Nicole Kidman and Constantin Brancusi —now that’s an unexpected pair. The award-winning actor appears in a new Christie’s ad promoting the upcoming auction of a sculpture by Brancusi from the late media mogul S.I. Newhouse ‘s collection. Titled Danaïde (1913), the bronze head will be offered for sale with the potentially record-setting estimate of $100 million on May 18 in New York. Newhouse bought it for $18.2 million in 2002, the highest price for a sculpture at the time.  Christie’s released the ad yesterday on its website, YouTube channel, and Instagram. The nearly two-minute film opens with the actor striding into the auction house’s Rockefeller Center headquarters in a pair of Louboutin stilettos and taking the elevator to a private viewing room where Danaïde awaits on a pedestal behind a wall of white curtains.   Nicole Kidman with Constantin Brancusi’s Danaïde (ca. 1913). Photo: Hunter Abrams, courtesy of Christie’s. Once inside, she interacts with the work from a respectful distance.…