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The Mass-to-Light Ratio of Early-Type Galaxies: Constraints from Gravitational Lensing in the Rich Cluster AC 114
Smail, Ian; Ellis, Richard S.; Kneib, Jean-Paul +1 more
We present a new wide-field image of the distant cluster AC 114 (z = 0.31) obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. This image considerably extends our knowledge of the lensing properties of the cluster beyond that derived earlier from a single WFPC1 pointing. In conjunction with published ground-based s…
Asteroids as far-infrared photometric standards for ISOPHOT
Mueller, T. G.; Lagerros, J. S. V.
Asteroids are used as far-IR calibrators for the imaging photopolarimeter ISOPHOT on board the Infrared Space Observatory ISO. For the 10 selected objects we compiled a large uniform database of 678 individual observations, ranging from 7-2 000 microns. Applying a new thermophysical model to the observations we derived thermal properties of the se…
Study of an unbiased sample of B stars observed with Hipparcos: the discovery of a large amount of new slowly pulsating B stars
Eyer, L.; Aerts, C.; Grenon, M. +2 more
We present a classification of 267 new variable B-type stars discovered by Hipparcos. We have used two different classification schemes and they both result in only a few new beta Cephei stars, a huge number of new slowly pulsating B stars, quite some supergiants with alpha Cyg-type variations and variable CP stars, and further some new periodic B…
Detection of intergalactic red-giant-branch stars in the Virgo cluster
Ferguson, Henry C.; von Hippel, Ted; Tanvir, Nial R.
It has been suspected for nearly 50 years that galaxy clusters contain a population of intergalactic stars ripped from the galaxies during cluster formation, or when the galactic orbits pass through the cluster centre. Observational support for theexistence of such a stellar population is provided both by measurements of the diffuse light in clust…
The Complex Kinematics of the Neutral Hydrogen Associated with I ZW 18
Salzer, John J.; Haynes, Martha P.; van Zee, Liese +1 more
We present the results of high velocity (1.3 km s^-1 channels) and high spatial (~5", or ~250 pc at the distance of I Zw 18) resolution H i synthesis observations of the blue compact dwarf galaxy I Zw 18 to investigate the link between its unique evolutionary history and the neutral gas distribution and kinematics. The H i distribution is extensiv…
Measuring the Sun's Eigenfrequencies from Velocity and Intensity Helioseismic Spectra: Asymmetrical Line Profile-fitting Formula
Kosovichev, A. G.; Nigam, R.
Solar eigenfrequencies are generally determined by fitting a Lorentzian to the spectral lines in the power spectrum. This assumes that the spectral line is symmetric. Recent observations from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory have indicated that the power spectra of p-modes show varying amounts of a…
Evidence for a 3 X 10^8 M_⊙ Black Hole in NGC 7052 from Hubble Space Telescope Observations of the Nuclear Gas Disk
van den Bosch, Frank C.; van der Marel, Roeland P.
We present a Hubble Space Telescope (HST) study of the nuclear region of the E4 radio galaxy NGC 7052, which has a nuclear disk of dust and gas. The Second Wide Field and Planetary Camera (WFPC2) was used to obtain B, V, and I broadband images and an Hα + [N II] narrowband image. The images yield the stellar surface brightness profile, the optical…
The Hubble Space Telescope Quasar Absorption Line Key Project. XIII. A Census of Absorption-Line Systems at Low Redshift
Turnshek, David A.; Schneider, Donald P.; Savage, Blair D. +9 more
We present a catalog of absorption lines obtained from the analysis of the ultraviolet spectra of 66 quasars. The data were acquired with the Faint Object Spectrograph of the Hubble Space Telescope (HST) as part of the Quasar Absorption Line Survey, a Key Project for the first four cycles of HST observations. This is the third of a series of catal…
Refining the Oort and Galactic constants
Merrifield, Michael R.; Olling, Rob P.
The local stellar kinematics of the Milky Way offer a useful tool for studying the rotation curve of the Galaxy. These kinematics - usually parametrized by the Oort constants AB - depend on the local gradient of the rotation curve as well as its absolute value (Theta_0), and the Sun's distance to the Galactic Centre (R_0). The density of interstel…
The Structure of the Prototype Bipolar Protoplanetary Nebula CRL 2688 (Egg Nebula): Broadband, Polarimetric, and H2 Line Imaging with NICMOS on the Hubble Space Telescope
Schneider, Glenn; Hines, Dean C.; Rieke, Marcia J. +5 more
High-resolution near-infrared (1.65-2.1 µm) images and 2 µm polarimetric images of the inner 19.5" × 19.3" region of the bipolar protoplanetary nebula CRL 2688, taken with the newly installed Near-Infrared Camera and Multiobject Spectrometer (NICMOS) aboard the Hubble Space Telescope (HST), are reported. The NICMOS images reveal a weal…