Question: When did the former Idol star who made an appearance for Cowell's tribute quit as a judge?

full_context: Document 1: American Idol: A special tribute to Simon Cowell was presented in the finale for his final season with the show. Many figures from the show's past, including Paula Abdul, made an appearance.
Document 2: American Idol: The fourteenth season premiered on January 7, 2015. Ryan Seacrest returned to host, while Jennifer Lopez, Keith Urban and Harry Connick, Jr. returned for their respective fourth, third and second seasons as judges. Eighth season runner-up Adam Lambert filled in for Urban during the New York City auditions. Randy Jackson did not return as the in-house mentor for this season.
Document 3: American Idol: The thirteenth season premiered on January 15, 2014, with Ryan Seacrest returning as host. Randy Jackson and Keith Urban returned, though Jackson moved from the judging panel to the role of in-mentor. Mariah Carey and Nicki Minaj left the panel after one season. Former judge Jennifer Lopez and former mentor Harry Connick, Jr. joined Urban on the panel. Also, Nigel Lythgoe and Ken Warwick were replaced as executive producers by Per Blankens, Jesse Ignjatovic and Evan Pragger. Bill DeRonde replaced Warwick as a director of the audition episodes, while Louis J. Horvitz replaced Gregg Gelfand as a director of the show.
Document 4: American Idol: Beginning in the tenth season[citation needed], permanent mentors were brought in during the live shows to help guide the contestants with their song choice and performance. Jimmy Iovine was the mentor in the tenth through twelfth seasons, former judge Randy Jackson was the mentor for the thirteenth season and Scott Borchetta was the mentor for the fourteenth and fifteenth season. The mentors regularly bring in guest mentors to aid them, including Akon, Alicia Keys, Lady Gaga, and current judge Harry Connick, Jr..
Document 5: American Idol: The final showdown was between Justin Guarini, one of the early favorites, and Kelly Clarkson. Clarkson was not initially thought of as a contender, but impressed the judges with some good performances in the final rounds, such as her performance of Aretha Franklin's "Natural Woman", and Betty Hutton's "Stuff Like That There", and eventually won the crown on September 4, 2002.
Document 6: American Idol: Towards the end of the season, Randy Jackson, the last remaining of the original judges, announced that he would no longer serve as a judge to pursue other business ventures. Both judges Mariah Carey and Nicki Minaj also decided to leave after one season to focus on their music careers.
Document 7: American Idol: The finals are broadcast in prime time from CBS Television City in Los Angeles, in front of a live studio audience. The finals lasted eight weeks in season one, eleven weeks in subsequent seasons until seasons ten and eleven which lasted twelve weeks except for season twelve, which lasted ten weeks, and season thirteen, which lasted for thirteen weeks. Each finalist performs songs based on a weekly theme which may be a musical genre such as Motown, disco, or big band, songs by artists such as Michael Jackson, Elvis Presley or The Beatles, or more general themes such as Billboard Number 1 hits or songs from the contestant's year of birth. Contestants usually work with a celebrity mentor related to the theme. In season ten, Jimmy Iovine was brought in as a mentor for the season. Initially the contestants sing one song each week, but this is increased to two songs from top four or five onwards, then three songs for the top two or three.
Document 8: American Idol: American Idol employs a panel of judges who critique the contestants' performances. The original judges were record producer and music manager Randy Jackson, pop singer and choreographer Paula Abdul and music executive and manager Simon Cowell. The judging panel for the most recent season consisted of country singer Keith Urban, singer and actress Jennifer Lopez, and jazz singer Harry Connick, Jr. The show was originally hosted by radio personality Ryan Seacrest and comedian Brian Dunkleman, with Seacrest continuing on for the rest of the seasons.
Document 9: American Idol: The show had originally planned on having four judges following the Pop Idol format; however, only three judges had been found by the time of the audition round in the first season, namely Randy Jackson, Paula Abdul and Simon Cowell. A fourth judge, radio DJ Stryker, was originally chosen but he dropped out citing "image concerns". In the second season, New York radio personality Angie Martinez had been hired as a fourth judge but withdrew only after a few days of auditions due to not being comfortable with giving out criticism. The show decided to continue with the three judges format until season eight. All three original judges stayed on the judging panel for eight seasons.
Document 10: American Idol: Season 12 premiered on January 16, 2013. Judges Jennifer Lopez and Steven Tyler left the show after two seasons. This season's judging panel consisted of Randy Jackson, along with Mariah Carey, Keith Urban and Nicki Minaj. This was the first season since season nine to have four judges on the panel. The pre-season buzz and the early episodes of the show were dominated by the feud between the judges Minaj and Carey after a video of their dispute was leaked to TMZ.
Document 11: American Idol: Season nine premiered on January 12, 2010. The upheaval at the judging panel continued. Ellen DeGeneres joined as a judge to replace Paula Abdul at the start of Hollywood Week.
Document 12: American Idol: Fox announced on May 11, 2015 that the fifteenth season would be the final season of American Idol; as such, the season is expected to have an additional focus on the program's alumni. Ryan Seacrest returns as host, with Harry Connick Jr., Keith Urban, and Jennifer Lopez all returning for their respective third, fourth, and fifth seasons as judges.
Document 13: American Idol: With the exception of seasons one and two, the contestants in the semifinals onwards perform in front of a studio audience. They perform with a full band in the finals. From season four to season nine, the American Idol band was led by Rickey Minor; from season ten onwards, Ray Chew. Assistance may also be given by vocal coaches and song arrangers, such as Michael Orland and Debra Byrd to contestants behind the scene. Starting with season seven, contestants may perform with a musical instrument from the Hollywood rounds onwards. In the first nine seasons, performances were usually aired live on Tuesday nights, followed by the results shows on Wednesdays in the United States and Canada, but moved to Wednesdays and Thursdays in season ten.
Document 14: American Idol: In season eight, Latin Grammy Award-nominated singer–songwriter and record producer Kara DioGuardi was added as a fourth judge. She stayed for two seasons and left the show before season ten. Paula Abdul left the show before season nine after failing to agree terms with the show producers. Emmy Award-winning talk show host Ellen DeGeneres replaced Paula Abdul for that season, but left after just one season. On January 11, 2010, Simon Cowell announced that he was leaving the show to pursue introducing the American version of his show The X Factor to the USA for 2011. Jennifer Lopez and Steven Tyler joined the judging panel in season ten, but both left after two seasons. They were replaced by three new judges, Mariah Carey, Nicki Minaj and Keith Urban, who joined Randy Jackson in season 12. However both Carey and Minaj left after one season, and Randy Jackson also announced that he would depart the show after twelve seasons as a judge but would return as a mentor. Urban is the only judge from season 12 to return in season 13. He was joined by previous judge Jennifer Lopez and former mentor Harry Connick, Jr.. Lopez, Urban and Connick, Jr. all returned as judges for the show's fourteenth and fifteenth seasons.
Document 15: American Idol: Guest judges may occasionally be introduced. In season two, guest judges such as Lionel Richie and Robin Gibb were used, and in season three Donna Summer, Quentin Tarantino and some of the mentors also joined as judges to critique the performances in the final rounds. Guest judges were used in the audition rounds for seasons four, six, nine, and fourteen such as Gene Simmons and LL Cool J in season four, Jewel and Olivia Newton-John in season six, Shania Twain in season eight, Neil Patrick Harris, Avril Lavigne and Katy Perry in season nine, and season eight runner-up, Adam Lambert, in season fourteen.
ground_truth: before season nine
sub_queries: Which former Idol star made an appearance for Cowell's tribute? Answer: Paula Abdul
When did Paula Abdul quit as a judge? Answer: before season nine