Search Publications
HST Imaging of the Inner 3 Arcseconds of NGC 1068 in the Light of [O iii] lambda 5007
Ford, H. C.; Armus, L.; Evans, I. N. +3 more
We have used the Planetary Camera on board the Hubble Space Telescope to obtain a high spatial resolution [O III] λ5007 image of the nucleus of NGC 1068. This image resolves the narrow-line region into several distinct clouds arranged in an apparently conical geometry. The individual emission-line regions appear to be resolved, with sizes ~0.1" -0…
PG 0027+260: an Example of a Class of Cataclysmic Binaries With Mysterious, But Consistent, Behavior
Thorstensen, John R.; Schmidt, Gary D.; Ringwald, F. A. +2 more
This paper reports extensive optical observations on the PG0027 + 260 binary, carried out on August 1984 with the 1.3 McGraw-Hill telescope and Mark II spectrometer at Michigan-Dartmouth-MIT Observatory on Kitt Peak. It is shown that this object is an eclipsing novalike variable with an orbital period of 3.51 hr. The PG0027 + 260 displays several …
Negative ions in the coma of comet Halley
Chaizy, P.; Anderson, K. A.; Reme, H. +8 more
IN March 1986, the Giotto spacecraft encountered comet Halley, approaching to within ~600 km of the nucleus. Results from this encounter have shown that the inner coma contains a mixture of cometary neutral gas and dust, thermal ions and electrons, fast cometary pick-up ions, and decelerated solar-wind ions and electrons, as well as fast neutrals<…
First Results from the Goddard High-Resolution Spectrograph: The Galactic Halo and the LY alpha Forest at Low Redshift in 3C 273
Savage, Blair D.; Morris, Simon L.; Gilliland, Ronald L. +1 more
We present results of initial spectroscopy using the Goddard High- Resolution Spectrograph and the Hubble Space Telescope on the bright low- redshift quasar 3C 273. We detect absorption lines produced by gas in the disk and halo of the Milky Way from numerous neutral and weakly ionized atoms and also from highly ionized atoms (Si IV, C IV, and N V…
Non-LTE analysis of four PG1159 stars.
Werner, K.; Heber, U.; Hunger, K.
A spectral analysis of four members of the PG1159 class is performed. These stars are believed to be very hot pre-White Dwarf stars. It is shown that the photospheres of PG1159 stars are dominated by helium and carbon and that a significant amount of oxygen is present. It is also found that the nonradial pulsations observed in some PG1159 stars ar…
Axisymmetric Model of the Ionized Gas in the Orion Nebula
Rubin, R. H.; Haas, M. R.; Erickson, E. F. +1 more
New ionization and thermal equilibrium models for the ionized gas in the Orion Nebula with an axisymmetric two-dimensional 'blister' geometry/density distribution are presented. The HII region is represented more realistically than in previous models, while the physical detail of the microphysics and radiative transfer of the earlier spherical mod…
The Ultraviolet Absorption Spectrum of 3C 273
Junkkarinen, V.; Schneider, D. P.; Jannuzi, B. T. +3 more
We identify six Lyα absorption systems with equivalent widths greater than 0.2 A in the ultraviolet spectrum of the nearby quasar 3C 273, more than expected on the basis of extrapolations of the observed number of Lyα clouds seen at large redshifts. Two Lyα lines appear to be produced by gas in the Virgo Cluster or by the halos of galaxies associa…
First Results from the Faint Object Camera: SN 1987A
Panagia, N.; Boksenberg, A.; Kirshner, R. P. +18 more
We present the first images of SN 1987A taken on day 1278 after outburst with the Faint Object Camera on board the Hubble Space Telescope. The supernova is well detected and resolved spatially in three broadband ultraviolet exposures spanning the 1500-3800 A range and in a narrow-band image centered on the [O III] λ5007 line. Simple uniform disk f…
Structure and Kinematics of the Broad-Line Regions in Active Galaxies from IUE Variability Data
Koratkar, Anuradha P.; Gaskell, C. Martin
IUE archival data are used to investigate the structure and kinematics of the broad-line regions (BLRs) in nine active galactic nuclei (AGNs). The cross-correlation technique, for unevenly sampled data, advocated by Gaskell and Sparke has been applied to spectra taken between 1978 and 1988. An extensive investigation of the errors has been carried…
Premaximum Observations of the Type IA SN 1990N
Filippenko, Alexei V.; Shields, Joseph C.; Kirshner, Robert P. +4 more
Spectroscopic and photometric observations of SN 1990N were obtained at ultraviolet and optical wavelengths, beginning 14 days before maximum light. The early observations reveal important differences from spectra of SN Ia's around maximum light. Photometry and spectroscopy obtained after maximum show that SN 1990N is a typical SN Ia and that most…