Search Publications
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…
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…
On the Absence of Young White Dwarf Companions to Five Technetium Stars
Smith, Verne V.; Lambert, David L.
A search for hot companions to five stars of type MS and S has been carried out using the International Ultraviolet Explorer (IUE) satellite. No hot companions were detected for the MS stars HR 85, 4647, 6702, and 8062, and the S star HR 8714. Limits on the luminosities of possible white dwarf companions provide lower limits of 2 - 5×108
A Nonspherically Symmetric Model for the Peculiar A Star Alpha 2 CVn
Bohm-Vitense, Erika; van Dyk, Schuyler D.
Observations show that in the optical region the peculiar A star α2CVn has a flatter energy distribution during maximum light than during minimum light. This indicates that during maximum light we see a lower-temperature region, but necessarily larger surface area, than during minimum light. This suggests a nonspherically symmetric star…
The Moderately Interacting Algol Binary RS Cephei
Plavec, Mirek J.; Dobias, Jan J.
In agreement with previous observers, it is found that the eclipsing binary RS Cep is an Algol-type semidetached system. From IUE spectra and Lick Observatory optical scans, the spectral types of the components are determined as B9.7e V + G8 III-IV. The effective temperature of the primary star is found to be 9670 K (with an uncertainty of about 1…
Search for X-Rays from the Region of the Aries-Perseus Flasher
Lewin, Walter H. G.; van Paradijs, Jan; Damen, Eugene +4 more
The region containing the Perseus flasher (Katz et al., 1986) was observed for 5.4 hr with the EXOSAT observatory. Upper limits (2 σ levels of confidence) to a point source with a steady X-ray flux were 2×10-12erg cm-2s-1 (0.1 - 2 keV) and 6×10-12erg cm-2s-1 (1 - 20 keV). Upper limi…
The Ultraviolet Variability of AY Ceti
Sonneborn, George; Simon, Theodore
AY Cet is a single-line binary comprised of a spotted G5 III primary and a white dwarf secondary. The authors obtained a series of UV spectra with the IUE satellite on five different dates covering a substantial part of the optical cycle of the primary star. They found no evidence that the continuum or the Lyα absorption line of the secondary star…