Abstract
Existence of an intrinsic magnetic field is one of the most important key factors for terrestrial planets to be habitable. Strong and stable magnetic field is formed by dynamo action which requires a vigorous convection within molten metallic core, and the vigorous convection within molten metallic core is driven when the mantle transports the heat from core to surface effectively. In this sense, whether a planet is habitable or not depends on its thermal evolution.
In this study, we constructed a new numerical model on the thermal evolution of terrestrial planets to investigate the duration of intrinsic magnetic field as a function of the planet's size. According to our numerical results, the planet can have its magnetic field for more than 2 billion years if its mass is less than 1.4 Earth-mass.
