ο Tauri, Latinized as Omicron Tauri, is a binary star system in the constellation Taurus, near the constellation border with Cetus. It has a yellow hue and is visible to the naked eye with an apparent visual magnitude of 3.61. It is approximately 191 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −20 km/s. This system has the Flamsteed designation 1 Tauri; Omicron Tauri is the Bayer designation. This is a single-lined spectroscopic binary system with the two components orbiting each other over a period of with an eccentricity of 0.263. The visible component is an aging G-type giant with a stellar classification of G6 III. This star has three times the mass of the Sun and eighteen times the Sun's radius. Based on the latter, interferometry-measured radius, it is rotating once every 533 days. It is radiating 149 times the luminosity of the Sun from its photosphere at an effective temperature of 5,180 K. References External links G-type giants Spectroscopic binaries Taurus (constellation) Tauri, Omicron Durchmusterung objects Tauri, 001 021120 015900 1030