14 DAY TRIAL // Planetary scientists at UCLA have discovered a new method of analyzing exactly how convection currents drive the movements of stars, planets, and pretty much everything in between. Convection refers to the heat transfer from one designated location to another, via the movement of gas, liquids, or even slow moving solids. For a long time, astrophysicists have been trying to determine the influence that the rotation of celestial bodies have on this process, and now they are finally able to do so. The details of the finds are provided in the January 15 edition of the journal Nature.
"The Nature paper allows us new and meaningful predictions for where we should observe different behaviors throughout the universe wherever there are rotating convection systems, and that means planets and stars. This allows us to make predictions for almost any body where we can measure the rotation rate and heat coming out. For me, that's exciting," UCLA associate professor of planetary physics Jonathan Aurnou, who is also the co-author of the study, says.
Earth and space sciences UCLA graduate student Eric King, the main author of the paper, states that, in the grand scheme of things, convection properties determine the movements of planetary cores and influences the magnetic fields or atmospheric influxes of planets. It also plays a major role in shaping heat flux patterns across planets, and is therefore of paramount importance to life on our planet.
In the research, the authors dispute previous established knowledge about convection, saying that the fluids' thermal (non-rotating) and the Ekman (rotating) boundary layers are the ones that determine the transition of heat between rotationally dominated and non-rotating convection systems. Previous theories held that the transfer was dominated by the Coriolis force and the non-rotational buoyancy force.
"Scientists have been arguing for decades that rotation should dominate all the convection, all the fluid dynamics on stars and planets, but nobody has systematically measured when this domination by the rotational Coriolis effects occur. When do the Coriolis effects take over? How does convection occur on a rotating body, such as a planet or star? All of these bodies are rotating; how does the rotation affect the convection? We actually went out and quantitatively measured when rotation controls the system," he explains. "We are asking, what is controlling the convection and how do you apply that to planets and stars?" Aurnou adds.
The device the team built, the RoMag, is the only such apparatus in the world, and can be used in the lab to measure convection forces in various liquids, by simply applying heat to the bottom of the machine. The heat transfers are then monitored, and a computer picks up and displays relevant data. "In building this device, we had to become electricians, plumbers, engineers, materials scientists," King concludes.