Nature. 1990 Mar 1;344(6261):43-5. doi: 10.1038/344043a0.
ELLIPTICAL galaxies acting as gravitational lenses occasionally produce spectacular images-Einstein rings-of distant objects. Giant arcs(1) and radio rings(2) have been observed. A wide variety of image morphologies is possible, the generation of which is qualitatively understood in terms of large magnifications at caustic and critical lines in the lensing geometry(3-5). From the angular size of the image, and with knowledge of the distances of the lensed and lensing object, rough estimates of the mass of the lensing galaxy can be obtained. We have made high-resolution radio-interferometric observations of MG1654 + 1346 (ref. 6) a radio quasar in near-perfect alignment with an elliptical galaxy, and show that radio emission is distorted into a narrow Einstein ring that lies within a diamond-shaped region bounded by caustic lines. From the details of the ring structure, a new model for the lensing geometry is deduced which leads to a more accurate estimate of the mass of the lensing galaxy.
椭圆星系作为引力透镜，偶尔会产生壮观的图像——爱因斯坦环——遥远物体的图像。已经观察到了巨大的弧形（1）和射电环（2）。可能存在各种各样的图像形态，根据透镜几何中的焦线和临界线处的大放大率，可以定性地理解它们的产生（3-5）。从图像的角度大小，并了解透镜和透镜物体的距离，可以粗略估计透镜星系的质量。我们对 MG1654 + 1346（参考文献 6）进行了高分辨率射电干涉观测，这是一个射电类星体，与一个椭圆星系近乎完美对齐，并显示射电发射被扭曲成一个狭窄的爱因斯坦环，位于由焦线限定的菱形区域内。从环结构的细节中，可以推断出一种新的透镜几何模型，这导致对透镜星系质量的更准确估计。
