CoKu Tau/4 is a pre-main-sequence binary T Tauri star system in the constellation Taurus. The stars are surrounded by a circumbinary disc with a central cavity of radius 10 astronomical units. Before its binary nature was known, the central cavity in the system's disc was thought to have been cleared out by a planet of at least 10 Jupiter masses, a rare example of a so-called "transitional disc". This model was disproven in 2008 when the star was resolved using adaptive optics as a system of two near-equal-mass stars with a projected separation of 8 AU. The central cavity is thus cleared out by the stars, not by the gravitational influence of a planet.
Epoch J2000.0 Equinox J2000.0 (ICRS)
|Right ascension||04h 41m 16.809s|
|Declination||+28° 39′ 59.99″|
|Apparent magnitude (V)||14.9|
CoKu Tauri/4, CoKu Tau-Aur Star 4, HBC 421, 2MASS J04411681+2840000