Oppenheimer stars Cillian Murphy, Emily Blunt and Robert Downey Jr. look delighted as they attend 96th Oscars Nominees Luncheon in Beverly Hills

Oppenheimer stars Cillian Murphy, Emily Blunt and Robert Downey Jr. looked thrilled as they attended the 96th Oscars nominees luncheon in Beverly Hills on Monday.

The stars – whose blockbuster historical epic has racked up 13 nominations at the upcoming ceremony on March 10 – joined director Christopher Nolan, 53, and his producer wife Emma Thomas, 52, at the glittering event.

Best Actor nominee Cillian, 47, who plays J.Robert Oppenheimer, looked dapper in a white shirt and maroon suit.

Best Supporting Actress nominee Emily, 40, who plays Kitty Oppenheimer, was chic in a purple satin two-piece with her blonde locks styled in soft waves.

Best Supporting Actor nominee Robert, 58, who plays Admiral Lewis Strauss, looked sharp in a pinstripe suit and tan shirt paired with sneakers.

It comes after Cillian revealed how he felt about playing J. Robert Oppenheimer in his Oscar-nominated film.

The Irish actor attended a screening of the Christopher Nolan biopic at the BFI IMAX Waterloo on Wednesday, where he discussed the research surrounding his role as a theoretical physicist considered the “father of the atomic bomb.”

Asked about the biggest lesson he took from his work on the film, Cillian replied thoughtfully: “The most important thing I learned or relied on was that he was human, that was the most important thing I wanted to access: his humanity .’

The incredible physical transformation Cillian underwent for the role was revealed by his co-star Emily Blunt, who plays Oppenheimer’s wife Kitty.

Emily remembered how Cillian ate just an ‘almond a day’ and became “so emaciated” while immersing himself in the project.

Speaking to Extra last year, Emily explained: ‘He had such a monumental business’

Cillian herself told The New York Times: ‘I love acting with my body, and Oppenheimer had a very distinct physicality and silhouette that I wanted to get right.

‘I had to lose quite a bit of weight and we started working on the costume and tailoring; he was very slim, almost emaciated, lived on martinis and cigarettes.’

The stars – whose blockbuster historical epic has racked up 13 nominations at the upcoming ceremony on March 10 – joined director Christopher Nolan, 53, and his producer wife Emma Thomas, 52, at the glittering event

Best Actor nominee Cillian, 47, who plays J.Robert Oppenheimer, is the favorite to win

The group looked cheerful as they hit the red carpet

Cillian looked smart at the event in a white shirt and maroon suit

Nominated for Best Supporting Actor Robert, 58, who plays Admiral Lewis Strauss, looked sharp in a pinstripe suit and tan shirt paired with sneakers

Director Christopher Nolan and his wife, producer Emma Thomas, were in attendance

Emily can be seen as Kitty Oppenheimer in the film with Cillian

Robert is seen in the film as Lewis Strauss

The annual Oscar class photo, taken during Monday’s Oscar nominees luncheon at the Beverly Hilton

But Cillian made it clear that his extreme diet was not safe and should not be tried by other people. “You get a little competitive with yourself, which is not healthy,” he said, adding, “I don’t recommend it.”

The film’s breakneck pace helped Murphy achieve his weight loss goal.

‘It’s like being on a damn train that’s just bombing. It’s boom, boom, boom, boom. You sleep for a few hours, get up and bang again,” he told The Guardian.

“I was running on crazy energy; I crossed a threshold where I stopped worrying about food or anything. I was in that state of hyper…something,” he explained.

“But it was good because the character was like that. He never ate.’

Cillian continued his streak of nominations as he received a Best Actor nod for his titular role in Oppenheimer.

He is currently the bookmakers’ frontrunner to win the award and will compete against Bradley Cooper – Maestro; Colman Domingo – Rustin; Paul Giamatti – The Holdovers and Jeffrey Wright – American fiction.