By Jake CoyleNEW YORK -- Star power and Oscar aspirations are reigning at the box office, where the space adventure Gravity and the Somali pirate docudrama Captain Phillips are holding off all comers. With $31 million over the weekend according to studio estimates Sunday, Gravity topped the box office for the third consecutive week, cementing its status as the juggernaut of the fall movie-going season. The 3-D Warner Bros. ( TWX) movie, staring Sandra Bullock and George Clooney, has now made more than $170 million in three weeks. The film's groundbreaking visuals have been particularly popular on IMAX screens, where it made an Avatar-like $7.4 million on the weekend. Captain Phillips, starring Tom Hanks and directed by Paul Greengrass, also held in second place, taking in $17.3 million in its second week. The Sony ( SNE) film slid only 33 percent from its debut last weekend of $25.7 million. The two movies and their veteran stars were able to keep three new wide releases at bay: the horror remake Carrie ($17 million for Sony and MGM), the Sylvester Stallone and Arnold Schwarzenegger action flick Escape Plan ($9.8 million for Lionsgate ( LGF)), and the WikiLeaks drama The Fifth Estate. The last utterly flopped -- a fate predicted by its subject, WikiLeaks founder Julian Assange -- taking in a paltry $1.7 million for Disney ( DIS). It's the worst debut this year for a film in such wide release (1,769 theaters). "It's a very strong lineup that is not budging," said Paul Dergarabedian, senior media analyst for box-office tracker Rentrak, who noted the primary family choice, Cloudy With a Chance of Meatballs 2, is also holding steady with $10.1 million in its fourth week. " Carrie came into a very competitive marketplace." In a limited release of just 19 theaters, Steven McQueen's highly-anticipated slavery epic 12 Years a Slave, starring Chiwetel Ejiofor, opened with $960,000. The exceptionally high theater average of $50,000 suggested considerable audience eagerness for the already much-lauded film.