A water maser flare in W49N - The superposition of the spectra of two component masers
A water maser flare in W49N - The superposition of the spectra of two component masers
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DOI：
10.1051/0004-6361:20020705
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发表时间：
2002-07
影响因子：
6.5
通讯作者：
J. Zhou;X. Zheng;Yang Chen
中科院分区：
文献类型：
--
作者：
J. Zhou;X. Zheng;Yang Chen
我们报告了我们对W 49 N的短时间尺度监测观测结果。发现水脉泽的三个特征表现为通量密度、线宽和中心速度的明显变化。在大约22天的时间里，-88.3、-56.9和-12.8 km s（-1）特征的通量密度分别以每天57、113和98.8 Jy的速率线性下降。-56.9 km s（-1）和-12.8 km s（-1）特征的线宽度分别以类似于每天0.022 km s（-1）和类似于每天0.046 km s（-1）的速度增加，而-88.3km/s（-1）特征的线宽以0.01km/s（-1）的速率增加在最初的17天内，每天的速度为0.017 km/s（-1），在其余的日子里，每天的速度下降。所有这三个特征都显示出中心速度的系统性偏移，其偏移量约为1 km/s（-1）。我们提出了一个基于两个脉泽云光谱叠加的模型来解释这些脉泽特征的变化：两个刚性旋转的、不饱和的球形脉泽云在下降阶段达到相同的视线速度，然后由于它们的相对加速度而彼此分离。
We report the results of our short time scale monitoring observations of W49N. Three water maser features were found to show obvious variations in flux density, line width and center velocity. Over a period of about 22 days, the -88.3, -56.9 and -12.8 km s(-1) features declined linearly in flux density at rates of 57, 113, 98.8 Jy per day, respectively. The line widths of the -56.9 and -12.8 km s(-1) features increased at rates of similar to0.022 and similar to0.046 km s(-1) per day, respectively, while the line width of the -88.3 km s(-1) feature increased at a rate of 0.01 km s(-1) per day during the first 17 days and decreased at a rate of 0.017 km s(-1) per day during the remainder of the days. All three features show a systematic shift of similar to1 km s(-1) in center velocity. We propose a model based on the superposition of the spectra of two maser clouds to explain the variations of these maser features: two rigidly rotating, unsaturated spherical maser clouds during the declining phase reach the same line-of-sight velocity, then they depart from each other because of their relative acceleration.