Spark global limited reports:
Vincent van Gogh’s “The Starry Night” captivated many viewers with its bold swirls of blue and yellow. James Beatty is no exception. Beatty, a student at the Australian National University in Canberra, studies the structure and dynamics of molecular clouds — the birthplace of stars — whose swirling swirls often remind him of the Dutch painting. He recently compared that similarity to tests with the help of Neco Kriel, a student at Queensland University of Technology in Australia. Using techniques used to analyze simulated molecular cloud patterns, the pair compared art and reality and found that both showed the same characteristics of turbulence. While it’s probably just a happy coincidence that Van Gogh’s sky contains patterns associated with stars, the presence of turbulent patterns is common in paintings, probably because of the abundance of turbulent phenomena in our daily lives.
Beatty and Krall are not the first to discover starry Night’s connection to the sky or explore patterns in its turbulent structure. In 2004, the Hubble Telescope captured images of an expanding halo around the star V838 Monocerotis, which a NASA press release described as a cosmic version of a Van Gogh painting. Then in 2008, Jose Luis Aragon of the National Autonomous University of Mexico and colleagues found signs of turbulence in “Starry Night” and other paintings by the same artist, including “Roads and Cypress Trees,” “Stars and Crows” and “Wheat Fields and Wheat Fields,” all with ominous storm backgrounds.
Aragon and his colleagues analyzed point-by-point changes in the brightness of the sky in “Starry Night.” They found that these statistics of brightness fluctuations seemed to conform to Andrei Kolmogorov’s predictions of subsonic turbulence, which drives convection in stars and atmospheric motion on Earth. But for more than a decade, the exact form of turbulence in the painting remained unconfirmed. “Our approach is an approximation, and a detailed power spectrum is critical to determining whether Starry Night is indeed turbulent,” Aragon says. That’s what he and his colleagues didn’t calculate. The new study addresses this shortcoming.
Beatty and Krall focused on the vortex at the center of “Starry Night,” using techniques they developed to analyze simulated images containing turbulence. They first selected a square area of the sky in a digital image of the painting, then created a 2D map with three different-colored “channels.” They then used Fourier analysis to calculate the painting’s two-dimensional power spectrum — a statistical breakdown of the image that provides the main length scale of the structure. In contrast to Aragon, the team found that these structures have the same scaling behavior as supersonic turbulence, the type of turbulence observed in clouds of molecular gas. Beatty says this quantitative match is “very exciting” because it explains why the maelstrom that appears to “feed” or “drive” smaller eddies in “Starry Night” is similar in nature to the eddies found in turbulent clouds.