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 This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outsid ...

of 8 AU. The central cavity is thus cleared out by the stars, not by the gravitational influence of a planet.

References

Ireland & Kraus (2008): The Disk Around CoKu Tauri/4: Circumbinary, Not Transitional

How Nature Builds a Planet
Adam Frank, ''Discover'' 26 (#7, July 2005); accessed online 1-II-2007.
On the Planet and the Disk of CoKu TAURI/4
Alice C. Quillen et al., ''Astrophysical Journal'' 612 (September 2004), pp. L137–L140; als
arXiv:astro-ph/0406445

Pre-main sequence star Proper Motion Catalogue
C. Ducourant et al., ''Astronomy and Astrophysics'' 438 (August 2005), pp. 769–778.
Observational studies of pre-main-sequence evolution
Martin Cohen and Leonard V. Kuhi, ''Astrophysical Journal Supplement Series'' 41 (December 1979), pp. 743–843. Binary stars T Tauri stars Circumstellar disks Taurus (constellation) {{Multi-star-stub