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Outer atmospheres of cool stars. I. The sharp division into solar-type and non-solar-type stars.
Linsky, J. L.; Haisch, B. M.
Observational evidence for a hot gaseous galactic corona.
Savage, B. D.; de Boer, K. S.
Galactic absorption features observed in high-dispersion far-UV spectra of two Large Magellanic Cloud (LMC) stars obtained with the IUE satellite are discussed. The stars observed were HD 38268 (OB + WN5) and HD 38282 (WN6), which lie at a distance of about 55 kpc and in the galactic direction corresponding to a latitude of about -32 deg and a lon…
Extinction of NGC 7027.
Seaton, M. J.
Emission intensities of recombination lines in hydrogenic spectra are known accurately relative to intensities in the free-free radio continuum. For NGC 7027 intensities have been measured for the radio continuum and for H I and He II lines in the wavelength range from 2.17 microns to 1640 A; comparison with the calculated emission intensities giv…
Outer atmospheres of cool stars. II. MG II flux profiles and chromospheric radiative loss rates.
Linsky, J. L.; Basri, G. S.
International Ultraviolet Explorer high-resolution spectra of the Mg II lines at 2796, 2803 A in 15 stars of spectral type G2-M2 including a wide range of luminosities are presented. These spectra are calibrated in absolute flux units at earth and at the stellar surface, and the chromospheric radiative loss rates in the Mg II lines are compared wi…
Ultraviolet observations of AM Herculis with IUE.
Davis, R. J.; Raymond, J. C.; Dupree, A. K. +4 more
Ultraviolet observations of the binary X-ray source AM Herculis from the IUE satellite show strong emission lines of ions from O I to N V, probably originating in photoionized gas, and a continuum which is partially eclipsed in phase with the X-ray eclipse. The emission lines have broad (about 600 km/s) and sharp (about 80 km/s) components at diff…
C III observable with IUE.
Nussbaumer, H.; Schild, H.
Theoretical emissivity ratios are presented for the C III UV multiplets at 977, 1176, 1247, 1908, and 2297 A. Proton-ion collision rates for the relevant transitions are calculated by using the semiclassical impact-parameter method as developed by Sahal-Brechot (1969). IUE observations of these multiplets in the planetary nebula NGC 7027, the slow…
Ultraviolet Night Airglow of Venus
Barth, C. A.; Stewart, A. I.
The night airglow spectrum of Venus in the ultraviolet is dominated by the v' = 0 progressions of the gamma and delta bands of nitric oxide. The bands are produced by two-body radiative recombination of nitrogen and oxygen atoms. Since the source of these atoms is in the dayside thermosphere, the night airglow is a tracer of the day-to-night therm…
Chromospheres of the active dwarf binaries EQ Pegasi and xi Bootis.
Dupree, A. K.; Raymond, J.; Hartmann, L. +3 more
Ultraviolet spectroscopic measurements of the M dwarf binary EQ Peg and the G8 V star Xi Boo A have been made with the International Ultraviolet Explorer satellite. High-temperature emission lines (N V, C IV, Si IV) are present with similar strengths in both stars. The surface fluxes of chromospheric and transition-region lines are enhanced relati…
IUE and visual spectrophotometry of 3C 120 and Markarian 79.
Oke, J. B.; Zimmerman, B.
Low-resolution ultraviolet spectra have been obtained with IUE and combined with similar visual observations. The continua of both objects show an excess of flux in the neighborhood of 3000 A. In both objects there appears to be a depression near 2200 A, which is probably the ultraviolet interstellar absorption feature centered at 2175 A. The stre…
The far-UV spectrum of the T Tauri star RU Lupi.
Liseau, R.; Gahm, G. F.; Fredga, K. +1 more
The spectrum of the T Tauri star RU Lupi from 1150 to 3100 A has been observed from the IUE satellite. It is rich in emission lines, seen superimposed on a background continuum and traceable from Ly-alpha to 3100 A. The region from 2000 to 3100 A is dominated by metal line emission of the same nature as previously observed in the optical region. T…