A long-lost photo of Abraham Lincoln is uncovered in ‘The Lost Lincoln,’ Mariah Carey releases her new memoir and more of this week’s best in pop culture

“Undiscovered: The Lost Lincoln” investigates a newly discovered photo of former president Abraham Lincoln on his deathbed. “The Lost Lincoln” is the first installment in Discovery’s new documentary series “Undiscovered,” which looks into some of the mysteries of our time. Could this photograph be the 131st and final image of Lincoln? “The Lost Lincoln” premieres Sunday, Oct. 4 at 9 p.m. on Discovery. Mariah Carey releases her new memoir, “The Meaning of Mariah Carey.” The singer shares intimate stories about her life, growing up biracial, and some of the high-profile relationships she’s had. Mimi reveals her time with Derek Jeter was "beautiful" and served as a "catalyst" to end her marriage to Tommy Mottola. "The Meaning of Mariah Carey" arrives at bookstores, including Amazon, Tuesday, Sept. 29. Check out the video above for more of “The It List,” Yahoo’s weekly look at the best in pop culture.