RV Tauri
A 2005 study of the elemental abundances of RV Tauri stars calculated that HP Lyr had a temperature around and typical abundances for an RV Tauri variable. It also revealed that the abundances were altered by dust-gas separation in circumstellar material. HP Lyr has been included in a catalog of confirmed post-AGB stars, highly evolved and on its way to becoming a white dwarf. In 2017, the temperature was calculated to be , still one of the hottest known RV Tau variables.