English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

A variation of the gravitational constant over cosmological ages modifies themain sequence lifetimes and white dwarf cooling ages. Using an state-of-the-artstellar evolutionary code we compute the effects of a secularly varying G onthe main sequence ages and, employing white dwarf cooling ages computed takinginto account the effects of a running G, we place constraints on the rate ofvariation of Newton's constant. This is done using the white dwarf luminosityfunction and the distance of the well studied open Galactic cluster NGC 6791.We derive an upper bound G'/G ~ -1.8 10^{-12} 1/yr. This upper limit for thesecular variation of the gravitational constant compares favorably with thoseobtained using other stellar evolutionary properties, and can be easilyimproved if deep images of the cluster allow to obtain an improved white dwarfluminosity function.

An upper limit to the secular variation of the gravitational constant from white dwarf stars