Dust Ejection from Planetary Bodies by Temperature Gradients: Laboratory Experiments

Abstract

Laboratory experiments show that dusty bodies in a gaseous environment eject dust particles if they are illuminated. We find that even more intense dust eruptions occur when the light source is turned off. We attribute this to a compression of gas by thermal creep in response to the changing temperature gradients in the top dust layers. The effect is studied at a light flux of 13 kW/(m*m) and 1 mbar ambient pressure. The effect is applicable to protoplanetary disks and Mars. In the inner part of protoplanetary disks, planetesimals can be eroded especially at the terminator of a rotating body. This leads to the production of dust which can then be transported towards the disk edges or the outer disk regions. The generated dust might constitute a significant fraction of the warm dust observed in extrasolar protoplanetary disks. We estimate erosion rates of about 1 kg/s for 100 m parent bodies. The dust might also contribute to subsequent planetary growth in different locations or on existing protoplanets which are large enough not to be susceptible to particle loss by light induced ejection. Due to the ejections, planetesimals and smaller bodies will be accelerated or decelerated and drift outward or inward, respectively. The effect might also explain the entrainment of dust in dust devils on Mars, especially at high altitudes where gas drag alone might not be sufficient.

7 pages, 10 figures

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• Thermal creep assisted dust lifting on Mars: Wind tunnel experiments for the entrainment threshold velocity
• An Insolation Activated Dust Layer on Mars
• A Mechanism to Produce the Small Dust Observed in Protoplanetary Disks
• Amplification of dust loading in Martian dust devils by self-shadowing
• Analog Experiments on Tensile Strength of Dusty and Cometary Matter
• Thermal Creep on Mars: Visualizing a Soil Layer under Tension
• Ice Particles Trapped by Temperature Gradients at mbar Pressure