Constraining planetesimal-formation models by comet observations
Final Report Abstract
The pathway from the dust of the solar nebula and protoplanetary disks to today's Solar System and especially to comets is still not fully understood. This project aimed to contribute to the scientific discussion about comet formation and shed light on the remaining open questions. Therefore, the current understanding of early Solar System formation is reviewed and the current most plausible formation scenario for planetesimals is presented. The possible evolutionary pathways are discussed, including radiogenic heating and collisional evolution, resulting in five possible small body outcomes. The expected physical properties of these bodies are summarized and compared to observations of comets. However, multiple pathways for the formation of comets are still plausible. To investigate the usability of the surface temperature and activity of comets to constrain the formation and evolution pathways, a thermophysical model was developed. We studied whether the surface temperature can be used to distinguish between different surface structures. We used a macro- and a micro-porous surface structure, which are implemented by their different temperature dependencies of the heat transport. A method was developed to distinguish between these two surface structures based on the observation of surface temperatures at sunrise for varying noontime solar irradiation. We further developed the thermophysical model to account for cometary activity by implementing the sublimation of ices and the ejection of dust. By investigating how several modelling approaches affect the results, we find that CO2-driven activity always results into a mismatch to observations. Only artificial H2O-driven activity produces outgassing ratios in the right order and only with reduced diffusivity the model shows a comparable steep slope of outgassing versus heliocentric distance. However, the absolute outgassing rates of H2O are always underestimated, whereas the dust production is always overestimated. This work demonstrates the need for more complex modeling to accurately determine how cometary activity works and use it for constraining formation and evolution of comets. In a one-week workshop, we discussed the current state of the art in most relevant aspects of comet formation and evolution, as well as observation and lab work with experts of these fields and summarized open questions.
Publications
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Talk at Europlanet Science Congress, 21 September – 9 October 2020, online: Thermophysical modelling of small bodies: influence of the radiative thermal conductivity, Vol.14
D. Bischoff, B. Gundlach & J. Blum
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A method to distinguish between micro- and macro-granular surfaces of small Solar system bodies. Monthly Notices of the Royal Astronomical Society, 508(4), 4705-4721.
Bischoff, D.; Gundlach, B. & Blum, J.
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Invited Early Career Talk at 24th Meeting of the NASA Small Bodies Assessment Group, 26-27 January 2021, online: A Method to Distinguish Between Granular and Consolidated Surfaces of Small Solar System Bodies
D. Bischoff, B. Gundlach & J. Blum
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Talk at Rosetta Dust Workshop, Online, 1-3 November 2021: Thermophysical Modelling: Constraining the Surface Structure from Remote Measurements
D. Bischoff, B. Gundlach & J. Blum
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Formation of Comets. Universe, 8(7), 381.
Blum, Jürgen; Bischoff, Dorothea & Gundlach, Bastian
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Sub-mm/mm optical properties of real protoplanetary matter derived from Rosetta/MIRO observations of comet 67P. Monthly Notices of the Royal Astronomical Society, 519(1), 641-665.
Bürger, Johanna; Glißmann, Thilo; Lethuillier, Anthony; Bischoff, Dorothea; Gundlach, Bastian; Mutschke, Harald; Höfer, Sonja; Wolf, Sebastian & Blum, Jürgen
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Talk at Comet Formation Workshop, Braunschweig, 7 - 10 June 2022: Thermophysical Modelling of Cometary Surface and Activity
D. Bischoff, B. Gundlach & J. Blum
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Talk at Europlanet Science Congress, 18 – 23 September 2022, Granada: The formation and evolution of planetesimals towards comets – an overview, Vol. 16
D. Bischoff, B. Gundlach & J. Blum
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A quantitative description of comet 67P’s dust and gas production remains enigmatic. Monthly Notices of the Royal Astronomical Society, 523(4), 5171-5186.
Bischoff, D.; Schuckart, C.; Attree, N.; Gundlach, B. & Blum, J.
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Micrometre-sized ice particles for planetary science experiments – CoPhyLab cryogenic granular sample production and storage. RAS Techniques and Instruments, 2(1), 686-694.
Kreuzig, C.; Bischoff, D.; Molinski, N. S.; Brecher, J. N.; Kovalev, A.; Meier, G.; Oesert, J.; Gorb, S. N.; Gundlach, B. & Blum, J.
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Talk at Meeting of ISSI Team Understanding the Activity of Comets Through 67P’s Dynamics, 6-10 February 2023, Bern and online: A quantitative description of cometary dust and gas production remains enigmatic
D. Bischoff, C. Schuckart, N. Attree, B. Gundlach & J. Blum
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Talk at Rosetta Dust Workshop, Paris, 7-10 March 2023, Paris: Thermophysical Modelling of Cometary Activity
D. Bischoff, C. Schuckart, N. Attree, B. Gundlach & J. Blum
