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Coordinated Optical and Ultraviolet Observations of DH Leo
Huenemoerder, David P.; Buzasi, Derek L.; Ramsey, Lawrence W. +4 more
Results are reported from contemporaneous KPNO optical spectroscopy, IUE UV spectroscopy, and KPNO R photometry of the DH Leo triple system in spring 1987. The data are presented in tables, graphs, and spectral phase images and discussed in detail. The H-alpha, H-beta, H-gamma, H-delta, and Ca II H and IRT lines are found to have excess emission, …
Extinction-independent determination of temperatures for central stars of planetary nebulae.
Grewing, M.; Neri, R.
A method to determine temperatures for central stars of planetary nebulae from ultraviolet color indices which are essentially extinction-independent is described and applied. Using a standard extinction law (Seaton, 1979) and assuming that the continuum emission from the nuclei of planetary nebulae can be approximated by black-body distributions,…
Activity in late-type stars. V. Rotational modulation and flaring in UV lines on the most rapidly rotating dMe star, GL 890 (BD -16 6218).
Byrne, P. B.; McKay, D.
A series of UV spectra of GI 890 taken at two epochs separated by more than two years (on October 11-13, 1984 and on December 26, 1986) where obtained by the IUE satellite and using both the spectrograph's short-wavelength and long-wavelength cameras. Based on these data, the energy balance in the star's magnetically heated chromosphere and the tr…
The Orbit and Colors of the Cepheid S MUSCAE
Evans, Nancy Remage
A new orbit has been computed for the binary Cepheid S Mus combining new data from Mount John Observatory with previous data. Corrections to the colors and reddening due to the light from the companion are derived. The spectral type determined from IUE low-dispersion spectra is used for these corrections. The corrections are small, even though the…
Self-consistent comptonized models for the spectra of low-mass X-ray binaries.
Ross, R. R.; Ponman, T. J.; Foster, A. J.
We have constructed Comptonized spectral models and fitted them to EXOSAT spectra of eleven bright low-mass X-ray binaries. The models are based on the premise that these systems contain circumstellar material which modifies the X-ray spectrum passing through it. We idealize this situation as a point source of X-rays, the neutron star, embedded in…
A computed spectrum for the normal star ι Herculis (B3 IV) in the region 122.8 - 195.0 nm.
Bonifacio, P.; Castelli, F.
The authors have compared Copernicus and IUE high resolution spectra of the sharp-lined normal star ι Her with an LTE synthetic spectrum computed by using a blanketed Kurucz's (1979) model with parameters Teff = 17180K, log g = 3.43, and the new line lists of Kurucz (1988). A microturbulence ξ = 0 km s-1 gives the best agreem…
CCD astrometry of visual binaries. II. Differential measurements of northern double stars.
Sinachopoulos, D.; Seggewiss, W.
Separations and position angles of 148 visual multiple systems were measured by means of a CCD detector attached to the Calar Alto 1.23-m telescope. The program stars are candidates for the Hipparcos Input Catalog.
High-Velocity Interstellar Gas in the Lines of Sight to the Wolf-Rayet Stars HD 97152 and HD 96548
Nichols-Bohlin, Joy; Fesen, Robert A.
The interstellar medium was studied in the direction to the WR stars HD 96548 and HD 97152, and the results are reported. New observational data on the UV spectra of several field stars near both these WR stars are presented. The high-velocity gas seen in the spectra of these stars suggests that the detected expanding interstellar gas structure co…
The EXOSAT low energy imaging telescopes and transmission grating spectrometers, calibration and in-flight verification.
Brinkman, A. C.; Paerels, F. B. S.; de Korte, P. A. J. +2 more
The calibrations of the Low Energy Imaging Telescope and Transmission Grating Spectrometers on the European X-ray Observatory Satellite Exosat are presented. The final calibration is based primarily on calibration data obtained in the laboratory; verifications and checks of these calibrations with the aid of suitable astrophysical data obtained wi…
Fe - MG II K line fluorescence in K giant and bright giant stars.
Harper, G. M.
Emission lines of Fe I from the multiplet uv44 are observed at 2823.28A and 2843.98A in late-type giant and bright giant stars. It has been recognized for some time that these lines can be excited by Mg II k line radiation in the transition at 2795.54A. The first radiative transfer calculations to account for the strength of the Fe I lines Iota Au…