Search Publications
Hybrid atmospheres and winds in supergiants stars.
Raymond, J. C.; Dupree, A. K.; Hartmann, L.
Ultraviolet spectra showing evidence for hybrid chromospheres and winds are found in the supergiant Alpha Aqr (G2 Ib) and Beta Aqr (G0 Ib). Characteristics of both solar-type transition regions and the cool chromospheric regions typical of later supergiants such as Lambda Vel (K5 Ib) are present. This suggests a gradual transition between activity…
Outer atmospheres of cool stars. V. IUE observations of Capella: the rotation-activity connection.
Linsky, J. L.; Ayres, T. R.
UV spectra of Capella (G6 III + F9 III) obtained with the IUE are analyzed. High-resolution emission-line profiles taken near the elongation at phase 78 days suggest that virtually all of the emission in transition-region lines and most of the emission in chromospheric lines comes from the late-F secondary of the system. It is suggested that the o…
Observations of quasars with the International Ultraviolet Explorer satellite.
Schmidt, M.; Green, R. F.; Lane, A. L. +3 more
The paper deals with the spectra of six quasars, ranging in redshift from 0.23 to 2.04, obtained with the 45-cm telescope mounted on the IUE satellite. The average emission-line intensity ratio for L-alpha to H beta and the detection of higher-order Lyman emission lines in two objects are found to be inconsistent with a simple optically thick reco…
IUE and visual observations of the Orion nebula and IC 418 : the carbon abundance.
Torres-Peimbert, S.; Daltabuit, E.; Peimbert, M.
The paper presents IUE and optical observations of the Orion Nebula and of the planetary nebula IC 418. Based on these data, log C = 8.5, log O = 8.6 and log N = 7.7 for the Orion Nebula, and log C = 9.0, log O = 8.7 and log N = 7.9 for IC 418 are obtained. These results imply that: (1) lambda-4267 is produced mainly by recombination and provides …
IUE spectra of a flare in the RS Canum Venaticorum-type system UX Arietis.
Linsky, J. L.; Simon, T.; Schiffer, F. H., III
IUE spectra of UX Ari obtained during the large flare of 1979 January 1 exhibit chromospheric and transition-region emission-line fluxes about 2.5 and 5.5 times brighter than quiescent fluxes, respectively, and up to 1400 times brighter than the quiet sun. A high-dispersion spectrum of the 2000-3000 A region exhibits enhanced Fe II emission, which…
Observations from earth orbit and variability of the polar aurora on Jupiter
Moos, H. W.; Atreya, S. K.; Clarke, J. T. +1 more
Spatially resolved spectra of Jupiter taken with the International Ultraviolet Explorer satellite show enhanced emissions from the polar regions at H L-alpha (1216 A) and in the Lyman and Werner bands of H2 (1175-1650 A). Two types of variability in emission brightness have been observed in these aurorae: an increase in the observed emission as th…
Detection of mass loss in stellar chromospheres.
Stencel, R. E.; Mullan, D. J.
IUE observations of 47 cool giants have been made in a search for the onset of expansion in the Mg II h and k emission cores. It is found that, in a statistical sense, the longward emission peak becomes dominant above a velocity dividing line in the H-R diagram, which lies close to a temperature dividing line reported by Linsky and Haisch (1979). …
The white dwarf companion of the barium star ZET Cap.
Boehm-Vitense, E.
It is shown that the barium star Zeta Cap has a white dwarf companion with a mass of approximately 1.0 solar masses and an effective temperature of 23,000 K. Strong emission lines and very deep reversals in the Mg II emission line cores indicate circumstellar gas which may be due to mass transfer in the system. The Ba star HD 65699 also shows the …
Evidence for hot gaseous coronae around the Magellanic clouds.
Savage, B. D.; de Boer, K. S.
High-dispersion IUE far-UV spectra were obtained for five stars in the LMC and two stars in the SMC. At Magellanic Cloud velocities, all the spectra exhibit very strong interstellar lines of Al III, Si IV, and C IV, in addition to the usual lower ionization stage lines associated with H I region absorption. In two stars interstellar N V is also de…
Simultaneous ultraviolet, optical and X-ray observations of the X-raysource Vel X-1 (HD 77581).
Davis, R. J.; Raymond, J. C.; Hammerschlag-Hensberge, G. +17 more
UV spectra (obtained by the IUE) of HD 77581, associated with the binary X-ray source Vela X-1, show a spectrum typical of an early B-type supergiant. However, the P Cygni profiles of strong resonance lines show substantial variations with orbital phase. These variations can be ascribed to the changing ionization state in the stellar wind caused b…