# The shortest periodic and flaring flux variability of a methanol maser emission at 6.7 GHz in G 014.23-00.50

## TL;DR

This study reports the discovery of the shortest periodic and flaring flux variability in a 6.7 GHz methanol maser, with a 23.9-day cycle, observed over several years, likely caused by binary interactions or shock heating in a high-mass star-forming region.

## Contribution

First detection of a 23.9-day periodic flux variability in methanol maser emission, revealing new insights into maser behavior and high-mass star formation processes.

## Key findings

- Periodic variability persisted over 47 cycles (~1100 days)
- Flares exceeded 180 times the quiescent flux level
- Flux rise times were typically two days or shorter

## Abstract

We detected flaring flux variability that regularly occurred with the period of 23.9 days on a 6.7 GHz methanol maser emission at Vlsr = 25.30 km/s in G 014.23-00.50 through highly frequent monitoring using the Hitachi 32-m radio telescope. By analyzing data from 05 January 2013 to 21 January 2016, the periodic variability has persisted in at least 47 cycles, corresponding to approximately 1,100 days. The period of 23.9 days is the shortest one observed in masers at around high-mass young stellar objects so far. The flaring component normally falls below the detection limit (3 sigma) of 0.9 Jy. In the flaring periods, the component rises above the detection limit with the ratio of the peak flux density more than 180 in comparison with a quiescent phase, showing intermittent periodic variability. The time-scale of the flux rise was typically two days or shorter, and both symmetric and asymmetric profiles of flux variability were observed through intraday monitoring. These characteristics might be explained by a change in the flux of seed photons by a colliding-wind binary (CWB) system or a variation of the dust temperature by an extra heating source of a shock formed by the CWB system within a gap region in a circumbinary disk, in which the orbital semi-major axes of the binary are 0.26-0.34 au.