Derek Laszlo Buzasi

Coordinated optical and ultraviolet observations of IM Pegasi

IUE spectra and optical observations of IM Peg obtained during the summers of 1985 and 1986 are analyzed. The modulations of the UV emission lines and the H-alpha, H-beta, and the CaII IR triplet (IRT) optical lines are examined. It is observed that: the UV emissin-line modulation increases as a function of height, H-alpha variability is related to stochastic events, H-beta displays excess absorption relative to a standard star, and the Ca IRT reveals a clear modulation with phase. It is noted that IM Peg corresponds to the solar paradigm used to explain RS CVn activity. 30 refs.

Titanium oxide variations in II Pegasi

TiO 8860 A band variations were detected in the RS CVn star II Pegasi during the fall of 1988. UBV photometry shows that the variations are correlated with the stars brightness. The TiO is stronger when the star is fainter. The results are used to estimate cool photospheric spot sizes of 2030 deg, with equivalent spectral types similar to an M4 to M6 star. 32 refs.

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.

Hα and Ca II emission line variability of FK Comae

The rapidly rotating G III star FK Comae was monitored for 18 days from Kitt Peak National Observatory, using the Penn State fiber optic echelle spectrograph on both the KPNO coude feed and 2.1 meter telescopes. We see significant changes from earlier observations.