Crystallized white dwarf stars in scalar-tensor gravity

We study the effects of massive scalar-tensor theories on the internal properties, crystallization, and cooling process of white dwarf stars that might potentially solve observational tensions. We show that these modified gravity theories alter the inner structure of the star leading to sub-Chandrasekhar mass white dwarfs. This further results in a modification of Debye temperature, ion and electron specific heats. Finally, we find that the cooling process is significantly shortened in scalar-tensor theories leading to reduced cooling ages.