Aims. Surveys of the Milky Way at various wavelengths have changed our view of star
formation in our Galaxy considerably in recent years. In this paper we give an overview of …

Long-term monitoring observations with the Hitachi 32 m radio telescope of the 6.7 GHz
methanol masers associated with the high-mass star-forming region G5. 900− 0.430 are …

Context. Periodicity in 6.7 GHz methanol maser sources is a rare phenomenon that was
discovered during long-term monitoring programmes. Understanding the underlying …

The variability study of 6.7 GHz methanol masers has become a useful way to improve our
understanding of the physical conditions in high-mass star-forming regions. Based on the …

We present the results of a 5-yr monitoring program of 42 sources targeted at 6.7-GHz
methanol masers, conducted from 2017 March to 2022 October using the Irbene 32-and 16 …

Context. Periodic flares of maser emission are thought to be induced either by variations of
the seed photon flux in young binary systems or the pump rate regulated by stellar and …

We have performed a molecular line search towards the flaring 6.7-GHz masers G 24.33+
0.13, and G 359.6− 0.24 using the Australia Telescope Compact Array. We present spectra …

Context. Maser flares are particularly significant in the study of massive star formation as
they not only signal but also provide unique insights into transient phenomena such as …

Aims. We report the discovery and analysis of a periodic methanol maser in the massive
protostar IRAS 20216+ 4104. Methods. To obtain the light curve, we used the 6.7 GHz …

Results of the long-term monitoring observations by the Hitachi 32 m radio telescope of the
6.7 GHz Class II methanol masers associated with four high-mass star-forming regions are …