Search Publications
The interstellar radiation field and the production of inverse-Compton gamma rays in the Galaxy
Bloemen, J. B. G. M.
An empirical model for the large-scale galactic distribution of the various components of the interstellar radiation field is constructed using recent observations, and the spectral and spatial distribution of inverse Compton (IC) gamma ray production in the Galaxy is determined using the most recent estimate of the interstellar electron spectrum …
The MG II emission in W UMa-type binaries.
Rucinski, S. M.
Low-resolution IUE spectra of the Mg II emission line in eight contact binaries are presented. They are discussed together with the available observations in both resolution modes for other binaries, 15 systems altogether. The relative flux R(Mg II) = f(Mg II)/f(bol), which is known to be independent of the orbital phase, is used as a measure of c…
The X-ray spectrum of the supernova remnant W 49B from EXOSAT.
Jones, L. R.; Smith, A.; Pye, J. P. +1 more
X-ray observations of the supernova remnant W49B made by the medium-energy detector and gas scintillation propotional counter experiments on board Exosat are presented. The detection of a very strong emission line feature at 6.7 keV indicates a thermal origin of the X-rays. Fitting the spectral data with an optically thin thermal plasma model indi…
35-DAY Cycle and the Rotation Period of HERCULES-X-1
Pietsch, W.; Kahabka, P.; Truemper, J. +2 more
Sampling observations of a complete 35d cycle of Her X-1 during 1 March to 5 April 1984 with the low and medium energy X-ray detectors of EXOSAT are presented. The intensities measured in the Argon detectors are compared with the UHURU 35d light curve to obtain the turn-on times of two consecutive cycles as JD 2445753.0 ± 1.0…
New EXOSAT Results from the Intermediate Polar V1223-SAGITTARIUS
Beuermann, K.; Osborne, J. P.; Mason, K. O. +1 more
We report new results obtained from the EXOSAT AO- 1 observation of the intermediate polar V1223 Sgr. The detection of a 12.4 minute period in the medium energy X-ray flux with an associated hardness ratio variation has been previously reported in Osborne et al. (1984a). Further work has revealed: a narrow dip at the phase zero in the folded mediu…
Abundances of O, Mg, S, Cr, Mn, Ti, NI and Zn from absorption lines of neutral gas in the Large Magellanic Cloud in front of R 136.
Savage, B. D.; de Boer, K. S.; Fitzpatrick, E. L.
The authors have searched six high-dispersion IUE spectra of R136 for weak absorption lines of C I, O I, Mg I, Mg II, Si I, Si II, P I, Cl I, Cr II, Mn II, Fe I, Ni II, Zn II, CO and C2. The absorption detected is from neutral gas in front of the 30 Doradus H II region. For the first time abundances of Mg, Cr, Mn, Ti, Ni, and Zn are det…
Detection and analysis of photospheric CNO features in the ultraviolet spectrum of the hot DO white dwarf PG 1034+001.
Sion, E. M.; Wesemael, F.; Liebert, J.
An analysis of PG 1034 + 001 extended to include the high-dispersion IUE spectra and the high-resolution optical multiple-mirror telescope echelle spectra is discussed. The observations reveal the presence of absorption lines (C IV at 1548 and 1551 A, N V at 1238 and 1242 A, and O V at 1371 A) from highly ionized species with large redshifts (+ 40…
Ultraviolet absorption by highly ionized halo gas near the galactic center.
Savage, B. D.; Massa, D.
As part of a program to survey highly ionized gas in the Milky Way disk and halo, the authors have obtained high-resolution IUE far-UV spectra of 12 stars at galactocentric distances less than 6 kpc. The stars are 0.7 - 2.2 kpc away from the plane. Most of the spectra contain exceedingly strong and broad interstellar absorption lines of weakly and…
Magnetic structure in cool stars. VIII. The MG II H and K surface fluxes in relation to the MT Wilson photometric CA II H and K measurements.
Zwaan, C.; Oranje, B. J.
Data from IUE observations of 14 F, G, and K stars of luminosity II-V in the Mg II h + k lines are presented in tables and compared with published Mt. Wilson photometry of the Ca II H + K lines, and empirical relations are derived to facilitate the use of Ca II H + K data in investigating the chromospheric structure of cool stars. The results are …
The ultraviolet spectra of normal elliptical galaxies : a population synthesis approach.
Perola, G. C.; Nesci, R.
Published UV spectra of elliptical galaxies are compared with the results of population syntheses (based on HB stars, accreting white dwarfs in binary systems, or young stars forming in bursts) in an attempt to explain the observed upturn shortward of 200 nm. The results are presented in tables and spectra and discussed in detail. Good agreement i…