Extended Red Emission (ERE) is a widely observed optical emission process, present in a wide range of circumstellar and interstellar environments in the Milky Way galaxy as well as other galaxies. Definitive identifications of the ERE carriers and the ERE process are still a matter of debate. Numerous models have been proposed in recent decades, often developed without consideration of the growing body of observational constraints, which by now invalidate many of these models. This review focuses on the most well-established observational constraints which should help to delineate the way toward a generally accepted explanation of the ERE and an understanding of its place in the radiation physics of the interstellar medium.

中文翻译：

---

扩展的红色发射：模型的观测约束

扩展红光发射 (ERE) 是一种广泛观察到的光学发射过程，存在于银河系以及其他星系的各种星周和星际环境中。ERE 载体的最终识别和 ERE 过程仍然是一个有争议的问题。近几十年来已经提出了许多模型，通常在开发时没有考虑到越来越多的观测约束，这些约束现在使许多这些模型无效。这篇综述侧重于最完善的观测约束，这些约束应该有助于描绘出对 ERE 的普遍接受的解释的方式，以及对其在星际介质辐射物理学中的地位的理解。