Very high-density planets: a possible remnant of gas giants
- Research areas:
- Year:
- 2014
- Authors:
- Journal:
- PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
- Volume:
- 372
- Number:
- 2014
- Month:
- APR 28
- ISSN:
- 1364-503X
- BibTex:
- Abstract:
- Data extracted from the Extrasolar Planets Encyclopaedia (see
http://exoplanet.eu) show the existence of planets that are more massive
than iron cores that would have the same size. After meticulous
verification of the data, we conclude that the mass of the smallest of
these planets is actually not known. However, the three largest planets,
Kepler-52b, Kepler-52c and Kepler-57b, which are between 30 and 100
times the mass of the Earth, have indeed density larger than an iron
planet of the same size. This observation triggers this study that
investigates under which conditions these planets could represent the
naked cores of gas giants that would have lost their atmospheres during
their migration towards the star. This study shows that for moderate
viscosity values (10(25) Pa s or lower), large values of escape rate and
associated unloading stress rate during the atmospheric loss process
lead to the explosion of extremely massive planets. However, for
moderate escape rate, the bulk viscosity and finite-strain
incompressibility of the cores of giant planets can be large enough to
retain a very high density during geological time scales. This would
make those a new kind of planet, which would help in understanding the
interior structure of the gas giants. However, this new family of
exoplanets adds some degeneracy for characterizing terrestrial
exoplanets.
