members of the WPC: Pat Brennan, Nancy Brickhouse, James Cornell, Kim Dow, Kathleen Entler, Nancy Finkelstein, Chris Hollander, Susanne Huettemeister, Jiahong Juda, Jonathan McDowell, Andrea Prestwich, Margaret Simonini, and Donna Thompson. Ex Officio members include: Marion Aymie (Equal Opportunity Officer), Ray Gonzalez (EO Counselor), and Smithsonian Institution Women's Committee representatives Donna Coletti and Judy Ryan.
"The WPC reflects a wide range of professions and personalities," says Habbal. "Its richness and strength lies in this diversity. My goals as coordinator are to raise awareness and consciousness at every level and to make the CfA a more exciting and hospitable environment."
"As part of our program this year, " Habbal adds, "We plan to hold dialogues and forums on issues affecting women and to sponsor a series of lectures by 'Adventurous Women' that may provide inspiration for everyone."
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"Women in Astronomy," a booklet that grew out of the conference on the Status of Women in Astronomy held in 1992 at the Space Telescope Science Institute, addressed the challenges faced by women at the graduate level and beyond. The highlight of the booklet is "The Baltimore Charter," which calls for specific action to improve the status of female astronomers. Recommendations include active recruitment to increase the numbers of women under consideration for new positions, and that strong stand be taken against sexual harassment. Director Irwin Shapiro endorsed "The Baltimore Charter" and its goals on behalf of the CfA.
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Annie Jump Cannon, renowned for her work in stellar spectroscopy at HCO in the 1920s and '30s, was inducted into the National Women's Hall of Fame in a ceremony held last September in Seneca Falls, New York. SAO science historian Barbara Welther, who has chronicled Cannon's life in articles, lectures, and a video, received the medallion on Cannon's behalf. Twenty-four other women, including celebrities such as Oprah Winfrey, Geraldine Ferraro, Bella Abzug, and the late Wilma Rudolph, were also inducted at the event, which was publicized on NPR and PBS.
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A new version of "Space For Women," a booklet designed to encourage young women to pursue careers in astronomy and related fields, will be available from the CfA's Publications Department in early March. The original book- let, now 20 years old, documented a 2-day symposium, titled "Earth in the Cosmos: Space for Women," held at the CfA in 1975. The Women's Program Committee sponsored two similar events in both 1992 and 1993, and will sponsor another in late September 1995. The new "Space for Women" includes 13 profiles of women who work in various capacities at the CfA--from administrative assistants to senior astrophysicists. The 20-page booklet also includes practical information about career planning and preparation, as well as a list of resources and a glossary.
Garibaldi, Pocahontas, Dionysus, and Walter Adams are critical; but Midas, Magellan, Nefertiti, and Bruce Murray are merely unusual. The aforementioned were among the scores of asteroids noted by the CfA-based Minor Planet Center as missing in action (critical) or following erratic paths (unusual). Watch the skies...and remember to duck.
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Notes on the refrigerator at 1815 Mass Ave:
"Sorry, we took your bag by mistake"
"Please replace my ginger ale. I don't like Diet Sprite."
"If you ever want to see your ginger ale again, leave a brown paper bag with unmarked bills beside the microwave after work tonight."
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Among the half-million additions to the collections of the Smithsonian in 1994:
An oil-on-velvet portrait of Andy Warhol.
Pieces of the Peekskill meteorite that crashed through a car trunk on October 9, 1993. (This was the first meteorite fall recorded on video--mainly by camera-toting parents attending high school football games up and down the East Coast that night.)
The original Kermit the Frog.
The personal papers of Brownie Wise, the woman who conceived of Tupperware Parties.
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Grant proposals no funding agency could refuse:
"Spots Before Your Eyes: A Multiwavelength Study of an Active K Dwarf" PI: Jay Bookbinder
"Dead or Just Sleeping? Status of Magnetic Dynamos in 'Maunder Minimum' Stars" PI: Stephen Saar