Search Publications
Optical-Radio Alignment in Compact Steep-Spectrum Radio Sources
O'Dea, C. P.; Baum, S. A.; de Vries, W. H. +1 more
We discuss Hubble Space Telescope (HST) WFPC2 observations through the broad red filter F702Wof 30 3CR sources from the Compact Steep Spectrum (CSS) radio source sample, and present 11 new HST/WFPC2 images through linear ramp filters (LRF), isolating either rest-frame [O II] 3727 Å or[O III] 5007 Å radiation. In nearly all the CSS galaxies, we fin…
Parallaxes versus p-Modes: Comparing HIPPARCOS and Asteroseismic Results for Pulsating AP Stars
Kurtz, D. W.; Matthews, Jaymie M.; Martinez, Peter
The p-mode eigenfrequency spacings of 12 rapidly oscillating Ap (roAp) stars provide estimates of their radii. By combining these with independent estimates of their effective temperatures via Hβ photometry, Martinez predicted luminosities for all but one of this sample. Hipparcos parallaxes, and hence luminosities, are now available for the entir…
Detection of C_2H_4 in Neptune from ISO/PHT-S observations
Lellouch, E.; Atreya, S. K.; Schulz, B. +3 more
The 6-12 mu m spectrum of Neptune has been recorded with the PHT-S instrument of the Infrared Space Observatory (ISO) at a resolution of 0.095 mu m. In addition to the emissions of CH_4, CH_3D and C_2H_6 previously identified, the spectrum shows the first firm identification of ethylene C_2H_4. The inferred column density above the 0.2-mbar level …
High-resolution abundance analysis of two individual stars of the bulge globular cluster NGC 6553
Bica, E.; Barbuy, B.; Ortolani, S. +2 more
A detailed abundance analysis of 2 giants of the metal-rich bulge globular cluster NGC 6553 was carried out using high resolution échelle spectra obtained at the ESO 3.6m telescope. The temperature calibration of metal-rich cool giants needs high quality photometric data. We have obtained JK photometry at ESO and VI photometry with the Hubble Spac…
The optical-infrared colour distribution of a statistically complete sample of faint field spheroidal galaxies
Menanteau, F.; Abraham, R. G.; Barger, A. J. +2 more
In hierarchical models, where spheroidal galaxies are primarily produced via a continuous merging of disc galaxies, the number of intrinsically red systems at faint limits will be substantially lower than in `traditional' models where the bulk of star formation was completed at high redshifts. In this paper we analyse the optical-near-infrared col…
The local stellar velocity distribution of the Galaxy. Galactic structure and potential
Bienaymé, O.
The velocity distribution of neighbouring stars is deduced from the Hipparcos proper motions. We have used a classical Schwarzschild decomposition and also developed a dynamical model for quasi-exponential stellar discs. This model is a 3-D derivation of Shu's model in the framework of Stäckel potentials with three integrals of motion. We determin…
Chemical evolution of carbonaceous materials in the last stages of stellar evolution
Volk, Kevin; Kwok, Sun; Hrivnak, Bruce J.
The out-of-plane bending modes of aromatic C-H bond at 11.3, 12.1, 12.4, and 13.3 mu m were detected in the ISO SWS spectra of the proto-planetary nebulae IRAS 07134+1005 and IRAS 22574+6609. In addition, unidentified emission features at 17.8, 18.9, and 19.1 mu m were detected in the SWS01 and SWS06 spectra of IRAS 07134+1005. The similar strengt…
The Environments of Supernovae in Post-Refurbishment Hubble Space Telescope Images
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Barth, Aaron J. +1 more
The locations of supernovae (SNe) in the local stellar and gaseous environment in galaxies contain important clues to their progenitor stars. Access to this information, however, has been hampered by the limited resolution achieved by ground-based observations. High spatial resolution Hubble Space Telescope (HST) images of galaxy fields in which s…
Probing early-type galaxy evolution with the Kormendy relation
Greggio, L.; Saglia, R. P.; Bender, R. +3 more
We investigate the evolution of early-type galaxies in four clusters at z=0.4 (Abell 370, Cl 0303+17, Cl 0939+47 and Cl 1447+26) and in one at z=0.55 (Cl 0016+16). The galaxies are selected according to their spectrophotometrically determined spectral types and comprise the morphological classes E, S0 and Sa galaxies. Structural parameters are det…
The Etched Hourglass Nebula MyCn 18. I. Hubble Space Telescope Observations
Ballester, Gilda E.; Crisp, David; Holtzman, Jon A. +15 more
We have obtained emission-line and continuum images of the young planetary nebula MyCn 18 with the Wide Field Planetary Camera 2 on the Hubble Space Telescope (HST). Although from the ground MyCn 18 appeared to have a triple-ring structure similar to SN 1987A, the HST images show that MyCn 18 has an overall hourglass shape. A series of arcs appear…