RUI: Dynamic Ultra-Compact Ionized Gas regions in the Star-Forming Region W49A: Continuing the Search for Flickering Sources

该团队将使用卡尔·g·詹斯基甚大阵列（VLA）来搜索与大质量恒星相关的时变源。这种射电波长的闪烁源表明，恒星是断断续续吸积气体的。这种令人惊讶的行为是通过模拟预测出来的。无线电信号的预期变化太小，无法逐年测量。但它们足够大，可以从十年到十年进行测量。VLA的寿命意味着这些预测现在可以得到验证。该团队将把他们新的VLA测量结果与20年前的测量结果进行比较。美国国家科学基金会最近对该设施进行了技术升级，使研究小组能够研究被吸积气体的运动。来自代表性不足群体的本科生将大量参与这项研究。PI和他的本科生将为中学生制作教育海报。他们还将在当地校园天文台的公共活动中演讲。这个天文台是我们太阳系的比例模型的著名中心，这个模型遍布乔治亚州的亚特兰大。该团队将利用VLA精致的空间分辨率和寿命来研究W49A，这是我们银河系中一个巨大的恒星形成复合体。他们的目标是：(1)寻找电离气体连续源的大小和通量密度的变化；(2)对模拟的预测结果进行检验；(3)描述电离气体的光谱线的性质；(4)寻找连续体闪烁的运动特征。

The team will use the Karl G. Jansky Very Large Array (VLA) to search for time-variable sources associated with massive stars. Such flickering sources at radio wavelengths suggest that the stars accrete gas in fits and starts. This surprising behavior was predicted from simulations. The expected changes in the radio signals are too small to measure from year to year. But they are big enough to measure from decade to decade. The longevity of the VLA means that the predictions can now be tested. The team will compare their new VLA measurements with those from two decades ago. Recent technical upgrades to this NSF facility will also let the team study the motions of the accreted gas. Undergraduates from underrepresented groups will be heavily involved in the research. The PI and his undergraduates will produce educational posters for middle-school students. They will also lecture at public events at the local campus observatory. The observatory is the well-known center of a scaled model of our Solar System spread throughout Atlanta, Georgia.The team will use the VLA's exquisite spatial resolution and longevity to study W49A, a massive star-forming complex in our Galaxy. Their goals are to (1) search for variations in the size and flux density of its continuum sources of ionized (HII) gas; (2) test the predictions of the simulations; (3) characterize the properties of the spectral lines from the ionized gas; and (4) look for kinematic signatures of continuum flickering.