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Some diatomic molecules from comet P/Halley's UV spectra near spacecraft flybys
Krishna Swamy, K. S.; Wallis, Max K.
The abundances of diatomic molecules seen in the UV both give clues to the parent compounds and help unravel the gas and ion mass spectrometry. From IUE spectra of comet Halley, the authors find upper limits on SH and CS+ column densities, and estimates of probable NO, S2, and SO. In particular, judged from the 226 nm γ-band,…
High-dispersion spectroscopy of the Of/WN stars R 84 and S 61 of the Large Magellanic Cloud.
Stahl, O.; Wolf, B.; Seifert, W.
The Of/WN stars R 84 and S 61 of the LMC have been studied with high-dispersion spectroscopy in the optical and satellite-UV range. The high resolution and high S/N spectra in the optical range are particularly distinguished by strong emission lines of H, He I and [N II]. The comparison of R 84 with S 61 shows that the peculiar emission line spect…
Soft X-ray imaging observations of the 39 millisecond pulsar PSR 1951+32.
Buccheri, R.; Oegelman, H.
The authors report observations of the newly discovered 39.5 millisecond pulsar PSR 1951+32 with the soft X-ray telescope on board the EXOSAT observatory. A point-like source coincident with the position of the pulsar was observed. For a power-law model with photon index of -2, a column density of 6×1021cm-2, and a distance o…
EXOSAT observations of the magnetic binary system E 1114+182.
Pietsch, W.; Schaaf, R.; Biermann, P.
In this short note we present EXOSAT X-ray light curves of the magnetic binary system E1114+182 for two epochs. The epochs of the eclipse minima follow closely the ephemeris of Biermann et al., demonstrating that the period has not changed since the first observation with the EINSTEIN X-ray observatory in 1979. We compare the new X-ray llght curve…
Hard X-ray observations of the quasar 3C 273.
Damle, S. V.; Kunte, P. K.; Naranan, S. +2 more
The quasar 3C 273 was observed with a balloon-borne phoswich scintillator detector system launched on December 12, 1983 from Hyderabad, India. 3C 273 was tracked for 130 minutes and the background was measured in the same ranges of elevation and azimuth when the source was not in the field of view, for approximately the same duration. The fluxes i…
A study of UV spectra of zeta Aur/VV CEP stars. X. Mass-loss of alphaSco A from high-resolution IUE spectra of alpha SCO B.
Reimers, D.; Hagen, H. -J.; Hempe, K.
We redetermine the rate of mass-loss of the M super- giant α Sco by means of circumstellar lines observed with IUE in the ultraviolet spectrum of its B star companion. We first show 1) that nearly all UV lines, on which previous mass-loss determinations (v.d. Hucht et al., 1978; Bernat, 1982) were based, are blends with interstellar lines and 2) t…
Detailed Analysis of a Surface Feature on Comet p/ Halley
Wilhelm, K.; Keller, H. U.; Schwarz, G. +9 more
The surface of the nucleus of comet P/Halley is visible on many images taken by the Halley Multicolour Camera on board the Giotto spacecraft. A number of structural features like "mountains" or "surface dips" are clearly discernible. This paper outlines the methods that can be applied to analyze a surface feature with the aim of obtaining its char…
The rapidly oscillating AP stars as a test of stellar chromospheric heating mechanisms.
Sonneborn, G.; Shore, S. N.; Brown, D. N. +1 more
The discovery of a new class of magnetic stars, the rapidly pulsating Ap stars, provides an unprecedented tool for the study of Alfvénic heating in the outer atmospheres of main sequence stars. In this note, the authors point out that detection of rotationally modulated chromospheric emission line fluxes, especially the Ca II, Mg II, and C IV line…
X-ray and UV observations of omega Centauri with EXOSAT.
Koch-Miramond, L.; Auriere, M.
The globular cluster ω Cen has been observed on two occasions, 6 months apart, with the Channel Multiplier Array on board EXOSAT, in the energy band 0.02 keV - 2.5 keV. The aim of the present investigation is to study the diffuse emission as well as the point sources discovered in the X-ray range with the EINSTEIN satellite (Hartwick et al., 1982)…
Line blanketed model atmospheres of Ap-stars. VI. HD 221568.
Muthsam, H.; Stepien, K.
Visual and UV spectroscopic observations of HD 221568 together with line blanketed model atmospheres show that the star has an effective temperature of 10300K if log g = 3.7 is assumed. The temperature may be lower by about 100K in the phase of reddest B-V. Models with variable chemical composition are not able to reproduce observed light variatio…