Discovery of 6.035GHz Hydroxyl Maser Flares in IRAS18566+0408

TL;DR

This paper reports the discovery of periodic 6.035GHz hydroxyl maser flares in IRAS18566+0408, a unique star-forming region showing simultaneous formaldehyde and methanol maser flares, suggesting a common IR pumping mechanism.

Contribution

First detection of hydroxyl maser flares in IRAS18566+0408, linking OH and CH3OH maser variability and supporting IR pumping as the excitation process.

Findings

Detected two OH maser flare events in 2009.

OH flares are correlated with CH3OH flares but not with H2CO flares.

Supports IR pumping as a common excitation mechanism.

Abstract

We report the discovery of 6.035GHz hydroxyl (OH) maser flares toward the massive star forming region IRAS18566+0408 (G37.55+0.20), which is the only region known to show periodic formaldehyde (4.8 GHz H2CO) and methanol (6.7 GHz CH3OH) maser flares. The observations were conducted between October 2008 and January 2010 with the 305m Arecibo Telescope in Puerto Rico. We detected two flare events, one in March 2009, and one in September to November 2009. The OH maser flares are not simultaneous with the H2CO flares, but may be correlated with CH3OH flares from a component at corresponding velocities. A possible correlated variability of OH and CH3OH masers in IRAS18566+0408 is consistent with a common excitation mechanism (IR pumping) as predicted by theory.