Search Publications
The Tolman Surface Brightness Test for the Reality of the Expansion. III. Hubble Space Telescope Profile and Surface Brightness Data for Early-Type Galaxies in Three High-Redshift Clusters
Sandage, Allan; Lubin, Lori M.
Photometric data for 34 early-type galaxies in the three high-redshift clusters Cl 1324+3011 (z=0.76), Cl 1604+4304 (z=0.90), and Cl 1604+4321 (z=0.92), observed with the Hubble Space Telescope (HST) and with the Keck 10 m telescopes by Oke, Postman, & Lubin, are analyzed to obtain the photometric parameters of mean surface brightness, magnitu…
Hydrodynamic Simulations for the Nuclear Morphology of NGC 4314
Ann, H. B.
We performed smoothed particle hydrodynamic (SPH) simulations to study the nuclear morphology of the barred galaxy NGC 4314. We have constructed the mass models based on the results of a profile decomposition into disk, bulge, and bar components. Our models have three different nuclear structures according to the assumption about the nuclear bar: …
CLASS B0739+366: A New Two-Image Gravitational Lens System
Pearson, T. J.; Blandford, R. D.; Koopmans, L. V. E. +10 more
We present the discovery of CLASS B0739+366, a new gravitational lens system from the Cosmic Lens All-Sky Survey. Radio imaging of the source with the Very Large Array shows two compact components separated by 0.54", with a flux density ratio of ~6:1. High-resolution follow-up observations using the Very Long Baseline Array (VLBA) at 1.7 GHz detec…
A High-Resolution H I Study of the Interstellar Medium Local to HD 193793
Arnal, E. Marcelo
A 2° field centered at the optical position of the Wolf-Rayet (WR) star HD 193793 (≡ WR 140) was surveyed in the H I 21 cm line and in the 1420 MHz radio continuum, using the Dominion Radio Astrophysical Observatory interferometer. The aim of this observations was to look for evidence of an interaction between the WR star and its local interstella…
Barnard's Merope Nebula Revisited: New Observational Results
Simon, Theodore; Herbig, G. H.
IC 349 is a small, fan-shaped reflection nebula located only 30" from 23 Tau; its nucleus is, by a factor 15, the brightest area of the Pleiades nebulosity. We propose that IC 349 is a fragment of the Taurus-Auriga molecular cloud that has been encountered by the Pleiades in that cluster's southward motion and is being illuminated and shaped by th…
Hubble Space Telescope-NICMOS Observations of M31'S Metal-Rich Globular Clusters and Their Surrounding Fields. I. Techniques
Rich, R. Michael; Jablonka, Pascale; Frogel, Jay A. +6 more
Astronomers are always anxious to push their observations to the limit-basing results on objects at the detection threshold, spectral features barely stronger than the noise, or photometry in very crowded regions. In this paper we present a careful analysis of photometry in crowded regions and show how image blending affects the results and interp…
The Accretion Disk and White Dwarf in the U Geminorum type Dwarf Novae UZ Serpentis and SS Aurigae during Quiescence
Sion, Edward M.; Lake, Joshua
We have carried out high-gravity model atmosphere and accretion disk synthetic spectral fits for the U Geminorum type dwarf novae during quiescence. For UZ Ser, we find that the far-UV spectrum is best fitted with a logg=8, Teff=27,000 K photosphere with abundances near solar. The best-fit accretion disk model for UZ Ser has Mwd
Investigation of Gravitational Lens Mass Models
Griffiths, Richard E.; Ratnatunga, Kavan U.; Knudson, Adam
We have previously reported the discovery of strong gravitational lensing by faint elliptical galaxies using the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope, and here we investigate their potential usefulness in placing constraints on lens mass models. We compare various ellipsoidal surface mass distributions, including tho…
The Tolman Surface Brightness Test for the Reality of the Expansion. II. The Effect of the Point-Spread Function and Galaxy Ellipticity on the Derived Photometric Parameters
Sandage, Allan; Lubin, Lori M.
To complete the Tolman surface brightness test on the reality of the expansion of the universe, we need to measure accurately the surface brightness profiles of the high-redshift galaxy sample. To quantify this accuracy, we investigate the effects of various sizes of point-spread functions composed of telescope diffraction, CCD pixel resolutions, …
Ultraviolet Observations of Triton in 1999 with the Space Telescope Imaging Spectrograph: 2150-3180 Å Spectroscopy and Disk-integrated Photometry
Stern, S. Alan; Young, Leslie A.
We observed Triton using the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) on 1999 August 28, September 11, and September 13 UT. On all three occasions, we obtained images at both 271 and 374 nm, and spectra from 215 to 318 nm. We find that Triton's geometric albedo is high through the near- and mid-UV, decreasing…