M5 (NGC5904) UBVRI photometry

Comparing modified stellar evolution sequences with observations provides some of the most restrictive limits on axions and other hypothetical low-mass particles and on non-standard neutrino properties. In particular, a putative neutrino magnetic dipole moment {mu}_{nu}_ enhances the plasmon decay process, postpones helium ignition in low-mass stars, and therefore extends the red-giant branch (RGB) in globular clusters (GCs).

The brightness of the tip of the RGB (TRGB) remains the most sensitive probe for {mu}_{nu}_ and we revisit this argument from a modern perspective. Based on a large set of archival observations, we provide high-precision photometry for the Galactic GC M5 (NGC 5904) and carefully determine its TRGB position.