On the Nature of the Protoplanetary Nebula OH\,231.8+4.2

Andreas Brunthaler, Yoon Kyung Choi, Karl M. Menten +1

Aims. OH 231.8+4.2 , also known as the Rotten Egg or Calabash nebula is a protoplanetary nebula which is seen in the direction of the open cluster M 46. While an association of the…