Search Publications
Disk and Bulge Morphology of WFPC2 Galaxies: The HUBBLE SPACE TELESCOPE Medium Deep Survey
Griffiths, Richard E.; Ratnatunga, Kavan U.; Ostrander, Eric J.
Quantitative morphological and structural parameters are estimated for galaxies detected in Hubble Space Telescope observations of WFPC2 survey fields. A modeling approach based on maximum likelihood has been developed for two-dimensional decomposition of faint undersampled galaxy images into components of disk and bulge morphology. Decomposition …
The Top 10 List of Gravitational Lens Candidates from the HUBBLE SPACE TELESCOPE Medium Deep Survey
Griffiths, Richard E.; Ratnatunga, Kavan U.; Ostrander, Eric J.
A total of 10 good candidates for gravitational lensing have been discovered in the WFPC2 images from the Hubble Space Telescope (HST) Medium Deep Survey (MDS) and archival primary observations. These candidate lenses are unique HST discoveries, i.e., they are faint systems with subarcsecond separations between the lensing objects and the lensed s…
Hubble Space Telescope Imaging of the Globular Clusters in the Fornax Cluster: Color and Luminosity Distributions
Forbes, Duncan A.; Brodie, Jean P.; Grillmair, Carl J. +1 more
We examine the luminosity and B-I color distribution of globular clusters for three early-type galaxies in the Fornax Cluster using imaging data from the Wide Field Planetary Camera 2 on the Hubble Space Telescope. The luminosity functions we derive are in most cases better than 50% complete down to B=26.6. We find that the color distributions of …
Stellar Encounters with the Oort Cloud Based on HIPPARCOS Data
Latham, David W.; García-Sánchez, Joan; Preston, Robert A. +4 more
We have combined Hipparcos proper-motion and parallax data for nearby stars with ground-based radial velocity measurements to find stars that may have passed (or will pass) close enough to the Sun to perturb the Oort cloud. Close stellar encounters could deflect large numbers of comets into the inner solar system, which would increase the impact h…
Unraveling the Structure of Aspherical Proto-Planetary Nebulae. I. Hubble Space Telescope Imaging and Hydroxyl Maser Line Observations of Roberts 22
Bujarrabal, V.; Sahai, Raghvendra; Zijlstra, A. +1 more
We have obtained high-resolution wide-band, narrowband, and polarimetric images of the bipolar proto-planetary nebula Roberts 22 with the Wide Field Planetary Camera 2 on the Hubble Space Telescope. OH maser-line emission has also been observed using the Australia Telescope Compact Array. The wide-band images at 0.6 µm show bright bipolar lo…
The Very Young Starburst Merger System NGC 1741
Leitherer, Claus; Johnson, Kelsey E.; Vacca, William D. +2 more
We use Hubble Space Telescope (HST) Faint Object Camera (FOC) ultraviolet (UV) and WFPC2 optical images in conjunction with UV spectroscopic observations taken with the Goddard High Resolution Spectrograph to examine the star formation history and properties of the interacting galaxy system NGC 1741 in the Hickson Compact Group 31. The high spatia…
Hubble Space Telescope Ultraviolet Spectral Energy Distributions for Three Ultraluminous Infrared Galaxies
Sanders, D. B.; Kormendy, John; Trentham, Neil
We present Hubble Space Telescope Faint Object Camera ultraviolet (lambda=2300 Å, 1400 Å) images of three ultraluminous infrared galaxies (ULIGs: L_ir>10^12 L_solar) selected from the IRAS Revised Bright Galaxy Sample. The purpose is to estimate spectral energy distributions (SEDs) to facilitate the identification of similar objects at high red…
WFPC2 Observations of the Ursa Minor Dwarf Spheroidal Galaxy
Burke, Christopher J.; Mighell, Kenneth J.
We present our analysis of archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations in F555W (~V) and F814W (~I) of the central region of the Ursa Minor dwarf spheroidal (dSph) galaxy. The V versus V-I color-magnitude diagram features a sparsely populated blue horizontal branch, a steep thin red giant branch, and a …
On the Origins of Starburst and Poststarburst Galaxies in Nearby Clusters
Caldwell, Nelson; Rose, James A.; Dendy, Kristi
Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images in B (F450W) and I (F814W) have been obtained for three starburst (SB) and two poststarburst (PSB) galaxies in the Coma Cluster and for three such galaxies in the cluster DC 048-52. V (F555W) and I images for an additional PSB galaxy in Coma have been extracted from the HST archive.…
Zeroing the Stellar Isochrone Scale: The Red Giant Clump Luminosity at Intermediate Metallicity
Twarog, Bruce A.; Anthony-Twarog, Barbara J.; Bricker, Andrew R.
The color-magnitude diagrams of the open clusters NGC 2420 and NGC 2506 have been investigated as intermediate links between the solar neighborhood and the Magellanic Clouds. Two sets of theoretical isochrones that include convective overshoot are zeroed to the Sun at solar abundance and to the unevolved main-sequence dwarfs of the Hipparcos Catal…