Holz & Wheeler (\cite{hw}) have recently proposed that a Schwarzschild blackhole may act as a retro-lens which, if illuminated by a powerful light source,deflects light ray paths to large bending angles and a series of luminous arcs(or rings in the case of aligned objects) centered on the black hole may form.Obviously, the most convenient geometry to get retro-lensing images would bethat of a very bright star close to a massive black hole, say the putative$\sim 4\times 10^6$ M$_{\odot}$ black hole at the galactic center. Recentobservations of the galactic center region in the $K$-band have revealed thepresence of a very bright main sequence star (labelled S2) with mass $\sim 15$M$_{\odot}$ orbiting at close distance (130-1900 AU) from Sgr A$^*$. Therelatively vicinity of S2 to the central massive black hole may offer a uniquelaboratory to test the formation of retro-lensing images. The next generationof space-based telescopes in the $K$-band (like NGST) may have high enoughlimiting magnitude necessary to observe such retro-lensing images.
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机译：Holz＆Wheeler（\ cite {hw}）最近提出，Schwarzschild黑洞可以充当反光镜，如果使用强大的光源照明，则该反光镜会将光线路径偏转到较大的弯曲角度和一系列发光弧（或显然，最容易获得逆向镜头图像的几何形状是一颗非常明亮的恒星靠近一个巨大的黑洞，例如假定的\ sim 4 \。在银河系中心乘以10 ^ 6 $ M $ _ {\ odot} $黑洞。最近对$ K $波段银河中心区域的观测表明，存在非常明亮的主序列恒星（标记为S2），其质量为\\ sim 15 $ M $ _ {\ odot} $ AU），来自Sgr A $ ^ * $。 S2与中央大质量黑洞的相对距离可能会提供一个独特的实验室来测试逆向镜头图像的形成。 $ K $波段的下一代天基望远镜（如NGST）可能具有足够高的限制幅值，以观察此类逆向镜头图像。
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