Chromospherically active stars. XIX. A reexamination of the variability ofHD 10909 = UV Fornacis

We have obtained new spectroscopy and photometry of the K0 IV, chromospheri cally active, single-lined spectroscopic binary HD 10909. Those observation s show that the previously reported orbital and light variability periods a re incorrect. HD 10909 has an orbital period of 30.1067 days and an eccentr icity of 0.499. Its rotation period of 64.1 days is more than twice as long as its orbital period. The primary is situated near the base of the first- ascent red giant branch. Thus, its asynchronous rotation is likely the resu lt of its recent evolution through the Hertzsprung gap, combined with its r elatively long orbital period and high eccentricity.