Jupiter and jovian exoplanets in Palatini $f(\overline{R})$ gravity

Some parts of the substellar evolution, such as fragmentation of a gaseous cloud and a Jupiter-like planet’s cooling, are demonstrated to be impacted by Palatini $f(\overline{R})$ gravity. Using simple models describing those processes we show that the opacity mass limit as well as cooling time of jovian planets differ in modified gravity.

Figure 1

The function (48) representing the behavior of dimensionless pressure $y$ with respect to the dimensionless radius $x$ for three different values of the parameter $\alpha$, which are in agreement with the constraints given in [39]. $\alpha =0$ corresponds to the GR/Newtonian case.

Figure 2

The Hertzsprung-Russell diagram for a jovian planet at the 5 AU distance from its parent star for a few values of the parameter $\alpha$. Each curve represents an evolution of a Jupiter-mass planet, starting from the radius $R=\sim {10}^{10}$ to the radius $R=\sim {10}^8$.