Periodic methanol masers in G9.62+0.20E (Research Note)

A number of mechanisms for understanding the periodic class II methanol masers associated with some high-mass star forming regions have been proposed in the past. Two recent proposals by Parfenov & Sobolev (2014, MNRAS, 444, 620) and Sanna et al. (2015, ApJ, 804, L2) have been presented in order to explain the periodic masers in sources with light curves similar to the methanol masers in G9.62+0.20E. We evaluate to what extent the proposals and models presented by these authors can explain the light curve of the methanol masers in G9.62+0.20E. It is argued that neither of the proposed mechanisms can reproduce the light curves of the methanol masers in G9.62+0.20E.