Formation and Evolution of Protoatmospheres

Autor(en)

H. Massol, K. Hamano, F. Tian, M. Ikoma, Y. Abe, Manuel Güdel, Alexander Stökl

Abstrakt

The origin and evolution of planetary protoatmospheres in relation to the protoplanetary disk is discussed. The initial atmospheres of planets can mainly be related via two formation scenarios. If a protoplanetary core accretes mass and grows inside the gas disk, it can capture H2, He and other gases from the disk. When the gas of the disk evaporates, the core that is surrounded by the H2/He gas envelope is exposed to the high X-ray and extreme ultraviolet flux and stellar wind of the young host star. This period can be considered as the onset of atmospheric escape. It is shown that lower mass bodies accrete less gas and depending on the host stars radiation environment can therefore lose the gaseous envelope after tens or hundreds of million years. Massive cores may never get rid of their captured hydrogen envelopes and remain as sub-Neptunes, Neptunes or gas giants for their whole life time. Terrestrial planets which may have lost the captured gas envelope by thermal atmospheric escape, or which accreted after the protoplanetary nebula vanished will produce catastrophically outgassed steam atmospheres during the magma ocean solidification process. These steam atmospheres consist mainly of water and CO2 that was incorporated into the protoplanet during its accretion. Planets, which are formed in the habitable zone, solidify within several million years. In such cases the outgassed steam atmospheres cool fast, which leads to the condensation of water and the formation of liquid oceans. On the other hand, magma oceans are sustained for longer if planets form inside a critical distance, even if they outgassed a larger initial amount of water. In such cases the steam atmosphere could remain 100 million years or for even longer. Hydrodynamic atmospheric escape will then desiccate these planets during the slow solidification process.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Centre National De La Recherche Scientifique (CNRS), University of Tokyo, Tokyo Institute of Technology (TIT), Chinese Academy of Sciences (CAS)

Journal

Space Science Reviews

Band

205

Seiten

153 - 211

Anzahl der Seiten

59

ISSN

0038-6308

DOI

https://doi.org/10.1007/s11214-016-0280-1

Publikationsdatum

12-2016

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/0e0f7e43-b6ff-40ac-b18a-4e773bfb9964