Search Publications
Relationship between wave energy and free energy from pickup ions in the Comet Halley Environment
Johnstone, A. D.; Huddleston, D. E.
The free energy available from the implanted heavy ion population at comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. We obtain upstream and downstream free energies separately for t…
Possible cataclysmic variable in the core of the globular cluster 47 Tucanae
Ferraro, Francesco R.; Paresce, Francesco; de Marchi, Guido
SEVERAL globular clusters have low-luminosity X-ray sources at their cores1-3, of which X0021.8-7221 in 47 Tucanae (NGC104) is one of the brightest. The nature of these sources is a mystery, and attempts to detect optical counterparts have been frustrated by the overcrowding of stars in cluster cores. The resolution of ground-based obse…
A Magnitude-limited Survey of Cepheid Companions in the Ultraviolet
Evans, Nancy R.
Results of a magnitude-limited survey of classic Cepheids brighter than 8th mag carried out to search for hot main-sequence companions are presented. Spectra of 76 stars obtained with the IUE satellite in the 2000-3200-A region were compared with the spectra of nonvariable supergiants and also the single Cepheid Delta Cep to search for excess flux…
LY alpha Emission from Cooling Flows and Measures of the Dust Content of Rich Clusters of Galaxies
Hu, Esther M.
We tabulate Ly α and UV continuum fluxes from measurements across the emission-line regions of 10 "cooling flow" clusters of galaxies. Comparison of Ly α emission fluxes obtained with the IUE satellite with optical Balmer emission fluxes is used to demonstrate that the lines of sight to the centers of these clusters show an average excess reddenin…
Hubble Space Telescope Wide Field Camera Imaging of the Gravitational Lens 2237+0305
Schneider, Donald P.; Rix, Hans-Walter; Bahcall, John N.
Hubble Space Telescope Wide Field Camera images of the gravitational lens 2237+0305 in the F336W ("U") and F702W ("A") filters are used to construct models of the system. Positions for the four quasar images, accurate to +/-0.015", and relative magnitudes in U and R, accurate to +/-0.06 and 0.04 mag respectively, are determined. The upper limits o…
The O/C abundance ratio in absorbing gas clouds at high redshift
Clavel, J.; Reimers, D.; Vogel, S. +5 more
THE intrinsic extreme ultraviolet (EUV) spectrum of quasars, in which spectral lines of He and CNO ions should appear, is in most cases strongly absorbed by the hydrogen Lyman continuum of intergalactic matter at cosmological distances. The bright quasar HS1700 + 6416 (at redshift z = 2.72), from the Hamburg survey1, is a fortuitous exc…
Hubble Space Telescope Faint Object Spectrograph and Ground-based Observations of the Broad Absorption Line Quasar 0226-1024
Turnshek, David A.; Burbidge, E. M.; Morris, Simon L. +6 more
Faint Object spectrograph data from the Hubble Space Telescope of the broad absorption line quasar 0226 - 1024 have revealed the presence of 8-10 absorbing ions between 680 and 1000 A (restframe): C III, N III, N IV, O III, O IV, O VI, S V, S VI, possibly Ne VIII, and possibly O V^*^ arising from a metastable excited state. We also present ground-…
Orbital elements of S stars : revisiting the evolutionary status of S stars.
Jorissen, A.; Mayor, M.
The hypothesis of an evolutionary link between barium stars and the non-Mira S stars is discussed. The hypothesis of an evolutionary link between the barium stars and the non-Mira S stars is confirmed. The mass function distribution of S stars, indicating that the companions are likely white dwarfs, as is the case for barium stars, supports this h…
On the Nature of the Symbiotic Binary AX Persei
Mikolajewska, Joanna; Kenyon, Scott J.
Photometric and spectroscopic observations of the symbiotic binary AX Persei are presented. This system contains a red giant that fills its tidal lobe and transfers material into an accretion disk surrounding a low-mass main-sequence star. The stellar masses - 1 solar mass for the red giant and about 0.4 solar mass for the companion - suggest AX P…
Nonlinear magnetosonic waves and mirror mode structures in the March 1991 Ulysses interplanetary event
Tsurutani, Bruce T.; Smith, Edward J.; Balogh, Andre +1 more
In examining the March 23-25, 1991 Ulysses (2.2 AU) high speed solar wind events, we find two distinct plasma wave modes: steepened magnetosonic waves with whistler precursors and mirror mode structures. These two modes are locally generated by plasma instabilities, presumably associated with anisotropies existing in the energetic shock particles …