Charles Parker Jr. (August 29, 1920 - March 12, 1955), also known as Yardbird and Bird, was an American jazz saxophonist and composer. Parker was a highly influential jazz soloist and a leading figure in the development of bebop, a form of jazz characterized by fast tempos, virtuosic technique and advanced harmonies. Parker was a blazingly fast virtuoso, and he introduced revolutionary harmonic ideas including rapid passing chords, new variants of altered chords, and chord substitutions. His tone ranged from clean and penetrating to sweet and somber.

Parker died on March 12, 1955, in the suite of his friend and patroness Baroness Pannonica de Koenigswarter at the Stanhope Hotel in New York City, while watching The Dorsey Brothers' Stage Show on television. The official causes of death were lobar pneumonia and a bleeding ulcer, but Parker also had an advanced case of cirrhosis and had suffered a heart attack. The coroner who performed his autopsy mistakenly estimated Parker's 34-year-old body to be between 50 and 60 years of age.  Since 1950, Parker had been living with Chan Berg, the mother of his son Baird (who lived until 2014) and his daughter Pree (who died as an infant of cystic fibrosis). He considered Chan his wife although he never married her, nor did he divorce his previous wife, Doris, whom he had married in 1948. His marital status complicated the settling of Parker's estate and would ultimately serve to frustrate his wish to be quietly interred in New York City.  Dizzy Gillespie paid for the funeral arrangements and organized a lying-in-state, a Harlem procession officiated by Congressman and Reverend Adam Clayton Powell, Jr., as well as a memorial concert. Parker's body was flown back to Missouri, in accordance with his mother's wishes. Berg criticized Doris and Parker's family for giving him a Christian funeral, even though they knew he was a confirmed atheist. Parker was buried at Lincoln Cemetery in Missouri, in a hamlet known as Blue Summit, located close to I-435 and East Truman Road.  Parker's estate is managed by Jampol Artist Management.

Using a quote from the above article, answer the following question: What caused his death?
The official causes of death were lobar pneumonia and