Constraints on the dipole magnetic moment of neutrinos are reexamined. The most stringent bound derived from the stellar cooling of helium stars in open clusters is ${\mu }_{\nu }$<1.1×${10}^{\mathrm{-}11}$${\mu }_B$, which is a factor 3 smaller than that required to account for the solar-neutrino problem.

• Received 22 June 1987

DOI:https://doi.org/10.1103/PhysRevD.36.3817