French Impressionist painter Edgar Degas, c. 1895.Wikimedia Commons

NEWS BRIEF Scientists uncovered a hidden figure within French Impressionist painter Edgar Degas’ 140-year-old painting “Portrait of a Woman,” solving a mystery that has puzzled art critics for decades.

The mystery figure was first revealed in a Scientific Reports study Thursday, which detailed the process through which Australian scientists, in coordination with the National Gallery of Victoria in Melbourne, used a high definition x-ray beam to scan the portrait and reveal Degas’ original composition. The non-invasive technique, which uses a particle accelerator known as a synchrotron, allows scientists to study the evolution of a portrait’s making.

Though art critics have been aware of the existence of a mystery figure in the Degas portrait—whose outline became increasingly apparent as the portrait aged—since the 1920s, the concealed figure was never identifiable. After unearthing the original image, researchers now believe the hidden face to be Emma Dobigny, one of the artist’s favorite models.

The scientists said they were surprised by the quality and detail of the images revealed through the x-ray technique, which has the potential to reveal other artistic mysteries. As the report states:

This study has successfully demonstrated a virtual reconstruction of a hidden portrait by Edgar Degas and has delivered a better understanding of his work and artistic practices. The authors propose that the unfolding technological developments for examining artwork using synchrotron radiation-based techniques will significantly impact the ways cultural heritage is studied for authentication, preservation and scholarly purposes.

It was not uncommon for artists in Degas’ time to paint over previous pieces, and synchrotron techniques have enabled scientists to reconstruct these concealed works of art. In 2008, scientists used the technique to uncover the image of a peasant woman in Vincent van Gogh’s 1887 “Patch of Grass.”

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