The B Fields in OB Stars (BOB) Survey

摘要

The B fields in OB stars (BOB) survey is an ESO large program collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars.As of July 2014, a total of 98 objects were observed over 20 nights with the FORS2 and HARPSpol.Our preliminary results indicate that the fraction of magnetic OB stars with an organized, detectable field is small.This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects.We discuss in this contribution some important issues addressed by our observations (e.g., the lower boundary of the field strength) and the discovery of some remarkable objects.