photophoretic motion of chondrules (CHONDRULE)

abstract

Asteriods, comets and terrestrial planets form from small particles in protoplanetary disks. These particles are embedded in gaseous environment and exposed to stellar light and infrared radiation from the disk during the different stages of planet formation. Due to interaction with gas and radiation particles are subject to photophoretic forces which leads to particle transport. Such particle transport is e.g. evident from studies of meteorites. Photophoresis as transport mechanism might explain why high temperature minerals formed close to the early sun are embedded in comets supposed to be be formed far out, why chondrules (meteorite particles) are size sorted and why other meteorite components (CAIs) survived for millions of years.

Photophoresis depends on various particle properties, i.e. optical and thermal properties or size and shape. During a first campaign (CHONDRULE) at the Drop Tower in Bremen the photophoretic force was measured for mm-size particles. While these experiments were pioneering and highly successful (Wurm et al., Icarus, 2010), the number of experiments and the accuracy was not yet sufficient to analyze the influence of the detailed particle properties.

We propose to the experimental setup and measure the photophoretic motion with higher accuracy. The experiments will complement laboratory experiments, e.g. the measurements of temperature distributions on illuminated particles with high spatial accuracy, the 3d tomographic analysis of the particle's interior structure and a detailed mineralogical analysis of particle sectionss.The actual measurements of the photophoretic force is only achievable under microgravity conditions.

• G. Wurm, O. Krauss, Concentration and Sorting of Chondrules and CAIs in the Late Solar Nebula. Icarus, 180, 487-495, 2006

• J. Teiser, G. Wurm, Decimetre Dust Aggregates in Protoplanetary Discs, Astronomy and Astrophysics, 505, 351-359, 2009

• G. Wurm, H. Haack, Outward Transport of CAIs during FU-Orionis Events, Meteoritics and Planetary Science, 44, 689-699, 2009

• G. Wurm, J. Teiser, A. Bischoff, H. Haack, J. Roszjar, Experiments on the Photophoretic Motion of Chondrules and Dust Aggregates - Indications for the Transport of Matter in Protoplanetary Disks, Icarus, 208 482-491, 2010

experiment year: 2012
number of catapult flights: 18

experiment year: 2011
number of catapult flights: 16

experiment year: 2010
number of catapult flights: 16

experiment year: 2008
number of catapult flights: 16