Search Publications
The Extended Atmosphere of lambda Pavonis at the Time of the Emergence of H-Emissions from Minimum Intensity
Cidale, Lydia; Sahade, Jorge; Kondo, Yoji +2 more
A study of the Be star λ Pavonis, particularly of the changes in the Balmer discontinuity in the interval 1949 - 1982, is presented. Nearly simultaneous observations carried out with the ESO 1.5 m reflector at La Silla and with the IUE satellite correspond to an epoch when the H emission is starting to increase in intensity immediately after havin…
HD 38451 : J.R. Hind's star that changed colour.
Sneden, Christopher; Warner, Brian
In 1851, John Russell Hind announced that a star previously observed by him to be very red had become bluish white in color. It is shown that this star, HD 38451, is a ninth magnitude shell star which presumably was ejecting a shell when Hind first observed it. From high dispersion coude spectra, low dispersion IUE spectra, and ground-based photom…
Coordinated X-ray and ultraviolet observations of the intermediate polar H2215-086
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +6 more
Quasi-simultaneous observations of H2215-086 (=FO Aqr), obtained with Exosat and IUE in 1983 and 1985 are reported. Secular variations in the X-ray flux and in the shape of the rotational light curve are observed. The modulation of the photoelectric absorption cutoff is studied by means of phase resolved X-ray spectra. A possible orbital modulatio…
Periodicity Search in Sources with Low Count Rate
Bisnovatyi-Kogan, G. S.; Gurin, L. S.; Beliaeva, N. P. +2 more
The problem of discovery and estimation of the period, slowly changing in time is considered, when the pulses are rare. Several criteria are proposed on the base of which a multilevel algorithm of the period detection is constructed. The reliability and precision of the period determination are investigated with taking into account of the correlat…
The far UV spectrum of the Be star 88 Herculis.
Danezis, E.; Theodossiou, E.
A high-resolution FUV spectrum of 88 Her, obtained with the IUE short-wavelength primary instrument on May 23, 1984, is analyzed. Line identifications for the 110-210-nm range, determined on the basis of the multiplet tables of Moore (1968) and Kelly and Palumbo (1979) are presented in a table, and a list of unidentified lines is also provided. Th…
The Long Period K + Be Binary HR 2577 (MWC 827)
Parsons, Sidney B.; Dempsey, Robert C.; Bopp, Bernard W.
New spectroscopic observations near Hα and Na I D, along with ultraviolet IUE scans, have been obtained for the K+Be composite system HR 2577. High-precision radial-velocity measures do not support the suggested 58-year orbit of Hendry (1982). The Hα emission from the Be component undergoes considerable variations typical of its class. The presenc…
IUE and optical spectrophotometry of the HZ Herculis/Hercules X-1 system
Howarth, I. D.; Raymond, J. C.; Wilson, R. +1 more
Photometric (B-filter) data of HZ Herculis obtained between 1972 and 1974 have been fitted by a model consisting of Roche-lobe-filling star transferring material to a neutron star via a tilted, preccessing, accretion disc. The disc inclination was found to be small, thus avoiding theoretical difficulties experienced with high-inclination discs. We…
Optical and UV observations of the symbiotic star CH Cygni after the jets ejection in 1984
Mikolajewska, J.; Mikolajewski, M.; Tomov, T.
The optical and UV observations of the symbiotic star CH Cyg are discussed in the context of the jet appearance. CH Cygni is an eclipsing binary with a period of 5700 days, consisting of an M 6 giant and a white dwarf surrounded by an accretion disk formed from the cool giant wind. Previous studies of the system are reviewed and emission line prof…
The IUE Spectrum of CN 1-2 (=PK 326 -10 1): A Southern Counterpart to V1016 Cygni and HM Sagittae?
Feibelman, Walter A.
Low-dispersion IUE spectra confirm that the emission-line object Cn 1-2 is a symbiotic star and not a planetary nebula. The UV spectrum of Cn 1-2 strongly resembles those of V1016 Cyg and HM Sge. The object is correctly identified in the finder field of Allen's Catalogue of Symbiotic Stars (1984) but misidentified in the Catalogue of Galactic Plan…
Ultraviolet observations of SN 1987A.
Panagia, N.
Results are presented from IUE observations of SN 1987A. The general UV spectral evolution of the supernova is described. The UV and optical photometric data for SN 1987A are examined, focusing on the importance of the data for supernova energetics. It is concluded that SN 1987A is a normal Type II explosion with an unusually compact initial confi…