Search Publications
Winds in Central Stars of Planetary Nebulae
Modigliani, A.; Patriarchi, P.; Perinotto, M.
We studied five central stars of planetary nebulae with IUE high-resolution spectra to determine the wind properties of their central stars. Using the best stellar and nebular parameters, and analyzing the P Cygni profiles seen in lines of the ions C IV, N V, N IV, O V, O IV, and Si IV with the SEI method, we have obtained the following values of …
The Hydrogen Lyman-Alpha Emission of Capella
Ayres, Thomas R.; Linsky, Jeffrey L.; Gayley, K. G. +1 more
We describe the hydrogen Ly-alpha emission of the spectroscopic binary Capella (G8 III + GO III) recorded at 0.1 A resolution by the International Ultraviolet Explorer. The overt changes in the composite line shape with orbital phase are controlled by the active GO III star and permit a dissection of the stellar components despite the obliteration…
X-Ray Light Curves of Active Galactic Nuclei Are Phase Incoherent
Done, Chris; Krolik, Julian; Madejski, Grzegorz
We compute the Fourier phase spectra for the light curves of five low- luminosity active galactic nuclei observed by EXOSAT. There is no statistically significant phase coherence in any of them. This statement is equivalent, subject to a technical caveat, to a demonstration that their fluctuation statistics are Gaussian. Models in which the X-ray …
Faint Object Camera Observations of the Shape and Expansion of SN 1987A
Panagia, N.; Jakobsen, P.; Macchetto, F.
New visible and near-UV imagery of SN 1987A obtained 1754 days after outburst with the Faint Object Camera on-board the Hubble Space Telescope is presented. A comparison between these data and previous FOC observations obtained 1278 days after outburst reveal that the supernova dimmed by a factor 0.35 +/- 0.04 between the two observations, corresp…
First Ultraviolet Spectropolarimetry of Radio-selected BL Lacertae Objects
Smith, Paul S.; Allen, Richard G.; Angel, J. R. P.
We present ultraviolet spectropolarimetry of the BL Lac objects OJ 287 and 0754+100 (OI 090.4) acquired with the Faint Object Spectrograph of the Hubble Space Telescope. These are the first such observations of radio-selected BL Lac objects and the polarimetry spans the wavelength range 1580-3300 A in the observer's frame. Neither object exhibited…
A Spectroscopic Search for Colliding Stellar Winds in O-Type Close Binary Systems. IV. IOTA Orionis
Wiggs, Michael S.; Gies, Douglas R.; Bagnuolo, William G., Jr.
We present H-alpha and He I 6678 A line profiles for the eccentric orbit binary Iota Ori. We have applied a tomography algorithm which uses the established orbital velocity curves and intensity ratio to reconstruct the spectral line profiles for each star. The He I profiles appear as pure photospheric lines, and H-alpha shows variable emission in …
Observations of Nearby Interstellar Gas and Dust in the Direction toward the Globular Cluster omega Centauri
Bates, B.; Wood, K. D.
High-resolution spectra of Na I D interstellar lines are presented for six stars which lie within 4°.0 of the globular cluster ω Centauri and at distances in the approximate range 100-600 pc. For one star (HD 116226) we discuss also the Ca II K line profile and spectra obtained with lUE. Sky flux images of the ω Cen field show considerable structu…
Faint Object Camera Far-Ultraviolet Objective Prism Observations of 12 Z > 3 Quasars
Boksenberg, A.; Barbieri, C.; Weigelt, G. +16 more
We present the first results of an exploratory objective prism survey of the far-ultraviolet (λλ1200-1800) spectra of high-redshift quasars obtained with the Faint Object Camera on-board the Hubble Space Telescope. The prime objective of this survey is to identify one or more candidates among the known quasars at Ζem > 3 with suffici…
Ultraviolet Properties of Individual Hot Stars in Globular Cluster Cores. I. NGC 1904 (M79)
Altner, B.; Matilsky, T. A.
As part of an observing program using the IUE satellite to investigate the properties of stars within the cores of Galactic globular clusters, we have obtained three spectra of the cluster NGC 1904 (M79). All three were long-integration-time, short-wavelength (SWP) spectra obtained at the so-called 'center-of-light', and all three showed evidence …
A Spectral Study of Four X-Ray--selected BL Lacertae Objects with EXOSAT
Maraschi, L.; Tagliaferri, G.; Treves, A. +2 more
We present new EXOSAT spectral results for four X-ray-selected BL Lac objects (H0323+022, H0414+009, H1426+428, and H1722+ 119). The data were retrieved from the EXOSAT data base. A spectral analysis was performed on the overall low-energy plus medium-energy distributions, which were modeled with a single, absorbed power law. In one case (H1426+42…