Demi, Jerry and the battle of the A-list art sales

The pair are offloading their paintings, but whose will prove to be worth the most?

The female subject has an affectionate smile and a loving gaze. She is infatuated with a much younger man, whom she holds adoringly. But this isn't a self-composed photograph posted on Twitter of Hollywood actress Demi Moore and toyboy husband Ashton Kutcher. It's part of Moore's art collection. And she's bored with it.

Until now, William Bouguereau's Frere et Soeur, a typically sentimental 19th-century painting of a young woman hoisting up her baby brother, has been one of the most treasured adornments in Moore's ostentatious 1950s pad in the Hollywood Hills.

But Moore and Kutcher now hope to renovate their house, and the traditional nature of Bouguereau's work no longer fits their style. Most people overhauling their home would have a car-boot sale. When Moore auctions the Bouguereau, and another 19th-century work by the Belgian painter Alfred Stevens at Sotheby's New York on 4 November, she hopes to raise $1.7m (£1.1m).

"I have owned these paintings, both the Bouguereau and Stevens, for 15 years and although I adore them, with the renovation and new direction our home is taking, it is time for a change," said Moore in a statement. "I am excited for a new owner to be able to share in the joy these paintings have brought us."

Moore is not the only A-list collector dispensing with their artwork. In an auction at Sotheby's in London tomorrow and Saturday, Jerry Hall is expected to raise at least £1.5m by selling key pieces from her own artistic treasure trove. Among the works are a Frank Auerbach oil painting, Andy Warhol's 1981 Dollar Sign and three portraits of Hall by Ed Ruscha, Francesco Clemente and Lucian Freud.

The Freud portrait shows Hall while eight months pregnant with her now 12-year-old son, Gabriel. Hall was quoted last month as saying that she was "horrified" to learn Freud had painted over her face and upper body in a separate portrait of her breastfeeding Gabriel, after she was unable to complete her sittings because of illness.

Despite Moore's justifications for the sale, the reality might be that she is simply cashing in on an increasingly buoyant art market and a rising appreciation of Bouguereau's work. Moore bought the Bouguereau and the Stevens for $178,500 (£112,400) and $200,500 (£126,300) respectively at a Christie's auction in 1995.

While Bouguereau was popular during his day, critics have increasingly sneered at his fussy, sentimental tributes to the female form. However the past 30 years have seen an increase in his reputation, and prices have followed suit.

Melanie Gerlis, art market editor at The Art Newspaper, said: "There are a number of intangibles involved in pricing such work but you could say that a painting's history of ownership can increase its value. Three years ago Hugh Grant famously made a £9m profit on an Andy Warhol, which was a much higher gain than if anyone else had tried the same thing. It's all about adding to the excitement and sex appeal of a sale.

"I am sure this is opportunistic. We are living in times where even Demi Moore could need to realise some cash, and selling her art is a good way of doing that."

Moore, though, hopes purchasers will appreciate her paintings for more than just their monetary value or celebrity cachet. "I love [Bouguereau's] combination of mythological themes, classical subjects and his photo realistic style," she said.

"There is a gentleness, a serenity, particularly in his depiction of women, combined with incredible strength that has inspired me."

Stars and their collections

Jeffrey Archer Archer raised about £20m from the 1998 sale of works by Andy Warhol.

Rod Stewart In 2001, the rocker sold a Victorian oil by Henry Nelson O'Neil for an undisclosed sum at Sotheby's.

Jimmy Page Two years ago the former Led Zeppelin guitarist sold a tapestry and five stained-glass windows by Sir Edward Burne-Jones.

Andrew Lloyd Webber The Andrew Lloyd Webber Art Foundation's Picasso portrait of Angel Fernández de Soto raised almost £35m at auction earlier this year.