1903 20160701171655.0 ASTROimport-60 Hensberge, H. 1991 On the origin of the statistical correlation between rotation periods and apparent radii for CP 2 stars Apparent rotational velocities and rotation periods for CP 2 stars are used to study the 'apparent' radius distribution of R sin i. It implies a distribution for the radii of CP 2 stars which is almost normal for their temperatures when compared to main sequence stars. However, a statistical correlation exists between rotation period P and R sin i. It is argued that, at least in the case of silicon stars, neither conservation of angular momentum on the main sequence, nor bias in the measured v sin i values are able to induce a correlation of the observed strength. Thus, one has to postulate either additional rotational braking depending statistically on R, or a detection bias depending statistically on i. It is shown that the correlation might be explained in both ways and the implications of each possibility are discussed. Blomme, R. van Rensbergen, W. Astronomy and Astrophysics 249 1991 401-410 http://esoads.eso.org/abs/1991A%26A...249..401H published in REFERD