A Survey of 12.2 GHz Methanol Masers and Their Polarization Properties

Methanol emission at 12.1786 GHz, 2 - 3(-1)E, has been searched for toward 78 nonstellar H2O masers and 33 type I OH/IR stars. Eleven new methanol sources were found in nonstellar water masers, whereas no sources were found in stellar masers. Most of the new sources show narrow lines with velocity widths smaller than 1 km/s and are considered to be masers. Tentative evidence is presented that the methanol masers are not all associated with H2O and OH masers. Polarization properties have also been observed for five strong sources including Cepheus A and G188.94 + 0.89, which were detected in this survey. Three sources, G188.94 + 0.89, Cepheus A, and NGC 7538, are completely unpolarized, and the other two sources show a small amount of linear polarization: a few percent for W3(OH) and 10 + or - 3 percent for NGC 6334.