OH Masers in G11.904-0.141

Abstract

The massive star-forming region G11.904-0.141 is one of only 11 sources to show maser emission in the highly-excited 13441 MHz transition of OH. VLBA observations of the 1665, 1667, 4765, and 13441 MHz transitions of OH toward G11.904-0.141 are presented. Masers are detected at 1665, 1667, and 4765 MHz, but the 13441 MHz masers are not detected. Consistent magnetic field strengths of approximately +3.5 mG are detected in the ground-state masers, in contrast with a possible -3.0 mG magnetic field previously detected at 13441 MHz. The variable 13441 MHz masers may be associated with an outflow.