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·詹斯基超大型阵列(VLA)来搜索与大质量恒星有关的时变源。这种在射电波长上闪烁的来源表明，恒星断断续续地吸积气体。这种令人惊讶的行为是从模拟中预测出来的。无线电信号的预期变化太小，无法每年进行测量。但它们的规模足够大，可以从十年到十年来衡量。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年前的结果进行比较。最近对NSF设施的技术升级也将使该团队能够研究吸积气体的运动。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。天文台是遍布乔治亚州亚特兰大的太阳系模型的著名中心。该团队将利用VLA的精致空间分辨率和寿命来研究W49A，这是我们银河系中的一个巨大的恒星形成复合体。他们的目标是(1)寻找其电离(HII)气体连续谱源的大小和通量密度的变化；(2)检验模拟的预测；(3)表征来自电离气体的谱线的特性；以及(4)寻找连续谱闪烁的运动学特征。

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.