Search Publications
Analysis of the Photospheric Epoch Spectra of Type IA Supernovae SN 1990N and SN 1991T
Kirshner, Robert P.; Leibundgut, Bruno; Sonneborn, George +3 more
An analysis of the photospheric epoch optical and UV spectra (obtained with the IUE satellite) of Type Ia supernovae SN 1990N and SN 1991T is presented. To perform the analysis, synthetic spectra calculated using an LTE radiative transfer procedure and white dwarf explosion models of Type Ia supernovae were fitted to the observations. For both sup…
A Multiwavelength Study of the Supernova Remnant N49 in the Large Magellanic Cloud
Blair, William P.; Raymond, John C.; Long, Knox S. +1 more
Using the 2.5 m du Pont telescope at Las Campanas, the International Ultraviolet Explorer satellite, and archival high-resolution imager X-ray data from the Einstein Observatory, we present a detailed imaging and spectroscopic study of the supernova remnant (SNR) N49 in the Large Magellanic Cloud. Although the X-ray and optical morphology of N49 a…
Combined Infrared and Analytical Electron Microscope Studies of Interplanetary Dust Particles
Bradley, J. P.; Humecki, H. J.; Germani, M. S.
Ultramicrotomed thin sections (less than 100 nm thick) of eight chondritic interplanetary dust particles (IDPs) were studied by analytical electron microscopy and IR microspectroscopy with the objective of identifying IDPs or their specific components with IR spectral transmission characteristics at 10 microns similar to those of comets. Two IDPs …
The Cepheid Distance to IC 4182: Calibration of M V(max) for SN IA 1937C and the Value of H 0
Saha, A.; Panagia, Nino; Sandage, Allan +2 more
Cepheid variables with periods from 2 to more than 50 days have been found in IC 4182 from observations with the Hubble Space Telescope over a time interval of 47 days, comprised of 20 epochs. The period-luminosity relation from photometry of 27 Cepheids in the F555W HST magnitude system gives an apparent V distance modulus of (m - M)_AV_ = 28.47 …
Improved Calculations for the C III lambda lambda 1907,1909 and SI III lambda lambda 1883,1892 Electron Density Sensitive Emission-Line Ratios, and a Comparison with IUE Observations
Feibelman, W. A.; Keenan, F. P.; Berrington, K. A.
Atomic data are used in conjunction with the statistical equilibrium code of Dufton (1977) to calculate relative C III and Si III level populations, and hence emission-line strengths for a range of electron temperatures and densities. It is assumed that photoexcitation and deexcitaton rates are negligible in comparison with the corresponding colli…
EXOSAT X-Ray Spectra of Quasars
Comastri, Andrea; Setti, Giancarlo; Zamorani, Giovanni +4 more
We have measured the X-ray spectra in the 0.1-10 keV energy range for 17 AGNs (mostly PG quasars) using the EXOSAT Low and Medium Energy arrays. The sample has been selected on the basis of soft X-ray flux and includes all the AGNs in the 1981 Zamorani et al. and 1986 Tananbaum et al. publications with an Einstein flux greater than 6x10^-12^ ergs …
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 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-…
A Prediction of the gamma -Ray Flux from Nova Herculis 1991
Truran, James W.; Shore, Steven N.; Sonneborn, George +3 more
UV observations made with the IUE satellite of Nova Her 1991 are presented and discussed. A distance of 3.4 kpc and reddening of 0.6 E(B-V) to Nova Her 1991 are determined by comparing its UV and optical outburst behavior with those of the extragalactic ONeMg nova LMC 1990 No. 1. Her 1991 was also detected by Rosat five days into its outburst, and…