LTSA 96 Accepted Proposals P.I.: Weinberg, D.H. 007-96ltsa Ohio State University Co.(s): Katz University of Washington Quasar Absorption in the UV: Probing the Intergalactic Medium Quasar spectra exhibit UV absorption produced by high redshift HeII and low redshift HI. We will use hydrodynamic cosmological simulations to support the analysis and interpretation of space-based UV absorption measurements, which probe the evolution of cosmic gas from high redshift to the present day. Artificial observations of a realistic, simulated universe are a powerful way to evaluate the statistical uncertainties and systematic biases of an observational analysis, to develop new techniques for extracting the physical content of observational data, to test cosmological models, and to combine information from a wide variety of observations into a coherent physical picture. The specific projects proposed fall into three categories: absorption by intergalactic HeII, the Lyman- alpha forest at low redshift, and the connection between absorbers and galaxies. P.I.: Baron, E.A. 014-96ltsa University of Oklahoma Co.(s): Branch University of Oklahoma Hauschildt Arizona State University Multi-Wavelength Studies of Supernovae We propose to model the atmospheres and spectra of both Type II and Type I supernovae in detail. We will calculate realistic, physically self-consistent, model atmospheres and synthetic spectra. The latter will be compared with multi-wavelength observations from the ultraviolet to the infrared, to determine ejection velocities, abundances, and distances of supernovae, and to constrain theoretical models for the explosion mechanisms, the progenitor systems, and the yields of radioactive nickel and titanium. We will use the results of our calculations and the Spectral-fitting Expanding Atmosphere Method that we have developed to estimate the cosmological parameters: the Hubble constant, the deceleration parameter, and cosmic peculiar velocities. P.I.: Latter, W.B. 015-96ltsa NASA/Ames Research Center Co.(s): Hora Institute for Astronomy, Univ. of Hawaii Tielens NASA/Ames Research Center Photon-Dominated Circumstellar Gas During Early and Late Stages of Stellar Evolution Exposure of molecular clouds and circumstellar envelopes to intense UV radiation results in the formation of regions in which the chemistry and physics are dominated by the presence of a time-varying UV field. Much of the important physics of the early and late stages of stellar evolution is similar, because of the high gas densities and the often dominating influence of UV photons. This study will determine the physical and chemical evolution of circumstellar gas in both the early and late stages of stellar evolution. We propose to 1) develop a model for the processes that occur in star formation regions and planetary nebulae due to the presence of an intense UV flux, and 2) incorporate time-dependence into our study of these evolving systems. Diagnostics will be identified for the study of processes that are far from equilibrium. The role of high density regions, clumps, tori, or disks -- including proplyds and the so-called evaporating gas globules -- will be examined in detail. P.I.: Silk, J.I. 018-96ltsa University of California at Berkeley Cosmological Studies of the Cosmic Microwave Background Interpretation of microwave background temperature anisotropies requires extensive modelling of extragalactic foregrounds as well as careful treatment of systematics in individual experiments. Data from COBE and other cosmic microwave background experiments at higher angular resolution will be combined, utilizing a variety of methods, including Wiener filtering, optimal eigenmode expansion and P(D) analysis, in order to make simulated sky maps. We will include realistic galactic and extragalactic foregrounds, in conjunction with the characteristics of proposed satellite experiments (TOP HAT, BOOMERANG), and complementary studies by ground-based interferometers (CBI, VSA), in order to simulate sky maps, and develop and sharpen experimental goals and parameters, such as frequency coverage, agular resolution and sky coverage. We will ascertain how well the various cosmological parameters can be determined from both existing and proposed data sets. We intend to make all relevant results available through the NSSDC, including fits to the COBE DMR data and simulated maps of the sky. P.I.: Filippenko, A.V. 019-96ltsa University of California at Berkeley Co.(s): Sargent California Institute of Technology Ho Harvard/Smithsonian Center for Astrophysics A Multi-Wavelength Study of a Complete Sample of Nearby Galactic Nuclei We propose to conduct a multi-wavelength study of the nuclei of the 486 brightest northern galaxies, with emphasis on identifying and determining the physical nature of activity similar to, but less luminous than, that seen in quasars and classical AGNs. This sample is the subject of our existing optical survey. We will investigate the physical conditions in the nuclei with the capability offered by archival HST and ROSAT data, together with additional pointed observations, ASCA and AXAF spectra, and complementary optical and radio data, as well as theoretical calculations. When finished, this program will constitute by far the most definitive multi-wavelength study yet of the nuclear regions of bright galaxies. It will be used to address a collection of fundamental questions concerning these environments. For example, we plan to quantify the luminosity function of AGNs at the faint end, predict the contribution of low-luminosity AGNs to the soft X-ray background, determine the excitation mechanism of various types of emission-line galaxies, and search for supermassive black holes in the central regions of nearby AGNs. P.I.: Sanders, W.T. 027-96ltsa University of Wisconsin - Madison Studies of the Hot Interstellar Medium and Halo of our Galaxy: Spatial Structure and Spectral Characteristics of the Low Energy X-ray Background We propose to extend our previous studies of the spatial structure and spectral characteristics of the X-ray background in the energy range ~ 70 - 1000 eV. The soft X-ray background originates from hot phases of the interstellar medium and the galactic halo. This hot matter is not uniformly distributed, but shows quite different intensities and spectral ratios in different directions on the sky. The goals of this program are to constrain the distances to the various hot interstellar regions, and to constrain their spectral emission parameters. These are necessary steps toward understanding the origin and evolution of the hot phases of the interstellar medium and their role in the evolution of our galaxy. The program uses data primarily from the ROSAT, DXS, and CUBIC orbiting missions, and secondarily from the EUVE, ALEXIS, and ASCA missions. In addition, data are used from University of Wisconsin sounding rocket flights, and from the ground-based WIYN telescope. P.I.: Hurley, K.C. 031-96ltsa University of California Co.(s): Ziock Lawrence Livermore National Laboratory Adding the Mars '96 Gamma-Ray Burst Experiment to the Third Interplanetary Network We propose to add a small gamma-ray burst experiment to the 3rd Interplanetary Network of burst detectors. This instrument was developed and built using discretionary funding from a number of sources external to NASA, and it has been integrated onto the Russian Mars '96 spacecraft for launch in November 1996. This experiment completes the network, which currently consists only of Ulysses as a distant spacecraft, and a number of near-Earth missions. In its current form, the network produces burst locations consisting of narrow annuli, which are not useful for deep multiwavelength counterpart searches. The addition of Mars '96 will reduce these annuli to error boxes of arcminute size. We anticipate that a total of approximately 200 bursts will be detected during the nominal 2.5 year Mars '96 lifetime. We will disseminate the positions of these bursts as the data are received to a worldwide network of >60 observers who are prepared to conduct counterpart searches. This proposal requests only the funding for Mars '96 data reduction and analysis. P.I.: Hughes, J.P. 036-96ltsa Rutgers University Co.(s): Birkinshaw University of Bristol Determining the Hubble Constant Using X-ray, Optical, and Radio Observations of Clusters of Galaxies Recent advances in instrumentation in the radio and X-ray bands, plus the development of sophisticated analysis and modeling techniques, have brought us to the era when the Sunyaev-Zel'dovich (SZ) effect is a viable method for determining distances to clusters of galaxies and hence the Hubble constant. The technique is competitive with those utilizing Cepheid variable stars and Type Ia supernovae, but the SZ effect has the potential for accurate application to larger distances, redshifts of 0.5 and beyond. We have X-ray, optical, and radio data on a sample of distant clusters that will allow us to determine H_0 to an accuracy of 8%. We propose a program of research using these and other data that will lead to a clear understanding of the sensitivity of the SZ effect method for distance determination, detailed knowledge of the systematic errors associated with such measurements, and a well- selected sample of clusters in time for definitive studies with AXAF later in the decade. P.I.: Wood, K. 042-96ltsa University of Wisconsin Exploring Asymetries In Circumstellar Environments: Winds, Disks, And Things That Go Clump In The Light We propose to use a multi-wavelength multi-technique approach to investigate the effects of rotation and inhomogeneities on the physical structure of circumstellar environments. From the analysis of new and existing space astrophysics data, using our 3-D radiation transfer analysis techniques, we shall determine the geometry, density, and ionization structure of hot star winds and the dusty environments of pre-main-sequence stars. Among the applications of our 3-D analysis techniques will be determination of the circumstellar temperature and ionization structure of Oe/Be stars from analysis of their line-blanketed UV spectropolarimetry, a more accurate determination of O and B stellar mass loss rates, the effect of non-spherical densities on the radiation driving force in Wolf Rayet stellar winds and luminous blue variables, a search for cometary material from analysis of the disk spectra of Beta Pictoris-like objects and Herbig Ae/Be stars, and observational testing of currently favored dynamical models for low mass star formation. P.I.: Crotts, A. 044-96ltsa Columbia University SN 1987A: Formation of a Supernova Remnant The explosion of SN 1987A near the giant star-forming region 30 Doradus in the LMC gives us 1) a fleeting opportunity to learn about the starburst process in unprecedented detail, 2) a unique probe of mass loss in high mass stars, & 3) a once-in-a-lifetime chance to study the formation process of supernovae and supernova remnants, with this case being the first with known initial conditions of the pre-existing circumstellar environment. Key elements of these opportunities have yet to be addressed, and the largely space-based study of these questions is the goal of my next few years of research. Even though SN 1987A has faded temporarily, in the next few years it will flare dramatically, forming SN Remnant 1987A. In the process the structures in the circumstellar environment that we have studied so carefully will begin to interact with the ejecta from the exploding star. Completing our observations of the nebula about to be destroyed, and continuing intensive study of SNR 1987A is the major goal of this proposed research. We can also measure the UV radiation from the initial SN shock breakout, and constrain the nature of dust in the LMC. This involves approved programs on HST, ISO, IUE and UIT, plus potential programs on SIRTF and SOFIA. P.I.: Mighell, K.J. 045-96ltsa Columbia University The Star Formation Histories of the Local Group Galaxies The understanding of the formation and evolution of galaxies is one of the most important goals of galactic astronomy. Comparative studies of the oldest stars and the field stellar populations in the Local Group galaxies can provide important structural, chemical and kinematic clues to the evolution of the parent galaxy. I propose a research program to determine the star formation histories of the Local Group galaxies. These star formation histories will be based principally on Hubble Space Telescope WFPC2 observations from my own general observer programs or the HST data archive. I will determine the star formation history of the stellar populations from a) the location and distribution of stars near the main- sequence turnoff, b) the luminosities, colors, and metallicities of stars on the giant branch, c) the relation of horizontal-branch morphology to stellar ages and metallicities, and d) the stellar luminosity function near the main-sequence turnoff. I will also use archival HST WFPC2 data to directly compare the globular clusters in the Milky Way and nearby Local Group galaxies. The age-spread of the oldest stars in the Local Group provides an important cosmological probe for the investigation of synchronized galaxy formation. P.I.: Wills, B.J. 047-96ltsa University of Texas at Austin Co.(s): Wills University of Texas at Austi The Parsec-Scale Environment of Luminous AGN: Spectroscopic Clues to Winds, Jets and Accretion We have successful, ongoing, interrelated programs using HST, ROSAT, IRAS, EINSTEIN, and ground-based observatories to probe the unresolved parsec-scale environments of luminous AGNs' (QSOs') central engines. This is an opportune time to consolidate our exciting results using a powerful combination of new tools to investigate the geometry, physics and chemical structure of the emitting and absorbing gas: (i) the Doppler-boosting of radio jets allows us to investigate the dependence of the continuum, line strengths and profiles on the inclination of the spin axis; (ii) the unprecedented sensitivity and resolution of ROSAT in soft X-rays allows, for the first time, a comparison of the photoionizing energy with UV continuum and emission-line spectra from HST observations, and optical-IR spectra from the ground, and, together with (iii) state-of-the-art photoionization codes, will provide new opportunities for solving the outstanding problem of the energy budget; and (iv) spectropolarimetry. Newly-discovered differences between radio-loud and radio-quiet QSOs should lead to understanding the role of the jets. The research is spawning projects that will introduce senior undergraduate and graduate P.I.: Zaritsky, D.F. 049-96ltsa The Regents of the University of California A Study of Dust In and Around Galaxies We propose a comprehensive study of the distribution of dust in galaxies that is unique in two respects: (1) we will study the global distribution of dust in the Magellanic Clouds at a level of spatial detail never attemtped, and (2) we will study the distribution of dust in galactic halos. The scientific goal of the first portion of this investigation is to use the three dimensional mapping of dust across an entire galaxy to learn about the nature of dust, its connection to the stellar populations and gas, and how best to interpret observations of the integrated properties (colors and luminosities) of more distant galaxies. The goal of the second portion of this investigation is to determine whether dust is present in the halos of galaxies in order to learn about the baryon component of galactic halos and to understand how observations of the distant universe may be affected by extinction from galactic halos along the line-of-sight. UV and IR observations (HST, IRAS, ISO) are the best way to sample both the absorption and emission properties of dust, and by doing so sample the range of dust components that may be present in and around galaxies. P.I.: Loredo, T.J. 057-96ltsa Cornell University Development and Application of New Tools For Statistical Analysis of Discrete Astrophysical Data I propose to develop and apply rigorous statistical methods for the analysis of a wide variety of discrete astrophysical data based on the principles of Bayesian inference. These methods will use discrete probability distributions (e.g., the Poisson distribution) to model data. The Bayesian approach specifies how to use these distributions without relying on questionable approximations that underly many current analyses, and also eliminates troublingly subjective aspects of current methods. I identify three areas that will benefit from development of new methods, chosen so that the resulting analysis tools will be of interest to a wide range of investigators, and for the potential scientific dividends that could result from applying the tools to the specific astrophysical problems I will study. These areas are: (1) Analysis of photon counting data, with applications to the analysis of gamma ray burst (GRB) spectra and time histories. (2) Analysis of arrival time data, with applications to the analysis of photon arrival times from GRBs and x ray and gamma ray pulsars. (3) Analysis of data from multidimensional point processes, with applications to x ray source detection, gamma ray bursts, and observational cosmology. P.I.: Leventhal, M. 058-96ltsa University of Maryland Co.(s): David University of Maryland ***SCIENCE PI*** Galactic Black Holes and Positron Annihilation Radiation I am proposing for funding to continue a number of projects related to Galactic black holes, Galactic positron-annihilation radiation, and the role of the former in producing the latter. The largest projectis one currently under way with support from the Compton Gamma Ray Observatory guest investigator program: mapping the annihilation line using data from BATSE. In the long term, I hope to combine these results with those from OSSE. The black hole candidate 1E 1740.7-2942 has been mentioned as a possible positron source; other projects in this proposal probe the nature of this source and a similar object, GRS 1758-258, using XTE. Smaller but related projects evolve naturally from the data and techniques of the main projects: a spectral study of Galactic diffuse x-ray emission with the XTE data and a study of the high-energy variability of Cygnus X-1 and x-ray novae with the BATSE data. Finally, the BATSE background-subtraction and mapping techniques can be adapted to the High Energy Solar Spectroscopic Imager, which is under second-round consideration for the Medium Class Explorer program. P.I.: Carr, J.S. 059-96ltsa Naval Research Laboratory Water in Pre-Main-Sequence Accretion Disks The properties of cool accretion disks around pre-main-sequence T Tauri stars will be investigated through the analysis and interpretation of new space-based spectra of water vapor and through theoretical modeling of accretion disk atmospheres. This work will be based on HST and ISO spectra of young stars in the near to far-infrared spectral regions. The ISO mission will provide data on the vibrational and rotational bands of H2O in the mid and far-infrared, and other molecular constituents such as H2, OH and CO. Hot water vapor will be studied using sensitive low-resolution spectra of the near-infrared vibrational bands obtained with NICMOS and the HST. As necessary, these data will be supplemented with ground-based high-resolution spectra of molecules in the near and mid-infrared. This database of infrared molecular spectra, combined with infrared continuum fluxes, will be modeled to provide information on the structure of the inner regions (< 5 AU) of the circumstellar disk. New calculations of accretion disk atmospheres, with updated opacities and self-consistent treatment of external radiation, will be carried out to provide physical interpretations of the results. P.I.: Lewin, W.H. 061-96ltsa Massachusetts Institute of Technology Co.(s): Kouveliotou University Space Research Association van Paradijs University of Alabama at Huntsville van der Klis University of Amsterdam Accreting Black Holes - An All Out Effort Black holes are fundamental to our understanding of physics. Yet, we do not know with certainty whether they exist. We only know that objects with the required large mass/radius ratio nearly certainly exist in more than half a dozen X-ray binaries and that such objects probably exist at the center of some galaxies. We propose to study the sites of the best black- hole candidates namely those in X-ray binaries. Our ultimate goal is to verify that black holes, with properties as predicted by General Relativity, actually exist. This goal is distant and perhaps elusive. However, in view of the fundamental importance for our understanding of physics, a comprehensive, systematic, and all-out effort on the observable phenomenology is justified and only possible with long-term support from the LTSA Research Program. P.I.: Allamandola, L.J. 072-96ltsa NASA - Ames Research Center Co.(s): Sandford NASA-Ames Research Center Salama SETI-Institute and NASA-Ames Interstellar Dust, Ice, and Polycyclic Aromatic Hydrocarbon Composition Derived from their IR and UV Spectral Properties Measured from Space. We propose to use our extensive data base of laboratory spectra of realistic interstellar analog materials to analyze infrared through ultraviolet spectra obtained from spacecraft such as ISO, IRTS, MSX, and HST to study the chemical composition and physical state of interstellar matter. We expect this data to provide (i) the identification of important new molecular species in interstellar ices (such as CO2, O3, and nitriles), (ii) the degree of amorphicity of these ices, (iii) a determination of the distribution of cosmic deuterium in these ices and in PAHs, (iv) the identification and evolution of PAH structures in infrared emitting objects, (v) a test of the suggestion that PAHs are responsible for the infrared cirrus, and (vi) the identification of specific PAHs and their charge state in the diffuse ISM. We are in a particularly unique position to carry out the proposed program since we have direct access to the data from three of the spacecraft and the investigators have extensive experience with astronomical data and a very productive laboratory devoted to studying the spectroscopic and physical properties of interstellar dust, ices, and PAHs. P.I.: Sembach, K.R. 082-96ltsa Smithsonian Astrophysical Observatory Diffuse Ionized Gas in Galactic Environments_ I propose to use the large amount of spectroscopic and imaging data obtainable from space missions and their archives to study the diffuse ionized gas distributions in the Milky Way and other galactic systems. The project will focus initially upon understanding the ionization, distribution, and kinematics of ionized gases in the Milky Way disk, low halo, and outer halo and their relationship with one another. I will also conduct studies of high velocity gas behind fast shocks in supernova remnants to refine models of shocked, radiatively cooling gas. These studies will further our understanding of how dust is processed by the supernova explosions that may produce much of the highly ionized gas in the Galactic halo. Further analyses of data for high velocity clouds in the Galactic halo will also be undertaken to understand the origin, abundances, and ionization of the Milky Way halo gas. Throughout this study, I will apply what I learn about ionized gas in the Galaxy to the gas in the distant galactic halos responsible for quasar absorption line systems. P.I.: Owocki, S.P. 087-96ltsa University of Delaware Co.(s): Cohen Department of Astronomny, U. of Wisconsin Multi-Spectral Diagnostics and Dynamical Modelling of Structured Hot-Star Winds Extensive observations hot stars in multiple wavebands by several orbiting observatories have provided strong evidence that the radiatively driven stellar winds of hot, luminous stars are highly structured at both large and small scales. This project aims to apply recently developed time-dependent radiation hydrodynamical models of these structured stellar winds to fundamental, physical interpretation of these observations. It will build upon new computational tools, conceptual insights, and observational datasets developed in the P.I.'s previous LTSA project, with a new emphasis on exploiting the EUV and X-ray databases and analysis methods developed from Co-I.'s recent Ph.D. thesis research. Specific projects include: 1) Reexamination of mass loss from B-stars in light of their unexpectedly high X-ray emission meaures; 2) Dynamical model interpretation of observed X-ray scaling laws for hot- stars; 3) 2-D and 3-D models of wind structure and X-ray variability; 4) Extension of our ongoing program of analysis of UV wind line variability; and 5) Long-term development of radiation hydrodynamics code to include MHD P.I.: Madore, B. 093-96ltsa Jet Propulsion Laboratory Optical Depth and Radiative Transfer in Disk Galaxies We are proposing a program to interpret the multi-wavelength images of galaxies in the context of the new radiative transfer models. Unique data sets from ASTRO, ISO, HST, and from IRAS are to be combined with a CCD survey of the LMC/SMC, as well as a new ground- based optical/infrared imaging database, with special emphasis on our proprietary ASTRO-2 UV images, pre-selected to cover the entire Hubble sequence. Our interpretive models now incorporate realistic physics, spatially resolved on ~100 parsec scales,and covering wavelengths from the vacuum UV to the thermal IR. Our immediate goals are (1) to understand the opacity structure of the nearest galaxies by a detailed investigation of high- resolution and multi-wavelength observations (made by ASTRO, IRAS and ISO) of individual systems, and (2) to provide an understanding and basis for the interpretation of the correlations and the statistical properties galaxies seen at the present epoch in large-sample broad-band color surveys, and ultimately (3) to place in context the HST (UV restframe) images of `normal' galaxies seen at high redshift, in comparison with the serendipitous UV images of nearby galaxies also being collected by HST. P.I.: Sakai, S. 094-96ltsa Jet Propulsion Laboratory The Local Distance Scale: Application of the Tip of the Red Giant Branch Distance Indicator A relatively new,yet very robust method of distance determination for distance determination for resolved galaxies has been developed in the last few years. The tip of the red giant branch (TRGB) method has been shown to be as precise as the Cepheid PL relation, but the uniqueness of the TRGB method is that it is applicable to any galaxy containing a detectable population of old, metal-poor, low-mass stars. This means that practically all nearby galaxies, regardless of Hubble type and/or inclination, can be placed on a common distance scale out to the crowding and the flux limits of modern detectors and telescopes. This proposal is designed to accomplish the following goals.(1) The precise distribution and detailed kinematics of galaxies in the vicinity of our own Local Group remains uncertain, largely due to lack of precise distance measurements. We propose to establish consistent distances to all galaxies within 2Mpc of the Local Group.(2) Pop II secondary distance indicators still lack a solid calibration. By detecting the RGB in giant elliptical galaxies in the Virgo and Fornax clusters, we will be able to double the number of calibrators.(3) We propose to establish a more solid calibration of the TRGB method that is directly P.I.: Mulchaey, J. 095-96ltsa The Observatories of the Carnegie Institution of Washington The Intragroup Medium Most galaxies in the universe occur in small groups, so studies of these environments are important. The recent discovery of extended X-ray emission in groups has provided new insight into the dynamics and evolution of such systems. ROSAT studies of the "intragroup medium" suggest X-ray emitting gas is not found in all groups, but only those dominated by early-type (E and S0) galaxies. I propose a five year study that will combine observations from ASCA, HST, AXAF and ASTRO-E with existing ground-based data to address three outstanding questions raised by the ROSAT observations: 1) What are the masses and dark matter fractions in groups?, 2) What is the origin of the intragroup medium? and 3) Does an intragroup medium exist in spiral-rich groups? P.I.: Brickhouse, N.S. 099-96ltsa Smithsonian Astrophysical Observatory Spectroscopic Determination of the Physical Conditions in Hot, Optically Thin Sources The high spectral resolution of current and future missions (EUVE, ASCA, AXAF, XMM) offers new opportunities to study the physical conditions of diverse sources. Plasma emission models, such as our new Brickhouse-Raymond-Liedahl code, are powerful tools for deriving temperatures, densities, and abundances of optically thin astrophysical plasmas from high energy spectra. Currently, however, no tools are available to study the effect of systematic errors in plasma emission models. We propose to study these systematic errors: (1) Given the dearth of laboratory measurements, we will test the atomic data with astrophysical spectra, particularly stellar coronae. (2) We will test the spectral implications of common simplifying assumptions. (3) We will include systematic errors in the spectral analysis. Enhanced confidence in spectroscopically derived parameters for stellar coronae, galaxies, clusters of galaxies, the interstellar medium, and supernova remnants will lead to improved models of physical processes, such as cooling flows and coronal heating. P.I.: Allard, F. 110-96ltsa Wichita State University Co.(s): Alexander Wichita State Universit Spectroscopic Properties of (Sub)Stellar Objects As progressively cooler stellar and substellar objects are discovered, the presence of first molecules and then condensed particulates greatly complicates the understanding of their physical properties. Brown dwarfs and giant planets emit over 65 % of their radiation in the infrared, out of reach of most ground-based telescopes. A variety of infrared sky surveys with IRTS, ISO, HST, and WIRE will soon deliver large data bases of red dwarfs, brown dwarfs and perhaps giant planets, which will necessitate the best possible theoretical foundation. In this project we propose to study in four thrust areas the spectroscopic and photometric properties of cool stellar and substellar objects. We will (1) improve existing low temperature opacities by treating the condensation of grains in more detail. (2) Construct grids of model atmospheres and interiors for low mass objects. (3) Establishing the atmospheric, spectroscopic and structural properties of cool brown dwarfs and giant planets. And (4) Interpret combined ground-based, HST and infrared space observations of red dwarfs, metal-poor subdwarfs, brown dwarfs and giant planets. P.I.: Szalay, A.S. 115-96ltsa The Johns Hopkins University Co.(s): Connolly The Johns Hopkins University The Evolution and Clustering of Galaxies at z=1 and Beyond We propose to use several novel techniques to estimate the redshifts of galaxies in deep HST samples, such as the Hubble Deep Field, and the Groth Strip, where traditional ways of obtaining spectroscopic redshifts are no more feasible. We have shown in a pilot project, that broad band magnitudes of galaxies correlate extremely well with their spectroscopically measured redshift (Connolly et al 1995). For fainter, thus more distant galaxies, evolution becomes much more pronounced, and various other complications arise. Here we describe several new ideas, how these problems can be circumvented, like using surface brightness as an additional measure of redshift, or applying the photometric redshift technique to several components of the galaxies separately (like bulge, disk, star forming regions). We expect that not only the redshifts of the objects can be determined with a reasonable accuracy, but their spectral type as well. Also, several important applications of the technique are discussed, like evolution of the luminosity function as a function of spectral type, clustering evolution as a function of color and morphology at various redshifts. This technique can also provide better constraints on cluster masses from gravitational lensing. P.I.: Weaver, K.A. 118-96ltsa The Johns Hopkins University A Robust Test of the Unified Model for Seyfert Galaxies, with Implications for the Starburst Phenomenon X-ray studies provide a solid test of the "obscuration-plus-viewing-angle" unified model hypothesis for Seyfert galaxies. Not only do iron K line profiles and variability probe accretion disks and molecular tori, but trends of equivalent width with column density, luminosity, and inclination give information about geometrical distributions of the gas and the degree of continuum isotropy. This proposal outlines a five-year research effort that entails detailed modeling of X-ray emission. Central to this research is my involvement with analysis of ASCA, Rosat, and XTE data of Seyfert and Starburst galaxies. I will build on current studies of Seyfert galaxies to compile a catalog of X-ray spectral properties. This catalog will then be used to perform a robust test of the unified model and investigate a possible AGN-Starburst connection. The research outlined here is timely because ASCA is providing, for the first time, a large sample of X-ray spectra of optically-detected Seyfert 2 galaxies. This allows comparisons with Seyfert 1 galaxies that have never before been possible. In creating an X-ray catalog, I plan to obtain all of the information possible to guide current theories of Seyferts. This information will allow more efficient use of future high- resolution X-ray missions such as AXAF and Astro-E.