Issue |
A&A
Volume 632, December 2019
|
|
---|---|---|
Article Number | A70 | |
Number of page(s) | 7 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/201936378 | |
Published online | 02 December 2019 |
Thermal evolution of Uranus and Neptune
I. Adiabatic models
1
Institut für Physik, Universität Rostock,
A.-Einstein-Str. 23,
18059 Rostock,
Germany
e-mail: ludwig.scheibe@uni-rostock.de
2
Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt,
Rutherfordstraße 2,
12489 Berlin,
Germany
Received:
25
July
2019
Accepted:
22
October
2019
The brightness of Neptune is often found to be in accordance with an adiabatic interior, while the low luminosity of Uranus challenges this assumption. Here we apply revised equation of state data of hydrogen, helium, and water and compute the thermal evolution of Uranus and Neptune assuming an adiabatic interior. For this purpose, we have developed a new planetary model and evolution code. We investigate the influence of albedo, solar energy influx, and equations of state of H and He, and water on the cooling time. Our cooling times of about τU = 5.1 × 109 yr for Uranus and τN = 3.7 × 109 yr for Neptune bracket the known age of the planets of 4.56 × 109 yr implying that neither planet’s present-day luminosity can be explained by adiabatic cooling. We also find that uncertainties on input parameters such as the level of irradiation matter generally more for Uranus than for Neptune. Our results suggest that in contrast to common assumptions, neither planet is fully adiabatic in the deeper interior.
Key words: planets and satellites: physical evolution / planets and satellites: interiors / planets and satellites: individual: Uranus / planets and satellites: individual: Neptune
© ESO 2019
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