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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…
Metal abundances in the hot DA white dwarfs Wolf 1346 and Feige 24.
Wesemael, F.; Henry, R. B. C.; Shipman, H. L.
Photospheric metal lines observed in high-dispersion IUE spectra of the hot DA white dwarfs Wolf 1346 and Feige 24 are analyzed with detailed model synthetic spectra in order to derive metal abundances in the two stars. The IUE images used in the analysis are first discussed together with the theoretical framework, an extensive set of metal line p…
Bolometric corrections for peculiar B-type stars.
Lanz, T.
Semi-empirical bolometric corrections are estimated for 25 peculiar stars and 13 comparison stars from IUE low dispersion spectrum and from theoretical fluxes best fitting the Geneva colour indices. When corrected for reddening, the relation BC vs. (B2-G)0 for main-sequence stars matches fairly well the theoretical relation computed by …
Nebular and interstellar absorption lines in planetary nebulae : the case of NGC 6543.
Pottasch, S. R.; Pwa, T. H.; Mo, J. E.
Using high resolution IUE spectra it is possible to separate the narrow absorption lines due to the interstellar material and the nebular matter. The analysis of nebular absorption lines has three advantages. First the column densities of ions different from those observed in emission can be determined. The abundance of the elements are then readi…
Characteristics of the Fe II and C II emission in high-resolution IUEspectra (2300-3000 A ) of alpha Orionis.
Carpenter, K. G.
A study is presented of Fe II and C II emission features in the 2300-3000 A region of four high-resolution IUE spectra of Alpha Ori obtained during the period 1978 April-1982 November. A set of 42 unmutilated, unblended Fe II lines of multiplets UV 1-3, 32-33, 35-36, and 60-64 and the C II (UV 0.01) intercombination lines have been identified and …
The 1200-3200 A spectra of Seyfert I galaxies : MK 304, NGC 7603, MCG8-11-11, ESO 12-G 21 and NGC 1566.
Clavel, J.; Joly, M.
The 5 Seyfert I galaxies MK 304, NGC 7603, MCG 8-11-11, ESO 12-G 21, and NGC 1566 have been observed with IUE (1200 - 3200 Å). Their UV spectrum is rich in emission lines. A steep rise of the continuum toward shorter wavelengths is observed below ≡2000 Å in 4 of these objects; this excess is interpreted as thermal emission from an accretion disk. …