D. P. Huenemoerder

A Versatile Fiber Coupled CCD/Echelle Spectrograph System

We have developed a versatile echelle spectrograph capable of moderate to high resolution precision spectroscopy. This highly stable instrument is in a temperature and humidity controlled room and is coupled to our 1.6 meter telescope via an optical fiber. Moderate resolution (λ/Δλ = 10000) spectra with near total spectral coverage from 400-900 nm are done at a Quasi-Littrow focus with no anamorphic magnification. A 200 mm f/2 camera focuses thirty-four orders of prism cross dispersed spectra onto a RCA SID501 CCD. A simple grating tilt can switch the beam to a cross-dispersing grating and long focus cameras allowing resolutions up to 80000. The high resolution beam has a more typical geometry with anamorphic magnification greater than one. Either small fibers or an image slicer can be used to obtain the highest resolution spectra. Observations conducted since Winter 1985 have shown the system to have excellent photometric and radial velocity characteristics; it is especially suited to long term, high signal-to-noise monitoring programs.

Spectroscopic monitoring of RS CVN stars at Kitt Peak using the Penn State Fiber Optic Echelle

The Penn State Fiber Optic Echelle has been moved to Kitt Peak and works with either the coude feed telescope or 2.1 meter. It is about twice as efficient as the coude Camera No. 5 for similar bandpass at 600 nm and is comparable at 400 nm using the coude feed telescope. The high illumination stability afforded by the fiber is a decided advantage where spectrophotometric and radial velocity stability are at a premium, as in the study of active stars. We are using this instrument to intensively monitor about 10 regular RS CVn systems and about six short period and W UMa systems for a two week period each observing semester.

Titanium oxide absorption and spot sizes in II PEG, HR 1099, and UX ARI

Excess TiO absorption line strengths have been detected in II Peg, HR 1099, and UX Ari, directly indicating large cool regions in the photosphere. Spot sizes of 10%–20% of the stellar surface area and temperatures equivalent to an M6 spectral type were derived from a spectroscopic model.

Optical and UV spectroscopy of the peculiar RS CVN system, RT lacertae

Spectra in the H-alpha and H-beta regions of the peculiar double-lined RS CVn binary, RT Lacertae, were obtained in the fall of 1984. Limited International Ultraviolet Explorer (IUE) long wavelength low and high resolution spectra were obtained concurrently. The ground based spectra have shown an asymmetry with orbital phase in the H-alpha profile. The H-beta profiles were consistent with the same effect. One hemisphere showed excess emission and the other excess absorption, with a broad Gaussian emission component superposed upon the excess H-alpha line. An improved radial velocity curve, giving a better determined mass ratio and geometry was derived. This combined with the radii implied by the rotational broadening of the spectra, showed one component to be 80 to 90% filling the equilibrium Roche surface. The two-faced nature is, therfore, very likely due to mass transfer from the contact component impacting upon its companion. Low resolution ultraviolet data showed that the supposed cooler component is bluer than its companion. High resolution ultraviolet data taken during secondary eclipse showed Mg II emission strength which decreased more slowly than the area visible. The phase behavior of the low resolution data support the former situation, indicating traditional chromospheric activity.