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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.

On gamma-ray sources, supernova remnants, OB associations, and the origin of cosmic rays.

Montmerle, T.

Spatial coincidences between supernova remnants and OB associations or H II regions are sought, and a list of about 30 objects (referred to as 'SNOBs') is obtained. On the basis of COS B data it is found that five, or perhaps six, of 11 as-yet unidentified gamma-ray sources are associated with SNOBs and that as many as three-fourths of the best-id…

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…

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…

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…

Ultraviolet spectrophotometry of degenerate stars.

Oke, J. B.; Greenstein, J. L.

Observations of one helium- and three hydrogen-atmosphere degenerates made with the International Ultraviolet Explorer are discussed. Fluxes in the UV give temperatures in good accordance with those determined from the ground and from the ANS satellite data. Profiles of the strong L-alpha absorption in two DA's fit predictions for the expected tem…

Ultraviolet spectroscopic measurements of globular clusters.

Davis, R. J.; Raymond, J. C.; Dupree, A. K. +4 more

Ultraviolet spectra of six globular clusters (M15, M92, NGC 1851, NGC 6624, 47 Tuc, and NGC 6752) have been taken with the International Ultraviolet Explorer satellite in order to investigate the surface brightness distributions in the central regions. The ultraviolet emission indicates composite stellar spectra. Short-wavelength emission (1200-19…

Detection of acetylene in the Saturnian atmosphere, using the IUE satellite.

Moos, H. W.; Clarke, J. T.

Direct evidence for the presence of acetylene in the upper part of the Saturnian atmosphere is reported. This evidence consists of two spectra of Saturn obtained by using the low-dispersion mode of the short-wavelength spectrograph on the IUE satellite. A series of distinct absorption bands in the reflected solar radiation at 1750 A is attributed …