Planetesimal Formation at High Temperatures
Final Report Abstract
Sticking properties in protoplanetary disks change with varying temperatures. In this project, we studied the influence of high temperatures. Chondritic dust was heated under different ambient conditions of oxidizing and reducing atmospheres up to 1400 K. Mössbauer spectroscopy traced various changes in the composition which alter the effective surface energy deduced from tensile strength measurements systematically by a small factor. The removal of all but a monolayer of water from the grain surfaces increases the sticking forces by a factor of 10. At higher temperatures an increase in sticking forces by another factor 100 can be attributed to all water being removed, eventually. This implies a change in aggregation and a sweet spot for planetesimal formation in the range roughly between 1000K and 1200K. In addition, iron is reduced to metallic iron at high temperatures in a H2-gas surrounding. Within the magnetic field of the protoplanetary disk, this adds another alteration in sticking properties, i.e., allowing magnetic aggregation outside of the Curie-line, which also supports planetesimal formation but with a bias in favor of the formation of Mercury-like planets.
Publications
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Drifting inwards in protoplanetary discs I Sticking of chondritic dust at increasing temperatures. Astronomy & Astrophysics, 638, A151.
Bogdan, T.; Pillich, C.; Landers, J.; Wende, H. & Wurm, G.
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Planetesimals in rarefied gas: wind erosion in slip flow. Monthly Notices of the Royal Astronomical Society, 493(4), 5456-5463.
Demirci, Tunahan; Schneider, Niclas; Steinpilz, Tobias; Bogdan, Tabea; Teiser, Jens & Wurm, Gerhard
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Drifting inwards in protoplanetary discs. Astronomy & Astrophysics, 652, A106.
Pillich, C.; Bogdan, T.; Landers, J.; Wurm, G. & Wende, H.
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The Curie line in protoplanetary disks and the formation of Mercury-like planets. Astronomy & Astrophysics, 670, A6.
Bogdan, T.; Pillich, C.; Landers, J.; Wende, H. & Wurm, G.
