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The orbit of the supergiant component of VELA X-1 derived from IUE radial velocities
Lloyd, C.; Stickland, D.; Radziun-Woodham, A.
47 short-wavelength, high-resolution IUE spectra have been used to derive the orbital elements of HD 77581, the supergiant companion to the neutron star in the X-ray source Vela X-1; the velocity amplitude is at the lower end of the range found by previous workers using primarily optical spectra, but other elements (e, omega) are in fair agreement…
Radiative Balance and Dynamics in the Stratosphere of Jupiter: Results from a Latitude-Dependent Aerosol Heating Model
Moreno, Fernando; Sedano, José
An updated dynamical model for the circulation in the jovian stratosphere has been developed. For computation of the heating and cooling rates in the stratosphere, required to obtain the radiative flux convergence, the model makes use of exponential-sum derived coefficients from laboratory and correlated-kdistributions from line listing data for t…
HIPPARCOS distances of X-ray selected stars: implications on their nature as stellar population.
Micela, G.; Favata, F.; Sciortino, S.
We present the parallaxes, measured by Hipparcos, for a sample of X-ray selected stars. The stars belong to the stellar sample of the Einstein Extended Medium Sensitivity Survey. They are all at galactic latitude |b|>20deg, and are generally far away from known star forming regions. Several of these stars show lithium abundance and activity lev…
Wide Field Planetary Camera 2 Photometry of the Bright, Mysterious White Dwarf Procyon B
Provencal, J. L.; Bergeron, P.; Sion, E. M. +4 more
Procyon B is one of a select group of white dwarf stars which are members of visual binary systems and represents a critically important object for testing the fundamental physics of stellar degeneracy. We have accurate measurements of the binary period and the white dwarf mass. However, the extreme brightness ratio and the small separation betwee…
High Spatial Resolution Near-Infrared Imaging of the Central Regions of M31
Doyon, R.; Davidge, T. J.; Rigaut, F. +1 more
H and K images with 0.15 arc sec angular resolution are used to probe the stellar content in the central 8 arcsec of M31. A large number of stars are detected, and the majority of these have K≥17.5 and H - K colors between 0 and 1. After correcting for differences in distance and reddening, the mean locus of the M31 (K,H- K) diagram is found to be…
Hubble Space Telescope and Ground-based Observations of I Zw 1 and Mrk 486 and the Variability of Polarization in Radio-quiet Active Galactic Nuclei
Hines, Dean C.; Schmidt, Gary D.; Smith, Paul S. +1 more
Hubble Space Telescope UV spectropolarimetry and new ground-based optical observations of the Seyfert 1/QSO I Zw 1 and highly polarized Seyfert 1 Mrk 486 are presented. I Zw 1 is found to be a polarimetric variable. Our data show that the polarization position angle has changed by ~50° compared to measurements obtained 10-15 yr ago. There is evide…
New, sub-0.1-arcsec radio maps of two young planetary nebulae
Pedlar, A.; Bryce, M.; Thomasson, P. +2 more
Sub-0.1-arcsec maps of the 5-GHz continuum emission from two young planetary nebulae (NGC7027 and BD+303639) have been obtained by combining MERLIN and VLA observations, resulting in the highest spatial resolution radio maps of these (or any) planetary nebulae to date. Small clumps of emission are resolved within the essentially ring-like structur…
Potential Measurement of the Luminosity Function of 158 Micron [C II] at High Redshifts: A Test of Galaxy Formation Models
Stark, Antony A.
Galaxy formation scenarios predict a burst of star formation in normal galaxies at a redshift between z ~ 2 and z ~ 6 (e.g., Katz & Gunn 1991); such a starburst may be accompanied by a significant brightening of the λ = 158 µm line of C+. Galaxies that will evolve to a total luminosity L* = 5 × 1010 L
Far-Infrared Spectroscopy of Planetary Nebulae with the Kuiper Airborne Observatory
Rubin, Robert H.; Haas, Michael R.; Colgan, Sean W. J. +2 more
We present new far-infrared line observations of the planetary nebulae (PNs) NGC 7027, NGC 7009, and NGC 6210 obtained with the Kuiper Airborne Observatory (KAO). The bulk of our data are for NGC 7027 and NGC 7009, including [Ne V] 24 µm, [O IV] 26 µm, [O III] (52, 88) µm, and [N III] 57 µm. Our data for [O III] (52, 88) an…
Hubble Space Telescope Wide Field Planetary Camera 2 Imaging of the Crab Nebula. I. Observational Overview
Blair, William P.; Davidson, Kris; Henry, Richard B. C. +3 more
We present Hubble Space Telescope WFPC2 images of a portion of the Crab Nebula supernova remnant obtained using narrow passband filters. These images show a wide range of filament morphologies including small individual isolated knots, long smooth arcs, and chaotic filament complexes, with evidence that some filament cores are far denser and coole…