Search Publications
The Stellar Winds of 203 Galactic O Stars: A Quantitative Ultraviolet Survey
Howarth, Ian D.; Prinja, Raman K.
Measurements of the resonance lines of C IV, N V, and Si IV in a sample of 203 O stars observed using IUE in a high-resolution mode are presented. The data are discussed using a consistent set of radius, luminosity, and mass estimates. The ratio of the maximum observed velocity and the terminal (farfield) velocity is found to average at 3.0 for 13…
Fitting Improved Accretion Disk Models to the Multiwavelength Continua of Quasars and Active Galactic Nuclei
Malkan, Matthew A.; Sun, Wei-Hsin
We present fits to the ultraviolet-optical-infrared spectra of 60 quasars and active galactic nuclei (AGNs) using improved black hole accretion disk models. The disk is assumed geometrically thin and optically thick. We included the relativistic effects of disk inclination, including Doppler boosting, gravitational focusing, and gravitational reds…
Kinematic Evidence for a Relativistic Keplerian Disk: ARP 102B
Filippenko, Alexei V.; Halpern, Jules P.; Chen, Kaiyou
The broad emission lines of the elliptical galaxy Arp 102B have peaks which are significantly displaced in velocity with respect to the host galaxy of the active galactic nucleus (AGN). We calculated line profiles for a Keplerian disk, including relativistic effects which were not treated rigorously in previous papers. We found an excellent fit of…
Detection of H3+ on Jupiter
Atreya, S. K.; Drossart, P.; Clarke, J. T. +9 more
SINCE their detection in the high latitudes of Jupiter, first by the Voyager Ultraviolet Spectrometer (UVS) experiment1,2, then by the International Ultraviolet Explorer (IDE) satellite3, the auroral particle precipitations have been associated with various phenomena in the jovian environment. In the magnetosphere, the H…
Hot Dust on the Outskirts of the Broad-Line Region in Fairall 9
Glass, I. S.; Clavel, J.; Wamsteker, W.
Since 1978, the Seyfert 1 galaxy F9 has been observed 54 times in the far-ultraviolet and optical (FES) range with the IUE, and at 27 different epochs at J, H, K, and L. The UV continuum underwent dramatic variations, its intensity decreasing by a factor 33, from a maximum in 1978 to a deep minimum in mid-1984. The near-IR and optical fluxes chang…
Narrow Ultraviolet Emission Lines from SN 1987A: Evidence for CNO Processing in the Progenitor
Panagia, N.; Fransson, C.; Kirshner, R. P. +4 more
UV observations of SN 1987A with the IUE satellite are reported. Spectra after 1987 May 24 show emission lines of He II, C III, N III, N IV, N V, and O III, increasing in strength with time. High-resolution observations show that the widths of the lines are less than ~30 km s^-1^ (FWHM). The line strengths and widths indicate an origin in a photoi…
The Evolution of Chromospheric Activity of Cool Giant and Subgiant Stars
Drake, Stephen A.; Simon, Theodore
IUE spectra for a large sample of cool subgiant stars are examined, and evidence is found that subgiants in the mass range 1.2-1.6 solar masses undergo a sudden decline in UV transition region emission near B - V = 0.6, which corresponds to spectral type G0 IV. The decline in UV emission coincides with a sharp decrease in stellar rotation rates, a…
The Infrared Emission Bands. III. Southern IRAS Sources
Tielens, A. G. G. M.; Allamandola, L. J.; Cohen, Martin +5 more
Airborne 5-8-micron spectra of southern IRAS sources are presented which display the strong PAH emission features. The sources studied include those in a previous paper (Cohen et al, 1986) and NGC 6302, HR 4049, and CPD -56 deg 8032. A good correlation is found between the intensity ratio of the 7.7-micron feature relative to the FIR dust continuu…
The winds of O-stars. I. an analysis of the UV line profiles with theSEI method.
Lamers, H. J. G. L. M.; Groenewegen, M. A. T.
The theoretical UV P Cygni profiles of the UV resonance lines for C IV, N V, Si IV, C III, and N IV of 26 O-type stars and one B star were calculated using the SEI method described by Lamers et al. (1987), taking into account the effects of turbulence in the wind, limb darkening, photospheric lines, and interstellar Ly alpha. The results were comp…
The winds of O-stars. II. The terminal velocities of stellar winds ofO-type stars.
Pauldrach, A. W. A.; Lamers, H. J. G. L. M.; Groenewegen, M. A. T.
The SEI method (Lamers et al., 1987) is used to obtain P Cygni profiles of the UV resonance lines of C IV, N V, and S IV and of the subordinate UV lines of N IV and C III observed in the spectra of 27 O-type stars. Theoretical profiles which include the turbulence effects agree well with the observations, and they can account for the deep absorpti…