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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus [1] |
| Right ascension | 04h 41m 16.810s [2] |
| Declination | +28° 40′ 00.07″ [2] |
| Apparent magnitude (V) | 14.68 [3] |
| Characteristics | |
| Spectral type | M1.5e [4] |
| Astrometry | |
| Proper motion (μ) | RA: +4.317 [2] mas/yr Dec.: −22.201 [2] mas/yr |
| Parallax (π) | 6.4456±0.1146 mas [2] |
| Distance | 506 ± 9 ly (155 ± 3 pc) |
| Other designations | |
| CoKu Tauri/4, CoKu Tau-Aur Star 4, HBC 421, 2MASS J04411681+2840000 [5] | |
| Database references | |
| SIMBAD | data |
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.
