Search Publications
The strength of the C IV 1550 A resonance lines in planetary nebulae.
Wehrse, R.; Koeppen, J.
The strengths of the C IV resonance lines (1548/51 A) in NGC 6210, NGC 7009,. NGC 3242 and IC 2003 obtained from IUE spectra are compared with the predictions of ionization models constructed with standard assumptions. The ratios of observed to computed fluxes range from 0.4 to 0.034. In order to understand these discrepancies, detailed transfer c…
Detection of a late B star companion of the bright cluster giant C PUP = HD 63032.
Reimers, D.; Groote, D.
IUE observations show that c Pup, the central bright K giant in the open cluster NGC 2451, has a blue companion. A fit of theoretical line blanketed model atmosphere fluxes to the observed energy distribution yields reddening E(B-V) = 0.15 (from λ2200 Å feature), an effective temperature Te = 10,200K, and an angular diameter θ = 0.060. …
Non-thermal phenomena in the atmosphere of hot subdwarfs : X-ray upper limit for BD -3 2179.
Viotti, R.; Rossi, L.; Dantona, F.
The investigation of the nonthermal phenomena in the atmosphere of hot sublimunous stars (sdO) provides information for the study of the subatmospheric structure in evolved stars. It is noted that large mass outflows have been measured from extensive ultraviolet (IUE) observations in a number of sdO stars, which also seem to exhibit a large microt…
Emission from the transition regions and coronae of three cool dwarf stars.
Rego, M.; Fernandez-Figueroa, M. J.; de Castro, E.
An analysis is presented of the outer atmospheres of three cool dwarf stars (Tau Cet, Delta Pav, and 61 Cyg A) observed with the IUE, for which Einstein X-ray observations are available. The ultraviolet emission line fluxes are used to derive the distribution of the emission measure as a function of temperature, and from these distributions the st…
Investigation of IUE spectra of the CP star ET And (HD 219749).
Barylak, M.; Rakos, K. D.
Seventeen IUE spectra of ET And (HD 219749, HR 8861) have been investigated. The rotational velocity as derived by using the Fourier technique is v sin i = 78.8 + or - 9.0 km/sec, which is in good agreement with the values given in the literature. However, there is a large difference between v sin i measurements of photospheric lines and those of …
On the stellar content of the galactic globular cluster M 5.
Altamore, A.; Capuzzo-Dolcetta, R.; Angeletti, L. +1 more
New IUE observations of the innermost region of the galactic globular cluster M5 (NGC 5904) are presented and discussed. Addition of IUE spectra and identification of spectral features were obtained from the present and previous IUE observations of M5. Synthetic models of the cluster were constructed by taking into account optical and UV data. A c…
Evidence for outburst in the shell star 17 Lep derived from ultraviolet spectra.
Molaro, P.; Morossi, C.; Ramella, M.
Seven high resolution spectra of the primary of the binary system 17 Lep are analyzed. Variations in the shell lines that dominate the ultraviolet spectrum are found. Two of the spectra show shortward enlargements of the strongest shell lines, reaching a FWHM up to 250 km s-1, and the weakening of the weakest lines. Our suggestion is th…
High resolution ultra-violet observations of alpha Lyrae using the University College London balloon-borne telescope system.
Boksenberg, A.; Welsh, B. Y.; Towlson, W. A. +1 more
Spectral observations at a resolution of 8 km s-1 covering the region 2000 - 3200 Å have been made of the bright star α Lyrae (Vega) using the University College London Balloon-borne Ultraviolet Telescope and Image-tube Spectrograph.
The authors report on the in-flight instrument performance and in particular the sensitivity and re…Predicted and observed spectrum of M5.
Nesci, R.
From a recently published, statistically complete HR diagram of the globular cluster M5, the number distribution of HB stars as a function of the effective temperature is derived and the bolometric luminosities obtained via the conversion tables by Kurucz (1979). The expected UV energy distribution is then computed and compared with the IUE and OA…
The UV spectrum of PKS 2251+113 and physical conditions in the broad line region.
Dultzin-Hacyan, D.
The IUE satellite's UV spectrum of PKS 2251+113 is discussed, in view of previous IR, optical and X-ray observations which indicate that one cannot fit a single power law to the entire continuum. The values of the intensity ratios of Lyman-alpha to Balmer lines and Si II 1196/1263 indicate that PKS 2251+113 exemplifies objects for which the Broad …