What does Harvard professor Henry Louis Gates Jr. have in common with explorer Amerigo Vespucci , poet Allen Ginsberg , and actress Mary Pickford ? They’re all new on the wall at the National Portrait Gallery in D.C. In an e-mail to friends and supporters, Gates called the unveiling of his portrait “one of the most exciting moments of my life.” (Gates could not be reached Monday.) The oil painting, done by artist Yuqi Wang , shows Gates standing beside a table with an African sculpture and books by W. E. B. Du Bois , Wole Soyinka , and Kwame Anthony Appiah on it. “The perfect portrait for the National Portrait Gallery is one that combines a nationally significant subject and the work of an exceptional artist,” Brandon Fortune, the Portrait Gallery’s chief curator, told us Monday. She said the painting was commissioned by Harvard and then offered to the Portrait Gallery. “It’s a long, drawn out process when we consider a portrait of someone who has not previously been in our collection,” Fortune said. One of the nation’s preeminent African-American scholars, Gates, you’ll recall, made headlines a few years ago when he was arrested by Cambridge police investigating a possible break-in at the professor’s Ware Street home near Harvard Square. Gates and the arresting officer, Sergeant James Crowley , later joined President Obama and Vice President Biden at the White House for what became known as the “Beer Summit.” The Gates portrait will be on display at the National Portrait Gallery until November, when it will join the 20,000 paintings, photos, and sculptures in the permanent collection.