text: Scott Tremaine proposed that an eccentric disk created this entity's nuclei in 1995 - that model was discussed in a paper by CY Peng that also described the 2 nuclei of this entity.
full_question: Scott Tremaine proposed that an eccentric disk created this entity's nuclei in 1995 - that model was discussed in a paper by CY Peng that also described the 2 nuclei of this entity. Walter Baade used observation of this body to classify stars into 2 populations. The Hooker telescope found the first Cepheid variables here, following up on hypotheses about this object discussed in the Curtis Shapley debate. The Triangulum Galaxy is thought to be bound to this other galaxy. Also known as M31, it is the largest galaxy in the Milky Way. For ten points, name this galaxy, predicted to collide with the Milky Way in a few billion years.
first_sentence: Scott Tremaine proposed that an eccentric disk created this entity's nuclei in 1995 - that model was discussed in a paper by CY Peng that also described the 2 nuclei of this entity.