Simulation of the Earth's paleo-magnetosphere for the late Hadean eon

Autor(en)

Manuel Scherf, Maxim L. Khodachenko, Marina Blokhina, Colin Johnstone, Igor Alexeev, Manuel Güdel

Abstrakt

Simulations of the Earth's magnetosphere obstacle, including the shape of the auroral oval and related field lines for early stages of the solar system are of particular importance for studying the evolution and mass loss of the Earth's atmosphere. Within this presentation, we will present simulations of the terrestrial paleo-magnetosphere of the Earth for the late Hadean, i.e. for ~4.1 billion years ago. These were performed with an adapted version of the Paraboloid Magnetospheric Model (PMM) of the Skobeltsyn Institute for Nuclear Physics of the Moscow State University, which serves as an ISO standard for the Earth's magnetosphere (see e.g. Alexeev et al., 2003). As an input parameter, the new measurements of the paleomagnetic field strength by Tarduno et al., 2015, are taken. These data from zircons between 3.3 billion and 4.2 billion years old vary between 1.0 and 0.12 of today's equatorial field strength. Available data at ~4.1 billion years ago are among the lowest field strength values. Another input into the adapted PMM is the solar wind pressure, which was derived from a newly developed solar/stellar wind evolution model (Johnston et al., 2015a, b), which is strongly dependent on the rotation rate of the early Sun. Our simulations of the terrestrial paleo-magnetosphere with the adapted PMM show that for the most extreme case of a fast rotating Sun and a paleomagnetic field strength with 0.12 of today's value, the stand-off distance of the magnetopause Rs shrinks down from today's 10 Re to 3.43 Re. Even for a slow rotating Sun Rs would be at only 4.27 Re. Taking the same magnetic field strength as that of today and a slow rotating Sun leads to an Rs of 8.23 Re, which would be the least extreme case for the terrestrial atmosphere. Another outcome of the modelling is that the auroral oval was significantly broader ~4.1 billion years ago than today. As demonstrated by our calculations a good approach of the relationship between auroral oval size Θpc (Θpc as oval co-latitude) and magnetospheric subsolar distance Rs is sin2Θpc = Re/Rs. Acknowledgments. The authors acknowledge the support of the FWF NFN project S116-N16 "Pathways to Habitability", in particular the related subproject S11606-N16 "Magnetospheric electrodynamics of exoplanets". This publication is supported by the Austrian Science Fund (FWF). References: Alexeev, I. I., Belenkaya, E. S., Bobrovnikov, S. Y., and Kalegaev, V. V. (2003), Modelling of the electromagnetic field in the interplanetary space and in the Earth's magnetosphere, Space Sci. Rev., 107, 7-26. Johnstone, C.P., Güdel, M., Lüftinger, T., Toth, G., and Brott, I. (2015), Stellar winds on the main-sequence: I. Wind model, Astron. Astrophys., 577, id.A28. Johnstone, C.P., Güdel, M., Brott, I., and Lüftinger, T. (2015), Stellar winds on the main-sequence: II. The evolution of rotation and winds, Astron. Astrophys., 577, id.A27. Tarduno, J. A., Cottrell, R. D., Davis, W. J., Nimmo, F., and Bono, R. K. (2015), A Hadean to Paleoarchean geodynamo recorded by single zircon crystals, Science, 349, 521-524.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Österreichische Akademie der Wissenschaften (ÖAW), Lomonosov Moscow State University (MSU)

Seiten

8822

Anzahl der Seiten

1

Publikationsdatum

04-2016

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/simulation-of-the-earths-paleomagnetosphere-for-the-late-hadean-eon(5274a80b-36cb-4571-b35f-20c3f5cb456e).html