2010ApJ...717L.133A

We report results of an extensive observational campaign of the 6 cm formaldehyde maser in the young massive stellar object IRAS 18566+0408 (G37.55+0.20) conducted from 2002 to 2009. Using the Arecibo Telescope, the Very Large Array, and the Green Bank Telescope, we discovered quasi-periodic formaldehyde flares (P ∼ 237 days). Based on Arecibo observations, we also discovered correlated variability between formaldehyde (H₂CO) and methanol (CH₃OH) masers. The H₂ CO and CH₃OH masers are not spatially coincident, as demonstrated by different line velocities and high angular resolution MERLIN observations. The flares could be caused by variations in the infrared radiation field, possibly modulated by periodic accretion onto a young binary system.