During the past year significant progress was made by STOEGER and ARAUJO (Department of Mathematics, University of Brasilia, Brazil, and the Vatican Observatory) with help from MAARTENS and HUMPHREYS (School of Mathematical Sciences, University of Portsmouth, Portsmouth, UK). They have completed their analysis of the exact spherical symmetric Einstein field equations in observational coordinates, showing how these equations can be integrated using data functions representing observer area distance and galaxy number counts given as functions of redshift. They are presently reexamining the freedom of the fluid-ray tetrad as a prelude to correcting and completing the integration of the generally perturbed field equations in observational coordinates and to finishing their analysis of the calculation of cosmic microwave background radiation anisotropies in observational coordinates.

STOEGER, HELMI (Sterrewacht Leiden, University of Leiden, The Netherlands) and TORRES (Departamento de Fisica, Universidad de La Plata, Argentina) are nearing completion of their weak-field treatment of averaging in cosmology. Their work focuses on averaging over perturbed Friedmann-Lemaitre-Robertson-Walker space-times and comparing their technique and results with those of other suggested approaches. They have been able to demonstrate the "almost covariance" of their procedure.

LISKA (Swedish Institute of Space Science, Sförs), in work with PACHOLCZYK (Steward Observatory) and STOEGER, has completed his statistical analysis of the rapid X-ray variability of Seyfert I galaxies, demonstrating that it does possess a definite low-level deterministic component, almost certainly originating in the sources themselves, as well as both transient and persistent tones and "chirps," indicating quasi-periodic phenomena in the source with periods between 20 and 400 seconds. LISKA has also demonstrated the signature of purely random, indeterministic signals in his wavelet ampligrams, and he has shown how weak deterministic components modify these. This work has strongly supported the conclusions concerning the Seyfert I X-ray variability data. On the basis of this work, PACHOLCZYK and STOEGER, with LISKA, have nearly completed their scenario for explaining such rapid X-ray variability, using the superposition of luminosity building blocks. These could be either magnetic flares developing in accretion disks around the central black holes that dominate Seyfert nuclei or X-ray bursts emanating from smaller black holes, traveling at high velocities in a central black hole cluster, as they puncture the accretion disks of the large central black hole or neighboring smaller black holes. PACHOLCZYK and STOEGER are completing the details of the physics of such proposed bursts, including the super-Eddington energy release (relative to the smaller black holes), and the degradation of the original gamma-ray release to X-rays via photon-photon pair production on the surrounding X-ray intracluster background.

STOEGER and JUST (Department of Physics, University of Arizona), along with JUST's graduate students, continue their fundamental work in quantum field theory. In particular, they are elaborating the results of JUST's quantum induction program for avoiding infinite renormalizations. They are strengthening and confirming preliminary results concerning estimates of the mass of the Higgs particle as well as estimates of the cosmological constant, which appears to be exactly zero in quantum induction. They have also been examining issues of unitarity, locality, and the sharpness of the electron mass in field theories in general, with particular application to quantum induction itself.

HELLER has continued research on applications of noncommutative geometries to physics, in particular, to the study of classical singularities and the unification of general relativity with quantum theory. An interesting result is that, if it is assumed that the pre-Planck era (quantum gravity regime) is governed by a noncommutative geometry, it can be shown that nonlocal phenomena, actually met in quantum mechanics, are remnants or "shadows" of the primordial noncommutativity. In this way one deduces the famous Einstein-Podolsky-Rosen effect from a noncommutative model. Noncommutative geometry describes a space with no points and no neighborhoods. The fact that two elementary particles know of each other despite the distance separating them can indeed be regarded as a trace of the original nonlocality. Further work is in progress.

Extragalactic Research

MOSS (Visiting Astronomer), working with WHITTLE (University of Virginia), is completing the analysis of results of an objective-prism, H-alpha survey of nearby clusters in an investigation of the evolution of spiral galaxies in these environments. Research in recent years with the Hubble Space Telescope has shown that distant, rich clusters of galaxies have a higher fraction of blue star-forming galaxies, which often have unusual morphology suggestive of mergers and tidal interactions. It has been suggested that an earlier population of spirals in distant clusters has been depleted by the present epoch. Based on this picture, spirals do not survive a rich environment but undergo drastic modification as they are being transformed into other Hubble types. Although this depletion process, with associated mergers and interactions, is likely to be more common in distant clusters at earlier times, it is clearly of interest to search for these same processes occurring more recently in nearby clusters.

Some 450 galaxies in 8 nearby Abell clusters have been surveyed for H-alpha emission by MOSS and WHITTLE. Additionally, some 180 galaxies in Abell 1060 were surveyed by BENNETT (University of Cambridge, UK) and MOSS. The H-alpha emission is used as an indicator of the current rate of massive star formation to compare global star formation rates between cluster galaxies and field galaxies, and thereby clarify the environmental influence on star formation. Approximately 35% of the surveyed spiral galaxies are detected in emission, of which half show extended disk-wide H-alpha emission typical of normal spirals. The remainder exhibit centrally concentrated emission that appears to be tidally induced by near-neighbor interaction, and possibly also by perturbation by the overall cluster field and by higher speed "harassment" interaction between galaxies. There is an enhancement of tidally induced star formation in cluster spirals compared to spirals in the field, with a number of early-type spirals discovered to have strong star formation, which is rare or absent in the field. A strong correlation has also been discovered between cluster mean central galaxy density and the fraction of spirals with tidally triggered star formation.

MOSS continues to collaborate with BENNETT and ARAGON-SALAMANCA (University of Cambridge, UK) in the study of broadband CCD imaging and near-infrared J and K imaging of detected emission-line galaxies. These data have provided a wealth of information on the present and past star formation in cluster galaxies, its spatial distribution, and its correlation with the properties of the galaxies and their environment.

VANSEVICIUS (National Astronomical Observatory, Tokyo, and Institute of Physics, Vilnius, Lithuania) is analyzing VATT CCD observations of the Whirlpool Galaxy, M51, made in the 7 Vilnius filters by BOYLE in January. They are attempting to determine stellar populations in M51 by analysis of precise color surface photometry.

During a working visit by MAGALHAES (Institute of Astronomy and Geophysics, University of São Paulo, Brazil) to Castel Gandolfo, he and COYNE furthered their plans for mapping the magnetic field over a large area in the Small Magellanic Cloud by polarization imaging of wide fields.

OMIZZOLO, in collaboration with CRISTIANI (Department of Astronomy, University of Padua), continues to study the evolution and the luminosity function of quasi-stellar objects (QSOs). One of the strongest pieces of evidence for an evolving universe has long been the observed evolution of the quasar population in co-moving space density. A statistically well defined sample of very bright QSOs is needed to remove the present uncertainties about the properties of the local QSO population. In this way it may be possible to disentangle the QSO evolutionary pattern. This may permit a determination of the fraction of radio-loud objects and of the optical to X-ray luminosity ratio. Some of these objects may be evolving in different ways, due possibly to different types of QSO hosts. A number of databases have been used to select candidates that will provide the high level of completeness needed to carry out a survey quickly and effectively. Such a sample should play a decisive role in determining the nature and evolution of QSOs. OMIZZOLO is studying a sample of about 800 objects, part of which are from the ROSAT catalogue of X-ray sources. With the assistance of CORBALLY, he obtained the spectra of 43 objects in October at the 90-inch telescope of Steward Observatory on Kitt Peak; images of the same were made at the VATT on Mt. Graham. The reduction of these data and of others obtained at La Silla by CRISTIANI is proceeding in Padua, Italy, and at Garching, Germany.

FUNES (University of Padua), in pursuit of his doctorate, continues research on the kinematics of ionized gas in disk galaxies. From emission lines in spectra taken with the 3.6-m telescope of the European Southern Observatory as well as from images in H-alpha taken at the VATT of a sample of early-type disk galaxies, it was shown that there is a possibility of detecting the presence of Keplerian gaseous disks using properly equipped, optical ground-based telescopes. The peculiar bidimensional shape of the emission lines was modeled as being due to the motion of a gaseous disk rotating in the combined potential of a central pointlike mass and of an extended stellar disk. The mass of the central black-hole candidate has been derived.

The Galaxy and Galactic Objects

CORBALLY and GRAY (Appalachian State University, Boone, North Carolina) have introduced an extension of the MK System of spectral classification that enables the precise classification of pre-main-sequence (PMS) A-type stars, including most Herbig Ae stars. This classification scheme characterizes the star by a standard MK type, the presence and strength of emission and/or shell lines, and the strength of the Balmer decrement.

Illustration of the spectroscopic appearance of two Herbig Ae stars -- AB Aur and XY Per -- compared with two MK standard stars, Vega and beta Leo. Noticeable is the strong emission core in the H-beta line of XY Per. The Fe II, Ti II lines at wavelength 4923, 5016, and 5166 are in emission in AB Aur, while they are in quite strong absorption in XY per.

They used this scheme to classify and so to follow temporal spectral changes in 38 Herbig Ae stars as well as 22 PMS stars in several young open clusters. This extended system also helped them search for lambda Bootis stars among PMS A-type stars. They found one definite lamda Bootis star among the Ae stars, and one marginal lamda Bootis star in NGC 2264. This is not significantly different from the 2 to 3% incidence of lamda Bootis stars among field A-type stars. They were led to conclude that the lamda Bootis mechanism operates over a wide range of ages from the late-PMS phase to well into the main-sequence lifetimes of A-type stars. They have been extending this study, via spectra and Strömgren photometry, to the young open clusters h and Persei.

CORBALLY has continued to obtain spectra for a list of photometrically peculiar stars provided by STRAIZYS (Vilnius Observatory, Lithuania). Observations with the Steward Observatory's 2.3-m telescope are now complete in the region between the North American and Pelican nebulae, for the reflection nebula NGC 1333, and for the open cluster IC 348. The high S/N CCD spectra are being classified to determine the specific peculiarities of the stars (three CH stars have been identified so far) and to obtain information on the properties of the dust-cloud material in which they are embedded.

STAGG (Mount Royal College, Calgary) has reduced UBVRI magnitudes obtained from the VATT for several fields at the North Galactic Pole (NGP). Part of his computations used a specially written, differential corrections technique to account for variable image size from seeing effects. In a preliminary analysis of the magnitudes and colors, CORBALLY compared the data with two recent CCD studies of the NGP and selected about 10 candidate G-dwarf stars for further spectroscopic observations. GARRISON (David Dunlap Observatory, University of Toronto) and RUEGER (Diocese of Brooklyn) are collaborating in this project.

ABT (National Optical Astronomical Observatories, Tucson) and CORBALLY are preparing for publication a full report on the 265 candidate Trapezium systems that they have observed photometrically and spectroscopically in previous years.

BOYLE and PHILIP (Institute for Space Observations and Union College, Schenectady, New York) made CCD observations at the Vatican Advanced Technology Telescope (VATT) in March and September with the 7 filter Stromvil Photometric System on open and globular clusters for their long-term investigation of stellar populations in the galactic disk and star clusters. To calibrate these data for accurate photometry, STRAIZYS and KAZLAUSKAS (Vilnius Observatory, Vilnius, Lithuania) have provided photoelectric photometry of stars in some of their fields.

DASGUPTA and SMRIGLIO (University of Rome) are processing VATT CCD observations taken by BOYLE with the 7 Vilnius filters on the old open cluster M67 and other stellar fields.

RUEGER (Diocese of Brooklyn), in collaboration with BOYLE, is processing multicolor CCD observations of the Crab Nebula made by them at the VATT.

Planetary Sciences

Meteorite Science

Work by CONSOLMAGNO on analyzing meteorite densities and porosities continued through 1998. This included further measurements of meteorite bulk density; the collection and analysis of unpublished and literature density data; and the first attempts to understand the implication of this research on the physical history of meteorites.

Most notable among the samples measured this year was the unusual Portales Valley meteorite, which was recovered soon after it fell in New Mexico on 13 June. In collaboration with KRING, D. HILL, GLEASON, and BRITT (University of Arizona), CONSOLMAGNO measured the density of seven large pieces, ranging in mass from 73 g to 1.5 kg. Though the average density of this meteorite is similar to that of a typical H chondrite, individual pieces had densities ranging from 2.45 to 4.75 g/cm³. This unusually large range matches the observed large-scale heterogeneity in the metal content of this meteorite, indicating that it may have been heavily shocked and metamorphosed deep within its parent body.

CONSOLMAGNO and BRITT used both Vatican data and that of many other authors to construct a comprehensive computer database of meteorite densities and porosities. With these other authors, especially PESONEN (Finnish Geological Survey) and FLYNN (SUNY Plattsburgh, New York), preparations are underway to publish this database in electronic form. In addition, the Vatican method of measuring meteorite bulk densities with glass-bead powders has been adopted by ROBINSON (Northwestern University) and others, who have consulted with the Vatican group on details of the measurement technique.

Meteorites contain minerals, like metallic iron, that may not be stable in Earth's water- and oxygen-rich atmosphere. Understanding how terrestrial conditions can weather these rocks can help correct for this weathering and make it possible to reconstruct the original structure of these meteorites. As reported in previous annual reports, work by BLAND (Open University/British Museum of Natural History) and CONSOLMAGNO suggests that the first, rapid stage of weathering proceeds by filling pore space with weathering products. This idea has now been confirmed, with the further assistance of RUSSELL (British Museum of Natural History), by examining thin sections of meteorites with different degrees of weathering using optical and electron microscopy, at magnifications of up to 1000×.

In these images, pore spaces can be easily traced out as a network of cracks only a few thousandths of a millimeter wide. As weathering proceeds, veins of material rich in iron and chlorine, but poor in nickel–as expected for weathering product–extend from nickel-iron grains into this network of cracks. Fresher meteorites have their cracks only partially filled, while older meteorites have the cracks completely filled. Future analysis will measure the volume of these veins and compare this with the measured porosities of these meteorites.

Even after correcting for weathering effects, CONSOLMAGNO, BRITT, and STOLL (Oakland, California) have noted that ordinary chondrites have generally uniform and relatively low porosity; they have begun to use these data to test various ideas for how meteorites were formed. Typical terrestrial conglomerate rocks have porosities of 30%, while meteorite porosities average only 10%. What compacted the meteorites? Impacts clearly play a major role, but laboratory results on how shock compresses rock cannot be completely reconciled with the meteorite data. An alternate theory supposes that today's meteorites originated in the cores of primordial, very large asteroids, which have since been broken up and dispersed.

Finally, the analysis at NASA Johnson Space Center, Houston, of the meteorites returned by the 1996 Antarctic Search for Meteorites (ANSMET) program, which included CONSOLMAGNO (see last year's annual report), indicates that one of the samples, EET 96008, is an extremely rare type of meteorite: it is identical in mineralogy, structure, and chemical isotope abundances to samples of the Earth's Moon that were returned by the Apollo program. It is presumed that EET 96008 was ejected by an impact from the lunar surface into an orbit that eventually carried it to Earth. EET 96008 is only the thirteenth lunar meteorite discovered.

Telescope Observations of Planetary Objects

In May RETTIG (University of Notre Dame) inaugurated the Notre Dame-VATT partnership with an observing program aimed at measuring the broad colors of Edgeworth-Kuiper Belt (EKB) Objects and the irregular moons of outer solar system planets. The EKB objects are a family of asteroid-sized objects orbiting beyond Neptune. They were first theorized to exist as far back as the 1940s by Edgeworth and Kuiper, but they have only been observed since the early 1990s. At magnitude 20 and fainter, they are in fact fainter than most Milky Way stars; it is generally agreed that detailed studies of such objects will require use of the new generation of very large telescopes, such as the Keck in Hawaii and the Large Binocular Telescope (LBT) now under construction on Mt. Graham, Arizona. However, thanks to the excellent optics of the VATT and the dark skies at its Mt. Graham site, the B, V, and R colors of objects as faint as 22nd magnitude can be obtained, allowing a preliminary survey of such objects to proceed.

Vatican Observatory astronomer Christopher Corbally, S.J. (l.) and Terrence Rettig of the University of Notre Dame at the Vatican Advanced Technology Telescope.

Joining RETTIG in this project were TEGLER (Northern Arizona University) and ROMANISHIN (University of Oklahoma), who were the first to report a separation of EKB objects into two distinct color classes, and CORBALLY and CONSOLMAGNO from the Vatican Observatory.

One strategy for understanding EKB objects is to look at Pluto and the irregular moons of the outer planets, which may represent captured EKB objects. Two such moons were recently discovered orbiting Uranus, and during the May observing run, the first set of colors for these moons were obtained. In September RETTIG and CONSOLMAGNO also obtained colors for Nereid, Neptune's irregular moon; Phoebe, the irregular moon of Saturn; and six of Jupiter's eight irregular moons.

Dark, C-type asteroids (like Mathilde, imaged by the NEAR spacecraft in 1997) may be dark because they are rich in carbon, like the CM and CI class meteorites; or they may be rich in magnetite, like CV meteorites; or they may simply be ordinary chondrite material that has been blackened by shock, like many meteorites in the Vatican collection. A diagnostic test is to look for the characteristic infrared absorption features of silicates, which are present in ordinary chondrites but rarer in carbonaceous chondrites. To search for them, BRITT and CONSOLMAGNO observed several such asteroids with the NASA Infrared Telescope Facility on Mauna Kea, Hawaii, in March.

History and Philosophy of Science; Interdisciplinary Studies

CONSOLMAGNO has been involved in an evaluation of how well journalists report on science. A recent study conducted by SCHAEFER (Yale) suggests that errors in reporting may not be entirely with the reporters. Schaefer asked a number of professional astronomers (including CONSOLMAGNO) to review ten years' worth of reporting from Sky and Telescope, Science News, the New York Times, and other sources, centering on reports of advances in three specific areas: Mars, gamma-ray astronomy, and the Hubble Constant. His preliminary results suggest that inaccuracies in the reports, although real, are due more to the tentative nature of the material being announced to the press by the scientists, and less due to mistakes made by journalists reporting those results. A detailed analysis of this survey is being prepared for publication.

STOEGER's work on God and time has been published. He was recently engaged in working on several philosophical problems related to the mind-brain problem, in connection with the joint Vatican Observatory-Center for Theology and the Natural Sciences (Berkeley, California) workshop held on that subject in Krakow, Poland, in June. He is attempting to develop more adequate concepts of reducibility, emergence, and supervenience on the basis of differentiating between the laws of nature that we have constructed and laws of nature as they really function, that is, the regularities, processes, and relationships that really obtain in reality. This is also intimately connected with how one conceives the soul in a way that has definite, scientifically accessible correlates but which inevitably transcends any adequate scientific description.

STOEGER has also been involved in a project on eschatology and the natural sciences with the Center of Theological Inquiry (Princeton, New Jersey), and he continues to pursue work on articulating the issues and the resolution of the issues in that area. He has been focusing on the scientific accounts of life-ending or culture-ending catastrophes and of death as a biological phenomenon; on the impact that these accounts, along with scientific knowledge in general, has on culture and values; and the response that Christian theology can give to them.