On the importance of ices more volatile than H2O-ice for cometary activity

• Applicant: Professor Dr. Bastian Gundlach
• Subject Area: Astrophysics and Astronomy
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274998229

When comets approach the Sun, the solar radiation leads to the sublimation of the volatile components. Together with the activity of the ices, dust particles are released from the surface of the nucleus. However, the mechanism of how the dust is released from the cometary surface is not understood. The outgassing of H2O-ice can only explain the dust activity of comets at heliocentric distances smaller than 2 AU. At larger heliocentric distances, a more volatile material than H2O-ice is required to explain the presence of the dust tails and the comae of comets. Observations of comets and theoretical models suggest that CO-ice and CO2-ice are the drivers for cometary dust activity at large heliocentric distances. However, modeling cometary activity suffers from the fact that too many model parameters are not or only barely known. Here, laboratory experiments can support the theoretical models by measuring the unknown parameters. However, laboratory experiments on the outgassing properties of CO-ice and CO2-ice are scarce. Thus, we propose to conduct experiments to measure the outgassing properties of CO2-ice (here, CO2-ice will serve as a proxy for any other material more volatile than H2O-ice) under cometary-like conditions. The obtained experimental data will then be used to improve existing theoretical models, which will then be applied to better understand the dust activity of comets.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Jürgen Blum