  A flare of OH maser emission was discovered in W75N in 2000. Its location was
determined with the VLBA to be within 110 au from one of the ultracompact H II
regions, VLA2. The flare consisted of several maser spots. Four of the spots
were found to form Zeeman pairs, all of them with a magnetic field strength of
about 40 mG. This is the highest ever magnetic field strength found in OH
masers, an order of magnitude higher than in typical OH masers. Three possible
sources for the enhanced magnetic field are discussed: (i) the magnetic field
of the exciting star dragged out by the stellar wind; (ii) the general
interstellar field in the gas compressed by the MHD shock; and (iii) the
magnetic field of planets which orbit the exciting star and produce maser
emission in gaseous envelopes.
