The evolution of white dwarfs with a varying gravitational constant

L. G. ALTHAUS; A. H. CÓRSICO; S. TORRES; P. LORÉN-AGUILAR; J. ISERN; E. GARCÍA-BERRO

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Les Ulis; Año: 2011 vol. 527 p. 72 - 76

0004-6361

Context. Within the theoretical framework of some modern unification theories the constants of nature are functions of cosmological time. White dwarfs offer the possibility of testing a possible variation of G and, thus, to place constraints on these theories. Aims: We present full white dwarf evolutionary calculations for a scenario where G decreases with time. Methods: White dwarf evolution is computed in a self-consistent way, including the most up-to-date physical inputs, non-gray model atmospheres and a detailed core chemical composition that results from the calculation of the full evolution of progenitor stars. Results: We find that the mechanical structure and the energy balance of white dwarfs are strongly modified by a varying G. In particular, for a rate of change of G higher than Ġ/G = -1 × 10-12 yr-1, the evolution of cool white dwarfs is markedly affected. The impact of a varying G is more pronounced for more massive white dwarfs. Conclusions: In view of the recent results reporting that a very accurate white dwarf cooling age can be derived for the old and metal-rich open cluster NGC 6791, our study suggests that this cluster could be a potential target to constrain or detect a hypothetical secular variation of G.