标题： II类甲醇脉泽源G12.89+0.49（IRAS 18089-1732）的短周期变化 显示英文标题

标题： Short-period variability in the Class II methanol maser source G12.89+0.49 (IRAS 18089-1732)

摘要： 给出了G12.89+0.49类II甲醇脉泽源的时间序列数据，该源在哈特比斯霍克射电天文台被监测了九年。在12.2 GHz和6.7 GHz处观测到的甲醇脉泽表现出快速且相关的变化，时间尺度小于一个月。每日监测显示这些变化具有一个周期成分，周期为29.5天。这个周期在时间序列跨越的110个周期内似乎保持稳定。每个周期的变化有所不同，耀斑峰值可能出现在11天窗口内的任何地方，但最小值总是在周期的同一相位出现。在6.7 GHz光谱特征之间观察到高达5.7天的时间延迟，在主导的12.2 GHz光谱特征与其6.7 GHz对应特征之间观察到1.1天的时间延迟。 显示英文摘要

摘要： Time series are presented for the class II methanol maser source G12.89+0.49, which has been monitored for nine years at the Hartebeesthoek Radio Astronomy Observatory. The 12.2 and 6.7 GHz methanol masers were seen to exhibit rapid, correlated variations on timescales of less than a month. Daily monitoring has revealed that the variations have a periodic component with a period of 29.5 days. The period seems to be stable over the 110 cycles spanned by the time series. There are variations from cycle to cycle, with the peak of the flare occurring anywhere within an eleven day window but the minima occur at the same phase of the cycle. Time delays of up to 5.7 days are seen between spectral features at 6.7 GHz and a delay of 1.1 day is seen between the dominant 12.2 GHz spectral feature and its 6.7 GHz counterpart.