Discovery of synchronized periodic variability of methanol maser features in G26.598-0.024

TL;DR

This study reports the discovery of a unique periodic and anticorrelated variability pattern in methanol masers associated with a high-mass young stellar object, revealing complex dynamics over a decade.

Contribution

First detection of synchronized periodic maser variability with anticorrelation in a high-mass star-forming region, using long-term monitoring and high-resolution data.

Findings

Periodic maser features with a 70-day cycle were identified.

Anticorrelated flux variations observed in blueshifted and redshifted features.

Masers are associated with dust cores separated by about 1500 au.

Abstract

Aims. We report the discovery of periodic maser variability of an unusual pattern in the high-mass young stellar object G26.598-0.024. Methods. A ten-year monitoring of the 6.7 GHz methanol maser was carried out with the Torun 32 m radio telescope. The archival data collected so far were also used to characterize the target with high angular resolution and examine its infrared variability. Results. We found anticorrelated flux variations of the opposite blueshifted and redshifted emission features with a period of 70.1 (2.2) d and the relative amplitude of 1.3 and 0.6, respectively. The light curves are best fit with a sinusoidal function modulated by mild changes in the average flux density on 3-5 yr timescales. The emission of the middle parts of the spectrum shows only long-term variability. High-angular-resolution data indicate that the maser is associated with one of the two 1.3 mm dust emission cores, while the periodic comes from two extended regions ~1500 au apart. We discuss several possible causes of the peculiar variability.