Search Publications
Discovery of Red Selected Arcs at Z = 4.04 behind Abell 2390
Broadhurst, Tom; Frye, Brenda
We describe the properties of three red arcs discovered at z=4.04 behind the cluster A2390 (z=0.23). We demonstrate that these arcs are images of a single galaxy where lensing is compounded by an elliptical cluster member near the critical curve of the cluster. The combined magnification is estimated to be ~20 using Hubble Space Telescope images, …
Dust, Gas, and the Evolutionary Status of the Radio Galaxy 8C 1435+635 at z = 4.25
Ivison, R. J.; Dunlop, J. S.; Stevens, J. A. +8 more
We present the results of new rest-frame far-IR observations of the z = 4.25 radio galaxy 8C 1435+635, which not only confirm that it contains an enormous quantity of dust (as first inferred from its millimeter-wave detection by Ivison in 1995), but also allow the first meaningful constraints to be placed on the mass of this dust and associated ga…
Coronal and Transition Region Structure in the RS Canum Venaticorum Binaries V711 Tauri, AR Lacertae, and II Pegasi. I. Data Analysis and Emission Measure Distributions
Jordan, C.; Griffiths, N. W.
We present a study of the transition regions and coronae of the RS CVn binaries V711 Tau, AR Lac, and II Peg. Archival data from the Extreme Ultraviolet Explorer (EUVE), International Ultraviolet Explorer (IUE), Goddard High-Resolution Spectrograph (GHRS), and a variety of X-ray telescopes have been analyzed and modeled. Emission measure distribut…
NICMOS 2 Micron Continuum and H2 Images of OMC-1
Schneider, Glenn; Chrysostomou, Antonio; Young, Erick T. +8 more
The core of OMC-1 has been imaged with the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) on board the Hubble Space Telescope at 0.2" resolution in 1% filters at 2.12 and 2.15 µm, revealing intricate structures in both continuum and shocked molecular hydrogen line emission. Numerous H2-emitting clumps surrounding the B…
Toward a Realistic Diffusion Tensor for Galactic Cosmic Rays
Burger, R. A.; Hattingh, M.
We present analytical expressions for the mean free path parallel to the background magnetic field, calculated from quasi-linear theory for a composite slab/two-dimensional geometry model of turbulence. Diffusion perpendicular to the field is assumed to be anisotropic and proportional to parallel diffusion. For the variation in the magnetic field …
Two Jets from the Protostellar System L1551 IRS 5
Liseau, René; Fridlund, C. V. Malcolm
Hubble Space Telescope and ground-based observations of the jet emanating from the young stellar object L1551 IRS 5 clearly show a structure with two components, one of which terminates in a working surface only 1500 AU from the originating sources. This particular jet is found to be less dense than the ambient medium. Its Mach disk is found to be…
The Virgo Cluster Distance from 21 Centimeter Line Widths
Sandage, Allan; Tammann, G. A.; Federspiel, Martin
The distance of the Virgo cluster is derived in the B band from the 21 cm line width-absolute magnitude relation. This relation is calibrated using 18 spirals with Cepheid distances, mainly from the Hubble Space Telescope. The calibration is applied to a complete sample of nonpeculiar spirals with i > 45° lying within the optical (n = 49) or X-…
Color-Luminosity Relations for the Resolved Hot Stellar Populations in the Centers of M31 and M32
Ferguson, Henry C.; Brown, Thomas M.; Stanford, S. A. +1 more
We present Faint Object Camera (FOC) ultraviolet images of the central 14" × 14" of Messier 31 and Messier 32. The hot stellar populations detected in the composite UV spectra of these nearby galaxies are partially resolved into individual stars, and their individual colors and apparent magnitudes are measured. We detect 433 stars in M31 and 138 s…
HD 98800: A Unique Stellar System of Post-T Tauri Stars
Torres, Guillermo; Latham, David W.; Henry, Todd J. +15 more
HD 98800 is a system of four stars, and it has a large infrared excess that is thought to be due to a dust disk within the system. In this paper we present new astrometric observations made with Hipparcos, as well as photometry from Hubble Space Telescope WFPC2 images. Combining these observations and reanalyzing previous work allow us to estimate…
Flows and Horizontal Displacements from Ring Diagrams
Schou, J.; Bogart, R. S.
A new algorithm for analyzing ring diagrams from helioseismic data is presented. This method is applied to two months of Solar and Heliospheric Observatory/Michelson Doppler Imager data from 1996 May 24 through July 24 to study flows and to measure the ratio of the horizontal displacement to the vertical displacement for the oscillations. We find …