Detection of Methanol Maser Flares Near 19.9 and 20.9 GHz toward the Massive Source of Active Star Formation G358.931-0.030

Abstract

We have investigated the methanol CH₃OH lines at frequencies of 19.967 GHz [2₁-3₀ E(v_t = 0) transition] and 20.971 GHz [10₁-11₂ E⁺(v_t = 1) transition] toward the massive region of active star formation G358.931-0.030 with the RT-22 (Simeiz) and RT-26 (HartRAO) radio telescopes. Two new flares have been detected. One of the flares (at 20.971 GHz) is extremely powerful in the frequency range 192-26 GHz. We present our monitoring of the flaring events detected at 19.967 and 20.971 GHz. The time dependence of the flare amplitude reflects the complex structure of the maser emission regions. The velocity structure of the flares is considered.