Interstellar Scattering Disks

星际散射Gwinn博士将对星际介质中散射盘的形状及其时间变化进行无线电波长观测研究。这些观测包括：用甚长基线干涉测量法测量了数年内双星散射盘的大小;用甚长基线干涉测量法对氢氧脉泽散射盘进行了灵敏的观测;并对船帆座脉冲星散射盘中的散斑进行了搜索。星际等离子体中的射电波长散射限制了许多射电源观测的分辨率和位置精度，随着VLBI基线延伸到太空，天体测量VLBI的精度接近微弧秒水平，这一限制将变得更加重要。大尺度的等离子体波动，作为透镜，可以聚焦和散焦的辐射从类星体和类星体，产生观察到的低频变化的这些来源。Gwinn博士的研究旨在提高我们对散射等离子体性质的理解。

Interstellar Scattering Disks. Dr. Gwinn will carry out a radio wavelength observational study of the shapes of scattering disks in the interstellar medium and of their temporal variations. The observations include Very Long Baseline Interferometry (VLBI) measurements of the sizes of the scattering disks of pulsars over periods of years; sensitive VLBI observations of the scattering disks of hydroxyl masers; and a search for speckles in the scattering disk of the Vela pulsar. Radio wavelength scattering in the interstellar plasma limits the resolution and positional accuracy of observations of many radio sources and will become more important as a limit as VLBI baselines are extended into space and the accuracy of astrometric VLBI approaches the microarcsecond level. Large scale plasma fluctuations, acting as lenses, can focus and defocus radiation from pulsars and quasars, producing the observed low frequency variability of these sources. Dr. Gwinn's research is directed toward improving our understanding of the properties of the scattering plasma.