ALMA Imaging of Circumstellar Disks: Where and When do Planets Form?

恒星和行星都是由气体和尘埃云形成的。天文学家最近发现，大多数（如果不是大多数的话）恒星都有行星，但这些行星系统中的许多看起来与我们的太阳系非常不同。这位研究人员已经使用ALMA毫米望远镜阵列调查了数百个年轻的行星系统。他将继续这项工作，并从阵列中搜索高分辨率图像，以寻找靠近母恒星的行星形成的迹象。一名研究生和一名本科生将参与这项工作。研究者将建造一个小型射电望远镜供本科生使用。他还在写一本关于恒星形成的气体和尘埃的教科书，并定期在初中课堂上演讲。在基线高达13公里的情况下，ALMA可以在1毫米波长下实现显著的0.02弧秒的角分辨率。在附近恒星形成区域的典型距离上，这相当于1.5天文单位的径向尺度。现在，在大多数行星被发现的尺度上，对行星盘进行成像和测量基本性质是可行的。迄今为止，大多数研究都集中在最亮的圆盘上，以获得高信噪比。然而，这些明亮圆盘的高光学深度使我们无法看到大多数行星所在的最里面的几个天文单位。PI将研究较暗的圆盘，以研究太阳系尺度的圆盘结构，因为如果它们确实具有低质量，即使在最小的ALMA光束中，它们的发射也不应该饱和。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Both stars and planets form out of clouds of gas and dust. Astronomers have recently discovered that a majority of, if not most, stars have planets, but many of these planetary systems look very different than our own Solar System. This investigator has already surveyed hundreds of young planetary systems using the ALMA array of millimeter telescopes. He will continue this work and search high resolution images from the array for signs of planet formation close to the parent stars. A graduate student and undergraduates will be involved in the work. The investigator will build a small radio telescope for use in undergraduate classes. He is also writing a textbook about the gas and dust from which stars form, and regularly speaks to classes at junior high schools.With baselines up to 13 km, ALMA can achieve a remarkable angular resolution of 0.02 arcseconds at a wavelength of one millimeter. This corresponds to radial scales of 1.5 au at the typical distance of nearby star-forming regions. It is now feasible to image disks and measure basic properties at the scales where most planets are found. Most studies to date have focused on the brightest disks to achieve high signal-to-noise ratios. However, the high optical depths in these bright disks prevent us from seeing into the innermost few au where most planets are found to reside. The PI will study fainter disks to investigate disk structure at solar system scales as their emission should not be saturated even in the smallest ALMA beam if they indeed have low masses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.