Sidney B. Parsons

Ultraviolet and optical studies of binaries with luminous cool primaries and hot companions. IV: Further IUE detections

We have obtained IUE spectra for 31 middle and late-type giant and supergiant stars whose TD-1 fluxes or ground-based spectra indicate the presence of a hot component, or whose radial velocities indicate an unseen component. Stellar components earlier than type F1 were detected in 22 cases. While 20 of the hot secondaries are seen weakly in optical spectra, two are UV discoveries: HD 58134 and HD 183864. The hot companions are classified accurately by temperature class from their far-UV spectra. The interstellar extinction of each system and the relative luminosities of the components are derived from the UV and optical fluxes, using a new grid of UV intrinsic colors for hot dwarfs. We find that many giant stars apparently have companions which are too hot and hence too luminous for consistency with the primarys spectral classification.

Orbital elements and optical spectroscopy of the enigmatic cF+B binary system HD 207739

The orbit of the peculiar interacting F8 + B binary system is established on the basis of 93 radial-velocity measurements mostly made photoelectrically. The period is 140.78 days, the velocity amplitude is 70 km/s, and the orbit has a small but nevertheless significant eccentricity. The mass function of 5 solar masses is extraordinarily large and probably indicates that the F-type component is the secondary in terms of mass. Optical spectroscopy in the red region reveals strong and variable H-alpha emission, forbidden N II emission at the gamma-velocity of the system, and N I and Na I absorption of circumstellar origin.

HD 43246 and HD 127208: two unusual F-G + B binary systems

New optical spectroscopic observations along with ultraviolet IUE observations have been obtained for the two interacting F or G III + B V binaries: HD 43246 and HD 127208. Photometric observations indicate random changes superimposed on regular ellipsoidal light variations, the latter probably the result of tidal distortion of the giant primaries. Mass transfer and loss is apparent in inverted mass ratios derived from orbital analysis, strong wind features present in the spectra, and the presence of circumsystem shells. Regular and irregular changes in the spectral features are discussed in this context.

A Large Spectral Class Dependence of the Wilson‐Bappu Effect among Luminous Stars

The striking correlation between Ca ii K-line emission width and absolute visual magnitude has not previously been well calibrated for stars more luminous than giants. From a sample of binary systems fit to isochrones, we find deviations of more than 2 mag, correlated with spectral class, between these binarity Mv values and the Wilson-Bappu relation. Additional Mv values derived from Hipparcos parallaxes are used to explore the systematics. The spectral class dependence vanishes for K-line parameter log W0 ≤ 1.80. Linear spectral class corrections are derived for the more luminous stars, with log W0 ≥ 2.00, while a table is provided for the transition region. The dispersion from these relations is about ±0.6 mag. This recalibration extends the demonstrated applicability of the Wilson-Bappu technique to Mv -5 or distance ≈20 kpc.

OPTICAL AND ULTRAVIOLET SPECTROSCOPY OF THREE F + B BINARY STARS

Optical and ultraviolet spectroscopy is presented for three F + B objects that are members of the first group of strongly interacting, F II + B systems. The data obtained confirm that HD 59771, HD 242257, and CoD -30 5135 are all binary star systems consisting of a luminous F-type component and a B star. Strong, variable H-alpha emission is seen in all the stars. It is found that the UV spectrum of HD 59771 resembles the spectrum of HD 207739. CoD -30 5135 has the most dramatic mid-UV spectrum seen among the scores of observed cool + hot star systems.

Evolution of science data processing for the Hubble Space Telescope: a user's perspective

Upgrades of the science instrument complement on the Hubble Space Telescope (HST) and observing strategy innovations have combined to greatly increase the number of observations and the volume of data during the first decade of HST operations. At the same time, the data processing component of HST operations has undergone a parallel evolution in strategy and implementation, partly in response to the increased volume of data from HST while reducing staffing requirements, and partly due to the phasing out of old technologies and the exploring of new ones. This paper describes the original HST data processing strategy and implementation, how it has evolved to the current design today, and where it may be going for future space telescope missions (HST, NGST, et al.).

THE LONG PERIOD K + BE BINARY HR 2577 (MWC 827)

New spectroscopic observations near Hα and Na I D, along with ultraviolet IUE scans, have been obtained for the K+Be composite system HR 2577. High-precision radial-velocity measures do not support the suggested 58-year orbit of Hendry (1982). The Hα emission from the Be component undergoes considerable variations typical of its class. The presence of a λ6707 Li I feature as well as the IUE observations support the idea that little or no interaction between the binary components of HR 2577 is taking place.

Optical Concepts For The Binary Star Explorer

We describe the conceptual design of a proposed first-generation optical in-terferometer in space, the Binary Star Explorer. The scientific objectives for this interferometer are to determine the fundamental astrophysical quantities of distance and mass for stars in binary systems. In particular, the interferometer will be able to make accurate distance measurements to an estimated 40 Cepheid binary systems in our Galaxy, and 28 supergiant binary systems in the LMC. The interferometer comprises two fixed telescopes on a 5 m baseline, beam-combining optics, and a visible/ultraviolet fringe detecting system. We determine the angular separation of binary systems made up of a cool giant star and hot dwarf companion by measuring the shift between the optical and ultraviolet fringes. In combination with knowledge of the physical size of the orbit (which must be obtained separately from radial velocity measurements on both stars), the distance to the binary is obtained as the ratio of the physical to angular sizes.