14 DAY TRIAL // Dr. Falk Herwig, of the Department of Physics and Astronomy at the University of Victoria, BC Canada, used swirling computer simulations which are reminiscent of Van Gogh's star paintings, to show the interior of a star during the Asymptotic Giant Branch (AGB) phase, the final stage of a low- and intermediate-mass star's life before it becomes a white dwarf. It is during this phase that many of the heavier elements, such as carbon and sodium, are created inside the stars.
The results contradict previous beliefs that the interiors of stars are uni-dimensional. Herwig's study, which appears in a Royal Astronomical Society publication, shows stunning simulations that give a multi-dimensional space glimpse into the interior of stars.
Herwig claims the swirling simulations are reminiscent of Van Gogh's star paintings, and show the interior of a star during the Asymptotic Giant Branch (AGB) phase, the final stage of a low- and intermediate - mass star's life before it becomes a white dwarf.
It is during this phase that many of the heavier elements, such as carbon and sodium, are created inside the stars, Herwig adds.
The core of the star is surrounded by shells of helium and hydrogen, in which nuclear fusion periodically switches off and on in a process called Helium-Shell Flashes, triggering increased bursts of mixing and heating.
Helium-Shell Flash convections are dominated by large convective cells that are centered in the lower half of the convection zone. The animations show entropy or temperature fluctuations which start off as small bumps at the bottom of the convection zone and expand upwards, developing mushroom-like instabilities that merge into large-scale features. The stable regions above and below are filled with horizontal waves, which are induced almost as soon as the convection plumes start to grow. This means that the gravity waves are not created by the plumes actually hitting the boundaries, but are induced by the build-up of pressure above the plumes.
"Until recently we've only had one-dimensional models of the interior. That's very different from being able to work out in detail and two or three dimensions what's going on deep inside and seeing how the different layers interact," Herwig says. "This is the first time that we've been able to see and actually measure the internal gravity waves that are caused by the convective motions in the unstable layer."