CoKu Tau/4

CoKu Tau/4
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Taurus
Right ascension 04h 41m 16.809s
Declination +28° 39′ 59.99″
Apparent magnitude (V) 14.9
Distance~420 ly
(~130 pc)
Other designations
CoKu Tauri/4, CoKu Tau-Aur Star 4, HBC 421, 2MASS J04411681+2840000
Database references
SIMBADdata

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.