view Abstract Citations (39) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The FK Comae candidate UZ Librae. Bopp, B. W. ; Goodrich, B. D. ; Africano, J. L. ; Noah, P. V. ; Meredith, R. J. ; Palmer, L. H. ; Quigley, R. J. Abstract New optical spectroscopic and photometric data are presented for the active chromosphere FK Com candidate UZ Lib. The star is shown to have an extremely large photometric amplitude in V of 0.35 mag, and its rotation period is established as 4.75 + or - 0.01 days. The optical spectrum is that of an early K giant, broadened by a rotation velocity of approximately 65 km/s. H-alpha is visible as a very broad emission feature, with a profile resembling that seen in FK Com. The emission intensity and profile are variable over the rotation period, with the strongest emission present at photometric minimum, in accord with dark starspot models. The photospheric absorption line profiles show variable asymmetries and distortions which are interpreted as due to the effects of the dark starspot rotating across the line of sight. New radial velocity measures are combined with published data to demonstrate the UZ Lib is a member of a binary system in synchronous rotation with a secondary of mass approximately 0.5 solar masses. This information is considered in light of the conflicting models for the origin of the optical and spectral variability of the FK Com stars, as well as their uncertain evolutionary status. Publication: The Astrophysical Journal Pub Date: October 1984 DOI: 10.1086/162492 Bibcode: 1984ApJ...285..202B Keywords: Binary Stars; Giant Stars; Optical Emission Spectroscopy; Stellar Spectrophotometry; Variable Stars; Chromosphere; Emission Spectra; K Stars; Line Spectra; Radial Velocity; Stellar Evolution; Stellar Rotation; Stellar Spectra; Astrophysics full text sources ADS | data products SIMBAD (4)