THE ZEEMAN EFFECT IN THE 44 GHZ CLASS I METHANOL MASER LINE TOWARD DR21(OH)

We report detection of the Zeeman effect in the 44 GHz Class I methanol maser line, toward the star-forming region DR21(OH). In a 219 Jy beam(-1) maser centered at an LSR velocity of 0.83 km s(-1), we find a 20-sigma detection of zB(los) = 53.5 +/- 2.7 Hz. If 44 GHz methanol masers are excited at n similar to 10(7-8) cm(-3), then the B versus n(1/2) relation would imply, from comparison with Zeeman effect detections in the CN(1 - 0) line toward DR21(OH), that magnetic fields traced by 44 GHz methanol masers in DR21(OH) should be similar to 10 mG. Combined with our detected zBlos. =. 53.5 Hz, this would imply that the value of the 44 GHz methanol Zeeman splitting factor z is similar to 5 Hz mG(-1). Such small values of z would not be a surprise, as the methanol molecule is non-paramagnetic, like H2O. Empirical attempts to determine z, as demonstrated, are important because there currently are no laboratory measurements or theoretically calculated values of z for the 44 GHz CH3OH transition. Data from observations of a larger number of sources are needed to make such empirical determinations robust.