Speaker
Description
We present the results of the most complete up-to-date spectropolarimetric survey of early-type peculiar (CP) stars in the association Orion OB1. The final sample contains 31 magnetic stars or 55% of the whole CP population in Orion OB1. For 14 CP stars, the longitudinal magnetic field exceeding approximately 500 G was detected for the first time. We show that the percentage of the magnetic CP stars and the field strength drop sharply with age. The mean longitudinal magnetic field in the young subgroup OB1b (log t=6.23) is confidently three times stronger than in the older subgroups OB1a (log t=7.05) and OB1c (log t=6.66). We conclude that the observed trends come from the different initial conditions in star formation regions. Meantime, in the Orion Nebula, a place with the youngest stellar population (log t < 6.0), the magnetic field appeared only in 20% of CP stars. Such occurrence drastically differs from 83% of magnetic CP stars in the nearby subgroup OB1c. We consider this effect an observational bias caused by the significant portion of the very young population with the signatures of Herbig Ae/Be stars.
