The Zeeman Effect in the 44 GHz Class I Methanol Maser Line toward DR21(OH)

Abstract

We report the 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 maser centered at an LSR velocity of 0.83 km s${}^{-1}$, we find a 20-$\sigma$ detection of $z{B}_{\text{los}}=53.5\pm 2.7$ Hz. If 44 GHz methanol masers are excited at $n\sim 10^{7-8}$ cm${}^{-3}$, then the $Bvs.n^{1/2}$ 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 $\sim$10 mG. Together with our detected $z{B}_{\text{los}}=53.5$ Hz, this would imply that the value of the 44 GHz methanol Zeeman splitting factor $z$ is $\sim$5 Hz mG${}^{-1}$. Such small values of $z$ would not be a surprise, as the methanol molecule is non paramagnetic, like H${}_2$O. Empirical attempts to determine $z$, as demonstrated, are important because currently there are no laboratory measurements or theoretically calculated values of $z$ for the 44 GHz methanol transition. Data from observations of a larger number of sources are needed to make such empirical determinations robust.

11 pages, 3 figures, accepted for publication in ApJ

References in corpus (2)

• The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X
• Non-Zeeman Circular Polarization of Molecular Maser Spectral Lines

Cited by in corpus (10)

• Review of Zeeman Effect Observations of Regions of Star Formation
• Online Database of Class I Methanol Masers
• Polarization studies of Rotating Radio Transients
• Methanol masers reveal the magnetic field of the high-mass protostar IRAS 18089-1732
• The magnetic field in the dense photodissociation region of DR 21
• OH maser toward IRAS 06056+2131: polarization parameters and evolution status
• The Zeeman Effect in the 44 GHz Class I Methanol (CH3OH) Maser Line Toward DR21W
• Long-term variability of Class I methanol masers in the high mass star forming region DR21(OH)
• A Curious Case of Circular Polarization in the 25 GHz Methanol Maser Line toward OMC-1
• Polarization properties of methanol masers