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Inflow of halo gas from the direction of the galactic North Pole.
Savage, B. D.; de Boer, K. S.
A far-UV echelle spectrum has been obtained of the UV-bright star vZ1128 in the globular cluster M3. This cluster lies in a direction 11° off the galactic North Pole at a distance of about 10 kpc. Only the usually strong interstellar lines are recognizable in the faint spectrum, and they show absorption at velocities from near +40 km s-1
IUE spectroscopy of the degenerate components in the Hyades close binaries V471 Tauri and HZ 9.
Sion, E. M.; Guinan, E. F.
Effective temperatures and gravities have been determined for the degenerate components in the Hyades close binaries V471 Tauri and HZ9 from model atmosphere analysis of IUE ultraviolet spectra. For V471 Tauri, T(e) = 35,000 K and log g is about 8. For HZ9, T(e) = 20,000 K and log g = 8. Both systems contain DA2 white dwarfs. No photospheric metal…
Observations of interstellar hydrogen and deuterium toward Alpha Centauri A.
Moos, H. W.; Linsky, J. L.; Landsman, W. B. +1 more
The authors present a composite profile of the Lyα emission line of α Cen A, obtained from 10 individual spectra with the high-resolution spectrograph aboard the satellite. There is excellent overall agreement with two previous Copernicus observations. Interstellar deuterium is detected, and a lower limit is set on the deuterium to hydrogen ratio …
The ultraviolet (IUE) spectra of the lambda Bootis stars.
Heck, A.; Jaschek, M.; Jaschek, C. +4 more
Ultraviolet spectra of several λ Boo stars and λ Boo candidates have been obtained with the IUE satellite in low- and in high-resolution. It is possible to discriminate the λ Boo stars from the normal A stars on low resolution spectra by their strong absorption features at λλ1600, 1657(C I), 1931(C I), and 3040 Å. The λ1600 feature, about 80 Å wid…
Variable blue supergiants in the Large Magellanic cloud : R 84, R 85 and R 99.
Stahl, O.; Leitherer, C.; Zickgraf, F. -J. +3 more
During a search for luminous blue variables in the LMC the three emission-line stars R 84 (OIafpe), R 85 (B5Iae), and R 99 (OBf:pe) have been found to show significant brightness and colour variations. Photometric and spectroscopic data from the UV to the IR have been used to discuss the nature of these variables. It is argued that they are closel…
Ultraviolet extinction and diffuse band strength correlations.
Snow, T. P., Jr.; Seab, C. G.
Correlations between UV extinction parameters and diffuse band strengths are south, using a data base of 50 stars with recently measured extinction curves. A novel aspect of this study is that the basic dependence of most interstellar parameters on E(B-V) (or, nearly equivalently, on the total hydrogen column density) has been largely canceled out…
The remarkable ultraviolet spectrum of the planetary nebula Abell 30.
Feibelman, W. A.; Harrington, J. P.
Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages o…
Evidence for an increasing 59-s period in the X-ray emission from Geminga
Caraveo, P. A.; Bignami, G. F.; Paul, J. A.
Einstein Observatory and Exosat X-ray data from 1E0630 + 178 reveal a ~50% periodic emission at >=59 s. This confirms the earlier SAS 2 and COS B findings on 2CG195 + 4 at E> 50 MeV, and provides the temporal signature for the identification of Geminga. The observations, spanning over a decade (1973-83), also suggest a very high positive per…
The orbital parameters and the X-ray pulsation of VELA X-1 (4U 0900-40).
van der Klis, M.; Bonnet-Bidaud, J. M.
Results are presented of an analysis of 83 d of 2 - 12 keV X-ray observations of Vela X-1 (4U 0900-40) obtained with the ESA COS-B satellite. Combining the present determinations of the orbital epoch from pulse timing with those obtained with other satellites, the data are found to be consistent with an increase of the orbital period at a rate (P/…
The chromospheres of classical cepheids. II. High-resolution profilesof the MG II H and K lines.
Parsons, S. B.; Schmidt, E. G.
The profiles of the Mg II h and k lines near 2900 A are studied on the basis of IUE long wavelength camera high resolution spectra for a number of phases of each of five Cepheids. An emission feature often appears at the centers of the two lines, and there are central absorption features as well, due to interstellar or circumstellar gas, which are…