The terrestrial paleo-magnetosphere and its implications on the origin and evolution of the nitrogen-dominated atmosphere

Autor(en)

Manuel Scherf, Maxim Khodachenko, Helmut Lammer, Igor Alexeev, Colin Johnstone, Manuel Guedel, Lin Tu, Marina Blokhina, John Tarduno, Herbert Lichtenegger, Yuri Kulikov

Abstrakt

The present-day terrestrial atmosphere, as dominated by the volatile elements nitrogen and oxygen, is providing a habitable environment for a diverse range of life forms. However, simulations of the terrestrial paleo-magnetosphere as well as of the solar wind induced atmospheric ion-pickup escape ˜4 Gyr ago (see e.g. [1]) are indicating that during the harsh conditions of the Hadean and early Archean eons a nitrogen dominated atmosphere would not have been able to survive, but would have been eroded within a few million years due to the high EUV flux and the strong solar wind of the early Sun [2][3]. In addition, these results are suggesting that the present-day nitrogen-dominated atmosphere has its origin during later stages of the geological history of the Earth, whereas for the late Hadean and early Archean, CO2 can be considered as the dominating atmospheric constituent. However, the small ¹⁴N/¹⁵N isotope disequilibrium between internal and surface reservoirs at the Earth [4] is indicating that some atmospheric escape of nitrogen should have taken place in the past. This escape, as well as the overall historical composition of the atmosphere are strongly coupled to the shape of the paleo-magnetosphere and to its interplay with the varying solar activity factors. We will present simulations of the terrestrial paleo-magnetosphere during the late Hadean and Archean eons and its influence on the evolution of the terrestrial nitrogen atmosphere. This also includes an estimation of nitrogen lost to space based on the observed terrestrial ¹⁴N/¹⁵N fractionation. Our results support the idea that the nitrogen dominated atmosphere started to build up during the Archean eon and slowly evolved from a low-pressure atmosphere via outgassing of N₂ into the present-day habitable environment. Important environmental conditions for this evolution and its interconnections will be discussed within this presentation. This also includes a potential solution for the before mentioned ¹⁴^N/¹⁵N disequilibrium. {Acknowledgement.} The authors acknowledge the support of the FWF NFN project Pathways to ``Habitability: From Disks to Active Stars, Planets and Life", in particular its related sub-projects S11604-N16, S11606-N16 and S11607-N16. This publication is supported by the Austrian Science Fund (FWF) and the 550 US NSF (EAR1015269 to JAT). {References:} [1] Lichtenegger, H. et al., Icarus, 210, 1-7, 2010. [2] Tu, L. et al., Astron. Astrophys, 577, L3, 2015. [3] Johnstone, C. et al., Astron. Astrophys. 577, A28, 2015. [4] Cartigny, P. & Marty, B., Elements, 9, 359-366, 2013.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Österreichische Akademie der Wissenschaften (ÖAW), Lomonosov Moscow State University (MSU), University of Rochester, Russian Academy of Sciences

Band

20

Seiten

16210

Publikationsdatum

04-2018

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/e73b554c-2c22-4f1e-9b23-2fb77eba480b