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Spectroscopic binary orbits from ultraviolet radial velocities. Paper 2: Plaskett's Star

Stickland, D. J.

Temporal variability of the massive X-ray binary 4U 1700-37.

Brinkmann, W.; Doll, H.

Results of a study of the time variability of the X-ray flux from the massive X-ray binary 4U 1700-37/HD 153919 from observations with the EXOSAT satellite are presented. Three types of intensity variations can be distinguished: flaring on time scales of 25 min to 2 h, flickering on time scales equal or less than 10 min with an amplitude equal or …

Rotational modulation of the wind of the PMS star AB AUR : new observations in C IV and MG II.

Catala, C.; Felenbok, P.; Praderie, F.

In continuation of a time monitoring program devoted to short-term spectral variability in Herbig pre-main-sequence stars, new results are presented for the star AB Aur. On a one day time scale, the variability of the blue edge velocity of the Mg II 2795-A line is confirmed, and that of the C IV 1548-A line established. Since the observations cove…

EXOSAT and Einstein Observations of the X-Ray Pulsar 4U 1145-619

Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +1 more

Results are presented of several Einstein and Exosat X-ray observations of 4U 1145 - 619, an X-ray pulsar orbiting the Be star HD 102567/Hen 715 with marked transient behavior. Pulse-timing analysis of data from imaging instruments on both missions was performed using a period-folding technique, which showed an interesting variation of the light c…

The relation between optical and X-ray flux variations of the black-hole candidate LMC X-3.

Maraschi, L.; Motch, C.; van Paradijs, J. +9 more

The authors present the results of V-band photometry of the optical counterpart of the black-hole candidate LMC X-3. The observations were made during a three-week period in December 1984, using CCD cameras at the Danish 1.5 m, and MPI 2.2 m telescopes at ESO, and the 1.0 m telescope at SAAO. In addition to an orbital brightness modulation of 0.15…

A Search for Technetium (Tc II) in Barium Stars

Little-Marenin, Irene R.; Little, Stephen J.

The authors searched without success for the lines of Tc II at 2647.02, 2610.00 and 2543.24 Å in IUE spectra of the barium stars HR 5058, ο Vir, and ζ Cap. The lack of Tc II implies that the observed s-process enhancements were produced more than half a million years ago and supports the suggestion that the spectral peculiarities of barium stars a…

Platinum and bismuth in HR 465

Cowley, Charles R.

Identifications in IUE spectra of HR 465 and a few other Ap stars in the magnetic sequence have been made using the method of wavelength coincidence statistics. These identifications have been supported by traditional techniques which rely on an examination of the strongest expected lines. The identification of Pt II made in a previous analysis of…

The Moderately Interacting Algol-Type Eclipsing Binary RY Geminorum

Plavec, Mirek J.; Dobias, Jan J.

Ultraviolet spectra of the Algol-type semidetached system RY Geminorum, whose components can be described as A0 V and K0 IV, have been matched to the ultraviolet spectrum by Kurucz (1979) model atmospheres, and a best fit is found for T(eff) = 9150 K. Comparison with standard star spectra requires that this value be raised to 9400 K. The color exc…

The peculiar emission-line supergiant HD 37836.

Stahl, O.; Wolf, B.

The luminous emission-line star HD 37836 of the LMC has been studied using high-dispersion spectra in the UV and in the optical. In addition, IUE low-dispersion spectra and UBVRIJHKL photometry have been used to study the energy distribution. The emission-line spectrum of the star is very peculiar. Its UV absorption-line spectrum is more normal an…

The Unusual Dust-Scattering Properties in the Reflection Nebula CED 201

Bohlin, R. C.; Witt, A. N.; Stecher, T. P. +1 more

Spectrophotometric data available from ground-based and IUE observations of the reflection nebula CED 201 and its illuminating star BD + 69.1231 deg are analyzed to deduce the most likely star-nebula geometry and the wavelength dependence of the scattering characteristics of the nebular grains. The dust albedo is found to decline from 0.72 at V to…