Weak-field limit of f(R) gravity to unify peculiar white dwarfs

Cooling process of substellar objects in scalar-tensor gravity

“…Moreover, the considered EoS suits well when a mixture of degenerate Fermi gas with hydrogen's and helium's ions must be considered which is the case of the brown dwarfs' interiors. This allowed us not only to derived the master equations describing the inner structure of those objects, but also to find the photospheric quantities which are crucial for modelling cooling processes, (33), (34), and (35), being dependent on the varying electron degeneracy (41).…”

“…Similarly like other modified theories of gravity, the Poisson and hydrostatic equilibrium equations in such theories acquire additional terms (see [21][22][23]; for review, [24][25][26]). Because of that, there have been a few studies undertaken which demonstrated that the Chandrasekhar mass for white dwarf stars [27][28][29][30][31][32][33][34] may differ in modified gravity; the same happens with the minimum masses for hydrogen and deuterium burning [35][36][37][38][39], as well as Jeans and opacity masses [40,41]. Apart from those, the evolutionary pictures of stars and planets are also distinct with respect to Newtonian gravity [42][43][44][45][46][47][48].…”

Giant planet formation in Palatini gravity

“…The fact that modified gravity introduces additional terms to the Poisson and hydrostatic equilibrium equations (see [26][27][28]); for review, [16,29], which are used to describe stellar and substellar bodies, provides that our understanding of the astrophysical objects and their evolution can slightly differ when compared to the results given by Newtonian gravity. The best known examples are altered limiting masses, such as the Chandrasekhar mass for white dwarf stars [30][31][32][33][34][35][36][37], the minimum Main Sequence mass [38][39][40][41], minimum mass for deuterium burning [42], or Jeans [43] and opacity mass [44]. Moreover, the most prominent feature of those modifications are related to the evolution and age of the nonrelativistic stars and planets: the stellar early and post-Main Sequence evolution [45][46][47][48] or cooling processes of brown dwarfs [49] and gaseous planets [44].…”

Fermi gas and modified gravity

“…So far, a few such tests have been proposed with the use of stellar and substellar objects [25][26][27] (for review, see [28]). The most common are altered limited masses, for example, the Chandrasekhar mass of white dwarfs [29][30][31][32][33][34][35][36], the minimum Main Sequence mass [37][38][39][40][41], Jeans [42] and opacity mass [43], or minimum mass for deuterium burning [44]. Modified gravity can also alter the light elements' abundances in stellar atmospheres [45].…”