Cycle 10 Abstract catalog (based on Phase I submissions) ================================================================================ Proposal Category: GO Scientific Category: Cosmology ID: 9033 Title: Measuring the mass distribution in the most distant, very X-ray luminous galaxy cluster known PI: Harald Ebeling PI Institution: Institute for Astronomy We propose to obtain a mosaic of deep HST/WFPC2 images to conduct a weak lensing analysis of the mass distribution in the massive, distant galaxy cluster ClJ1226.9+3332, recently discovered by us. At z=0.888 this exceptional system is more X-ray luminous and more distant than both MS1054.4-0321 and ClJ0152.7-1357, the previous record holders, thus providing yet greater leverage for cosmological studies of cluster evolution. ClJ1226.9+3332 differs markedly from all other currently known distant clusters in that it exhibits little substructure and may even host a cooling flow, suggesting that it could be the first cluster to be discovered at high redshift that is virialized. We propose joint HST and Chandra observations to investigate the dynamical state of this extreme object. This project will 1) take advantage of HST's superb resolution at optical wavelengths to accurately map the mass distribution within 1.9 h^-1_ 50 Mpc via strong and weak gravitational lensing, and 2) use Chandra's unprecedented resolution in the X-ray waveband to obtain independent constraints on the gas and dark matter distribution in the cluster core, including the suspected cooling flow region. As a bonus, the proposed WFPC2 observations will allow us to test the results by van Dokkum et al. (1998, 1999) on the properties of cluster galaxies (specifically merger rate and morphologies) at z~ 0.8 from their HST study of MS1054.4-0321. ================================================================================ Proposal Category: GO Scientific Category: Stellar Populations ID: 9034 Title: The Masses and Luminosities of Population II Stars PI: Elliott Horch PI Institution: Rochester Institute of Technology Very little is currently known concerning the mass-luminosity relation (MLR) of Population II stars. However, with the advent of the Hipparcos Catalogue, improved distances to many spectroscopic binaries known to be Pop II systems are now available. After surveying the literature and making reasonable estimates of the secondary masses, we find 13 systems whose minimum separation should be larger than the resolution limit of FGS1. Because of the expected magnitude differences and separations, it is not possible to resolve the systems from the ground. We therefore propose FGS observations of the sample. In combination with the known spectroscopic orbits and Hipparcos distances, these observations will yield up to 26 precise stellar mass determinations of metal-poor stars, if all systems are resolved and the relative orbits are determined. A combination of FGS data and ground-based observations will lead to component luminosities and effective temperatures. This program will allow for a significantly better understanding of the Pop II main sequence, which in turn will lead to better ages and distances of the galactic globular clusters, and a Pop II MLR will be constructed for the first time. ================================================================================ Proposal Category: GO Scientific Category: Solar System ID: 9035 Title: Spatially Resolved Spectroscopy of Uranus and Neptune PI: Erich Karkoschka PI Institution: University of Arizona We propose to use STIS to obtain data cubes for Uranus (Cycle 10) and Neptune (Cycle 11). The spectrum between 290 and 1020 nm is sampled at 2000 wavelengths. The north-south position on the planetary disk is sampled along the slit every 0.05". The east-west position is sampled by successive exposures every 0.05" (longward of 520 nm wavelength) and 0.3" (shortward of 520 nm). Such data have never been obtained. Only HST, with STIS, has the capability to record spatial variations of narrow methane and hydrogen absorption and Raman scattering features. We have obtained such data for Saturn by ground-based observations which permitted a comprehensive understanding of the vertical haze and cloud structure as a function of latitude. Similar improvements are expected from the proposed data for Uranus and Neptune. HST has revealed exciting images of Uranus and Neptune while their quantitative analysis has been slow due to limitations in available filters. Our short, spatially-resolved spectroscopic program will reveal accurate spectral shapes across each WFPC2 filter which then will greatly improve the reliability of interpretations based on hundreds of past anf future WFPC2 images. Similarly, WFPC2 images of Titan required the addition of STIS spectra before the latest improvements in our understanding of its atmosphere were possible. ================================================================================ Proposal Category: GO Scientific Category: Galaxies ID: 9036 Title: An Ultraviolet Spectroscopic Survey of Star-Forming Galaxies in the Local Universe PI: Claus Leitherer PI Institution: Space Telescope Science Institute We propose a comprehensive STIS ultraviolet spectroscopic survey of star- forming galaxies in the local universe. The sample covers a broad range of morphologies, chemical composition, and luminosity. The observations will provide spectral coverage between 1200 and 3100 Angstrom, at a resolution of 100 to 200 kms and S/N of about 30. The data set will allow us to document and quantify the effects of massive stars on the interstellar medium and to infer implications for the evolution of the host galaxies. Specific issues to be addressed are: (i) the relation of interstellar-line profiles to gravity and macroturbulence, and indications for large-scale outflows of the cool gas; (ii) the search for systematic trends of interstellar-line strengths with metallicity, with the goal of calibrating a new metallicity indicator; (iii) the properties of the low- and high-ionization absorption lines of the interstellar medium and their relation to the X-ray emitting gas; (iv) the properties of dust obscuration in star-forming galaxies and its consequences for deriving star-formation rates; (v) studying the star-formation histories and relating the stellar properties to those of the interstellar medium. This data set, while fundamental in its own right, will also be significant as a template for the restframe-ultraviolet of high-z galaxies. We will entirely waive our proprietary rights to give the community immediate access to the data. ================================================================================ Proposal Category: GO Scientific Category: Cool Stars ID: 9037 Title: Imaging the Dust Disk around Epsilon Eridani PI: Mario Livio PI Institution: Space Telescope Science Institute Epsilon Eridani is the closest star to the Sun, around which a planet has been discovered. An asymmetric dust disk around the star has been detected in sub- millimeter observations. The clumps in the disk have been interpreted as resulting from resonant interaction, and the pattern has been predicted to revolve around star at a rate of ~0.7^degrees per year. We propose first epoch observations of the dust disk with STIS, to be followed up in subsequent cycles. These observations will not only reveal what may be the first extra- solar `Kuiper belt', but will also provide a crucial step in the development of observational techniques that can determine the presence and properties of planets, from the visible morphology of the disks around the parent stars. ================================================================================ Proposal Category: GO Scientific Category: Hot Stars ID: 9038 Title: The Evolution of Cataclysmic Variable Stars PI: Thomas Marsh PI Institution: Department of Physics and Astronomy, Southampton University We have discovered that EM Cygni, one of the most well-known cataclysmic variable stars (CVs), is very likely in a triple system with a spatially- unresolved K dwarf. EM Cyg has well measured masses, and the white dwarf's mass of 1.1, M_ shows that it must have come from an AGB star. This, together with considerations of binary evolution, can be used to predict a lower limit to the present-day separation of EM Cyg and the K dwarf of > 18, AU. Ground-based imaging only puts an upper limit on the angular separation of 0.2'', equivalent to < 60, AU at the 300, pc distance of EM Cyg; this does not seriously test the evolutionary prediction. With HST and FGS1R on the other hand, we can resolve a separation 6, AU, providing a direct test of the evolutionary path that leads to CVs, as well as to the Super-Soft X-ray sources widely believed to be the progenitors of Type Ia supernovae. ================================================================================ Proposal Category: GO Scientific Category: Galaxies ID: 9039 Title: Getting to the Core of The Matter: The Inner Region of M15 PI: Bernard McNamara PI Institution: New Mexico State University We propose to measure the velocity dispersion profile within 15 arcseconds of the core of M15 to determine whether the mass distribution in this region is best fit by the presence of a Black Hole or by a more extended distribution of mass. We will test three models of the core region, that is possesses (1) a massive Black Hole, (2) a more extended distribution of neutron stars, or (3) is in the process of core collapse. Our observational data will consist of PC WFPC2 images. Using